PetroChina Changqing Oilfield Company(hereinafter referred to as Changqing Oilfield)built the largest oil and gas production base of China in the Ordos Basin in 2013,achieving the yearly natural gas production of 375&...PetroChina Changqing Oilfield Company(hereinafter referred to as Changqing Oilfield)built the largest oil and gas production base of China in the Ordos Basin in 2013,achieving the yearly natural gas production of 375×10^(8) m^(3) in 2015.For the further sustainable and stable production and quality and benefit improvement,such great achievements made in the 12th Five-Year Plan were first summarized,and the relevant favorable conditions for natural gas development were also analyzed as follows:abundant natural gas resources;increasingly mature E&P technologies;continuously improved delicacy management;and a surging demand for natural gas.Then,challenges to natural gas development were also discussed,including obvious deterioration of natural gas resources;diminished capacity of stable production of produced gasfields;increasing number of low-yield wells;and prominent supplyedemand contradiction in present natural gas market.Finally,its prospect in the 13th Five-Year Plan was studied:to carry out natural gas exploration with focus on Upper Paleozoic tight gas,Lower Paleozoic carbonate rocks,and new areas and new domains,so as to achieve rapid growth of natural gas reserves and orderly replacement in exploration domains;to make rational development planning with focus on the stable production of mature gasfields;and to enhance tight gas recovery and strengthen capacity building in new areas,so as to achieve a steady rise of annual gas production in the giant gas province.It is expected that by the end of 13th Five-Year Plan period,Changqing Oilfield will achieve its annual gas production of up to 400×10^(8) m^(3).展开更多
It is difficult to build an effective water flooding displacement pressure system in the middle section of a horizontal well in an ultra-low permeability sandstone reservoir.To solve this problem,this study proposes t...It is difficult to build an effective water flooding displacement pressure system in the middle section of a horizontal well in an ultra-low permeability sandstone reservoir.To solve this problem,this study proposes to use packers,sealing cannula and other tools in the same horizontal well to inject water in some fractures and produce oil from other fractures.This new energy supplement method forms a segmental synchronous injection-production system in a horizontal well.The method can reduce the distance between the injection end and the production end,and quickly establish an effective displacement system.Changing the displacement between wells to displacement between horizontal well sections,and point water flooding to linear uniform water flooding,the method can enhance water sweeping volume and shorten waterflooding response period.The research shows that:(1)In the synchronous injection and production of horizontal well in an ultra-low-permeability sandstone reservoir,the water injection section should select the section where the natural fractures and artificial fractures are in the same direction or the section with no natural fractures,and the space between two sections should be 60?80 m.(2)In addition to controlling injection pressure,periodic water injection can be taken to reduce the risk of re-opening and growth of natural fractures or formation fracture caused by the gradual increase of water injection pressure with water injection going on.(3)Field tests have verified that this method can effectively improve the output of single well and achieve good economic benefits,so it can be widely used in the development of ultra-low permeability sandstone reservoirs.展开更多
The development course of Changqing Oilfield is a history of struggles for scientific and technological innovation.Generations of oilmen at Changqing Oilfield regard scientific and technological innovation as the firs...The development course of Changqing Oilfield is a history of struggles for scientific and technological innovation.Generations of oilmen at Changqing Oilfield regard scientific and technological innovation as the first driving force of development.They dare to forge a revolution at the grindstone and constantly challenge the low permeability limit.They have promoted continuous breakthroughs in exploration and development,and achieved the large-scale and profitable development of unconventional oil and gas such as ultra-low permeability reservoirs,shale oil and tight gas.Changqing Oilfield has become the fastest growing oil and gas region in China in terms of its increase in reserves and production,and it will achieve 60 million tons of oil and gas equivalent by the end of 2020,becoming the first large oilfield in China with an annual output exceeding 60 million tons.展开更多
To address the discrepancies between well and seismic data in stratigraphic correlation of the Triassic Yanchang Formation in the Ordos Basin,NW China,traditional stratigraphic classification schemes,the latest 3D sei...To address the discrepancies between well and seismic data in stratigraphic correlation of the Triassic Yanchang Formation in the Ordos Basin,NW China,traditional stratigraphic classification schemes,the latest 3D seismic and drilling data,and reservoir sections are thoroughly investigated.Guided by the theory of sequence stratigraphy,the progradational sequence stratigraphic framework of the Yanchang Formation is systematically constructed to elucidate new deposition mechanisms in the depressed lacustrine basin,and it has been successfully applied to the exploration and development practices in the Qingcheng Oilfield.Key findings are obtained in three aspects.First,the seismic progradational reflections,marker tuff beds,and condensed sections of flooding surfaces in the Yanchang Formation are consistent and isochronous.Using flooding surface markers as a reference,a progradational sequence stratigraphic architecture is reconstructed for the middle-upper part of Yanchang Formation,and divided into seven clinoform units(CF1-CF7).Second,progradation predominantly occurs in semi-deep to deep lake environments,with the depositional center not always coinciding with the thickest strata.The lacustrine basin underwent an evolution of“oscillatory regression-progradational infilling-multi-phase superimposition”.Third,the case study of Qingcheng Oilfield reveals that the major pay zones consist of“isochronous but heterochronous”gravity-flow sandstone complexes.Guided by the progradational sequence stratigraphic architecture,horizontal well oil-layer penetration rates remain above 82%.The progradational sequence stratigraphic architecture and associated geological insights are more consistent with the sedimentary infilling mechanisms of large-scale continental depressed lacustrine basins and actual drilling results.The research results provide crucial theoretical and technical support for subsequent refined exploration and development of the Yanchang Formation,and are expected to offer a reference for research and production practice in similar continental lacustrine basins.展开更多
A flexible sidetracking stimulation technology of horizontal wells is formed to develop the lateral deep remaining oil and gas resources of the low-permeability mature oilfields.This technology first uses the flexible...A flexible sidetracking stimulation technology of horizontal wells is formed to develop the lateral deep remaining oil and gas resources of the low-permeability mature oilfields.This technology first uses the flexible sidetracking tool to achieve low-cost sidetracking in the old wellbore,and then uses the hydraulic jet technology to induce multiple fractures to fracture.Finally,the bullhead fracturing of multi-cluster temporary plugging for the sidetracking hole is carried out by running the tubing string,to realize the efficient development of the remaining reserves among the wells.The flexible sidetracking stimulation technology involves flexible sidetracking horizontal wells drilling and sidetracking horizontal well fracturing.The flexible sidetracking horizontal well drilling includes three aspects:flexible drill pipe structure and material optimization,drilling technology,and sealed coring tool.The sidetracking horizontal well fracturing includes two aspects:fracturing scheme optimization,fracturing tools and implementation process optimization.The technology has been conducted several rounds of field tests in the Ansai Oilfield of Changqing,China.The results show that by changing well type and reducing row spacing of oil and water wells,the pressure displacement system can be well established to achieve effective pressure transmission and to achieve the purpose of increasing liquid production in low-yield and low-efficiency wells.It is verified that the flexible sidetracking stimulation technology can provide favorable support for accurately developing remaining reserves in low-permeability reservoirs.展开更多
