Located in the Sichuan Basin,the Yuanba Gasfield is the deepest marine sour gasfield among those developed in China so far.Its biohermal gas reservoir of the Upper Permian Changxing Fm is characterized by ultra depth,...Located in the Sichuan Basin,the Yuanba Gasfield is the deepest marine sour gasfield among those developed in China so far.Its biohermal gas reservoir of the Upper Permian Changxing Fm is characterized by ultra depth,high content of hydrogen sulfide,mediumelow porosity and permeability,and small reservoir thickness.Economic evaluation on it shows that horizontal well drilling is the only way to develop this gas reservoir efficiently and to reduce the total development investment.At present,the petroleum engineering technology for this type of ultra-deep sour gas reservoir is less applied in the world,so an ultra-deep horizontal well is subject to a series of petroleum engineering technology difficulties,such as safe and fast well drilling and completion,mud logging,well logging,downhole operation,safety and environmental protection.Based on the successful development experience of the Puguang Gasfield,therefore,Sinopec Southwest Petroleum Engineering Co.,Ltd.took the advantage of integrated engineering geology method to carry out specific technical research and perform practice diligently for 7 years.As a result,18 key items of technologies for ultra-deep sour gas reservoirs were developed,including horizontal-well drilling speed increasing technology,horizontal-well mud logging and well logging technology,downhole operation technology,and safety and environmental protection technology.These technologies were applied in 40 wells during thefirst and second phases of productivity construction of the Yuanba Gasfield.All the 40 wells have been built into commercial gas wells,and the productivity construction goal of 3.4 billion m3 purified gas has also been achieved.These petroleum engineering technologies for ultra-deep sour gasfields play a reference role in exploring and developing similar gas reservoirs at home and abroad.展开更多
Data-driven approaches and artificial intelligence(AI)algorithms are promising enough to be relied on even more than physics-based methods;their main feed is data which is the fundamental element of each phenomenon.Th...Data-driven approaches and artificial intelligence(AI)algorithms are promising enough to be relied on even more than physics-based methods;their main feed is data which is the fundamental element of each phenomenon.These algorithms learn from data and unveil unseen patterns out of it The petroleum industry as a realm where huge volumes of data are generated every second is of great interest to this new technology.As the oil and gas industry is in the transition phase to oilfield digitization,there has been an increased drive to integrate data-driven modeling and machine learning(ML)algorithms in different petroleum engineering challenges.ML has been widely used in different areas of the industry.Many extensive studies have been devoted to exploring AI applicability in various disciplines of this industry;however,lack of two main features is noticeable.Most of the research is either not practical enough to be applicable in real-field challenges or limited to a specific problem and not generalizable.Attention must be given to data itself and the way it is classified and stored.Although there are sheer volumes of data coming from different disciplines,they reside in departmental silos and are not accessible by consumers.In order to derive as much insight as possible out of data,the data needs to be stored in a centralized repository from where the data can be readily consumed by different applications.展开更多
Petroleum engineering service is one of the pillars that support the petroleum industry in China. Being one of CNPC’s main businesses, the sector has always been escorting the Group to realize its strategic goals. Si...Petroleum engineering service is one of the pillars that support the petroleum industry in China. Being one of CNPC’s main businesses, the sector has always been escorting the Group to realize its strategic goals. Since a new round of specialized re-structuring in 2007, the sector has been promoting all its展开更多
Major bottlenecks in the development of the sector Compared with foreign peers, the sector still lags behind in capacity and performance, reflecting the sector needs to do more in improving technology innovation abili...Major bottlenecks in the development of the sector Compared with foreign peers, the sector still lags behind in capacity and performance, reflecting the sector needs to do more in improving technology innovation ability, setting up favorable mechanism and investing more in technology research. The current situation indicates that the following factors have been affecting the development of the sector.展开更多
In Ref.[1],Eq.(8)has a typo,the following replacement should be done.γ_(bb)/2rδ/δr(rδ(r,t)/δr=2γ_(bb)/R_(bb)-Þ(t,t)-Ⅱ[h[r,t)](bubble=drop-bubble=drop)The publisher regrets an error in the original–article...In Ref.[1],Eq.(8)has a typo,the following replacement should be done.γ_(bb)/2rδ/δr(rδ(r,t)/δr=2γ_(bb)/R_(bb)-Þ(t,t)-Ⅱ[h[r,t)](bubble=drop-bubble=drop)The publisher regrets an error in the original–article,and the sentence that explained the equation“Eqs.(8)–(10)show the augmented Young–Laplace equation for the interactions of gas bubbles or liquid droplets in different configurations,where Rb is the bubble/drop radius,Rp is the particle radius,Rbp=(1/Rb+1/Rp)1.展开更多
Natural gas hydrates(hereinafter referred to as hydrates)are a promising clean energy source.However,their current development is far from reaching commercial exploitation.Reservoir stimulation tech-nology provides ne...Natural gas hydrates(hereinafter referred to as hydrates)are a promising clean energy source.However,their current development is far from reaching commercial exploitation.Reservoir stimulation tech-nology provides new approaches to enhance hydrate development effectiveness.Addressing the current lack of quantitative and objective methods for evaluating the fracability of hydrate reservoirs,this study clarifies the relationship between geological and engineering fracability and proposes a comprehensive evaluation model for hydrate reservoir fracability based on grey relational analysis and the criteria importance through intercriteria correlation method.By integrating results from hydraulic fracturing experiments on hydrate sediments,the fracability of hydrate reservoirs is assessed.The concept of critical construction parameter curves for hydrate reservoirs is introduced for the first time.Additionally,two-dimensional fracability index evaluation charts and three-dimensional fracability construction condition discrimination charts are established.The results indicate that as the comprehensive fracability index increases,the feasibility of forming fractures in hydrate reservoirs improves,and the required normalized fracturing construction parameters gradually decrease.The accuracy rate of the charts in judging experimental results reached 89.74%,enabling quick evaluations of whether hydrate reservoirs are worth fracturing,easy to fracture,and capable of being fractured.This has significant engineering implications forthehydraulicfracturingof hydratereservoirs.展开更多
