With the grade of hydrocarbon resources becoming poorer,tight sandstone gas reservoirs may serve as the key to the enhancement of both reserves and productivity.Accordingly,high efficient and sustainable development o...With the grade of hydrocarbon resources becoming poorer,tight sandstone gas reservoirs may serve as the key to the enhancement of both reserves and productivity.Accordingly,high efficient and sustainable development of the large and over-large tight sandstone reservoirs is very important.However,currently,there is no effective method available for macro-analysis.Based on the latest research findings from the Sulige Gasfield,the largest onshore tight sandstone gas reservoir in China,studies were conducted in five aspects,i.e.reserve scale,development scale,dynamic reserve evaluation,rules in production declines of gasfields and undeveloped resource evaluation,to identify challenges to the production stabilization of gas reservoirs.In addition,key evidences and constraints for the solutions to the difficulties in production stabilization were proposed to provide necessary technical supports for high-efficient development in later stages.Research results show that the major challenges to production stabilization include seven aspects,such as low development induced by improper allocation of well patterns,uneven declines in productivity induced by specific features of reservoir formations and fluids,difficulties in the development of some reserves due to complex gas/water correlation,and differences in production performances by using different production techniques.Finally,guided by the development principles of“promoting productivity by using innovative technologies in different spaces and time”,13 key technologies,such as comprehensive optimization of development well patterns,multi-dimensional matrix for gas well management and“positive”water discharging and gas production technologies,were proposed to further prolong peak production time and enhance the recovery rates of tight gas reservoirs.展开更多
For the sake of figuring out the influential mechanisms of structural characteristics on the productivity of shale gas wells,the structural characteristics of the Jiaoshiba Block in the Fuling shale gasfield,Sichuan B...For the sake of figuring out the influential mechanisms of structural characteristics on the productivity of shale gas wells,the structural characteristics of the Jiaoshiba Block in the Fuling shale gasfield,Sichuan Basin,were analyzed.Then,based on well test data of more than 190 horizontal wells,the effects of structures on shale gas well productivity were discussed systematically,and the main structural factors of different structural units in the Jiaoshiba Block that influence the productivity of shale gas wells were clarified.The following results were obtained.First,the structural units in the Jiaoshiba Block were obviously different in structural characteristics and their deformation strength is different.Second,the influence of structural characteristics on shale gas well productivity is directly manifested in gas-bearing property and fracturing effect.The stronger the structural deformation and the more developed the large faults and natural fractures,the more easily shale gas escapes and the poorer the gas bearing property will be,and vice versa.Third,The stronger the structural deformation,the more developed the fractures,the greater the burial depth and the higher the compressive stress of negative structures,the worse the fracturing effect will be,and vice versa.And fourth,Tectonics is the key factor controlling the difference of shale gas productivity between different structural units in the Jiaoshiba Block,but the main structural factors influencing the productivity are different in different structural units.展开更多
Located in the Sichuan Basin,the Yuanba Gasfield is the deepest high-sulfur carbonate gasfield among those discovered in the world.Its biohermal gas reservoir of the Upper Permian Changxing Fm is characterized by ultr...Located in the Sichuan Basin,the Yuanba Gasfield is the deepest high-sulfur carbonate gasfield among those discovered in the world.Its biohermal gas reservoir of the Upper Permian Changxing Fm is characterized by ultra depth,multi-stage small and scattered reef,thin reservoir,poor physical properties,strong heterogeneity,complexfluid distribution,and low production of vertical wells.The development of the bio-hermal gas reservoir is subject to many difficulties.For example,it is necessary to deepen the studies on timeespace distribution laws of reef dolomite reservoirs;it is difficult to characterize small reefs precisely and predict thin reservoirs quantitatively;the deployment and optimization design of horizontal wells are influenced by multiple factors;and the difficulty for horizontal wells with long horizontal sections to run through high-quality thin reservoirs is high.In order to develop the Yuanba Gasfield efficiently,therefore,it is necessary to carry out a series of technical researches on the distribution laws and development models of biohermal reservoirs,precise characterization of small reefs,quantitative pre-diction of thin reservoirs,optimization design of horizontal wells in banded small reef gas reservoirs,and real-time trajectory optimization and adjustment of horizontal wells in ultra-deep thin reservoirs.These research results provide a powerful support for the development and con-struction of the Yuanba Gasfield.Based on these technologies,China'sfirst ultra-deep high-sulfur large biohermal gasfield was built with a mixed gas annual production capacity of 40108 m3.The successful commissioning of the Yuanba Gasfield lays a basis for the leading position of China in thefield of high-sulfur gasfield development.In addition,it is of great significance to the long-term stable gas supply in 70 cities of six provinces and two municipalities along the“Sichuan-to-East China Gas Transmission Pipeline”,as well as to the industrial structure adjustment in centralewestern China and the economic development along the Yangtze River.展开更多
