Currently,unconventional reservoirs are characterized by low single well-controlled reserves,high initial production but fast production decline.This paper sorts out the problems of energy dispersion and limited lengt...Currently,unconventional reservoirs are characterized by low single well-controlled reserves,high initial production but fast production decline.This paper sorts out the problems of energy dispersion and limited length and height of main hydraulic fractures induced in staged multi-cluster fracturing,and proposes an innovative concept of“energy-focused fracturing development”.The technical connotation,theoretical model,and core techniques of energy-focused fracturing development are systematically examined,and the implementation path of this technology is determined.The energy-focused fracturing development technology incorporates the techniques such as geology-engineering integrated design,perforation optimization design,fracturing process design,and drainage engineering control.It transforms the numerous,short and dense hydraulic fractures to limited,long and sparse fractures.It focuses on fracturing energy,and aims to improve the fracture length,height and lateral width,and the proppant long-distance transportation capacity,thus enhancing the single well-controlled reserves and development effect.The energy-focused fracturing development technology has been successfully applied in the carbonate reservoirs in buried hill,shallow coalbed methane reservoirs,and coal-rock gas reservoirs in China,demonstrating the technology's promising application.It is concluded that the energy-focused fracturing development technology can significantly increase the single well production and estimated ultimate recovery(EUR),and will be helpful for efficiently developing low-permeability,unconventional and low-grade resources in China.展开更多
Multiple sets of marine shale sequences occur in western Hubei Province and its adjacent areas within the Middle-Upper Yangtze region,offering substantial resource potential.However,their shale gas preservation condit...Multiple sets of marine shale sequences occur in western Hubei Province and its adjacent areas within the Middle-Upper Yangtze region,offering substantial resource potential.However,their shale gas preservation conditions differ significantly due to the heterogeneous porosity and fracture system resulting from multistage tectonic reworking.This necessitates developing region-specific evaluation systems and exploitation techniques.Drawing on previous application cases and guided by the research paradigm of geology-engineering integration,this study presents key technologies potentially applicable to shales in western Hubei Province,spanning from reservoir and sweet spot evaluation to fractu ring scheme design and fracturing perfo rmance monitoring.Several insights are gained accordingly.In terms of pore evaluation,the pore heterogeneity caused by compaction and rebound can be quantified using ideal shape coefficients and fractal dimensions,both of which are influenced by structural deformations,thereby guiding reservoir classification.For seismic data interpretation,pre-stack elastic inversion and azimuthal anisotropy inversion can be employed as core techniques,overcoming the limitation of individual post-stack attributes in typically detecting only major faults.Furthermore,the inversion boundaries are constrained using log-seismic joint quality control and geomechanical simulation,contributing to enhanced reliability of sweet spot evaluation and efficient exploration in areas with complex structures.For fracturing scheme design,scientifically formulated well shut-in strategies,tailored to regional geological characteristics,are essential to activate the fracture-matrix imbibition effect.Parameters with vastly different scales used in the design,such as meter-scale fracture halflength and millidarcy-scale fracture conductivity,can be co-optimized using artificial intelligence(AI)algorithms such as the genetic algorithm(GA)and the simultaneous perturbation stochastic approximation(SPSA)algorithm.Dynamic monitoring of fracturing performance can be achieved using trace chemical tracer technology,thereby reducing target ambiguity caused by structural complexity.Research on shale gas in the structurally complex areas of western Hubei faces multiple challenges,spanning from basic geological understanding to development engineering.These challenges create an urgent need for deep interdisciplinary collaboration.Therefore,this study highlights research into geology-engineering integration,aiming to enhance the efficiency of shale gas exploration and development in western Hubei.展开更多
The Zhaotong national shale gas demonstration area in Yunnan(hereinafter referred to as demonstration area)is China's third largest national shale gas production base after ChangningeWeiyuan in Sichuan and Fuling ...The Zhaotong national shale gas demonstration area in Yunnan(hereinafter referred to as demonstration area)is China's third largest national shale gas production base after ChangningeWeiyuan in Sichuan and Fuling in Chongqing.And after more than ten years of deep and careful cultivation,a series of important achievements have been obtained in the exploration and development.From the perspective of exploration and development history,theory and technology,this paper systematically summarizes the exploration discovery process and productivity construction progress of shale gas in the demonstration area,expounds the geological exploration theories and key technologies of mountain shale gas,and predicts their development prospect and direction.And the following research results are obtained.First,the exploration and development in the demonstration area has gone through five development stages,and so far,three major productivity construction zones have been formed,including Huangjinba and Zijinba middleedeep shale gas zones and Taiyang shallow shale gas zone,with cumulative proved geological reserves more than 3100×10^(8) m^(3) and cumulative gas production more than 72×10^(8) m^(3).It has been constructed into the third largest green shale gas demonstration base in China.Second,the“multi-field coordination and multi-element coupling”mountain shale gas enrichment,accumulation