Casing deformation is a widespread problem in a certain block of Jiaoshiba Shale Gas Field in Sichuan Basin,China,and it severely limits the development benefits of shale gas in that block.Based on the spatiotemporal ...Casing deformation is a widespread problem in a certain block of Jiaoshiba Shale Gas Field in Sichuan Basin,China,and it severely limits the development benefits of shale gas in that block.Based on the spatiotemporal characteristics of block formation,fracture development,and casing deformation occurrence,this paper employs an integrated geological—engineering research approach to identify the primary mechanisms governing casing deformation within the block and proposes countermeasures to prevent such deformation.The present research indicates the following findings:(1)The block has undergone multiple phases of tectonic superposition,with fracture development serving as the geological factor causing casing deformation.(2)Fracturing activation constitutes the engineering factor causing casing deformation,with 4 mm of formation slip inducing deformation.(3)The fracture activation risk map shows that Class Ⅰ and Class Ⅱ fractures account for 73.36%of the total recorded in the block.Within the most susceptible Class I risk zone,the critical activation pressure increment for fracturing operations ranges from 13.43 MPa to 13.99 MPa.Based on the distribution of casing failure risk zones identified in the fracture activation risk map,this paper proposes relevant technical countermeasures for preventing casing failure from three perspectives:shale gas well location deployment,drilling techniques,and fracturing techniques.These measures provide robust support for safeguarding the integrity of casing systems within the studied block.展开更多
Antarctica contains numerous scientific mysteries,and the Antarctic ice sheet and its underlying bedrock contain important information about the geological structure of Antarctica and the evolutionary history of the i...Antarctica contains numerous scientific mysteries,and the Antarctic ice sheet and its underlying bedrock contain important information about the geological structure of Antarctica and the evolutionary history of the ice sheet.In order to obtain the focus of these scientific explorations,the Antarctic drilling engineering is constantly developing.The drilling fluid performance directly determines the success or failure of drilling engineering.In order to enhance the poor performance for drilling fluids due to poor dispersion stability and easy settling of organoclay at ultra-low temperatures,the small-molecule wetting agent(HSR)for drilling fluid suitable for Antarctica was prepared by oleic acid,diethanolamine and benzoic acid as raw materials.Its chemical structure,properties and action mechanism were investigated by various experimental methods.The experimental results showed that 2%HSR could improve the colloidal rate for drilling fluid from 6.4%to 84.8%,and the increase rate of yield point was up to 167%.Meanwhile,it also made the drilling fluid excellent in shear dilution and thixotropy.In addition,2%HSR could increase the density from 0.872 to 0.884 g/cm^(3) at-55 ficial.And the drilling fluid with 2%HSR had a good thermal conductivity of 0.1458 W/(m·K)at-55 ficial.This study gives a new direction for the research of drilling fluid treatment agents suitable for the Antarctic region,which will provide strong support for the scientific exploration of the Antarctic region.展开更多
As the well drilling depth has broken through the 10,000 m in China,accurate measurements of downhole engineering parameters,such as annulus temperature and pressure for the whole wellbore,are significant in controlli...As the well drilling depth has broken through the 10,000 m in China,accurate measurements of downhole engineering parameters,such as annulus temperature and pressure for the whole wellbore,are significant in controlling potential downhole complexities.In this present work,a new micro-measurer is developed by integrating measurements of downhole temperature,pressure,magnetic field strength,and its own dynamic signals.The micro-measurer can flow with drilling fluid from the drillstring to the bottomhole and then float up back to the ground via the wellbore annulus.Compared with other downhole measurement tools that are fixedly connected to the drill string,its“measure-and-move-on”approach reduces the residence time in the high-temperature and high-pressure zone at the bottomhole;moreover,both the pressure and temperature at different well depth can be measured,thereby the temperature and pressure profiles of the whole wellbore can be constructed.In addition,the bluetooth low energy(BLE)technique is applied to offer the micro-measurer with the capability of wireless information transmission;while hydrodynamic optimization of the micro-measurer is carried out to design the structure of the micro-measurer,which can promote its recovery rate from downhole.In addition,an intelligent joint for releasing micro-measurers from the wellbore annulus is also proposed,aiming to overcome the limitation imposed by the nozzle on the size of the micro-measurer.Both the indoor experiments and the field tests have verified the feasibility of the newly designed micro-measurer,which is a key step for establishing a complete downhole internet of things(IoT)system to serve the intelligent drilling in the future.展开更多
Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and ...Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and chemicals.However,studies on the depolymerization and functionalization of challenging super engineering plastics have remained in early stage and underexplored.In this review,we would like to discuss the representative accomplishments and mechanism insights on chemical protocols achieved in depolymerization of super engineering plastics,especially for poly(phenylene sulfide)(PPS),poly(aryl ether)s including poly(ether ether ketone)(PEEK),polysulfone(PSU),polyphenylsulfone(PPSU)and polyethersulfone(PES).We anticipate that this review will provide an overall perspective on the current status and future trends of this emerging field.展开更多
Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagati...Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagation behavior.To address the unclear mechanisms governing fracture penetration across coal-gangue interfaces,this study employs the Continuum-Discontinuum Element Method(CDEM)to simulate and analyze the vertical propagation of hydraulic fractures initiating within coal seams,based on geomechanical parameters derived from the deep Benxi Formation coal seams in the southeastern Ordos Basin.The investigation systematically examines the influence of geological and operational parameters on cross-interfacial fracture growth.Results demonstrate that vertical stress difference,elastic modulus contrast between coal and gangue layers,interfacial stress differential,and interfacial cohesion at coal-gangue interfaces are critical factors governing hydraulic fracture penetration through these interfaces.High vertical stress differences(>3 MPa)inhibit interfacial dilation,promoting predominant crosslayer fracture propagation.Reduced interfacial stress contrasts and enhanced interfacial cohesion facilitate fracture penetration across interfaces.Furthermore,smaller elastic modulus contrasts between coal and gangue correlate with increased interfacial aperture.Finally,lower injection rates effectively suppress vertical fracture propagation in deep coal reservoirs.This study elucidates the characteristics and mechanisms governing cross-layer fracture propagation in coal–rock composites with interbedded partings,and delineates the dynamic evolution laws and dominant controlling factors involved.Thefindings provide critical theoretical insights for the optimization of fracture design and the efficient development of deep coalbed methane reservoirs.展开更多
