To satisfy the increasing global energy demand,while searching for new energy sources,it’s important to take a closer look at the resources already at our disposal and optimize their use.This comprehensive review exp...To satisfy the increasing global energy demand,while searching for new energy sources,it’s important to take a closer look at the resources already at our disposal and optimize their use.This comprehensive review explores the evolving landscape of unconventional oil resources,focusing on the environmental and economic implica-tions of bitumen partial upgrading technologies,particularly within the Canadian context.With over 55%of the world’s oil reserves comprising of unconventional oil,which includes extra-heavy oil and oil sand bitumen,there is a growing trend to shift from traditional oil sources to these abundant yet under-utilized reserves.This review delves into the challenges and advancements in bitumen partial upgrading,highlighting the latest technologies in thermal cracking,hydrocracking,catalytic cracking,and innovative methods like surfactant integration,cavi-tation,microwave,and plasma-assisted upgrading.It also discusses the environmental implications and eco-nomic feasibility of these technologies,emphasizing the necessity for sustainable and cost-effective solutions at petroleum field sites.Furthermore,the report introduces the transformative concept of Bitumen Beyond Com-bustion(BBC),which explores the non-combustion uses of bitumen and its asphaltene fraction in manufacturing high-value carbon-based products.These novel approaches align with global sustainability goals,offering the potential for significant reductions in greenhouse gas emissions and new routes to diversify the economic ap-plications of bitumen.The review then concludes with an assessment of current challenges and future research directions,advocating for a balanced approach that harmonizes technological innovation,environmental stewardship,and economic viability in the field of bitumen upgrading.展开更多
Under the fact that considerable explo ration and production of unconventional re sources and wo rsening global climate,reducing carbon emission and rationally utilizing carbon resources have been drawn increasing att...Under the fact that considerable explo ration and production of unconventional re sources and wo rsening global climate,reducing carbon emission and rationally utilizing carbon resources have been drawn increasing attention.Supercritical CO_(2)(SC-CO_(2)) has been proposed as anhydrous fracturing fluid to develop unconventional reservoirs,since its advantages of reducing water consumption,reservoir contamination etc.Well understanding of SC-CO_(2)fracturing mechanism and key influencing factors will exert significant impact on the application of this technology in the field.In this paper,the fundamental studies on SC-CO_(2)fracturing from the aspects of laboratory experiment and simulation are reviewed.The fracturing experimental setups,fracture monitoring and characterizing methods,unconventional formation categories,numerical simulation approaches,fracturing mechanism and field application etc.,are analyzed.The fundamental study results indicate that compared with conventional hydraulic fracturing,SC-CO_(2)fracturing can reduce fracture initiation pressure and easily induce complex fracture networks with multiple branches.The field test further verifies the application prospect and the possibility of carbon storage.However,due to the limitation of reservoir complexity and attributes of SC-CO_(2),massive challenges will be encountered in SC-CO_(2)fracturing.According to the current research status,the limitations in basic research and field application are summarized,and the future development direction of this technology and relevant suggestions are proposed.展开更多
The main achievements in the development of hardly-recoverable resources are currently associated with shale oil and gas. The result of the ＂shale revolution＂ was billions of dollars in losses for oil exporters. The...The main achievements in the development of hardly-recoverable resources are currently associated with shale oil and gas. The result of the ＂shale revolution＂ was billions of dollars in losses for oil exporters. The question is how this situation w＇ill be long-lasting or ＂shale bubble＂ will burst. The success of the shale revolution can be not only an economic win or economic defeat of the United States, the question is about reputation as a global political leader and the country＇s ability to solve the most difficult technological problems. Everything at stake to extend the ＂shale gas revolution＂ as it is possible longer, in time to prepare the conditions and technologies for a new energy revolution and to maintain the usual high level of energy consumption. The situation is further complicated by the introduction in the game of OPEC （organization of petroleum exporting countries） causing oil prices dropped below the cost of shale oil. The future of high technology in the production of oil depends on whether exporters and importers to negotiate the best price for oil, to ensure the sustainable development of the world economy.展开更多
Unconventional hydrocarbon resources, which are only marginally economically explored and developed by traditional methods and techniques, are different from conventional hydrocarbon resources in their accumulation me...Unconventional hydrocarbon resources, which are only marginally economically explored and developed by traditional methods and techniques, are different from conventional hydrocarbon resources in their accumulation mechanisms, occurrence states, distribution models, and exploration and development manners. The types of unconventional hydrocarbon are controlled by the evolu- tion of the source rocks and the combinations of different types of unconventional reservoirs. The fundamental dis- tinction between unconventional hydrocarbon resources and conventional hydrocarbon resources is their non- buoyancy-driven migration. The development of the micro- to nano-scale pores results in rather high capillary resis- tance. The accumulation mechanisms of the unconven- tional and the conventional hydrocarbon resources are also greatly different. In conventional hydrocarbon resources, oil and gas entrapment is controlled by reservoir-forming factors and geological events, which is a dynamic balance process; while for unconventional hydrocarbon resources, the gas content is affected by the temperature and pressure fields, and their preservation is crucial. Unconventional and conventional hydrocarbons are distributed in an orderly manner in subsurface space, having three distribution models of intra-source rock, basin-centered, and source rock interlayer. These results will be of great significance to unconventional hydrocarbon exploration.展开更多
Commercial production of unconventional oil and gas resources will not be easily achieved without large-scale engineering measures,let alone the additional operation cost,increasingly stricter requirement for safety a...Commercial production of unconventional oil and gas resources will not be easily achieved without large-scale engineering measures,let alone the additional operation cost,increasingly stricter requirement for safety and environment,fluctuating low oil and gas prices,etc.,defeating the confidence of those investors.Therefore,unconventional measures are urgently needed to guide the exploration and exploitation of unconventional oil and gas resources.Thus,we put forward the concept of joint exploration and development by integrating research methodologies and operating techniques for a variety of oil and gas resources to simultaneously achieve analysis,construction,gathering and exploitation of multiple hydrocarbon sources.In this way,the annoying interference between the produced mixture of hydrocarbon flow resulting in the reduction of single-well flowrate will be possibly turned into a dynamic mutual force to enhance the well's flowrate.We also point out that the inevitability of joint exploration and development is determined by the occurrence conditions of oil and gas resources,its feasibility relies on the advancement of technologies,and its arduous and long-term nature is attributed to the current energy market and environment.In spite of various problems and difficulties,we believe that joint exploration and development will be a feasible option to achieve both cost reduction and production&benefit enhancement,boost investors'confidence,raise energy comprehensive utilization,and enhance energy supply efficiency.In conclusion,the advantages of joint exploration and development outweigh its disadvantages for both countries and enterprises.展开更多