and occurrence theory of“sedimentary background controlling source rock and reservoir,reworking intensity controlling preservation,and three-dimensional sealing controlling enrichment”is put forward innovatively,and the“three-dimensional sealing system”accumulation model of extrabasinal shallow shale gas is established.Third,a series of zone selection and evaluation technologies for mountain shale gas in strongly reworked complex structural areas have been developed,and the concept of geologyeengineering integration has first been adopted to create transparent shale gas reservoirs and cultivate high-yield wells.A major exploration breakthrough has been achieved from marginal basin medium deep shale gas layers to extrabasin ultra shallow to medium shallow ones,and domestic first large-scale monoblock shallow shale gas field with reserves over 2570×10^(8) m^(3) has been discovered.Fourth,a landmark technological achievement and efficient development model with geologyeengineering integration and shale geomechanical evaluation as the core has been formed,which leads the clean,green and efficient exploration and development of mountain shale gas.In conclusion,it is necessary to implement the exploration strategic idea of“two outgoing”in the demonstration area,i.e.,“walking out of the stable area of the basin and marching into the complex structure areas in the Dianqianbei Depression”and“walking out of the WufengeLongmaxi Formation and exploring other layers for breakthrough”.What's more,it is recommended to carry out the double-layer stereoscopic horizontal well pattern deployment of“Leping Formation CBM(coal measure gas)þLongmaxi Formation shale gas”appropriately in a large scale,so as to establish a new integrated development model for the three-dimensional efficient development of mountain shale gas and CBM.展开更多
Since the approval to establishment,the Changning-Weiyuan National Shale Gas Demonstration Area in the Sichuan Basin(hereinafter referred to as Demonstration Area)has been built up into a shale gas industry demonstrat...Since the approval to establishment,the Changning-Weiyuan National Shale Gas Demonstration Area in the Sichuan Basin(hereinafter referred to as Demonstration Area)has been built up into a shale gas industry demonstration base characterized with scale,technology,management and green after more than 10 years of exploration and practice.Its successful experience is of great guiding significance to the efficient development of unconventional oil and gas resources in China.In this paper,the technologies which were developed for the beneficial development of the Demonstration Area during the 13th Five-Year Plan are systematically reviewed and summarized.Then,some countermeasures are proposed to solve the difficulties and challenges to the long-term benefit and stable production of middle-deep shale gas in this area.And the following research results are obtained.First,during the construction of the Demonstration Area,the“three-control”shale gas enrichment and high-production theory is innovatively proposed,and the shale gas enrichment model in the southern Sichuan Basin is clarified.Second,a high-production well cultivation method based on geology-engineering integration is established by developing six main technologies for shale gas exploration and development,which effectively supports the large-scale beneficial development of shale gas in the Demonstration Area.Third,the beneficial development model of middle-deep shale gas in the southern Sichuan Basin is preliminarily formed,and the benefit and efficiency of productivity construction are improved comprehensively.Fourth,the three measures of“controlling the decline rate,enhancing the reserve production and expanding the periphery”are used to support the replacement and stable production of middle-deep shale gas.In conclusion,to sustainably ensure the long-term benefit and stable production of shale gas in the southern Sichuan Basin,it is still necessary to deepen fine reservoir description and complex mechanism understanding and explore EOR technologies.What’s more,the important mean to improve the single-well shale gas production rate in this area is to strengthen the fine fracturing design and implementation under the deep integration of geology and engineering and improve the construction quality of fracturing network continuously.Furthermore,the only way to the low-cost development of the demonstration area is to promote the management reform and innovation continuously and improve the beneficial development model further.展开更多
基金Supported by the PetroChina Scentific and Technological Projects(2023ZZ082023ZZ28)。
文摘Currently,unconventional reservoirs are characterized by low single well-controlled reserves,high initial production but fast production decline.This paper sorts out the problems of energy dispersion and limited length and height of main hydraulic fractures induced in staged multi-cluster fracturing,and proposes an innovative concept of“energy-focused fracturing development”.The technical connotation,theoretical model,and core techniques of energy-focused fracturing development are systematically examined,and the implementation path of this technology is determined.The energy-focused fracturing development technology incorporates the techniques such as geology-engineering integrated design,perforation optimization design,fracturing process design,and drainage engineering control.It transforms the numerous,short and dense hydraulic fractures to limited,long and sparse fractures.It focuses on fracturing energy,and aims to improve the fracture length,height and lateral width,and the proppant long-distance transportation capacity,thus enhancing the single well-controlled reserves and development effect.The energy-focused fracturing development technology has been successfully applied in the carbonate reservoirs in buried hill,shallow coalbed methane reservoirs,and coal-rock gas reservoirs in China,demonstrating the technology's promising application.It is concluded that the energy-focused fracturing development technology can significantly increase the single well production and estimated ultimate recovery(EUR),and will be helpful for efficiently developing low-permeability,unconventional and low-grade resources in China.