Identifying geohazards such as landslides and methane leakage is crucial during gas extraction from natural gas hydrate(NGH)reservoirs,and understanding reservoir settlement behavior is central to this assessment.Hori...Identifying geohazards such as landslides and methane leakage is crucial during gas extraction from natural gas hydrate(NGH)reservoirs,and understanding reservoir settlement behavior is central to this assessment.Horizontal wells can enlarge the pressure relief zone within the formation,improving single-well productivity,and are therefore considered a promising approach for NGH development.This study examines the settlement response of hydrate-bearing sediments during depressurization using horizontal wells.A fully coupled thermal,hydraulic,mechanical,and chemical(THMC)model with representative reservoir properties(Shenhu region in the South China Sea)is presented accordingly.The simulations show that lower production pressures,while increasing gas output,also intensify formation settlement.The maximum difference in settlement between the lowest and highest production pressures reaches 0.016 m,contributing to more pronounced differential subsidence.Optimal well placement,specifically targeting a low-saturation hydrate zone containing free gas and situated adjacent to a high-saturation hydrate layer,markedly improves both gas production rate and cumulative yield,while reducing overall settlement and limiting changes in effective stress.展开更多
The increased interest in geothermal energy is evident,along with the exploitation of traditional hydrothermal systems,in the growing research and projects developing around the reuse of already-drilled oil,gas,and ex...The increased interest in geothermal energy is evident,along with the exploitation of traditional hydrothermal systems,in the growing research and projects developing around the reuse of already-drilled oil,gas,and exploration wells.The Republic of Croatia has around 4000 wells,however,due to a long period since most of these wells were drilled and completed,there is uncertainty about how many are available for retrofitting as deep-borehole heat exchangers.Nevertheless,as hydrocarbon production decreases,it is expected that the number of wells available for the revitalization and exploitation of geothermal energy will increase.The revitalization of wells via deep-borehole heat exchangers involves installing a coaxial heat exchanger and circulating the working fluid in a closed system,during which heat is transferred from the surrounding rock medium to the circulating fluid.Since drilled wells are not of uniformdepth and are located in areas with different thermal rock properties and geothermal gradients,an analysis was conducted to determine available thermal energy as a function of well depth,geothermal gradient,and circulating fluid flow rate.Additionally,an economic analysis was performed to determine the benefits of retrofitting existing assets,such as drilled wells,compared to drilling new wells to obtain the same amount of thermal energy.展开更多
With the maturation of coalbed methane(CBM)exploitation and the transition into the late stages of dewatering and gas production,liquid loading in gathering pipelines has emerged as a major constraint on productivity ...With the maturation of coalbed methane(CBM)exploitation and the transition into the late stages of dewatering and gas production,liquid loading in gathering pipelines has emerged as a major constraint on productivity and operational stability.Based on real-time field data and gas-liquid physicochemical analyses,this study elucidates the mechanisms governing liquid loading formation under varying temperature,pressure,and water saturation conditions.An HYSYS model is employed to determine the water dew point,while the Turner model is used to evaluate the critical conditions for liquid holdup.The results indicate that gas water saturation exerts the dominant influence on liquid loading risk,followed by pressure,whereas temperature plays a comparatively minor role.When water saturation exceeds 2%and the operating temperature falls below the dew point,condensation-driven liquid loading increases sharply.To further characterize the spatial distribution of liquid accumulation,a steady-state OLGA model of a DN100 gathering pipeline network is developed to examine the effects of pipe diameter,water saturation,and soil temperature.The simulations show that larger pipe diameters and higher water saturation significantly aggravate liquid holdup,while elevated soil temperature mitigates liquid accumulation.Moreover,the liquid holdup ratio is found to correlate closely with flow regime transitions,confirming its suitability as a key indicator of liquid loading risk.Based on these findings,optimization strategies for pipeline design and operation are proposed.To mitigate liquid loading,the gathering pipeline velocity should be maintained above the critical value of 1.63 m/s,and the gas water content should be strictly controlled below 2%.Under operating conditions representative of the Hancheng block,it is recommended to reduce the pipeline diameter from DN130 to DN100 to enhance self-cleaning capacity.In addition,thermal insulation should be applied during winter operation to maintain the pipe wall temperature above 10◦C,thereby suppressing condensation-induced liquid accumulation.展开更多
1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a u...1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a unique case among them as it evolved into the largest rift basin.The rift basin filling of SB includes Huoshiling Formation,Shahezi Formation,and Yingcheng Formation in ascending order.The mega-rifting was controlled by the Mongol-Okhotsk Collisional Belt to the north and northwest and the Pacific Subduction Zone to the east(Wang PJ et al.,2016).As the first rifting succession,the Huoshiling Formation contains key information about the formation of the rifting basins and records the evolution of the Mongol-Okhotsk Collisional Belt and the Pacific Subduction Zone.However,the geological period of the Huoshiling Formation has not been well constrained for two main reasons.First,it is easily confused with the Yingcheng Formation,as both are dominated by volcanogenic-sedimentary successions.Second,there is lack of reliable dating samples from the uppermost part of the Huoshiling Formation due to its considerable burial depth.展开更多