Controlled by fluctuating paleoclimates and sedimentary environments,the organic and inorganic features of the Lucaogou Formation exhibit strong heterogeneity in the vertical profile,challenging conventional geologica...Controlled by fluctuating paleoclimates and sedimentary environments,the organic and inorganic features of the Lucaogou Formation exhibit strong heterogeneity in the vertical profile,challenging conventional geological interpretation.To elucidate the possible influence of heterogeneity on resource evaluation,a high-resolution sampling approach was applied to an 86.2 cm long core from the Lucaogou Formation of the Jimsar sag in the Junggar Basin.86 sets of samples were micro-drilled from the core and subjected to comparative Rock-Eval pyrolysis.Following the classical guidelines,the organic abundance,kerogen type,and maturity of source rocks were exhaustively analyzed.Experimental results revealed that organic richness and composition vary significantly under different sedimentary backgrounds,which in turn leads to differential hydrocarbon generation.The combination of hydrocarbon generation,transport,and expulsion results in peculiar patterns for hydrocarbon accumulation in the Lucaogou Formation.Laminated shales in the Lucaogou Formation serve as both hydrocarbon source rocks and reservoirs,with laminae being migration pathways.Organic-rich dolomites in the Lucaogou Formation have a considerable hydrocarbon-generating capacity and present the characteristics of self-generation and self-storage.However,massive mudstones act purely as hydrocarbon source rocks.展开更多
The Early Paleocene to Middle Eocene Apollonia Formation in the BED‒9 field has been particularly interesting for unconventional hydrocarbon exploration since its discovery in 2006.However,the multiscale compositional...The Early Paleocene to Middle Eocene Apollonia Formation in the BED‒9 field has been particularly interesting for unconventional hydrocarbon exploration since its discovery in 2006.However,the multiscale compositional and diagenetic inconsistencies present challenges for its characterization.This study aims to evaluate the petrophysical properties of the Apollonia Formation to locate the sweet-spot intervals.Moreover,it seeks to investigate reservoir rock types(RRTs),depositional settings,and the impact of diagenesis on reservoir quality.The findings of this study are as follows.1)The Apollonia A5 and C1 units are identified as"sweet-spot"intervals.Their effective porosity ranges from 18%to 35%,average permeability varies from 0.1 to 2.0 mD,and water saturation falls between 40%and 50%,indicating good reservoir quality.2)High-order eustatic sea-level changes and repetitive climatic change cycles significantly influence the alternating carbonate productivity and dilution cycles.Five distinct RRTs are classified,denoting a gradational facies change from clean,argillaceous,and carbonaceous chalky limestone to marl and interbedded shale intervals.3)Interpreting the electro-facies responses,collated with microfacies variations and faunal content,deepens our understanding of the depositional environment,which extends from the inner to outer-shelf setting.4)The diagenetic processes have a dual impact that enhances and diminishes the reservoir quality.Finally,the gap in evaluating the petrophysical characteristics of all the Apollonia members has been addressed based on integrating the petrophysical and facies analysis for A,B,and C members.The Apollonia Formation has unique characteristics as an unconventional hydrocarbon resource.展开更多
As a milestone of the entire energy industry,unconventional resources have inevitably swept the world in the last decade,and will certainly dominate the global oil and gas industry in the near future.Eventually,the ＂...As a milestone of the entire energy industry,unconventional resources have inevitably swept the world in the last decade,and will certainly dominate the global oil and gas industry in the near future.Eventually,the ＂unconventional＂ will become ＂conventional＂.Along with the rapid development,however,some issues have emerged,which are closely related to the viability of unconventional resources development.Under the current circumstances of low crude oil and gas price,coupled with the prominent environmental concerns,the arguments about the development and production of unconventional resources have been recently heated up.This work introduced the fullblown aspects of unconventional resources especially shale reservoirs,by discussing their concepts and definitions,reviewing the shale gas and shale oil development history and necessity,analyzing the shale plays＇ geology and petroleum systems with respects to key hydrocarbon accumulation elements and mechanisms,and summarizing the technology resolution.This study also discussed the relevant key issues,including significant estimation uncertainty of technically recoverable resources,the equivocal understanding of complex geology preventing the production and technologies implementation optimization,the difficulties of experiences and technologies global expanding,and the corresponding risks and uncertainties.In addition,based on the latest production and exploration data,the future perspective of the unconventional resources was depicted from global unconventional resources assessments,technology development,and limitations constraining the development.展开更多
Unconventional oil and gas resources have become the most important and realistic field for increasing China’s domestic oil and gas reserves and production.At present,the production scale does not match the massive a...Unconventional oil and gas resources have become the most important and realistic field for increasing China’s domestic oil and gas reserves and production.At present,the production scale does not match the massive amount of resources and the rapid growth of proven geological reserves.The challenges of technology,cost,management,and methodology restrict large-scale and economic development.Based on successful practices,a"one engine with six gears"system engineering methodology is put forward,which includes life-cycle management,overall synergy,interdisciplinary cross-service integration,marketoriented operation,socialized support,digitalized management,and low-carbon and green development.The methodology has been proved to be effective in multiple unconventional oil and gas national demonstration areas,including the Jimusar continental shale oil demonstration area.Disruptive views are introduced-namely,that unconventional oil and gas do not necessarily yield a low return,nor do they necessarily have a low recovery factor.A determination to achieve economic benefit must be a pervasive underlying goal for managers and experts.Return and recovery factors,as primary focuses,must be adhered to during China’s development of unconventional oil and gas.The required methodology transformation includes a revolution in management systems to significantly decrease cost and increase production,resulting in technological innovation.展开更多
Based on commercial databases from S&P Global and Rystad Energy and public information from oil companies around the world,a systematic analysis has been conducted on the global hydrocarbon exploration investment,...Based on commercial databases from S&P Global and Rystad Energy and public information from oil companies around the world,a systematic analysis has been conducted on the global hydrocarbon exploration investment,award of exploration blocks,exploratory drilling,new conventional oil and gas discoveries,and exploration of associated resources in 2023.In 2023,the global hydrocarbon exploration investment increased steadily and the total number and area of awarded exploration blocks increased significantly.The decline in the number and success rate of high-impact exploration wells directly affected the quantity of additional oil and gas reserves discovered globally in 2023.In recent years,the deepwater areas of passive margin basins have been the major targets for seeking medium-and large-sized conventional oil and gas fields.In 2023,however,the newly discovered onshore reserves were equivalent to the newly discovered offshore reserves,and fine exploration in mature blocks achieved significant results.Oil companies continued to plan and perform unconventional oil and gas exploration activities and accelerated access to associated mineral resources such as natural hydrogen and helium and other emerging industries.For Chinese oil companies international exploration business,it is recommended to:(1)continue the upstream investment to strengthen upstream services for consolidating the strategic position of oil and gas resources;(2)uphold oil and gas exploration activities by further deploying exploration activities in the deepwater areas of passive margin basins,deeply exploring mature basins,closely following hotspot basins,and gaining access to frontier basins;(3)follow the principle of integrated development to plan the exploration of associated resources while exploiting conventional and unconventional resources;and(4)make technological innovations to develop and improve core technologies and promote the application of artificial intelligence.展开更多
1.Introduction With the increasing demand for petroleum and natural gas resources,along with technological advancements in exploration and production,the primary frontier of oil and gas resources has shifted from conv...1.Introduction With the increasing demand for petroleum and natural gas resources,along with technological advancements in exploration and production,the primary frontier of oil and gas resources has shifted from conventional oil and gas development to the domains of“Two Deeps,One Unconventional,One Mature,”which include deep onshore,deepwater,unconventional resources,and mature oilfields[1].展开更多