At present,natural gas accounts for a low proportion in China's primary energy consumption structure and is highly dependent on foreign sources.Changqing gas province of the Ordos Basin where PetroChina Changqing ...At present,natural gas accounts for a low proportion in China's primary energy consumption structure and is highly dependent on foreign sources.Changqing gas province of the Ordos Basin where PetroChina Changqing Oilfield Company(referred to as Changqing Oilfield)is located is one of China's four major natural gas production bases.It bears the important responsibility for ensuring people's livelihood and promoting the healthy development of society economy.In recent years,Changqing Oilfield actively implements national instructive spirit on vigorously promoting domestic oil and gas exploration and development strength and formulates the secondary acceleration development strategies.Its annual natural gas production in 2020 reaches 448.5×10^(8) m^(3) and oil and gas equivalent exceeds 6000×10^(4) t,tamping its important position of“Western Daqing”in this industry.In order to further promote the continuous stable production and realize the goal of quality and efficiency improvement in Changqing gas province,this paper analyzes the situations and challenges of natural gas development in this gas province,prepares the development technological countermeasures and forecast the natural gas development prospect.And the following research results are obtained.First,the natural gas exploration and development in Changqing gas province is divided into four stages and the main technologies for the development of low-permeability carbonate gas reservoir,low-permeability sandstone gas reservoir and tight sandstone gas reservoir are formed.Second,the natural gas development in Changqing gas province faces six challenges,such as low reserve production degree,sharp decline of production rates and complex distribution of remaining undeveloped reserves of developed gas fields.And twenty-six development technological countermeasures are put forward correspondingly,such as well pattern thickening,extension and reserve increase,secondary production layer potential tapping and fine gas well management.Third,the development direction and goal of natural gas development in Changqing gas province is to pay equal attention to the stable production of old gas fields and the production increase of new areas and carry out conventional gas and unconventional gas research simultaneously.In conclusion,the annual natural gas production of Changqing gas province will maintain a sound momentum of steady growth and will exceed 500×10^(8) m^(3) at the end of the 14th Five-Year Plan and maintain at a stable level for a long term,which is conducive to the optimization of domestic energy consumption structure and realization of“carbon peak and carbon neutrality”.展开更多
Xin’anbian Oilfield of the Ordos Basin is the large tight oilfield to be first exploration discovery in china.The production of tight oil increased significantly in recent years.It shows great exploration potential o...Xin’anbian Oilfield of the Ordos Basin is the large tight oilfield to be first exploration discovery in china.The production of tight oil increased significantly in recent years.It shows great exploration potential of Chang 7 tight oil.But the physical property and hydrocarbon enrichment characteristics of Chang 7 tight oil reservoirs were rarely studied,The forming conditions of tight oil reservoirs are systematically summarized and analyzed through the study of hydrocarbon generation,sedimentary reservoirs and hydrocarbon migration and accumulation based on production and core experimental data.The result shows that,The porosity of the Chang 7_(2)reservoir mainly distributed in 5.0-11.0%,average at 7.9%,The permeability mainly distributed in 0.04-0.18×10^(-3)μm^(2),average at 0.12×10^(-3)μm^(2),The pore diameters of the tight oil reservoir distributed in 2-8μm.The high-quality Chang 7_(3)source rocks and the micropsammite of Chang 7_(2)subaqueous distributary channel were widely distributed in the study area.The lenticular or banded sand bodies are distributed among mudstone or hydrocarbon source rocks and have the advantage of migration distance for hydrocarbon accumulation.The reservoir space is composed of micro-nanometer pores and throat,that is formed in the process of increasing pressure during hydrocarbon generation and hydrocarbon accumulation.The Chang 7 tight oil was generated in the early Cretaceous and injected into the sand of the subaqueous distributary channel driven by continuous hydrocarbon generation supercharging.The formation and accumulation of tight oil reservoirs are mainly controlled by source rocks,sedimentary microfacies and reservoirs of good quality.展开更多
The reservoirs in the seventh member of the Triassic Yanchang Formation (Chang 7 Member) in the Qingcheng Oilfield of the Ordos Basin are characterized by thin sandbody, tight rocks, high heterogeneity, low formation ...The reservoirs in the seventh member of the Triassic Yanchang Formation (Chang 7 Member) in the Qingcheng Oilfield of the Ordos Basin are characterized by thin sandbody, tight rocks, high heterogeneity, low formation pressure coefficient, and complex geomorphology. Through the efforts in the stages of exploration, appraisal, pilot testing and development, a series of key technologies have been formed, including “sweet spot” optimization, differentiated three-dimensional well deployment, fast drilling and completion of large-cluster horizontal well, intensively-staged volume fracturing in long horizontal well, and optimization of rational production system. Furthermore, a production organization mode represented by factory-like operations on loess platform has been implemented. Application of these technologies has enabled to significantly improve the single-well production of the Qingcheng Oilfield, reduce the investment cost, and realize a large-scale and beneficial development at a full cost below $55 per barrel. In 2022, the annual production of Chang 7 shale oil in the Ordos Basin reached 221×10^(4) t, accounting for 70% of the annual shale oil production of China. The practice of development technologies in the Qingcheng Oilfield provides valuable references for efficient development of continental shale oil.展开更多
By December 19 2009, annual output of Changqing Oilfield located in western China surpassed 30 million tons oil equivalent, only second to Daqing Oilfield. Changqing Oilfield has the most late-development advantage in...By December 19 2009, annual output of Changqing Oilfield located in western China surpassed 30 million tons oil equivalent, only second to Daqing Oilfield. Changqing Oilfield has the most late-development advantage in oil and gas growth and it has become China's important strategic energy replacement area and the hub of onshore natural gas network. So it is irreplaceable in ensuring national energy security and developing the western region. After 40 years of hard work, Changqing Oilfield Company has tackled the world-class problem of "low-permeability" oil and gas field development. The cumulative crude oil output in the oilfield totaled 134 million tons and the cumulative natural gas output totaled 84.066 billion cubic meters. Even in 2009 when the financial crisis spread throughout the world, the company has made historic breakthroughs in the growth of oil and gas reserves and production. It made new contributions to ensure national energy security, optimize energy structure and promote rapid development of national economy.展开更多
A promising method is to use coring of high-inclination well to find ancient flow direction and orient tiny natural fractures in massive sandstone of sandy debris flow. Determination of ancient flow direction can redu...A promising method is to use coring of high-inclination well to find ancient flow direction and orient tiny natural fractures in massive sandstone of sandy debris flow. Determination of ancient flow direction can reduce the number of exploration wells, and orientation of natural fractures is of guiding significance to the deployment of water injection development well pattern. In Block X of Huaqing Oilfield, Ordos Basin, the cores of Chang 6<sub>3</sub> section were obtained from Well Y through 16 coring operations, with a total length of 105 m. Cores is oriented through drilling parameters, the number of cores, the angle between the core edge and horizontal bedding, the coincidence degree of core profile and directional flame structure. Therefore, the micro-fractures on the core are directional. The ancient flow directions of sandy debris flow were restored by load casting, groove casting, groove casting and imbricate structure. Our results show that the ancient flow directions of sandy debris flows were southwest, southeast, northwest, and west from bottom to top. The front of the Wuqi Delta is the main source of blocky sandstone with the best oil-bearing property. Affected by the topography of the lake bottom, the sandy debris flow turned locally in the northeast direction, and the sandy debris flow from this direction was formed. The NEE-SWW-trending fractures formed in the Yanshanian period are most developed in the Huaqing area, which should be considered in deploying the flooding well network. The north-south micro-fractures formed in the Himalayan period can improve the physical properties of tight sandstone, which is of great significance for tight sandstone reservoirs.展开更多
Wu Chunsheng is a senior engineer of oil and gas field development,and the deputy director of the Oil Production Technology Research Institute of the No.10 Oil Production Plant of PetroChina Changqing Oilfield Company...Wu Chunsheng is a senior engineer of oil and gas field development,and the deputy director of the Oil Production Technology Research Institute of the No.10 Oil Production Plant of PetroChina Changqing Oilfield Company.He has devoted himself to working in the field of oilfield development technology since the very beginning of his career.During the period of"Building a Western Daqing Oilfield"and the"Second Round of Development Acceleration"in Changqing Oilfield,he worked hard and studied diligently,and took the initiative to take on responsibilities while focused on practical work,growing into an outstanding young technical cadre step by step.His achievements in the research,application,promotion of new techniques and technologies,and the application of scientific research results proved extraordinary.展开更多
Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,a...Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,and reservoir characteristics of shale oil of fine-grained sediment deposition in continental freshwater lacustrine basins,with a focus on the Chang 7_(3) sub-member of Triassic Yanchang Formation.The research integrates a variety of exploration data,including field outcrops,drilling,logging,core samples,geochemical analyses,and flume simulation.The study indicates that:(1)The paleoenvironment of the Chang 7_(3) deposition is characterized by a warm and humid climate,frequent monsoon events,and a large water depth of freshwater lacustrine basin.The paleogeomorphology exhibits an asymmetrical pattern,with steep slopes in the southwest and gentle slopes in the northeast,which can be subdivided into microgeomorphological units,including depressions and ridges in lakebed,as well as ancient channels.(2)The Chang 7_(3) sub-member is characterized by a diverse array of fine-grained sediments,including very fine sandstone,siltstone,mudstone and tuff.These sediments are primarily distributed in thin interbedded and laminated arrangements vertically.The overall grain size of the sandstone predominantly falls below 62.5μm,with individual layer thicknesses of 0.05–0.64 m.The deposits contain intact plant fragments and display various sedimentary structure,such as wavy bedding,inverse-to-normal grading sequence,and climbing ripple bedding,which indicating a depositional origin associated with density flows.(3)Flume simulation experiments have successfully replicated the transport processes and sedimentary characteristics associated with density flows.The initial phase is characterized by a density-velocity differential,resulting in a thicker,coarser sediment layer at the flow front,while the upper layers are thinner and finer in grain size.During the mid-phase,sliding water effects cause the fluid front to rise and facilitate rapid forward transport.This process generates multiple“new fronts”,enabling the long-distance transport of fine-grained sandstones,such as siltstone and argillaceous siltstone,into the center of the lake basin.(4)A sedimentary model primarily controlled by hyperpynal flows was established for the southwestern part of the basin,highlighting that the frequent occurrence of flood events and the steep slope topography in this area are primary controlling factors for the development of hyperpynal flows.(5)Sandstone and mudstone in the Chang 7_(3) sub-member exhibit micro-and nano-scale pore-throat systems,shale oil is present in various lithologies,while the content of movable oil varies considerably,with sandstone exhibiting the highest content of movable oil.(6)The fine-grained sediment complexes formed by multiple episodes of sandstones and mudstones associated with density flow in the Chang 7_(3) formation exhibit characteristics of“overall oil-bearing with differential storage capacity”.The combination of mudstone with low total organic carbon content(TOC)and siltstone is identified as the most favorable exploration target at present.展开更多
The lamina(combination)types,reservoir characteristics and shale oil occurrence states of organic-rich shale in the Triassic Yanchang Formation Chang 73 sub-member in the Ordos Basin were systematically investigated t...The lamina(combination)types,reservoir characteristics and shale oil occurrence states of organic-rich shale in the Triassic Yanchang Formation Chang 73 sub-member in the Ordos Basin were systematically investigated to reveal the main controlling factors of shale oil occurrence under different lamina combinations.The differential enrichment mechanisms and patterns of shale oil were discussed using the shale oil micro-migration characterization and evaluation methods from the perspectives of relay hydrocarbon supply,stepwise migration,and multi-stage differentiation.The results are obtained in five aspects.First,Chang 73 shale mainly develops five types of lamina combination,i.e.non-laminated shale,sandy laminated shale,tuffaceous laminated shale,mixed laminated shale,and organic-rich laminated shale.Second,shales with different lamina combinations are obviously different in the reservoir space.Specifically,shales with sandy laminae and tuffaceous laminae have a large number of intergranular pores,dissolution pores and hydrocarbon generation-induced fractures.The multi-scale pore and fracture system constitutes the main place for liquid hydrocarbon occurrence.Third,the occurrence and distribution of shale oil in shale with different lamina combinations are jointly controlled by organic matter abundance,reservoir property,thermal evolution degree,mineral composition and laminae scale.The micro-nano-scale pore-fracture networks within shales containing rigid laminae,particularly sandy and tuffaceous laminations,primarily contain free-state light hydrocarbon components.In contrast,adsorption-phase heavy hydrocarbon components predominantly occupy surfaces of organic matter assemblages,clay mineral matrices,and framework mineral particulates.Fourth,there is obvious shale oil micro-migration between shales with different lamina combinations in Chang 73.Generally,such micro-migration is stepwise in a sequence of organic-rich laminated shale→tuffaceous laminated shale→mixed laminated shale→sandy lamiated shale→non-laminated shale.Fifth,the relay hydrocarbon supply of organic matter under the control of the spatial superposition of shales with various laminae,the stepwise migration via multi-scale pore and fracture network,and the multi-differentiation in shales with different lamina combinations under the control of organic-inorganic interactions fundamentally decide the differences of shale oil components between shales with different lamina combinations.展开更多
Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores s...Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores systematically the boundary,distribution,geological structure,and tectonic attributes of the Ordos prototype basin in the geological historical periods.The results show that the Ordos block is bounded to the west by the Engorwusu Fault Zone,to the east by the Taihangshan Mountain Piedmont Fault Zone,to the north by the Solonker-Xilamuron Suture Zone,and to the south by the Shangnan-Danfeng Suture Zone.The Ordos Basin boundary was the plate tectonic boundary during the Middle Proterozoic to Paleozoic,and the intra-continental deformation boundary in the Meso-Cenozoic.The basin survived as a marine cratonic basin covering the entire Ordos block during the Middle Proterozoic to Ordovician,a marine-continental transitional depression basin enclosed by an island arc uplift belt at the plate margin during the Carboniferous to Permian,a unified intra-continental lacustrine depression basin in the Triassic,and an intra-continental cratonic basin circled by a rift system in the Cenozoic.The basin scope has been decreasing till the present.The large,widespread prototype basin controlled the exploration area far beyond the present-day sedimentary basin boundary,with multiple target plays vertically.The Ordos Basin has the characteristics of a whole petroleum(or deposition)system.The Middle Proterozoic wide-rift system as a typical basin under the overlying Phanerozoic basin and the Cambrian-Ordovician passive margin basin and intra-cratonic depression in the deep-sited basin will be the important successions for oil and gas exploration in the coming years.展开更多
In addition to the organic matter type,abundance,thermal maturity,and shale reservoir space,the preservation conditions of source rocks play a key factor in affecting the quantity and quality of retained hydrocarbons ...In addition to the organic matter type,abundance,thermal maturity,and shale reservoir space,the preservation conditions of source rocks play a key factor in affecting the quantity and quality of retained hydrocarbons in source rocks of lacustrine shale,yet this aspect has received little attention.This paper,based on the case analysis,explores how preservation conditions influence the enrichment of mobile hydrocarbons in shale oil.Research showns that good preservation conditions play three key roles.(1)Ensure the retention of sufficient light hydrocarbons(C_(1)–C_(13)),medium hydrocarbons(C_(14)–C_(25))and small molecular aromatics(including 1–2 benzene rings)in the formation,which enhances the fluidity and flow of shale oil;(2)Maintain a high energy field(abnormally high pressure),thus facilitating the maximum outflow of shale oil;(3)Ensure that the retained hydrocarbons have the miscible flow condition of multi-component hydrocarbons(light hydrocarbons,medium hydrocarbons,heavy hydrocarbons,and heteroatomic compounds),so that the heavy hydrocarbons(C_(25+))and heavy components(non-hydrocarbons and asphaltenes)have improved fluidity and maximum flow capacity.In conclusion,in addition to the advantages of organic matter type,abundance,thermal maturity,and reservoir space,good preservation conditions of shale layers are essential for the formation of economically viable shale oil reservoirs,which should be incorporated into the evaluation criteria of shale oil-rich areas/segments and considered a necessary factor when selecting favorable exploration targets.展开更多
Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic re...Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic resin and n-octanol were used to synthesize the main agent SCA-2.Hexamethylenetetramine and vinyl carbonate were selected to prepare the curing agent YGA-1,which was then compounded with SCA-2 to develop a sand fixation and water plugging system.Firstly,single-factor experiments were conducted to determine the optimal concentrations of SCA-2 and YGA-1,subsequently,the system’s sand fixation and water blocking performance were evaluated.Finally,a pilot test was carried out in the mining site.Experimental results showed that the optimal formula composition of the system was 10%SCA-2+5%YGA-1.The gelation time of the system was 180 minutes and the viscosity after gelation could reach 108.4 mPa·s.When the dosage of the drug system was 0.6 PV,the sand production rate remained below 0.08%.Dual-tube parallel experiments showed that the sand fixation and water plugging system had a water flow channel plugging rate of 87.5%,while the oil flow channel plugging rate was only 11.3%,indicating minimal damage to the oil-bearing reservoir.The field test showed that after the measures taken in Well M of X oilfield,the sand free oil recovery period exceeded 360 days,the water content decreased by 5.0%and the cumulative oil production increased by 7092 m^(3).This study provides new ideas for efficient development of loose sandstone reservoirs.展开更多
As industrialization and informatization in China deeply integrate and the Internet of Things rapidly develops,industrial control systems are facing increasingly severe information security challenges.The industrial c...As industrialization and informatization in China deeply integrate and the Internet of Things rapidly develops,industrial control systems are facing increasingly severe information security challenges.The industrial control system of the gas extraction plant is characterized by numerous points and centralized operations,with a strong reliance on the system and stringent real-time requirements.展开更多
By summarizing the characteristics of the global energy structure and China’s energy resource endowment, this study analyzes the historical context and opportunities for China to build an “energy powerhouse”, and p...By summarizing the characteristics of the global energy structure and China’s energy resource endowment, this study analyzes the historical context and opportunities for China to build an “energy powerhouse”, and proposes pathways and measures for its realization. It is indicated that the energy resource endowment in China is characterized by abundant coal, limited oil and gas, and vast renewable potential, coupled with an energy consumption structure characterized by high coal consumption, low oil and gas consumption, and rapidly growing renewable energy use. The “whole-energy system” approach that integrates multi-energy complementarity, green development, stable supply, smart utilization and carbon neutrality is an effective solution to addressing energy transition and energy independence. To build an “energy powerhouse”, China can follow the approach of the steady and orderly low-carbon development of fossil fuels, the safe and scaled development of new energy, the integrated development of a carbon-neutral “whole-energy system”, and the shared development of the “Belt and Road” energy corridor. The construction of an “energy powerhouse” should follow a “three-phase” strategic pathway: from 2025 to 2030, achieving peak primary energy consumption and “carbon peaking”;from 2031 to 2050, energy production will achieve parity with consumption for the first time, striving for “energy independence”;and from 2051 to 2060, aiming for “carbon neutrality”, and establishing an “energy powerhouse”. Building an “energy powerhouse” will fundamentally safeguard national energy security, advance the achievement of carbon neutrality goals, provide Chinese solutions for global energy transition and green Earth construction, and support the modernization and great rejuvenation of the Chinese nation.展开更多
In recent years,fueled by significant advancements in oil exploration technologies within the Ordos Basin,an increasing number of low-permeability or ultra-low-permeability reservoirs have been identified.Elucidating ...In recent years,fueled by significant advancements in oil exploration technologies within the Ordos Basin,an increasing number of low-permeability or ultra-low-permeability reservoirs have been identified.Elucidating their reservoir characteristics and formation mechanisms has become a critical priority for sustainable hydrocarbon development.The study focused on the Chang 6 Member of the Upper Triassic Yanchang Formation in the Heshui area of the Ordos Basin,systematically investigating its petrological features,porosity and permeability characteristics,diagenesis,and diagenetic evolution sequence.By integrating core observation,thin-section identification,and physical property measurements,a comprehensive quantitative evaluation of reservoir pore evolution was performed.These analytical outcomes were subsequently applied to simulate hydrocarbon migration and accumulation.These research results will provide a scientific basis for in-depth quantitative study of the pore evolution in ultra-low-permeability oil reservoirs and accurately constructing basin models.As indicated,the reservoir lithology in the study area predominantly comprises siltstone interbedded with mudstone or argillaceous siltstone,characterized by low porosity and permeability.Through diagenetic characteristics-based reconstruction constrained by the existing porosity data,pore evolution during diagenesis was quantitatively modeled.The simulated pore evolution aligns with actual geological observations,validating the reliability of the methodology.Furthermore,the quantified pore evolution results were applied to simulate hydrocarbon migration using PetroMod software,showing that hydrocarbon charging in the basin began at the end of the Late Jurassic(J3),peaking in hydrocarbon generation,expulsion,and accumulation by the end of the Early Cretaceous(K1)and maintaining high accumulation rates until the late Cretaceous,though significantly decreasing at the present stage.The simulation results were verified by comparison with actual drilling data,which confirms their reliability and applicability to other analogous oilfields.展开更多
To clarify the mechanism of differential enrichment of intrasource shale oil,taking the third of seventh member of the Triassic Yanchang Formation(Chang 7_(3)submember for short)in the Ordos Basin,NW China as an examp...To clarify the mechanism of differential enrichment of intrasource shale oil,taking the third of seventh member of the Triassic Yanchang Formation(Chang 7_(3)submember for short)in the Ordos Basin,NW China as an example,we integrated high-resolution scanning electron microscopy(SEM),optical microscopy,laser Raman spectroscopy,rock pyrolysis,and organic solvent extraction experiments to identify solid bitumen of varying origins,obtain direct evidence of intrasource micro-migration of shale oil,and establish the coupling between the shale nano/micro-fabric and the oil generation,migration and accumulation.The Chang 7_(3)shale with rich alginite in laminae has the highest hydrocarbon generation potential but a low thermal transformation ratio.Frequent alternations of micron-scale argillaceous-felsic laminae enhance the hydrocarbon expulsion efficiency,yielding consistent aromaticity between in-situ and migrated solid bitumen.Mudstone laminae rich in terrestrial organic matter(OM)and clay minerals exhibit lower hydrocarbon generation threshold but stronger hydrocarbon retention capacity,with a certain amount of light oil/bitumen preserved to differentiate the chemical structure of in-situ versus migrated bitumen.Tuffaceous and sandy laminae contain abundant felsic minerals and migrated bitumen.Tuffaceous laminae develop high-angle microfractures under shale overpressure,facilitating oil charging into rigid mineral intergranular pores of sandy laminae.Fractionation during micro-migration progressively decreases the aromatization of solid bitumen from shale,through tuffaceous and mudstone,to sandy laminae,while increasing light hydrocarbon components and enhancing OM-hosted pore development.The intrasource micro-migration and enrichment of the Chang 7_(3)shale oil result from synergistic organic-inorganic diagenesis,with crude oil component fractionation being a key mechanism for forming sweet spots in laminated shale oil reservoirs.展开更多
文摘PetroChina Changqing Oilfield Company(hereinafter referred to as Changqing Oilfield)built the largest oil and gas production base of China in the Ordos Basin in 2013,achieving the yearly natural gas production of 375×10^(8) m^(3) in 2015.For the further sustainable and stable production and quality and benefit improvement,such great achievements made in the 12th Five-Year Plan were first summarized,and the relevant favorable conditions for natural gas development were also analyzed as follows:abundant natural gas resources;increasingly mature E&P technologies;continuously improved delicacy management;and a surging demand for natural gas.Then,challenges to natural gas development were also discussed,including obvious deterioration of natural gas resources;diminished capacity of stable production of produced gasfields;increasing number of low-yield wells;and prominent supplyedemand contradiction in present natural gas market.Finally,its prospect in the 13th Five-Year Plan was studied:to carry out natural gas exploration with focus on Upper Paleozoic tight gas,Lower Paleozoic carbonate rocks,and new areas and new domains,so as to achieve rapid growth of natural gas reserves and orderly replacement in exploration domains;to make rational development planning with focus on the stable production of mature gasfields;and to enhance tight gas recovery and strengthen capacity building in new areas,so as to achieve a steady rise of annual gas production in the giant gas province.It is expected that by the end of 13th Five-Year Plan period,Changqing Oilfield will achieve its annual gas production of up to 400×10^(8) m^(3).