Carbonate gas reservoirs are often characterized by strong heterogeneity,complex inter-well connectivity,extensive edge or bottom water,and unbalanced production,challenges that are also common in many heterogeneous g...Carbonate gas reservoirs are often characterized by strong heterogeneity,complex inter-well connectivity,extensive edge or bottom water,and unbalanced production,challenges that are also common in many heterogeneous gas reservoirs with intricate storage and flow behavior.To address these issues within a unified,data-driven framework,this study develops a multi-block material balance model that accounts for inter-block flow and aquifer influx,and is applicable to a wide range of reservoir types.The model incorporates inter-well and well-group conductive connectivity together with pseudo–steady-state aquifer support.The governing equations are solved using a Newton–Raphson scheme,while particle swarm optimization is employed to estimate formation pressures,inter-well connectivity,and effective aquifer volumes.An unbalanced exploitation factor,UEF,is introduced to quantify production imbalance and to guide development optimization.Validation using a synthetic reservoir model demonstrates that the approach accurately reproduces pressure evolution,crossflow behavior,and water influx.Application to a representative case(the Longwangmiao)field further confirms its robustness under highly heterogeneous conditions,achieving a 12.9%reduction in UEF through optimized production allocation.展开更多
This study investigates in-station pressure drop mechanisms in a shale gas gathering system,providing a quantitative basis for flow system optimization.Computational fluid dynamics(CFD)simulations,based on field-measu...This study investigates in-station pressure drop mechanisms in a shale gas gathering system,providing a quantitative basis for flow system optimization.Computational fluid dynamics(CFD)simulations,based on field-measured parameters related to a representative case(a shale gas platform located in Sichuan,China)are conducted to analyze the flow characteristics of specific fittings and manifolds,and to quantify fitting resistance coefficients and manifold inlet interference.The resulting coefficients are integrated into a full-station gathering network model in PipeSim,which,combined with production data,enables evaluation of pressure losses and identification of equivalent pipeline blockages.The results indicate that the resistance coefficients,valid only for fittings under the studied field-specific geometries,are 0.21 for 90◦elbows in the fully open position,0.16 for gate valve passages in the fully open position,and 2.3 for globe valve passages.Manifold interference decreases with lower high-pressure inlet values,whereas inlets farther from the high-pressure side experience stronger disturbances.Interestingly,significant discrepancies between simulated and measured pressure drops reveal partial blockages,corresponding to effective diameter reductions of 65 mm,38 mm,44 mm,38 mm,and 28 mm for Wells 1#,3#,5#,and 6#,respectively.展开更多
In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leadi...In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leading to suboptimal reservoir performance.Currently,there is no well-established method for accurately evaluating the effectiveness of such stimulation.This study introduces,for the first time,the concept of the Fracture Network Bridging Coefficient(FNBC)as a novel metric to assess stimulation performance.By quantitatively coupling the proportions of unstimulated and overstimulated volumes,the FNBC effectively characterizes the connectivity and efficiency of the fracture network.A background grid calibration method is developed to quantify the stage-controlled volume,effectively stimulated volume,unstimulated volume,and repeatedly stimulated volume among different stages of horizontal wells.Furthermore,an optimization model is constructed by taking the FNBC as the objective function and the fracturing injection rate and fluid volume as optimization variables.The Simultaneous Perturbation Stochastic Approximation(SPSA)algorithm is employed to iteratively perturb and optimize these variables,progressively improving the FNBC until the optimal displacement rate and fluid volume corresponding to the maximum FNBC are obtained.Field application in a typical CBM multistage fractured horizontal well in China demonstrates that the FNBC increased from 0.358 to 0.539(a 50.6% improvement),with the injection rate rising from 16 m^(3)/min to 24 m^(3)/min and the average fluid volume per stage increasing from 2490 m^(3) to 3192 m^(3),significantly enhancing the stimulation effectiveness.This research provides theoretical support for designing high-efficiency stimulation strategies in unconventional reservoirs under dynamic limits.展开更多
This study integrates experimental investigation with molecular dynamics simulations to elucidate the hydrogen transport mechanisms in polyetheretherketone(PEEK)and polytetrafluoroethylene(PTFE),offering fundamental i...This study integrates experimental investigation with molecular dynamics simulations to elucidate the hydrogen transport mechanisms in polyetheretherketone(PEEK)and polytetrafluoroethylene(PTFE),offering fundamental insights into the barrier properties of high-performance polymeric materials.Experimental results demonstrate that PEEK exhibits superior hydrogen barrier performance compared to PTFE at both ambient and elevated temperatures.However,detailed molecular dynamics simulations uncover a distinctive,enthalpy-driven"high solubility-low diffusivity"transport mechanism:although PEEK displays higher hydrogen solubility due to its stronger thermodynamic affinity,its diffusion coefficient is markedly lower than that of PTFE.This mechanism remains operative across a broad operational temperature range(233 K to358 K),yet its influence on overall permeability is strongly temperature-dependent.At room and high temperatures,the exceptionally low diffusivity of PEEK governs the entire permeation process,establishing its effectiveness as a high-performance hydrogen barrier material.In contrast,under low-temperature conditions(e.g.,233 K),the general suppression of diffusion allows the high solubility of PEEK to dominate,resulting in greater overall permeability than PTFE and giving rise to a performance“reversal”phenomenon.This distinct transport behavior originates from the strong non-covalent interactions between hydrogen molecules and the aromatic rings as well as polar functional groups present in the amorphous regions of PEEK,which simultaneously enhance solubility and impose significant kinetic energy barriers.The"structure-mechanism"correlation framework established in this work provides a robust theoretical foundation for the rational design of next-generation hydrogen barrier materials tailored to specific operational temperature requirements.展开更多
基金supported by the Sinopec Technical Development Project"Pilot Test for Ultra-deep Horizontal Well Acid Fracturing Technology for Marine Reservoirs in Yuanba Gasfield"(No.:GJ-258-1254)Sinopec Group Technical Application Project“Optimization Design of Teas for High-presure High-yield Sour Gas Wells in the Northeaster Sichuan Basin”(No.:JPO8001).