The global exploration investment, new oil and gas discoveries, exploration business adjustment strategies of oil companies in 2021, and future favorable exploration domains are systematically analyzed using commercia...The global exploration investment, new oil and gas discoveries, exploration business adjustment strategies of oil companies in 2021, and future favorable exploration domains are systematically analyzed using commercial databases such as IHS and public information of oil companies. It has been found that the world oil and gas exploration situation in 2021 has continued the downturn since the outbreak of COVID-19. The investment and drilling workload decreased slightly, but the success rate of exploration wells, especially deepwater exploration wells, increased significantly, and the newly discovered reserves increased slightly compared with last year. Deep waters of the passive continental margin basins are still the leading sites for discovering conventional large and medium-sized oil and gas fields. The conventional oil and gas exploration in deep formations of onshore petroliferous basins has been keeping a good state, with tight/shale oil and gas discoveries made in Saudi Arabia, Russia, and other countries. While strengthening the exploration and development of local resources, national, international, and independent oil companies have been focusing on major overseas frontiers using their advantages, including risk exploration in deep waters and natural gas. Future favorable exploration directions in the three major frontiers, the global deep waters, deep onshore formations, and unconventional resources, have been clarified. Four suggestions are put forward for the global exploration business of Chinese oil companies: first, a farm in global deepwater frontier basins in advance through bidding at a low cost and adopt the “dual exploration model” after making large-scale discoveries;second, enter new blocks of emerging hot basins in the world through farm-in and other ways, to find large oil and gas fields quickly;third, cooperate with national oil companies of the resource host countries in the form of joint research and actively participate exploration of deep onshore formations of petroliferous basins;fourth, track tight/shale oil and gas cooperation opportunities in a few countries such as Saudi Arabia and Russia, and take advantage of mature domestic theories and technologies to farm in at an appropriate time.展开更多
With the implementation of the production tests in permafrost and offshore regions in Canada,US,Japan,and China,the study of natural gas hydrate has progressed into the stage of technology development for industrial e...With the implementation of the production tests in permafrost and offshore regions in Canada,US,Japan,and China,the study of natural gas hydrate has progressed into the stage of technology development for industrial exploitation.The depressurization method is considered as a better strategy to produce gas from hydrate reservoirs based on production tests and laboratory experiments.Multi-well production is proposed to improve gas production efficiency,to meet the requirement for industrial production.For evaluating the applicability of multi-well production to hydrate exploitation,a 2D model is established,with numerical simulations of the performance of the multi-well pattern carried out.To understand the dissociation behavior of gas hydrate,the pressure and temperature distributions in the hydrate reservoir are specified,and the change in permeability of reservoir sediments is investigated.The results obtained indicate that multi-well production can improve the well connectivity,accelerate hydrate dissociation,enhance gas production rate and reduce water production as compared with single-well production.展开更多
Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performa...Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.展开更多
China is a top world producer of coal resources with numerous coal-rich basins country-wide that also contain coalbed methane(CBM),an unconventional natural gas resource.Recent exploration of coal and CBM resources ha...China is a top world producer of coal resources with numerous coal-rich basins country-wide that also contain coalbed methane(CBM),an unconventional natural gas resource.Recent exploration of coal and CBM resources has also led to the discovery of rare,precious,and scattered metal minerals,including sandstone-type U and Ga–Ge–Li.High-grade and industrial-value deposits have been discovered in the Ordos,Junggar,and other basins across China during exploration for coal resources.Application of coordinated exploration theories and techniques in multiple energy and coal-associated ore deposits,such as coal and unconventional natural gas in coal,achieves efficient and practical exploration of natural resources.Based on the systematic study of accumulation and occurrence of coal and coal-associated mineral resources in coal basins,the basic idea of coordinated exploration for coal and coal-associated deposits is proposed,and multi-targets and multi-methods based on a coordinated exploration model of coal-associated deposits is developed.Coordinated exploration expands the main exploration objective from coal seams to coal-associated series,extending the exploration target from targeting coal only to coal-associated deposits.Entrance times for exploration are decreased to realize coordinated exploration for coal,unconventional natural gas and syngenetic/associated mineral resources in coal by implementing a’one-time approach’―one time in and out of a coal seam to minimize disturbance and time needed for extraction.According to the differences of geological background in China’s coal basins,four coordinated exploration model types,including co-exploration of coal and coal-associated unconventional natural gas,coal and solid minerals,coal and metal minerals,and coal with water resources are established.Other models discussed include a multi-target coordinated exploration model for the combination of coal,coal-associated gas,solid minerals,and metal minerals accordingly.The exploration techniques of coal and coal-associated resources include regional geological investigation and research and synthetic application of other techniques including seismic surveys,drilling,logging,and geochemical exploration.Particularly,applying the’multi-purpose drill hole’or reworking coalfield drill holes into parameter wells,adding sample testing and logging wells,determining gas-bearing layers by logging and gas content measurement,jointly measuring multiple logging parameters,sampling,and testing of coal-strata help in the exploration and evaluation of coal resources,coal-associated unconventional natural gas resources,and coal-associated element minerals.Accordingly,a system of integrated Space–Air–Ground exploration techniques for coordinated exploration of coal and coal-associated minerals is established.This includes high-resolution,hyperspectral remote-sensing technique,high-precision geophysical exploration and fast,precise drilling,testing of experimental samples,as well as coordinated exploration and determination methods of multi-target factors,multi-exploration means,multi-parameter configuration and optimization,big data fusions and interpretation techniques.In recent years,the application of this integrated system has brought significant breakthroughs in coal exploration in Inner Mongolia,Xinjiang and other provinces,discovering several large,ten-billionton coalfields,such as the Eastern Junggar and Tuha basins,and also in exploration and development of CBM from lowrank coals in Fukang,Xinjiang,discovery the Daying U Deposit in Inner Mongolia,the Junggar Ultralarge Ga Deposit,Lincang,Yunnan,and the Wulantuga,Inner Mongolia,Ge-bearing coal deposits,and the Pingshuo Ultralarge Li–Ge Deposit.展开更多
This manuscript introduces a new decline curve analysis(DCA) technique to analyze and predict the potentials of hydraulically fractured unconventional resources.The new approach relies on the ratenormalized flow rate ...This manuscript introduces a new decline curve analysis(DCA) technique to analyze and predict the potentials of hydraulically fractured unconventional resources.The new approach relies on the ratenormalized flow rate derivative(RNFD) concept.It uses the significant constant behavior of the RNFD that identifies the power-law type flow regime models of fractured reservoirs.This technique merges the RNFD with a new numerical model for the flow rate derivative(flow rate noise-reducing derivative model).The concept of the RNFD [1/q(txq')] is developed based on the power-law type analytical models of the flow regimes that can be characterized from the production history of gas or oil-producing wells.The production rate,cumulative production,and the calculated RNFDs from the production history are used for this purpose.The constant RNFD values and the flow rate derivative's numerical model can be used to simulate the production history or predict future performance.The impact of the skin factor is introduced to the approach by developing new RNFD models that could replace the constant pattern of RNFD when this impact does not exist.For a severe condition of skin factor,the RNFD shows a linear relationship with time instead of the constant value.The proposed approach gives an excellent match with the production history of the case studies examined in this study.The transition between flow regimes does not impact the application of the RNFD,i.e.,the calculations move very smoothly throughout the flow regime.The novelty of the proposed technique is represented by introducing an approach for the DCA that considers the observed flow regimes during the production history and the impact of the skin factor.The approach proposes new numerical flow rate and cumulative production models to predict future performance as well as new models for estimating the impact of skin factors on production history,especially for early time flow regimes.展开更多
Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100...Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100~300-m-thick dark shale,mudstone and limestone encountered in the lower third member of the Eocene Shahejie Formation(Es3l member)in Zhanhua Sag,Bohai Bay Basin,eastern China,routine core analysis,thin sectioning,scanning electron microscopy(SEM),mineralogical and geochemical measurements were used to understand detailed facies characterization and paleoclimate in the member.This Es3l shale sediment includes three sedimentary cycles(C3,C2 and C1),from bottom to top,with complex sedimentary characters and spatial distribution.In terms of the composition,texture,bedding and thickness,six lithofacies are recognized in this succession.Some geochemical parameters,such as trace elements(Sr/Ba,Na/Al,V/Ni,V/(V+Ni),U/Th),carbon and oxygen isotopes(δ^(18)O,δ^(13)C),and total organic carbon content(TOC)indicate that the shales were deposited in a deep to semi-deep lake,with the water column being salty,stratified,enclosed and reductive.During cycles C3 and C2 of the middle-lower sections,the climate was arid,and the water was salty and stratified.Laminated and laminar mudstone-limestone was deposited with moderate organic matter(average TOC 1.8%)and good reservoir quality(average porosity 6.5%),which can be regarded as favorable reservoir.During the C1 cycle,a large amount of organic matter was input from outside the basin and this led to high productivity with a more humid climate.Massive calcareous mudstone was deposited,and this is characterized by high TOC(average 3.6%)and moderate porosity(average 4%),and provides favorable source rocks.展开更多
Unconventional oil and gas resources require petrophysical logs to answer the question of how best to optimize geological and engineering‘sweet spots'.Therefore,the establishment of a key well with comprehensive ...Unconventional oil and gas resources require petrophysical logs to answer the question of how best to optimize geological and engineering‘sweet spots'.Therefore,the establishment of a key well with comprehensive descriptions of lithology,reservoir properties,hydrocarbon-bearing properties,electronic well log responses,source rock properties,brittleness,and in situ stress magnitude and direction is important for the effective exploration and production of unconventional hydrocarbon resources.Cores,thin sections,scanning electron microscopy(SEM)and comprehensive well log suites are used to build a key well for the Permian Lucaogou Formation,Jimusar Sag of the Junggar Basin.The results show that there are three main types of lithologies,including siltstone,mudstone and dolostone.Lithologies can be predicted using the combination of conventional well and image logs.The pore spaces consist of interparticle pores,intragranular dissolution pores and micropores.Nuclear Magnetic Resonance(NMR)T_(2)components longer than 1.7 ms are superposed as effective porosity.Permeability is calculated using the Coates model from NMR T_(2)spectra.The ratio of T_(2)components>7.0 ms to T_(2)components>0.3 ms is used to calculate oil saturation.TOC is calculated using theΔlog R method.Brittleness index is calculated using Poisson-Young's method,ranging from 13.42%-70.53%.In situ stress direction is determined,and in situ stress magnitudes(maximum horizontal stress SH_(max),minimum horizontal stress Sh_(min),vertical stress S_(v))are calculated using density and sonic logs.The strike-slip stress type(SH_(max)>S_(v)>Sh_(min))is encountered.The key well which comprehensively includes the above seven properties is established.Geological and engineering(geomechanical)‘sweet spots'are then optimized from the key well by fully analyzing lithology,reservoir property,oilbearing potential,in situ stress magnitude and brittleness.It is hoped that the results support engineers'and geologists'decisions for the future exploitation of unconventional hydrocarbon resources.展开更多
The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second larg...The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second largest production and consumption center of liquid fuel, and is also the world＇s largest natural gas producer. In 2016, the Americas had 85.3 billion tons of proven oil reserves and 18.7 trillion m3 of proven natural gas reserves, which account for 35.4% and 10.0% of world＇s total reserves, respectively. It produced 1267.1 Mt of oil and 1125.4 billion m3 of natural gas, which account for 28.9% and 31.7% of the world＇s total production, respectively. The crude oil and natural gas reserves are mainly distributed in the U.S., Canada and Venezuela. The U.S. is the earliest and most successful country in shale gas exploration and development, and its shale gas is concentrated in the southern, central and eastern U.S., including the Marcellcus shale, Barnett shale, EagleFord shale, Bakken shale, Fayettevis shale, Haynsvill shale, Woodford shale and Monterey/Santos shale. The potential oil and gas resources in the Americas are mainly concentrated in the anticline and stratigraphic traps in the Middle- Upper Jurassic slope deposition of the North Slope Basin, the Paleozoic Madsion group dolomite and limestone in the Williston Basin, dominant stratigraphic traps and few structural traps in the Western Canada Sedimentary Basin, the Eocene structural-stratigraphic hydrocarbon combination, structural- unconformity traps and structural hydrocarbon combination, and the Upper Miocene stratigraphic- structural hydrocarbon combination in the Maracaibo Basin of Venezuela, the stratigraphic-structural traps and fault horst, tilting faulted blocks and anticlines related to subsalt structure and basement activity in the Campos Basin, the subsalt central low-uplift belt and supra-salt central low-uplift belt in the Santos Basin of Brazil, and the structural-stratigraphic traps in the Neuquen Basin of Argentina. In addition, the breakthrough of seismic subsalt imaging technology makes the subsalt deepwater sea area of eastern Barzil an important oil and gas potential area.展开更多
Shale gas is a practical resource with great potential that could be economically explored and developed in the near future. It has been commercially developed in North America and other places. Featuring a vast distr...Shale gas is a practical resource with great potential that could be economically explored and developed in the near future. It has been commercially developed in North America and other places. Featuring a vast distribution, a low abundance,unfavorable reservoir conditions, ultra-low permeability and a fast production decline, shale gas is more difficult to develop than conventional natural gas, as it needs advanced drilling and completion technology to develop. During the early stage of shale gas exploration and development, the United States offered enterprises necessary incentives such as tax reductions and exemptions and subsidies to achieve sustainable shale gas development and encourage technological progresses. By comparing the state of China's shale gas development with that of the US' in terms of geological conditions, production technology,market price, tax relief, subsidy periods and amount, this paper intends to put forward related suggestions for the effective development of shale gas according to the current status of development.展开更多
文摘To satisfy the increasing global energy demand,while searching for new energy sources,it’s important to take a closer look at the resources already at our disposal and optimize their use.This comprehensive review explores the evolving landscape of unconventional oil resources,focusing on the environmental and economic implica-tions of bitumen partial upgrading technologies,particularly within the Canadian context.With over 55%of the world’s oil reserves comprising of unconventional oil,which includes extra-heavy oil and oil sand bitumen,there is a growing trend to shift from traditional oil sources to these abundant yet under-utilized reserves.This review delves into the challenges and advancements in bitumen partial upgrading,highlighting the latest technologies in thermal cracking,hydrocracking,catalytic cracking,and innovative methods like surfactant integration,cavi-tation,microwave,and plasma-assisted upgrading.It also discusses the environmental implications and eco-nomic feasibility of these technologies,emphasizing the necessity for sustainable and cost-effective solutions at petroleum field sites.Furthermore,the report introduces the transformative concept of Bitumen Beyond Com-bustion(BBC),which explores the non-combustion uses of bitumen and its asphaltene fraction in manufacturing high-value carbon-based products.These novel approaches align with global sustainability goals,offering the potential for significant reductions in greenhouse gas emissions and new routes to diversify the economic ap-plications of bitumen.The review then concludes with an assessment of current challenges and future research directions,advocating for a balanced approach that harmonizes technological innovation,environmental stewardship,and economic viability in the field of bitumen upgrading.