基金Supported by the China National Science and Technology Major Project(2016ZX05050)
文摘It is difficult to build an effective water flooding displacement pressure system in the middle section of a horizontal well in an ultra-low permeability sandstone reservoir.To solve this problem,this study proposes to use packers,sealing cannula and other tools in the same horizontal well to inject water in some fractures and produce oil from other fractures.This new energy supplement method forms a segmental synchronous injection-production system in a horizontal well.The method can reduce the distance between the injection end and the production end,and quickly establish an effective displacement system.Changing the displacement between wells to displacement between horizontal well sections,and point water flooding to linear uniform water flooding,the method can enhance water sweeping volume and shorten waterflooding response period.The research shows that:(1)In the synchronous injection and production of horizontal well in an ultra-low-permeability sandstone reservoir,the water injection section should select the section where the natural fractures and artificial fractures are in the same direction or the section with no natural fractures,and the space between two sections should be 60?80 m.(2)In addition to controlling injection pressure,periodic water injection can be taken to reduce the risk of re-opening and growth of natural fractures or formation fracture caused by the gradual increase of water injection pressure with water injection going on.(3)Field tests have verified that this method can effectively improve the output of single well and achieve good economic benefits,so it can be widely used in the development of ultra-low permeability sandstone reservoirs.
文摘The development course of Changqing Oilfield is a history of struggles for scientific and technological innovation.Generations of oilmen at Changqing Oilfield regard scientific and technological innovation as the first driving force of development.They dare to forge a revolution at the grindstone and constantly challenge the low permeability limit.They have promoted continuous breakthroughs in exploration and development,and achieved the large-scale and profitable development of unconventional oil and gas such as ultra-low permeability reservoirs,shale oil and tight gas.Changqing Oilfield has become the fastest growing oil and gas region in China in terms of its increase in reserves and production,and it will achieve 60 million tons of oil and gas equivalent by the end of 2020,becoming the first large oilfield in China with an annual output exceeding 60 million tons.
基金Supported by the National Science and Technology Major Project(2017ZX05001)CNPC Technology Project(2023YQX20111).
文摘To address the discrepancies between well and seismic data in stratigraphic correlation of the Triassic Yanchang Formation in the Ordos Basin,NW China,traditional stratigraphic classification schemes,the latest 3D seismic and drilling data,and reservoir sections are thoroughly investigated.Guided by the theory of sequence stratigraphy,the progradational sequence stratigraphic framework of the Yanchang Formation is systematically constructed to elucidate new deposition mechanisms in the depressed lacustrine basin,and it has been successfully applied to the exploration and development practices in the Qingcheng Oilfield.Key findings are obtained in three aspects.First,the seismic progradational reflections,marker tuff beds,and condensed sections of flooding surfaces in the Yanchang Formation are consistent and isochronous.Using flooding surface markers as a reference,a progradational sequence stratigraphic architecture is reconstructed for the middle-upper part of Yanchang Formation,and divided into seven clinoform units(CF1-CF7).Second,progradation predominantly occurs in semi-deep to deep lake environments,with the depositional center not always coinciding with the thickest strata.The lacustrine basin underwent an evolution of“oscillatory regression-progradational infilling-multi-phase superimposition”.Third,the case study of Qingcheng Oilfield reveals that the major pay zones consist of“isochronous but heterochronous”gravity-flow sandstone complexes.Guided by the progradational sequence stratigraphic architecture,horizontal well oil-layer penetration rates remain above 82%.The progradational sequence stratigraphic architecture and associated geological insights are more consistent with the sedimentary infilling mechanisms of large-scale continental depressed lacustrine basins and actual drilling results.The research results provide crucial theoretical and technical support for subsequent refined exploration and development of the Yanchang Formation,and are expected to offer a reference for research and production practice in similar continental lacustrine basins.
基金Supported by the National Key Research and Development Program of China(2023YFF0615403)CNPC Science and Technology Project(2023ZZ0803).
文摘A flexible sidetracking stimulation technology of horizontal wells is formed to develop the lateral deep remaining oil and gas resources of the low-permeability mature oilfields.This technology first uses the flexible sidetracking tool to achieve low-cost sidetracking in the old wellbore,and then uses the hydraulic jet technology to induce multiple fractures to fracture.Finally,the bullhead fracturing of multi-cluster temporary plugging for the sidetracking hole is carried out by running the tubing string,to realize the efficient development of the remaining reserves among the wells.The flexible sidetracking stimulation technology involves flexible sidetracking horizontal wells drilling and sidetracking horizontal well fracturing.The flexible sidetracking horizontal well drilling includes three aspects:flexible drill pipe structure and material optimization,drilling technology,and sealed coring tool.The sidetracking horizontal well fracturing includes two aspects:fracturing scheme optimization,fracturing tools and implementation process optimization.The technology has been conducted several rounds of field tests in the Ansai Oilfield of Changqing,China.The results show that by changing well type and reducing row spacing of oil and water wells,the pressure displacement system can be well established to achieve effective pressure transmission and to achieve the purpose of increasing liquid production in low-yield and low-efficiency wells.It is verified that the flexible sidetracking stimulation technology can provide favorable support for accurately developing remaining reserves in low-permeability reservoirs.
基金Project supported by the National Science and Technology Major Project"Development Demonstration Engineeing of Large Low-Permability Lithologic and Stratigraphic Oil and Gas Reservoirs in the Ordos Basin"(No.2016ZX05050)the PetoChina's Science and Technology Major Project,"Study on Production Stabilization and EOR Technologics of Changqing Gas Field"(No.2016E-0509).