文摘Located in the Sichuan Basin,the Yuanba Gasfield is the deepest marine sour gasfield among those developed in China so far.Its biohermal gas reservoir of the Upper Permian Changxing Fm is characterized by ultra depth,high content of hydrogen sulfide,mediumelow porosity and permeability,and small reservoir thickness.Economic evaluation on it shows that horizontal well drilling is the only way to develop this gas reservoir efficiently and to reduce the total development investment.At present,the petroleum engineering technology for this type of ultra-deep sour gas reservoir is less applied in the world,so an ultra-deep horizontal well is subject to a series of petroleum engineering technology difficulties,such as safe and fast well drilling and completion,mud logging,well logging,downhole operation,safety and environmental protection.Based on the successful development experience of the Puguang Gasfield,therefore,Sinopec Southwest Petroleum Engineering Co.,Ltd.took the advantage of integrated engineering geology method to carry out specific technical research and perform practice diligently for 7 years.As a result,18 key items of technologies for ultra-deep sour gas reservoirs were developed,including horizontal-well drilling speed increasing technology,horizontal-well mud logging and well logging technology,downhole operation technology,and safety and environmental protection technology.These technologies were applied in 40 wells during thefirst and second phases of productivity construction of the Yuanba Gasfield.All the 40 wells have been built into commercial gas wells,and the productivity construction goal of 3.4 billion m3 purified gas has also been achieved.These petroleum engineering technologies for ultra-deep sour gasfields play a reference role in exploring and developing similar gas reservoirs at home and abroad.
文摘Data-driven approaches and artificial intelligence(AI)algorithms are promising enough to be relied on even more than physics-based methods;their main feed is data which is the fundamental element of each phenomenon.These algorithms learn from data and unveil unseen patterns out of it The petroleum industry as a realm where huge volumes of data are generated every second is of great interest to this new technology.As the oil and gas industry is in the transition phase to oilfield digitization,there has been an increased drive to integrate data-driven modeling and machine learning(ML)algorithms in different petroleum engineering challenges.ML has been widely used in different areas of the industry.Many extensive studies have been devoted to exploring AI applicability in various disciplines of this industry;however,lack of two main features is noticeable.Most of the research is either not practical enough to be applicable in real-field challenges or limited to a specific problem and not generalizable.Attention must be given to data itself and the way it is classified and stored.Although there are sheer volumes of data coming from different disciplines,they reside in departmental silos and are not accessible by consumers.In order to derive as much insight as possible out of data,the data needs to be stored in a centralized repository from where the data can be readily consumed by different applications.
文摘Petroleum engineering service is one of the pillars that support the petroleum industry in China. Being one of CNPC’s main businesses, the sector has always been escorting the Group to realize its strategic goals. Since a new round of specialized re-structuring in 2007, the sector has been promoting all its
文摘Major bottlenecks in the development of the sector Compared with foreign peers, the sector still lags behind in capacity and performance, reflecting the sector needs to do more in improving technology innovation ability, setting up favorable mechanism and investing more in technology research. The current situation indicates that the following factors have been affecting the development of the sector.
文摘In Ref.[1],Eq.(8)has a typo,the following replacement should be done.γ_(bb)/2rδ/δr(rδ(r,t)/δr=2γ_(bb)/R_(bb)-Þ(t,t)-Ⅱ[h[r,t)](bubble=drop-bubble=drop)The publisher regrets an error in the original–article,and the sentence that explained the equation“Eqs.(8)–(10)show the augmented Young–Laplace equation for the interactions of gas bubbles or liquid droplets in different configurations,where Rb is the bubble/drop radius,Rp is the particle radius,Rbp=(1/Rb+1/Rp)1.
基金support of the National Natural Science Foundation of China(Grant No.52074332).
文摘Natural gas hydrates(hereinafter referred to as hydrates)are a promising clean energy source.However,their current development is far from reaching commercial exploitation.Reservoir stimulation tech-nology provides new approaches to enhance hydrate development effectiveness.Addressing the current lack of quantitative and objective methods for evaluating the fracability of hydrate reservoirs,this study clarifies the relationship between geological and engineering fracability and proposes a comprehensive evaluation model for hydrate reservoir fracability based on grey relational analysis and the criteria importance through intercriteria correlation method.By integrating results from hydraulic fracturing experiments on hydrate sediments,the fracability of hydrate reservoirs is assessed.The concept of critical construction parameter curves for hydrate reservoirs is introduced for the first time.Additionally,two-dimensional fracability index evaluation charts and three-dimensional fracability construction condition discrimination charts are established.The results indicate that as the comprehensive fracability index increases,the feasibility of forming fractures in hydrate reservoirs improves,and the required normalized fracturing construction parameters gradually decrease.The accuracy rate of the charts in judging experimental results reached 89.74%,enabling quick evaluations of whether hydrate reservoirs are worth fracturing,easy to fracture,and capable of being fractured.This has significant engineering implications forthehydraulicfracturingof hydratereservoirs.