基金supported by the Natural Science Foundation of China(Grant Nos.51922107,51874318,51827804and 41961144026)
文摘Under the fact that considerable explo ration and production of unconventional re sources and wo rsening global climate,reducing carbon emission and rationally utilizing carbon resources have been drawn increasing attention.Supercritical CO_(2)(SC-CO_(2)) has been proposed as anhydrous fracturing fluid to develop unconventional reservoirs,since its advantages of reducing water consumption,reservoir contamination etc.Well understanding of SC-CO_(2)fracturing mechanism and key influencing factors will exert significant impact on the application of this technology in the field.In this paper,the fundamental studies on SC-CO_(2)fracturing from the aspects of laboratory experiment and simulation are reviewed.The fracturing experimental setups,fracture monitoring and characterizing methods,unconventional formation categories,numerical simulation approaches,fracturing mechanism and field application etc.,are analyzed.The fundamental study results indicate that compared with conventional hydraulic fracturing,SC-CO_(2)fracturing can reduce fracture initiation pressure and easily induce complex fracture networks with multiple branches.The field test further verifies the application prospect and the possibility of carbon storage.However,due to the limitation of reservoir complexity and attributes of SC-CO_(2),massive challenges will be encountered in SC-CO_(2)fracturing.According to the current research status,the limitations in basic research and field application are summarized,and the future development direction of this technology and relevant suggestions are proposed.
文摘The main achievements in the development of hardly-recoverable resources are currently associated with shale oil and gas. The result of the ＂shale revolution＂ was billions of dollars in losses for oil exporters. The question is how this situation w＇ill be long-lasting or ＂shale bubble＂ will burst. The success of the shale revolution can be not only an economic win or economic defeat of the United States, the question is about reputation as a global political leader and the country＇s ability to solve the most difficult technological problems. Everything at stake to extend the ＂shale gas revolution＂ as it is possible longer, in time to prepare the conditions and technologies for a new energy revolution and to maintain the usual high level of energy consumption. The situation is further complicated by the introduction in the game of OPEC （organization of petroleum exporting countries） causing oil prices dropped below the cost of shale oil. The future of high technology in the production of oil depends on whether exporters and importers to negotiate the best price for oil, to ensure the sustainable development of the world economy.
基金supported by Major Projects of Oil and Gas of China (No. 2011ZX05018-002)
文摘Unconventional hydrocarbon resources, which are only marginally economically explored and developed by traditional methods and techniques, are different from conventional hydrocarbon resources in their accumulation mechanisms, occurrence states, distribution models, and exploration and development manners. The types of unconventional hydrocarbon are controlled by the evolu- tion of the source rocks and the combinations of different types of unconventional reservoirs. The fundamental dis- tinction between unconventional hydrocarbon resources and conventional hydrocarbon resources is their non- buoyancy-driven migration. The development of the micro- to nano-scale pores results in rather high capillary resis- tance. The accumulation mechanisms of the unconven- tional and the conventional hydrocarbon resources are also greatly different. In conventional hydrocarbon resources, oil and gas entrapment is controlled by reservoir-forming factors and geological events, which is a dynamic balance process; while for unconventional hydrocarbon resources, the gas content is affected by the temperature and pressure fields, and their preservation is crucial. Unconventional and conventional hydrocarbons are distributed in an orderly manner in subsurface space, having three distribution models of intra-source rock, basin-centered, and source rock interlayer. These results will be of great significance to unconventional hydrocarbon exploration.
文摘Commercial production of unconventional oil and gas resources will not be easily achieved without large-scale engineering measures,let alone the additional operation cost,increasingly stricter requirement for safety and environment,fluctuating low oil and gas prices,etc.,defeating the confidence of those investors.Therefore,unconventional measures are urgently needed to guide the exploration and exploitation of unconventional oil and gas resources.Thus,we put forward the concept of joint exploration and development by integrating research methodologies and operating techniques for a variety of oil and gas resources to simultaneously achieve analysis,construction,gathering and exploitation of multiple hydrocarbon sources.In this way,the annoying interference between the produced mixture of hydrocarbon flow resulting in the reduction of single-well flowrate will be possibly turned into a dynamic mutual force to enhance the well's flowrate.We also point out that the inevitability of joint exploration and development is determined by the occurrence conditions of oil and gas resources,its feasibility relies on the advancement of technologies,and its arduous and long-term nature is attributed to the current energy market and environment.In spite of various problems and difficulties,we believe that joint exploration and development will be a feasible option to achieve both cost reduction and production&benefit enhancement,boost investors'confidence,raise energy comprehensive utilization,and enhance energy supply efficiency.In conclusion,the advantages of joint exploration and development outweigh its disadvantages for both countries and enterprises.