文摘At present,natural gas accounts for a low proportion in China's primary energy consumption structure and is highly dependent on foreign sources.Changqing gas province of the Ordos Basin where PetroChina Changqing Oilfield Company(referred to as Changqing Oilfield)is located is one of China's four major natural gas production bases.It bears the important responsibility for ensuring people's livelihood and promoting the healthy development of society economy.In recent years,Changqing Oilfield actively implements national instructive spirit on vigorously promoting domestic oil and gas exploration and development strength and formulates the secondary acceleration development strategies.Its annual natural gas production in 2020 reaches 448.5×10^(8) m^(3) and oil and gas equivalent exceeds 6000×10^(4) t,tamping its important position of“Western Daqing”in this industry.In order to further promote the continuous stable production and realize the goal of quality and efficiency improvement in Changqing gas province,this paper analyzes the situations and challenges of natural gas development in this gas province,prepares the development technological countermeasures and forecast the natural gas development prospect.And the following research results are obtained.First,the natural gas exploration and development in Changqing gas province is divided into four stages and the main technologies for the development of low-permeability carbonate gas reservoir,low-permeability sandstone gas reservoir and tight sandstone gas reservoir are formed.Second,the natural gas development in Changqing gas province faces six challenges,such as low reserve production degree,sharp decline of production rates and complex distribution of remaining undeveloped reserves of developed gas fields.And twenty-six development technological countermeasures are put forward correspondingly,such as well pattern thickening,extension and reserve increase,secondary production layer potential tapping and fine gas well management.Third,the development direction and goal of natural gas development in Changqing gas province is to pay equal attention to the stable production of old gas fields and the production increase of new areas and carry out conventional gas and unconventional gas research simultaneously.In conclusion,the annual natural gas production of Changqing gas province will maintain a sound momentum of steady growth and will exceed 500×10^(8) m^(3) at the end of the 14th Five-Year Plan and maintain at a stable level for a long term,which is conducive to the optimization of domestic energy consumption structure and realization of“carbon peak and carbon neutrality”.
基金financially supported by the Chinese National Special Plan Project"Formation conditions,enrichment regularity and resource potential of tight oil”(No.2016ZX05046-001)。
文摘Xin’anbian Oilfield of the Ordos Basin is the large tight oilfield to be first exploration discovery in china.The production of tight oil increased significantly in recent years.It shows great exploration potential of Chang 7 tight oil.But the physical property and hydrocarbon enrichment characteristics of Chang 7 tight oil reservoirs were rarely studied,The forming conditions of tight oil reservoirs are systematically summarized and analyzed through the study of hydrocarbon generation,sedimentary reservoirs and hydrocarbon migration and accumulation based on production and core experimental data.The result shows that,The porosity of the Chang 7_(2)reservoir mainly distributed in 5.0-11.0%,average at 7.9%,The permeability mainly distributed in 0.04-0.18×10^(-3)μm^(2),average at 0.12×10^(-3)μm^(2),The pore diameters of the tight oil reservoir distributed in 2-8μm.The high-quality Chang 7_(3)source rocks and the micropsammite of Chang 7_(2)subaqueous distributary channel were widely distributed in the study area.The lenticular or banded sand bodies are distributed among mudstone or hydrocarbon source rocks and have the advantage of migration distance for hydrocarbon accumulation.The reservoir space is composed of micro-nanometer pores and throat,that is formed in the process of increasing pressure during hydrocarbon generation and hydrocarbon accumulation.The Chang 7 tight oil was generated in the early Cretaceous and injected into the sand of the subaqueous distributary channel driven by continuous hydrocarbon generation supercharging.The formation and accumulation of tight oil reservoirs are mainly controlled by source rocks,sedimentary microfacies and reservoirs of good quality.
基金Supported by the PetroChina Science and Technology Major Project(2021DJ1806,2023ZZ15).
文摘The reservoirs in the seventh member of the Triassic Yanchang Formation (Chang 7 Member) in the Qingcheng Oilfield of the Ordos Basin are characterized by thin sandbody, tight rocks, high heterogeneity, low formation pressure coefficient, and complex geomorphology. Through the efforts in the stages of exploration, appraisal, pilot testing and development, a series of key technologies have been formed, including “sweet spot” optimization, differentiated three-dimensional well deployment, fast drilling and completion of large-cluster horizontal well, intensively-staged volume fracturing in long horizontal well, and optimization of rational production system. Furthermore, a production organization mode represented by factory-like operations on loess platform has been implemented. Application of these technologies has enabled to significantly improve the single-well production of the Qingcheng Oilfield, reduce the investment cost, and realize a large-scale and beneficial development at a full cost below $55 per barrel. In 2022, the annual production of Chang 7 shale oil in the Ordos Basin reached 221×10^(4) t, accounting for 70% of the annual shale oil production of China. The practice of development technologies in the Qingcheng Oilfield provides valuable references for efficient development of continental shale oil.
文摘By December 19 2009, annual output of Changqing Oilfield located in western China surpassed 30 million tons oil equivalent, only second to Daqing Oilfield. Changqing Oilfield has the most late-development advantage in oil and gas growth and it has become China's important strategic energy replacement area and the hub of onshore natural gas network. So it is irreplaceable in ensuring national energy security and developing the western region. After 40 years of hard work, Changqing Oilfield Company has tackled the world-class problem of "low-permeability" oil and gas field development. The cumulative crude oil output in the oilfield totaled 134 million tons and the cumulative natural gas output totaled 84.066 billion cubic meters. Even in 2009 when the financial crisis spread throughout the world, the company has made historic breakthroughs in the growth of oil and gas reserves and production. It made new contributions to ensure national energy security, optimize energy structure and promote rapid development of national economy.
文摘A promising method is to use coring of high-inclination well to find ancient flow direction and orient tiny natural fractures in massive sandstone of sandy debris flow. Determination of ancient flow direction can reduce the number of exploration wells, and orientation of natural fractures is of guiding significance to the deployment of water injection development well pattern. In Block X of Huaqing Oilfield, Ordos Basin, the cores of Chang 6<sub>3</sub> section were obtained from Well Y through 16 coring operations, with a total length of 105 m. Cores is oriented through drilling parameters, the number of cores, the angle between the core edge and horizontal bedding, the coincidence degree of core profile and directional flame structure. Therefore, the micro-fractures on the core are directional. The ancient flow directions of sandy debris flow were restored by load casting, groove casting, groove casting and imbricate structure. Our results show that the ancient flow directions of sandy debris flows were southwest, southeast, northwest, and west from bottom to top. The front of the Wuqi Delta is the main source of blocky sandstone with the best oil-bearing property. Affected by the topography of the lake bottom, the sandy debris flow turned locally in the northeast direction, and the sandy debris flow from this direction was formed. The NEE-SWW-trending fractures formed in the Yanshanian period are most developed in the Huaqing area, which should be considered in deploying the flooding well network. The north-south micro-fractures formed in the Himalayan period can improve the physical properties of tight sandstone, which is of great significance for tight sandstone reservoirs.
文摘Wu Chunsheng is a senior engineer of oil and gas field development,and the deputy director of the Oil Production Technology Research Institute of the No.10 Oil Production Plant of PetroChina Changqing Oilfield Company.He has devoted himself to working in the field of oilfield development technology since the very beginning of his career.During the period of"Building a Western Daqing Oilfield"and the"Second Round of Development Acceleration"in Changqing Oilfield,he worked hard and studied diligently,and took the initiative to take on responsibilities while focused on practical work,growing into an outstanding young technical cadre step by step.His achievements in the research,application,promotion of new techniques and technologies,and the application of scientific research results proved extraordinary.
基金Supported by the CNPC Major Science and Technology Project(2021DJ1806).