文摘Casing deformation is a widespread problem in a certain block of Jiaoshiba Shale Gas Field in Sichuan Basin,China,and it severely limits the development benefits of shale gas in that block.Based on the spatiotemporal characteristics of block formation,fracture development,and casing deformation occurrence,this paper employs an integrated geological—engineering research approach to identify the primary mechanisms governing casing deformation within the block and proposes countermeasures to prevent such deformation.The present research indicates the following findings:(1)The block has undergone multiple phases of tectonic superposition,with fracture development serving as the geological factor causing casing deformation.(2)Fracturing activation constitutes the engineering factor causing casing deformation,with 4 mm of formation slip inducing deformation.(3)The fracture activation risk map shows that Class Ⅰ and Class Ⅱ fractures account for 73.36%of the total recorded in the block.Within the most susceptible Class I risk zone,the critical activation pressure increment for fracturing operations ranges from 13.43 MPa to 13.99 MPa.Based on the distribution of casing failure risk zones identified in the fracture activation risk map,this paper proposes relevant technical countermeasures for preventing casing failure from three perspectives:shale gas well location deployment,drilling techniques,and fracturing techniques.These measures provide robust support for safeguarding the integrity of casing systems within the studied block.
基金financially supported by the National Natural Science Foundation of China(No.52274021)the National Key Research and Development Program of China(No.2021YFA0719102)。
文摘Antarctica contains numerous scientific mysteries,and the Antarctic ice sheet and its underlying bedrock contain important information about the geological structure of Antarctica and the evolutionary history of the ice sheet.In order to obtain the focus of these scientific explorations,the Antarctic drilling engineering is constantly developing.The drilling fluid performance directly determines the success or failure of drilling engineering.In order to enhance the poor performance for drilling fluids due to poor dispersion stability and easy settling of organoclay at ultra-low temperatures,the small-molecule wetting agent(HSR)for drilling fluid suitable for Antarctica was prepared by oleic acid,diethanolamine and benzoic acid as raw materials.Its chemical structure,properties and action mechanism were investigated by various experimental methods.The experimental results showed that 2%HSR could improve the colloidal rate for drilling fluid from 6.4%to 84.8%,and the increase rate of yield point was up to 167%.Meanwhile,it also made the drilling fluid excellent in shear dilution and thixotropy.In addition,2%HSR could increase the density from 0.872 to 0.884 g/cm^(3) at-55 ficial.And the drilling fluid with 2%HSR had a good thermal conductivity of 0.1458 W/(m·K)at-55 ficial.This study gives a new direction for the research of drilling fluid treatment agents suitable for the Antarctic region,which will provide strong support for the scientific exploration of the Antarctic region.
基金supported by the National Natural Science Foundation of China(No.U22B2072)the Research Project of China Petroleum Science and Technology Innovation Fund(No.2025DQ02-0144).
文摘As the well drilling depth has broken through the 10,000 m in China,accurate measurements of downhole engineering parameters,such as annulus temperature and pressure for the whole wellbore,are significant in controlling potential downhole complexities.In this present work,a new micro-measurer is developed by integrating measurements of downhole temperature,pressure,magnetic field strength,and its own dynamic signals.The micro-measurer can flow with drilling fluid from the drillstring to the bottomhole and then float up back to the ground via the wellbore annulus.Compared with other downhole measurement tools that are fixedly connected to the drill string,its“measure-and-move-on”approach reduces the residence time in the high-temperature and high-pressure zone at the bottomhole;moreover,both the pressure and temperature at different well depth can be measured,thereby the temperature and pressure profiles of the whole wellbore can be constructed.In addition,the bluetooth low energy(BLE)technique is applied to offer the micro-measurer with the capability of wireless information transmission;while hydrodynamic optimization of the micro-measurer is carried out to design the structure of the micro-measurer,which can promote its recovery rate from downhole.In addition,an intelligent joint for releasing micro-measurers from the wellbore annulus is also proposed,aiming to overcome the limitation imposed by the nozzle on the size of the micro-measurer.Both the indoor experiments and the field tests have verified the feasibility of the newly designed micro-measurer,which is a key step for establishing a complete downhole internet of things(IoT)system to serve the intelligent drilling in the future.
基金supported by the National Natural Science Foundation of China(Nos.22125103 and 22301077)STCSM(22JC140100)Shanghai Pujiang Program(No.22PJ1403200)。
文摘Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and chemicals.However,studies on the depolymerization and functionalization of challenging super engineering plastics have remained in early stage and underexplored.In this review,we would like to discuss the representative accomplishments and mechanism insights on chemical protocols achieved in depolymerization of super engineering plastics,especially for poly(phenylene sulfide)(PPS),poly(aryl ether)s including poly(ether ether ketone)(PEEK),polysulfone(PSU),polyphenylsulfone(PPSU)and polyethersulfone(PES).We anticipate that this review will provide an overall perspective on the current status and future trends of this emerging field.
文摘Hydraulic fracturing serves as a critical technology for reservoir stimulation in deep coalbed methane(CBM)development,where the mechanical properties of gangue layers exert a significant control on fracture propagation behavior.To address the unclear mechanisms governing fracture penetration across coal-gangue interfaces,this study employs the Continuum-Discontinuum Element Method(CDEM)to simulate and analyze the vertical propagation of hydraulic fractures initiating within coal seams,based on geomechanical parameters derived from the deep Benxi Formation coal seams in the southeastern Ordos Basin.The investigation systematically examines the influence of geological and operational parameters on cross-interfacial fracture growth.Results demonstrate that vertical stress difference,elastic modulus contrast between coal and gangue layers,interfacial stress differential,and interfacial cohesion at coal-gangue interfaces are critical factors governing hydraulic fracture penetration through these interfaces.High vertical stress differences(>3 MPa)inhibit interfacial dilation,promoting predominant crosslayer fracture propagation.Reduced interfacial stress contrasts and enhanced interfacial cohesion facilitate fracture penetration across interfaces.Furthermore,smaller elastic modulus contrasts between coal and gangue correlate with increased interfacial aperture.Finally,lower injection rates effectively suppress vertical fracture propagation in deep coal reservoirs.This study elucidates the characteristics and mechanisms governing cross-layer fracture propagation in coal–rock composites with interbedded partings,and delineates the dynamic evolution laws and dominant controlling factors involved.Thefindings provide critical theoretical insights for the optimization of fracture design and the efficient development of deep coalbed methane reservoirs.