基金supported by the National Natural Science Foundation of China(No.U22B6004)the Basic Research and Strategic Reserve Technology Research Project of CNPC(No.2020D-5008-01)the Scientific Research and Technology Development Project of PetroChina Exploration&Development Research Institute(Nos.2021DJ0104 and 2021DJ1808)。
文摘Controlled by fluctuating paleoclimates and sedimentary environments,the organic and inorganic features of the Lucaogou Formation exhibit strong heterogeneity in the vertical profile,challenging conventional geological interpretation.To elucidate the possible influence of heterogeneity on resource evaluation,a high-resolution sampling approach was applied to an 86.2 cm long core from the Lucaogou Formation of the Jimsar sag in the Junggar Basin.86 sets of samples were micro-drilled from the core and subjected to comparative Rock-Eval pyrolysis.Following the classical guidelines,the organic abundance,kerogen type,and maturity of source rocks were exhaustively analyzed.Experimental results revealed that organic richness and composition vary significantly under different sedimentary backgrounds,which in turn leads to differential hydrocarbon generation.The combination of hydrocarbon generation,transport,and expulsion results in peculiar patterns for hydrocarbon accumulation in the Lucaogou Formation.Laminated shales in the Lucaogou Formation serve as both hydrocarbon source rocks and reservoirs,with laminae being migration pathways.Organic-rich dolomites in the Lucaogou Formation have a considerable hydrocarbon-generating capacity and present the characteristics of self-generation and self-storage.However,massive mudstones act purely as hydrocarbon source rocks.
文摘The Early Paleocene to Middle Eocene Apollonia Formation in the BED‒9 field has been particularly interesting for unconventional hydrocarbon exploration since its discovery in 2006.However,the multiscale compositional and diagenetic inconsistencies present challenges for its characterization.This study aims to evaluate the petrophysical properties of the Apollonia Formation to locate the sweet-spot intervals.Moreover,it seeks to investigate reservoir rock types(RRTs),depositional settings,and the impact of diagenesis on reservoir quality.The findings of this study are as follows.1)The Apollonia A5 and C1 units are identified as"sweet-spot"intervals.Their effective porosity ranges from 18%to 35%,average permeability varies from 0.1 to 2.0 mD,and water saturation falls between 40%and 50%,indicating good reservoir quality.2)High-order eustatic sea-level changes and repetitive climatic change cycles significantly influence the alternating carbonate productivity and dilution cycles.Five distinct RRTs are classified,denoting a gradational facies change from clean,argillaceous,and carbonaceous chalky limestone to marl and interbedded shale intervals.3)Interpreting the electro-facies responses,collated with microfacies variations and faunal content,deepens our understanding of the depositional environment,which extends from the inner to outer-shelf setting.4)The diagenetic processes have a dual impact that enhances and diminishes the reservoir quality.Finally,the gap in evaluating the petrophysical characteristics of all the Apollonia members has been addressed based on integrating the petrophysical and facies analysis for A,B,and C members.The Apollonia Formation has unique characteristics as an unconventional hydrocarbon resource.
文摘As a milestone of the entire energy industry,unconventional resources have inevitably swept the world in the last decade,and will certainly dominate the global oil and gas industry in the near future.Eventually,the ＂unconventional＂ will become ＂conventional＂.Along with the rapid development,however,some issues have emerged,which are closely related to the viability of unconventional resources development.Under the current circumstances of low crude oil and gas price,coupled with the prominent environmental concerns,the arguments about the development and production of unconventional resources have been recently heated up.This work introduced the fullblown aspects of unconventional resources especially shale reservoirs,by discussing their concepts and definitions,reviewing the shale gas and shale oil development history and necessity,analyzing the shale plays＇ geology and petroleum systems with respects to key hydrocarbon accumulation elements and mechanisms,and summarizing the technology resolution.This study also discussed the relevant key issues,including significant estimation uncertainty of technically recoverable resources,the equivocal understanding of complex geology preventing the production and technologies implementation optimization,the difficulties of experiences and technologies global expanding,and the corresponding risks and uncertainties.In addition,based on the latest production and exploration data,the future perspective of the unconventional resources was depicted from global unconventional resources assessments,technology development,and limitations constraining the development.
基金supported by the Project of Basic Science Center for the National Natural Science Foundation of China(72088101)。
文摘Unconventional oil and gas resources have become the most important and realistic field for increasing China’s domestic oil and gas reserves and production.At present,the production scale does not match the massive amount of resources and the rapid growth of proven geological reserves.The challenges of technology,cost,management,and methodology restrict large-scale and economic development.Based on successful practices,a"one engine with six gears"system engineering methodology is put forward,which includes life-cycle management,overall synergy,interdisciplinary cross-service integration,marketoriented operation,socialized support,digitalized management,and low-carbon and green development.The methodology has been proved to be effective in multiple unconventional oil and gas national demonstration areas,including the Jimusar continental shale oil demonstration area.Disruptive views are introduced-namely,that unconventional oil and gas do not necessarily yield a low return,nor do they necessarily have a low recovery factor.A determination to achieve economic benefit must be a pervasive underlying goal for managers and experts.Return and recovery factors,as primary focuses,must be adhered to during China’s development of unconventional oil and gas.The required methodology transformation includes a revolution in management systems to significantly decrease cost and increase production,resulting in technological innovation.
基金Supported by the Major Science and Technology Projects of China National Petroleum Corporation(2023ZZ07-01,2023ZZ07-02,2023ZZ07-03,2023ZZ07-05)。
文摘Based on commercial databases from S&P Global and Rystad Energy and public information from oil companies around the world,a systematic analysis has been conducted on the global hydrocarbon exploration investment,award of exploration blocks,exploratory drilling,new conventional oil and gas discoveries,and exploration of associated resources in 2023.In 2023,the global hydrocarbon exploration investment increased steadily and the total number and area of awarded exploration blocks increased significantly.The decline in the number and success rate of high-impact exploration wells directly affected the quantity of additional oil and gas reserves discovered globally in 2023.In recent years,the deepwater areas of passive margin basins have been the major targets for seeking medium-and large-sized conventional oil and gas fields.In 2023,however,the newly discovered onshore reserves were equivalent to the newly discovered offshore reserves,and fine exploration in mature blocks achieved significant results.Oil companies continued to plan and perform unconventional oil and gas exploration activities and accelerated access to associated mineral resources such as natural hydrogen and helium and other emerging industries.For Chinese oil companies international exploration business,it is recommended to:(1)continue the upstream investment to strengthen upstream services for consolidating the strategic position of oil and gas resources;(2)uphold oil and gas exploration activities by further deploying exploration activities in the deepwater areas of passive margin basins,deeply exploring mature basins,closely following hotspot basins,and gaining access to frontier basins;(3)follow the principle of integrated development to plan the exploration of associated resources while exploiting conventional and unconventional resources;and(4)make technological innovations to develop and improve core technologies and promote the application of artificial intelligence.
基金the Science Foundation of China University of Petroleum,Beijing(Grant No.2462024YJRC021)the National Natural Science Foundation of China(Grant No.U24B2031 and 52104013).