基金supported by the Excellence Research Group Program of the Hubei Provincial Natural Science Foundation(originally termed Basic Science Center Program)(JCKXXM202500016)the Key Program of the National Natural Science Foundation of China(42230812)the National Natural Science Foundation of China(42073068)。
文摘Multiple sets of marine shale sequences occur in western Hubei Province and its adjacent areas within the Middle-Upper Yangtze region,offering substantial resource potential.However,their shale gas preservation conditions differ significantly due to the heterogeneous porosity and fracture system resulting from multistage tectonic reworking.This necessitates developing region-specific evaluation systems and exploitation techniques.Drawing on previous application cases and guided by the research paradigm of geology-engineering integration,this study presents key technologies potentially applicable to shales in western Hubei Province,spanning from reservoir and sweet spot evaluation to fractu ring scheme design and fracturing perfo rmance monitoring.Several insights are gained accordingly.In terms of pore evaluation,the pore heterogeneity caused by compaction and rebound can be quantified using ideal shape coefficients and fractal dimensions,both of which are influenced by structural deformations,thereby guiding reservoir classification.For seismic data interpretation,pre-stack elastic inversion and azimuthal anisotropy inversion can be employed as core techniques,overcoming the limitation of individual post-stack attributes in typically detecting only major faults.Furthermore,the inversion boundaries are constrained using log-seismic joint quality control and geomechanical simulation,contributing to enhanced reliability of sweet spot evaluation and efficient exploration in areas with complex structures.For fracturing scheme design,scientifically formulated well shut-in strategies,tailored to regional geological characteristics,are essential to activate the fracture-matrix imbibition effect.Parameters with vastly different scales used in the design,such as meter-scale fracture halflength and millidarcy-scale fracture conductivity,can be co-optimized using artificial intelligence(AI)algorithms such as the genetic algorithm(GA)and the simultaneous perturbation stochastic approximation(SPSA)algorithm.Dynamic monitoring of fracturing performance can be achieved using trace chemical tracer technology,thereby reducing target ambiguity caused by structural complexity.Research on shale gas in the structurally complex areas of western Hubei faces multiple challenges,spanning from basic geological understanding to development engineering.These challenges create an urgent need for deep interdisciplinary collaboration.Therefore,this study highlights research into geology-engineering integration,aiming to enhance the efficiency of shale gas exploration and development in western Hubei.
基金Project supported by the Scientific Research and Technology Development Project PetroChina Company Limited“Research on microscopic characteristics and enrichment mechanism of shallow shale gas reservoirs in Zhaotong”(No.2021DJ1903)“Field test of downhole fiber intelligent monitoring technology”(No.2020F-44).