基金supported by the State Key Research Development Program of China(Grant No.2021YFC2800905-02)the National Natural Science Foundation of China(Grant No.52304208)。
文摘Identifying geohazards such as landslides and methane leakage is crucial during gas extraction from natural gas hydrate(NGH)reservoirs,and understanding reservoir settlement behavior is central to this assessment.Horizontal wells can enlarge the pressure relief zone within the formation,improving single-well productivity,and are therefore considered a promising approach for NGH development.This study examines the settlement response of hydrate-bearing sediments during depressurization using horizontal wells.A fully coupled thermal,hydraulic,mechanical,and chemical(THMC)model with representative reservoir properties(Shenhu region in the South China Sea)is presented accordingly.The simulations show that lower production pressures,while increasing gas output,also intensify formation settlement.The maximum difference in settlement between the lowest and highest production pressures reaches 0.016 m,contributing to more pronounced differential subsidence.Optimal well placement,specifically targeting a low-saturation hydrate zone containing free gas and situated adjacent to a high-saturation hydrate layer,markedly improves both gas production rate and cumulative yield,while reducing overall settlement and limiting changes in effective stress.
文摘The increased interest in geothermal energy is evident,along with the exploitation of traditional hydrothermal systems,in the growing research and projects developing around the reuse of already-drilled oil,gas,and exploration wells.The Republic of Croatia has around 4000 wells,however,due to a long period since most of these wells were drilled and completed,there is uncertainty about how many are available for retrofitting as deep-borehole heat exchangers.Nevertheless,as hydrocarbon production decreases,it is expected that the number of wells available for the revitalization and exploitation of geothermal energy will increase.The revitalization of wells via deep-borehole heat exchangers involves installing a coaxial heat exchanger and circulating the working fluid in a closed system,during which heat is transferred from the surrounding rock medium to the circulating fluid.Since drilled wells are not of uniformdepth and are located in areas with different thermal rock properties and geothermal gradients,an analysis was conducted to determine available thermal energy as a function of well depth,geothermal gradient,and circulating fluid flow rate.Additionally,an economic analysis was performed to determine the benefits of retrofitting existing assets,such as drilled wells,compared to drilling new wells to obtain the same amount of thermal energy.
基金supported by PetroChina Coalbed Methane Co.,Ltd.
文摘With the maturation of coalbed methane(CBM)exploitation and the transition into the late stages of dewatering and gas production,liquid loading in gathering pipelines has emerged as a major constraint on productivity and operational stability.Based on real-time field data and gas-liquid physicochemical analyses,this study elucidates the mechanisms governing liquid loading formation under varying temperature,pressure,and water saturation conditions.An HYSYS model is employed to determine the water dew point,while the Turner model is used to evaluate the critical conditions for liquid holdup.The results indicate that gas water saturation exerts the dominant influence on liquid loading risk,followed by pressure,whereas temperature plays a comparatively minor role.When water saturation exceeds 2%and the operating temperature falls below the dew point,condensation-driven liquid loading increases sharply.To further characterize the spatial distribution of liquid accumulation,a steady-state OLGA model of a DN100 gathering pipeline network is developed to examine the effects of pipe diameter,water saturation,and soil temperature.The simulations show that larger pipe diameters and higher water saturation significantly aggravate liquid holdup,while elevated soil temperature mitigates liquid accumulation.Moreover,the liquid holdup ratio is found to correlate closely with flow regime transitions,confirming its suitability as a key indicator of liquid loading risk.Based on these findings,optimization strategies for pipeline design and operation are proposed.To mitigate liquid loading,the gathering pipeline velocity should be maintained above the critical value of 1.63 m/s,and the gas water content should be strictly controlled below 2%.Under operating conditions representative of the Hancheng block,it is recommended to reduce the pipeline diameter from DN130 to DN100 to enhance self-cleaning capacity.In addition,thermal insulation should be applied during winter operation to maintain the pipe wall temperature above 10◦C,thereby suppressing condensation-induced liquid accumulation.
基金supported by the National Natural Science Foundation of China(42102135,42072140,42202122 and 41790453)Science and Technology Research Program of Chongqing Municipal Education Commission(KJZD-M202101502,KJQN202201549 and KJQN202101535)+1 种基金Natural Science Foundation of Chongqing(CSTB2022NSCQ-JQX0031 and CSTB2022NSCQMSX1586)China Scholarship Council(202208505055)。
文摘1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a unique case among them as it evolved into the largest rift basin.The rift basin filling of SB includes Huoshiling Formation,Shahezi Formation,and Yingcheng Formation in ascending order.The mega-rifting was controlled by the Mongol-Okhotsk Collisional Belt to the north and northwest and the Pacific Subduction Zone to the east(Wang PJ et al.,2016).As the first rifting succession,the Huoshiling Formation contains key information about the formation of the rifting basins and records the evolution of the Mongol-Okhotsk Collisional Belt and the Pacific Subduction Zone.However,the geological period of the Huoshiling Formation has not been well constrained for two main reasons.First,it is easily confused with the Yingcheng Formation,as both are dominated by volcanogenic-sedimentary successions.Second,there is lack of reliable dating samples from the uppermost part of the Huoshiling Formation due to its considerable burial depth.
基金supported by the National Natural Science Foundation of China(No.52104018,52274030)China National Petroleum Corporation(CNPC)Innovation Foundation(No.2024DQ02-0303)China National Petroleum Corporation(CNPC)14th Five-Year Plan Major Strategic Scientific and Technological Project for Prospective and Fundamental Research(2024DJ86).