文摘1.Introduction With the increasing demand for petroleum and natural gas resources,along with technological advancements in exploration and production,the primary frontier of oil and gas resources has shifted from conventional oil and gas development to the domains of“Two Deeps,One Unconventional,One Mature,”which include deep onshore,deepwater,unconventional resources,and mature oilfields[1].
基金Petro China Scientific Research and Technology Development Project(2021DJ3101,2022-FW-041)。
文摘The global exploration investment, new oil and gas discoveries, exploration business adjustment strategies of oil companies in 2021, and future favorable exploration domains are systematically analyzed using commercial databases such as IHS and public information of oil companies. It has been found that the world oil and gas exploration situation in 2021 has continued the downturn since the outbreak of COVID-19. The investment and drilling workload decreased slightly, but the success rate of exploration wells, especially deepwater exploration wells, increased significantly, and the newly discovered reserves increased slightly compared with last year. Deep waters of the passive continental margin basins are still the leading sites for discovering conventional large and medium-sized oil and gas fields. The conventional oil and gas exploration in deep formations of onshore petroliferous basins has been keeping a good state, with tight/shale oil and gas discoveries made in Saudi Arabia, Russia, and other countries. While strengthening the exploration and development of local resources, national, international, and independent oil companies have been focusing on major overseas frontiers using their advantages, including risk exploration in deep waters and natural gas. Future favorable exploration directions in the three major frontiers, the global deep waters, deep onshore formations, and unconventional resources, have been clarified. Four suggestions are put forward for the global exploration business of Chinese oil companies: first, a farm in global deepwater frontier basins in advance through bidding at a low cost and adopt the “dual exploration model” after making large-scale discoveries;second, enter new blocks of emerging hot basins in the world through farm-in and other ways, to find large oil and gas fields quickly;third, cooperate with national oil companies of the resource host countries in the form of joint research and actively participate exploration of deep onshore formations of petroliferous basins;fourth, track tight/shale oil and gas cooperation opportunities in a few countries such as Saudi Arabia and Russia, and take advantage of mature domestic theories and technologies to farm in at an appropriate time.
基金This work is funded by the Ministry of Science and Technology of the People's Republic of China(Grant No.2017YFC0307603)the China Geological Survey(Grant No.DD20190234 and HD-JJHT-20).
文摘With the implementation of the production tests in permafrost and offshore regions in Canada,US,Japan,and China,the study of natural gas hydrate has progressed into the stage of technology development for industrial exploitation.The depressurization method is considered as a better strategy to produce gas from hydrate reservoirs based on production tests and laboratory experiments.Multi-well production is proposed to improve gas production efficiency,to meet the requirement for industrial production.For evaluating the applicability of multi-well production to hydrate exploitation,a 2D model is established,with numerical simulations of the performance of the multi-well pattern carried out.To understand the dissociation behavior of gas hydrate,the pressure and temperature distributions in the hydrate reservoir are specified,and the change in permeability of reservoir sediments is investigated.The results obtained indicate that multi-well production can improve the well connectivity,accelerate hydrate dissociation,enhance gas production rate and reduce water production as compared with single-well production.
基金supported by the National Natural Science Foundation of China(Nos.52222403,52074333,52120105007)Taishan Scholar Young Expert(No.tsqn202211079)。
文摘Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.
文摘China is a top world producer of coal resources with numerous coal-rich basins country-wide that also contain coalbed methane(CBM),an unconventional natural gas resource.Recent exploration of coal and CBM resources has also led to the discovery of rare,precious,and scattered metal minerals,including sandstone-type U and Ga–Ge–Li.High-grade and industrial-value deposits have been discovered in the Ordos,Junggar,and other basins across China during exploration for coal resources.Application of coordinated exploration theories and techniques in multiple energy and coal-associated ore deposits,such as coal and unconventional natural gas in coal,achieves efficient and practical exploration of natural resources.Based on the systematic study of accumulation and occurrence of coal and coal-associated mineral resources in coal basins,the basic idea of coordinated exploration for coal and coal-associated deposits is proposed,and multi-targets and multi-methods based on a coordinated exploration model of coal-associated deposits is developed.Coordinated exploration expands the main exploration objective from coal seams to coal-associated series,extending the exploration target from targeting coal only to coal-associated deposits.Entrance times for exploration are decreased to realize coordinated exploration for coal,unconventional natural gas and syngenetic/associated mineral resources in coal by implementing a’one-time approach’―one time in and out of a coal seam to minimize disturbance and time needed for extraction.According to the differences of geological background in China’s coal basins,four coordinated exploration model types,including co-exploration of coal and coal-associated unconventional natural gas,coal and solid minerals,coal and metal minerals,and coal with water resources are established.Other models discussed include a multi-target coordinated exploration model for the combination of coal,coal-associated gas,solid minerals,and metal minerals accordingly.The exploration techniques of coal and coal-associated resources include regional geological investigation and research and synthetic application of other techniques including seismic surveys,drilling,logging,and geochemical exploration.Particularly,applying the’multi-purpose drill hole’or reworking coalfield drill holes into parameter wells,adding sample testing and logging wells,determining gas-bearing layers by logging and gas content measurement,jointly measuring multiple logging parameters,sampling,and testing of coal-strata help in the exploration and evaluation of coal resources,coal-associated unconventional natural gas resources,and coal-associated element minerals.Accordingly,a system of integrated Space–Air–Ground exploration techniques for coordinated exploration of coal and coal-associated minerals is established.This includes high-resolution,hyperspectral remote-sensing technique,high-precision geophysical exploration and fast,precise drilling,testing of experimental samples,as well as coordinated exploration and determination methods of multi-target factors,multi-exploration means,multi-parameter configuration and optimization,big data fusions and interpretation techniques.In recent years,the application of this integrated system has brought significant breakthroughs in coal exploration in Inner Mongolia,Xinjiang and other provinces,discovering several large,ten-billionton coalfields,such as the Eastern Junggar and Tuha basins,and also in exploration and development of CBM from lowrank coals in Fukang,Xinjiang,discovery the Daying U Deposit in Inner Mongolia,the Junggar Ultralarge Ga Deposit,Lincang,Yunnan,and the Wulantuga,Inner Mongolia,Ge-bearing coal deposits,and the Pingshuo Ultralarge Li–Ge Deposit.
文摘This manuscript introduces a new decline curve analysis(DCA) technique to analyze and predict the potentials of hydraulically fractured unconventional resources.The new approach relies on the ratenormalized flow rate derivative(RNFD) concept.It uses the significant constant behavior of the RNFD that identifies the power-law type flow regime models of fractured reservoirs.This technique merges the RNFD with a new numerical model for the flow rate derivative(flow rate noise-reducing derivative model).The concept of the RNFD [1/q(txq')] is developed based on the power-law type analytical models of the flow regimes that can be characterized from the production history of gas or oil-producing wells.The production rate,cumulative production,and the calculated RNFDs from the production history are used for this purpose.The constant RNFD values and the flow rate derivative's numerical model can be used to simulate the production history or predict future performance.The impact of the skin factor is introduced to the approach by developing new RNFD models that could replace the constant pattern of RNFD when this impact does not exist.For a severe condition of skin factor,the RNFD shows a linear relationship with time instead of the constant value.The proposed approach gives an excellent match with the production history of the case studies examined in this study.The transition between flow regimes does not impact the application of the RNFD,i.e.,the calculations move very smoothly throughout the flow regime.The novelty of the proposed technique is represented by introducing an approach for the DCA that considers the observed flow regimes during the production history and the impact of the skin factor.The approach proposes new numerical flow rate and cumulative production models to predict future performance as well as new models for estimating the impact of skin factors on production history,especially for early time flow regimes.