文摘Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,and reservoir characteristics of shale oil of fine-grained sediment deposition in continental freshwater lacustrine basins,with a focus on the Chang 7_(3) sub-member of Triassic Yanchang Formation.The research integrates a variety of exploration data,including field outcrops,drilling,logging,core samples,geochemical analyses,and flume simulation.The study indicates that:(1)The paleoenvironment of the Chang 7_(3) deposition is characterized by a warm and humid climate,frequent monsoon events,and a large water depth of freshwater lacustrine basin.The paleogeomorphology exhibits an asymmetrical pattern,with steep slopes in the southwest and gentle slopes in the northeast,which can be subdivided into microgeomorphological units,including depressions and ridges in lakebed,as well as ancient channels.(2)The Chang 7_(3) sub-member is characterized by a diverse array of fine-grained sediments,including very fine sandstone,siltstone,mudstone and tuff.These sediments are primarily distributed in thin interbedded and laminated arrangements vertically.The overall grain size of the sandstone predominantly falls below 62.5μm,with individual layer thicknesses of 0.05–0.64 m.The deposits contain intact plant fragments and display various sedimentary structure,such as wavy bedding,inverse-to-normal grading sequence,and climbing ripple bedding,which indicating a depositional origin associated with density flows.(3)Flume simulation experiments have successfully replicated the transport processes and sedimentary characteristics associated with density flows.The initial phase is characterized by a density-velocity differential,resulting in a thicker,coarser sediment layer at the flow front,while the upper layers are thinner and finer in grain size.During the mid-phase,sliding water effects cause the fluid front to rise and facilitate rapid forward transport.This process generates multiple“new fronts”,enabling the long-distance transport of fine-grained sandstones,such as siltstone and argillaceous siltstone,into the center of the lake basin.(4)A sedimentary model primarily controlled by hyperpynal flows was established for the southwestern part of the basin,highlighting that the frequent occurrence of flood events and the steep slope topography in this area are primary controlling factors for the development of hyperpynal flows.(5)Sandstone and mudstone in the Chang 7_(3) sub-member exhibit micro-and nano-scale pore-throat systems,shale oil is present in various lithologies,while the content of movable oil varies considerably,with sandstone exhibiting the highest content of movable oil.(6)The fine-grained sediment complexes formed by multiple episodes of sandstones and mudstones associated with density flow in the Chang 7_(3) formation exhibit characteristics of“overall oil-bearing with differential storage capacity”.The combination of mudstone with low total organic carbon content(TOC)and siltstone is identified as the most favorable exploration target at present.
基金Supported by the National Natural Science Foundation of China(42302184)Innovation Group Project of Basic Research in Gansu Province,China(22JR5RA045)。
文摘The lamina(combination)types,reservoir characteristics and shale oil occurrence states of organic-rich shale in the Triassic Yanchang Formation Chang 73 sub-member in the Ordos Basin were systematically investigated to reveal the main controlling factors of shale oil occurrence under different lamina combinations.The differential enrichment mechanisms and patterns of shale oil were discussed using the shale oil micro-migration characterization and evaluation methods from the perspectives of relay hydrocarbon supply,stepwise migration,and multi-stage differentiation.The results are obtained in five aspects.First,Chang 73 shale mainly develops five types of lamina combination,i.e.non-laminated shale,sandy laminated shale,tuffaceous laminated shale,mixed laminated shale,and organic-rich laminated shale.Second,shales with different lamina combinations are obviously different in the reservoir space.Specifically,shales with sandy laminae and tuffaceous laminae have a large number of intergranular pores,dissolution pores and hydrocarbon generation-induced fractures.The multi-scale pore and fracture system constitutes the main place for liquid hydrocarbon occurrence.Third,the occurrence and distribution of shale oil in shale with different lamina combinations are jointly controlled by organic matter abundance,reservoir property,thermal evolution degree,mineral composition and laminae scale.The micro-nano-scale pore-fracture networks within shales containing rigid laminae,particularly sandy and tuffaceous laminations,primarily contain free-state light hydrocarbon components.In contrast,adsorption-phase heavy hydrocarbon components predominantly occupy surfaces of organic matter assemblages,clay mineral matrices,and framework mineral particulates.Fourth,there is obvious shale oil micro-migration between shales with different lamina combinations in Chang 73.Generally,such micro-migration is stepwise in a sequence of organic-rich laminated shale→tuffaceous laminated shale→mixed laminated shale→sandy lamiated shale→non-laminated shale.Fifth,the relay hydrocarbon supply of organic matter under the control of the spatial superposition of shales with various laminae,the stepwise migration via multi-scale pore and fracture network,and the multi-differentiation in shales with different lamina combinations under the control of organic-inorganic interactions fundamentally decide the differences of shale oil components between shales with different lamina combinations.
基金Supported by the National Natural Science Foundation of China(42330810)Major Science and Technology Project of PetroChina Changqing Oilfield Company(ZDZX2021-01).
文摘Based on the analysis of surface geological survey,exploratory well,gravity-magnetic-electric and seismic data,and through mapping the sedimentary basin and its peripheral orogenic belts together,this paper explores systematically the boundary,distribution,geological structure,and tectonic attributes of the Ordos prototype basin in the geological historical periods.The results show that the Ordos block is bounded to the west by the Engorwusu Fault Zone,to the east by the Taihangshan Mountain Piedmont Fault Zone,to the north by the Solonker-Xilamuron Suture Zone,and to the south by the Shangnan-Danfeng Suture Zone.The Ordos Basin boundary was the plate tectonic boundary during the Middle Proterozoic to Paleozoic,and the intra-continental deformation boundary in the Meso-Cenozoic.The basin survived as a marine cratonic basin covering the entire Ordos block during the Middle Proterozoic to Ordovician,a marine-continental transitional depression basin enclosed by an island arc uplift belt at the plate margin during the Carboniferous to Permian,a unified intra-continental lacustrine depression basin in the Triassic,and an intra-continental cratonic basin circled by a rift system in the Cenozoic.The basin scope has been decreasing till the present.The large,widespread prototype basin controlled the exploration area far beyond the present-day sedimentary basin boundary,with multiple target plays vertically.The Ordos Basin has the characteristics of a whole petroleum(or deposition)system.The Middle Proterozoic wide-rift system as a typical basin under the overlying Phanerozoic basin and the Cambrian-Ordovician passive margin basin and intra-cratonic depression in the deep-sited basin will be the important successions for oil and gas exploration in the coming years.
基金Supported by the National Natural Science Foundation of China(U22B6004)Project of PetroChina Research Institute of Petroleum Exploration and Development(2022yjcq03)Core Technology Key Project of China Petroleum Changqing Oilfield Company(KJZX2023-01).
文摘In addition to the organic matter type,abundance,thermal maturity,and shale reservoir space,the preservation conditions of source rocks play a key factor in affecting the quantity and quality of retained hydrocarbons in source rocks of lacustrine shale,yet this aspect has received little attention.This paper,based on the case analysis,explores how preservation conditions influence the enrichment of mobile hydrocarbons in shale oil.Research showns that good preservation conditions play three key roles.(1)Ensure the retention of sufficient light hydrocarbons(C_(1)–C_(13)),medium hydrocarbons(C_(14)–C_(25))and small molecular aromatics(including 1–2 benzene rings)in the formation,which enhances the fluidity and flow of shale oil;(2)Maintain a high energy field(abnormally high pressure),thus facilitating the maximum outflow of shale oil;(3)Ensure that the retained hydrocarbons have the miscible flow condition of multi-component hydrocarbons(light hydrocarbons,medium hydrocarbons,heavy hydrocarbons,and heteroatomic compounds),so that the heavy hydrocarbons(C_(25+))and heavy components(non-hydrocarbons and asphaltenes)have improved fluidity and maximum flow capacity.In conclusion,in addition to the advantages of organic matter type,abundance,thermal maturity,and reservoir space,good preservation conditions of shale layers are essential for the formation of economically viable shale oil reservoirs,which should be incorporated into the evaluation criteria of shale oil-rich areas/segments and considered a necessary factor when selecting favorable exploration targets.