文摘Carbonate gas reservoirs are often characterized by strong heterogeneity,complex inter-well connectivity,extensive edge or bottom water,and unbalanced production,challenges that are also common in many heterogeneous gas reservoirs with intricate storage and flow behavior.To address these issues within a unified,data-driven framework,this study develops a multi-block material balance model that accounts for inter-block flow and aquifer influx,and is applicable to a wide range of reservoir types.The model incorporates inter-well and well-group conductive connectivity together with pseudo–steady-state aquifer support.The governing equations are solved using a Newton–Raphson scheme,while particle swarm optimization is employed to estimate formation pressures,inter-well connectivity,and effective aquifer volumes.An unbalanced exploitation factor,UEF,is introduced to quantify production imbalance and to guide development optimization.Validation using a synthetic reservoir model demonstrates that the approach accurately reproduces pressure evolution,crossflow behavior,and water influx.Application to a representative case(the Longwangmiao)field further confirms its robustness under highly heterogeneous conditions,achieving a 12.9%reduction in UEF through optimized production allocation.
基金the National Natural Science Foundation of China under Grant 52441411,52325402 and 52274057Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project under Grant 2024ZD1004302-04the National Key R&D Program of China under Grant 2023YFB4104200.
文摘This study investigates in-station pressure drop mechanisms in a shale gas gathering system,providing a quantitative basis for flow system optimization.Computational fluid dynamics(CFD)simulations,based on field-measured parameters related to a representative case(a shale gas platform located in Sichuan,China)are conducted to analyze the flow characteristics of specific fittings and manifolds,and to quantify fitting resistance coefficients and manifold inlet interference.The resulting coefficients are integrated into a full-station gathering network model in PipeSim,which,combined with production data,enables evaluation of pressure losses and identification of equivalent pipeline blockages.The results indicate that the resistance coefficients,valid only for fittings under the studied field-specific geometries,are 0.21 for 90◦elbows in the fully open position,0.16 for gate valve passages in the fully open position,and 2.3 for globe valve passages.Manifold interference decreases with lower high-pressure inlet values,whereas inlets farther from the high-pressure side experience stronger disturbances.Interestingly,significant discrepancies between simulated and measured pressure drops reveal partial blockages,corresponding to effective diameter reductions of 65 mm,38 mm,44 mm,38 mm,and 28 mm for Wells 1#,3#,5#,and 6#,respectively.
基金the financial support from National Natural Science Foundation of China(No.52474029)Strategic and Applied Scientific Research Project of PetroChina Company Limited(2023ZZ18,2023ZZ18YJ04).
文摘In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leading to suboptimal reservoir performance.Currently,there is no well-established method for accurately evaluating the effectiveness of such stimulation.This study introduces,for the first time,the concept of the Fracture Network Bridging Coefficient(FNBC)as a novel metric to assess stimulation performance.By quantitatively coupling the proportions of unstimulated and overstimulated volumes,the FNBC effectively characterizes the connectivity and efficiency of the fracture network.A background grid calibration method is developed to quantify the stage-controlled volume,effectively stimulated volume,unstimulated volume,and repeatedly stimulated volume among different stages of horizontal wells.Furthermore,an optimization model is constructed by taking the FNBC as the objective function and the fracturing injection rate and fluid volume as optimization variables.The Simultaneous Perturbation Stochastic Approximation(SPSA)algorithm is employed to iteratively perturb and optimize these variables,progressively improving the FNBC until the optimal displacement rate and fluid volume corresponding to the maximum FNBC are obtained.Field application in a typical CBM multistage fractured horizontal well in China demonstrates that the FNBC increased from 0.358 to 0.539(a 50.6% improvement),with the injection rate rising from 16 m^(3)/min to 24 m^(3)/min and the average fluid volume per stage increasing from 2490 m^(3) to 3192 m^(3),significantly enhancing the stimulation effectiveness.This research provides theoretical support for designing high-efficiency stimulation strategies in unconventional reservoirs under dynamic limits.
基金financially supported by the National Natural Science Foundation of China(No.5247401)the Research and Technology Development Project of the China National Petroleum Corporation(No.2021DJ5002(JT))。
文摘This study integrates experimental investigation with molecular dynamics simulations to elucidate the hydrogen transport mechanisms in polyetheretherketone(PEEK)and polytetrafluoroethylene(PTFE),offering fundamental insights into the barrier properties of high-performance polymeric materials.Experimental results demonstrate that PEEK exhibits superior hydrogen barrier performance compared to PTFE at both ambient and elevated temperatures.However,detailed molecular dynamics simulations uncover a distinctive,enthalpy-driven"high solubility-low diffusivity"transport mechanism:although PEEK displays higher hydrogen solubility due to its stronger thermodynamic affinity,its diffusion coefficient is markedly lower than that of PTFE.This mechanism remains operative across a broad operational temperature range(233 K to358 K),yet its influence on overall permeability is strongly temperature-dependent.At room and high temperatures,the exceptionally low diffusivity of PEEK governs the entire permeation process,establishing its effectiveness as a high-performance hydrogen barrier material.In contrast,under low-temperature conditions(e.g.,233 K),the general suppression of diffusion allows the high solubility of PEEK to dominate,resulting in greater overall permeability than PTFE and giving rise to a performance“reversal”phenomenon.This distinct transport behavior originates from the strong non-covalent interactions between hydrogen molecules and the aromatic rings as well as polar functional groups present in the amorphous regions of PEEK,which simultaneously enhance solubility and impose significant kinetic energy barriers.The"structure-mechanism"correlation framework established in this work provides a robust theoretical foundation for the rational design of next-generation hydrogen barrier materials tailored to specific operational temperature requirements.