基金This work is granted by the China State Lithologic Key Program(grant no.2017ZX05001-002-002).
文摘Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100~300-m-thick dark shale,mudstone and limestone encountered in the lower third member of the Eocene Shahejie Formation(Es3l member)in Zhanhua Sag,Bohai Bay Basin,eastern China,routine core analysis,thin sectioning,scanning electron microscopy(SEM),mineralogical and geochemical measurements were used to understand detailed facies characterization and paleoclimate in the member.This Es3l shale sediment includes three sedimentary cycles(C3,C2 and C1),from bottom to top,with complex sedimentary characters and spatial distribution.In terms of the composition,texture,bedding and thickness,six lithofacies are recognized in this succession.Some geochemical parameters,such as trace elements(Sr/Ba,Na/Al,V/Ni,V/(V+Ni),U/Th),carbon and oxygen isotopes(δ^(18)O,δ^(13)C),and total organic carbon content(TOC)indicate that the shales were deposited in a deep to semi-deep lake,with the water column being salty,stratified,enclosed and reductive.During cycles C3 and C2 of the middle-lower sections,the climate was arid,and the water was salty and stratified.Laminated and laminar mudstone-limestone was deposited with moderate organic matter(average TOC 1.8%)and good reservoir quality(average porosity 6.5%),which can be regarded as favorable reservoir.During the C1 cycle,a large amount of organic matter was input from outside the basin and this led to high productivity with a more humid climate.Massive calcareous mudstone was deposited,and this is characterized by high TOC(average 3.6%)and moderate porosity(average 4%),and provides favorable source rocks.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42002133,42072150)the Strategic Cooperation Project of Petro China and CUPB(Grant No.ZLZX2020-01-06-01)the Science Foundation of China University of Petroleum,Beijing(Grant No.2462021YXZZ003)。
文摘Unconventional oil and gas resources require petrophysical logs to answer the question of how best to optimize geological and engineering‘sweet spots'.Therefore,the establishment of a key well with comprehensive descriptions of lithology,reservoir properties,hydrocarbon-bearing properties,electronic well log responses,source rock properties,brittleness,and in situ stress magnitude and direction is important for the effective exploration and production of unconventional hydrocarbon resources.Cores,thin sections,scanning electron microscopy(SEM)and comprehensive well log suites are used to build a key well for the Permian Lucaogou Formation,Jimusar Sag of the Junggar Basin.The results show that there are three main types of lithologies,including siltstone,mudstone and dolostone.Lithologies can be predicted using the combination of conventional well and image logs.The pore spaces consist of interparticle pores,intragranular dissolution pores and micropores.Nuclear Magnetic Resonance(NMR)T_(2)components longer than 1.7 ms are superposed as effective porosity.Permeability is calculated using the Coates model from NMR T_(2)spectra.The ratio of T_(2)components>7.0 ms to T_(2)components>0.3 ms is used to calculate oil saturation.TOC is calculated using theΔlog R method.Brittleness index is calculated using Poisson-Young's method,ranging from 13.42%-70.53%.In situ stress direction is determined,and in situ stress magnitudes(maximum horizontal stress SH_(max),minimum horizontal stress Sh_(min),vertical stress S_(v))are calculated using density and sonic logs.The strike-slip stress type(SH_(max)>S_(v)>Sh_(min))is encountered.The key well which comprehensively includes the above seven properties is established.Geological and engineering(geomechanical)‘sweet spots'are then optimized from the key well by fully analyzing lithology,reservoir property,oilbearing potential,in situ stress magnitude and brittleness.It is hoped that the results support engineers'and geologists'decisions for the future exploitation of unconventional hydrocarbon resources.
基金financially supported by the National Natural Science Foundation of China(grant No.41402219)
文摘The world＇s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world＇s second largest production and consumption center of liquid fuel, and is also the world＇s largest natural gas producer. In 2016, the Americas had 85.3 billion tons of proven oil reserves and 18.7 trillion m3 of proven natural gas reserves, which account for 35.4% and 10.0% of world＇s total reserves, respectively. It produced 1267.1 Mt of oil and 1125.4 billion m3 of natural gas, which account for 28.9% and 31.7% of the world＇s total production, respectively. The crude oil and natural gas reserves are mainly distributed in the U.S., Canada and Venezuela. The U.S. is the earliest and most successful country in shale gas exploration and development, and its shale gas is concentrated in the southern, central and eastern U.S., including the Marcellcus shale, Barnett shale, EagleFord shale, Bakken shale, Fayettevis shale, Haynsvill shale, Woodford shale and Monterey/Santos shale. The potential oil and gas resources in the Americas are mainly concentrated in the anticline and stratigraphic traps in the Middle- Upper Jurassic slope deposition of the North Slope Basin, the Paleozoic Madsion group dolomite and limestone in the Williston Basin, dominant stratigraphic traps and few structural traps in the Western Canada Sedimentary Basin, the Eocene structural-stratigraphic hydrocarbon combination, structural- unconformity traps and structural hydrocarbon combination, and the Upper Miocene stratigraphic- structural hydrocarbon combination in the Maracaibo Basin of Venezuela, the stratigraphic-structural traps and fault horst, tilting faulted blocks and anticlines related to subsalt structure and basement activity in the Campos Basin, the subsalt central low-uplift belt and supra-salt central low-uplift belt in the Santos Basin of Brazil, and the structural-stratigraphic traps in the Neuquen Basin of Argentina. In addition, the breakthrough of seismic subsalt imaging technology makes the subsalt deepwater sea area of eastern Barzil an important oil and gas potential area.
文摘Shale gas is a practical resource with great potential that could be economically explored and developed in the near future. It has been commercially developed in North America and other places. Featuring a vast distribution, a low abundance,unfavorable reservoir conditions, ultra-low permeability and a fast production decline, shale gas is more difficult to develop than conventional natural gas, as it needs advanced drilling and completion technology to develop. During the early stage of shale gas exploration and development, the United States offered enterprises necessary incentives such as tax reductions and exemptions and subsidies to achieve sustainable shale gas development and encourage technological progresses. By comparing the state of China's shale gas development with that of the US' in terms of geological conditions, production technology,market price, tax relief, subsidy periods and amount, this paper intends to put forward related suggestions for the effective development of shale gas according to the current status of development.