文摘Sand production and high water content in oil wells are two major challenges that restrict high and stable production in loose sandstone reservoirs.In this paper,nano SiO_(2),coupling agent triethoxysilane,phenolic resin and n-octanol were used to synthesize the main agent SCA-2.Hexamethylenetetramine and vinyl carbonate were selected to prepare the curing agent YGA-1,which was then compounded with SCA-2 to develop a sand fixation and water plugging system.Firstly,single-factor experiments were conducted to determine the optimal concentrations of SCA-2 and YGA-1,subsequently,the system’s sand fixation and water blocking performance were evaluated.Finally,a pilot test was carried out in the mining site.Experimental results showed that the optimal formula composition of the system was 10%SCA-2+5%YGA-1.The gelation time of the system was 180 minutes and the viscosity after gelation could reach 108.4 mPa·s.When the dosage of the drug system was 0.6 PV,the sand production rate remained below 0.08%.Dual-tube parallel experiments showed that the sand fixation and water plugging system had a water flow channel plugging rate of 87.5%,while the oil flow channel plugging rate was only 11.3%,indicating minimal damage to the oil-bearing reservoir.The field test showed that after the measures taken in Well M of X oilfield,the sand free oil recovery period exceeded 360 days,the water content decreased by 5.0%and the cumulative oil production increased by 7092 m^(3).This study provides new ideas for efficient development of loose sandstone reservoirs.
文摘As industrialization and informatization in China deeply integrate and the Internet of Things rapidly develops,industrial control systems are facing increasingly severe information security challenges.The industrial control system of the gas extraction plant is characterized by numerous points and centralized operations,with a strong reliance on the system and stringent real-time requirements.
基金Supported by the National Social Science Fund Major Project(24&ZD106)。
文摘By summarizing the characteristics of the global energy structure and China’s energy resource endowment, this study analyzes the historical context and opportunities for China to build an “energy powerhouse”, and proposes pathways and measures for its realization. It is indicated that the energy resource endowment in China is characterized by abundant coal, limited oil and gas, and vast renewable potential, coupled with an energy consumption structure characterized by high coal consumption, low oil and gas consumption, and rapidly growing renewable energy use. The “whole-energy system” approach that integrates multi-energy complementarity, green development, stable supply, smart utilization and carbon neutrality is an effective solution to addressing energy transition and energy independence. To build an “energy powerhouse”, China can follow the approach of the steady and orderly low-carbon development of fossil fuels, the safe and scaled development of new energy, the integrated development of a carbon-neutral “whole-energy system”, and the shared development of the “Belt and Road” energy corridor. The construction of an “energy powerhouse” should follow a “three-phase” strategic pathway: from 2025 to 2030, achieving peak primary energy consumption and “carbon peaking”;from 2031 to 2050, energy production will achieve parity with consumption for the first time, striving for “energy independence”;and from 2051 to 2060, aiming for “carbon neutrality”, and establishing an “energy powerhouse”. Building an “energy powerhouse” will fundamentally safeguard national energy security, advance the achievement of carbon neutrality goals, provide Chinese solutions for global energy transition and green Earth construction, and support the modernization and great rejuvenation of the Chinese nation.
基金funded by National Science and Technology Major Projects(Grant No.2016ZX05050,2017ZX05001002-008)China National Petroleum Corporation Major Projects(No.2021DJ2203)Key Laboratory of Petroleum Resources Exploration and Evaluation,Gansu Province(No.KLPREEGS-2024-22)。
文摘In recent years,fueled by significant advancements in oil exploration technologies within the Ordos Basin,an increasing number of low-permeability or ultra-low-permeability reservoirs have been identified.Elucidating their reservoir characteristics and formation mechanisms has become a critical priority for sustainable hydrocarbon development.The study focused on the Chang 6 Member of the Upper Triassic Yanchang Formation in the Heshui area of the Ordos Basin,systematically investigating its petrological features,porosity and permeability characteristics,diagenesis,and diagenetic evolution sequence.By integrating core observation,thin-section identification,and physical property measurements,a comprehensive quantitative evaluation of reservoir pore evolution was performed.These analytical outcomes were subsequently applied to simulate hydrocarbon migration and accumulation.These research results will provide a scientific basis for in-depth quantitative study of the pore evolution in ultra-low-permeability oil reservoirs and accurately constructing basin models.As indicated,the reservoir lithology in the study area predominantly comprises siltstone interbedded with mudstone or argillaceous siltstone,characterized by low porosity and permeability.Through diagenetic characteristics-based reconstruction constrained by the existing porosity data,pore evolution during diagenesis was quantitatively modeled.The simulated pore evolution aligns with actual geological observations,validating the reliability of the methodology.Furthermore,the quantified pore evolution results were applied to simulate hydrocarbon migration using PetroMod software,showing that hydrocarbon charging in the basin began at the end of the Late Jurassic(J3),peaking in hydrocarbon generation,expulsion,and accumulation by the end of the Early Cretaceous(K1)and maintaining high accumulation rates until the late Cretaceous,though significantly decreasing at the present stage.The simulation results were verified by comparison with actual drilling data,which confirms their reliability and applicability to other analogous oilfields.
基金Supported by the National Science and Technology Major Project(2024ZD1404901,2017ZX05035)Strategic Priority Research Program(Category B)of the Chinese Academy of Sciences(XDB10050100).
文摘To clarify the mechanism of differential enrichment of intrasource shale oil,taking the third of seventh member of the Triassic Yanchang Formation(Chang 7_(3)submember for short)in the Ordos Basin,NW China as an example,we integrated high-resolution scanning electron microscopy(SEM),optical microscopy,laser Raman spectroscopy,rock pyrolysis,and organic solvent extraction experiments to identify solid bitumen of varying origins,obtain direct evidence of intrasource micro-migration of shale oil,and establish the coupling between the shale nano/micro-fabric and the oil generation,migration and accumulation.The Chang 7_(3)shale with rich alginite in laminae has the highest hydrocarbon generation potential but a low thermal transformation ratio.Frequent alternations of micron-scale argillaceous-felsic laminae enhance the hydrocarbon expulsion efficiency,yielding consistent aromaticity between in-situ and migrated solid bitumen.Mudstone laminae rich in terrestrial organic matter(OM)and clay minerals exhibit lower hydrocarbon generation threshold but stronger hydrocarbon retention capacity,with a certain amount of light oil/bitumen preserved to differentiate the chemical structure of in-situ versus migrated bitumen.Tuffaceous and sandy laminae contain abundant felsic minerals and migrated bitumen.Tuffaceous laminae develop high-angle microfractures under shale overpressure,facilitating oil charging into rigid mineral intergranular pores of sandy laminae.Fractionation during micro-migration progressively decreases the aromatization of solid bitumen from shale,through tuffaceous and mudstone,to sandy laminae,while increasing light hydrocarbon components and enhancing OM-hosted pore development.The intrasource micro-migration and enrichment of the Chang 7_(3)shale oil result from synergistic organic-inorganic diagenesis,with crude oil component fractionation being a key mechanism for forming sweet spots in laminated shale oil reservoirs.