文摘The Zhaotong national shale gas demonstration area in Yunnan(hereinafter referred to as demonstration area)is China's third largest national shale gas production base after ChangningeWeiyuan in Sichuan and Fuling in Chongqing.And after more than ten years of deep and careful cultivation,a series of important achievements have been obtained in the exploration and development.From the perspective of exploration and development history,theory and technology,this paper systematically summarizes the exploration discovery process and productivity construction progress of shale gas in the demonstration area,expounds the geological exploration theories and key technologies of mountain shale gas,and predicts their development prospect and direction.And the following research results are obtained.First,the exploration and development in the demonstration area has gone through five development stages,and so far,three major productivity construction zones have been formed,including Huangjinba and Zijinba middleedeep shale gas zones and Taiyang shallow shale gas zone,with cumulative proved geological reserves more than 3100×10^(8) m^(3) and cumulative gas production more than 72×10^(8) m^(3).It has been constructed into the third largest green shale gas demonstration base in China.Second,the“multi-field coordination and multi-element coupling”mountain shale gas enrichment,accumulation and occurrence theory of“sedimentary background controlling source rock and reservoir,reworking intensity controlling preservation,and three-dimensional sealing controlling enrichment”is put forward innovatively,and the“three-dimensional sealing system”accumulation model of extrabasinal shallow shale gas is established.Third,a series of zone selection and evaluation technologies for mountain shale gas in strongly reworked complex structural areas have been developed,and the concept of geologyeengineering integration has first been adopted to create transparent shale gas reservoirs and cultivate high-yield wells.A major exploration breakthrough has been achieved from marginal basin medium deep shale gas layers to extrabasin ultra shallow to medium shallow ones,and domestic first large-scale monoblock shallow shale gas field with reserves over 2570×10^(8) m^(3) has been discovered.Fourth,a landmark technological achievement and efficient development model with geologyeengineering integration and shale geomechanical evaluation as the core has been formed,which leads the clean,green and efficient exploration and development of mountain shale gas.In conclusion,it is necessary to implement the exploration strategic idea of“two outgoing”in the demonstration area,i.e.,“walking out of the stable area of the basin and marching into the complex structure areas in the Dianqianbei Depression”and“walking out of the WufengeLongmaxi Formation and exploring other layers for breakthrough”.What's more,it is recommended to carry out the double-layer stereoscopic horizontal well pattern deployment of“Leping Formation CBM(coal measure gas)þLongmaxi Formation shale gas”appropriately in a large scale,so as to establish a new integrated development model for the three-dimensional efficient development of mountain shale gas and CBM.
基金supported by the National Major Science and Technology Project“Changning-Weiyuan shale gas development demonstration project”(No.2016ZX05062)the Major Science and Technology Project of PetroChina Company Limited“Research and application of key technologies for producing 30 billion cubic meters of natural gas in Southwest Oil and Gas Field”(No.2016E-0611).
文摘Since the approval to establishment,the Changning-Weiyuan National Shale Gas Demonstration Area in the Sichuan Basin(hereinafter referred to as Demonstration Area)has been built up into a shale gas industry demonstration base characterized with scale,technology,management and green after more than 10 years of exploration and practice.Its successful experience is of great guiding significance to the efficient development of unconventional oil and gas resources in China.In this paper,the technologies which were developed for the beneficial development of the Demonstration Area during the 13th Five-Year Plan are systematically reviewed and summarized.Then,some countermeasures are proposed to solve the difficulties and challenges to the long-term benefit and stable production of middle-deep shale gas in this area.And the following research results are obtained.First,during the construction of the Demonstration Area,the“three-control”shale gas enrichment and high-production theory is innovatively proposed,and the shale gas enrichment model in the southern Sichuan Basin is clarified.Second,a high-production well cultivation method based on geology-engineering integration is established by developing six main technologies for shale gas exploration and development,which effectively supports the large-scale beneficial development of shale gas in the Demonstration Area.Third,the beneficial development model of middle-deep shale gas in the southern Sichuan Basin is preliminarily formed,and the benefit and efficiency of productivity construction are improved comprehensively.Fourth,the three measures of“controlling the decline rate,enhancing the reserve production and expanding the periphery”are used to support the replacement and stable production of middle-deep shale gas.In conclusion,to sustainably ensure the long-term benefit and stable production of shale gas in the southern Sichuan Basin,it is still necessary to deepen fine reservoir description and complex mechanism understanding and explore EOR technologies.What’s more,the important mean to improve the single-well shale gas production rate in this area is to strengthen the fine fracturing design and implementation under the deep integration of geology and engineering and improve the construction quality of fracturing network continuously.Furthermore,the only way to the low-cost development of the demonstration area is to promote the management reform and innovation continuously and improve the beneficial development model further.