Mixed deposition is a sedimentary phenomenon of special significance to the tectonic movement, material supply, sea level change, andpaleoclimate of the sedimentary environment. The sediments of the Late Carboniferous...Mixed deposition is a sedimentary phenomenon of special significance to the tectonic movement, material supply, sea level change, andpaleoclimate of the sedimentary environment. The sediments of the Late Carboniferous-Early Permian System in the North China Craton, whichare composed of clastic rock and limestone, are mixed clastic-platform carbonate sediments in the epicontinental sea. Based on the geologicaland well logging data of nearly 100 exploratory wells and hundreds of development wells in the region, the lithologic association and cyclefeatures of the Upper Carboniferous-Lower Permian were determined. From this data, the Benxi Formation and the Taiyuan Formation of theDaniudi Gasfield are considered to belong to a mixed clastic coastline-carbonate platform sedimentary system and coastal plain sedimentarysystem in the epicontinental sea. Based on the six transgressions and regressions during the Late Carboniferous-Early Permian epochs in theregion, combined with the regional evolution history, this study analyzed the sedimentary evolution history of the Daniudi Gasfield from the LateCarboniferous to the Early Permian.展开更多
World Bank offered 255 million RMB Yuan bank loan and 10 million RMB Yuan donation in equivalent US dollars to"Sichuan Natural Gas Development and Energy-saving Project".This project includes evaluation and ...World Bank offered 255 million RMB Yuan bank loan and 10 million RMB Yuan donation in equivalent US dollars to"Sichuan Natural Gas Development and Energy-saving Project".This project includes evaluation and development of 13 gasfields and gas-bearing structures in the east-ern Sichuan,reformation of low-permeability gas fields,reformation and expanding of gas pipeline system and related environmental protection in Moxi,Bajiaocang in Middle Sichuan,technical assistance and personnel training,etc.The loan period is limited to 20 years,including five years of extension period.展开更多
With complicated formation mechanisms,liquid loading in gas wells during gasfield development may significantly affect the productivity of gas wells and the ultimate recovery rate.Dynamic monitoring data of the Samand...With complicated formation mechanisms,liquid loading in gas wells during gasfield development may significantly affect the productivity of gas wells and the ultimate recovery rate.Dynamic monitoring data of the Samandepe Gasfield in Turkmenistan shows that liquid loading can be found extensively in gas wells.Their formation mechanisms and negative impacts on gasfield development severely restrict the productivity enhancement of this gasfield.With their origins taken into consideration,liquid loads in gas wells were classified into three types:formation water,condensed liquid,and external liquid.By using the hydrostatic pressure gradient method and through PLT monitoring,properties of liquid loads in the Samandepe Gasfield were determined.In addition,formation mechanisms related to liquid loading in gas wells were obtained through analyses of critical fluid-carrying capacities and by using gas-reservoir production data.The following findings were obtained.Liquid loading was commonly found in this gas well with majority of reservoir formations in lower well intervals flooded.However,the formation mechanisms for these liquid loads are different from those of other gasfields.Due to long-term shut-down of gas wells,killing fluids precipitated and pores in lower reservoir formations were plugged.As a result,natural gas had no access to boreholes,killing fluids were impossibly carried out of the borehole.Instead,the killing fluid was detained at the bottomhole to generate liquid load and eliminate the possibility of formation water coning.Moreover,since the gasfield was dominated by block reservoirs with favorable physical properties and connectivity,impacts of liquid load on gasfield development were insignificant.Thus,to enhance the recovery rate of the Samandepe Gasfield significantly,it is necessary to expand the gasfield development scale and strengthen the development of marginal gas reservoirs.展开更多
Based on the exploration and development achievements of the Sulige Gasfield in the Ordos Basin,tight sandstone gas yield has been increased essentially in China.Recovery enhancement is always the core subject in rese...Based on the exploration and development achievements of the Sulige Gasfield in the Ordos Basin,tight sandstone gas yield has been increased essentially in China.Recovery enhancement is always the core subject in researches.In this paper,the development history of the Sulige Gasfield was reviewed focusing on the technological progress in single well production enhancement.Then,the technical ideas on and countermeasures for transforming the traditional development modes and increasing recovery factor were discussed.It is shown that the development technologies in the evaluation and the production enhancement and stabilization of giant tight sandstone gas reservoirs are changed progressively.The fast increase of gas production in this field is made possible by well location arrangement technology based on sweep spot screening,horizontal well development technology,well type and well pattern optimization technology,fast drilling technology,reservoir stimulation technology,drainage gas recovery technology and integrated construction mode.And finally,the technical ideas of recovery enhancement during the 13th Five-Year Plan were proposed in nine aspects,including gas field development,planning and evaluation technology based on single-well life cycle analysis;dynamic evaluation and infilling technology for mixed well patterns targeting recovery enhancement;one-shot recovery enhancement technology for a new areal pattern area with integrated multiple well patterns and multiple series of strata;reserve evaluation model based on risk and benefit evaluation;gas-well precise management technology with multi-dimensional matrix;potential tapping technology for low production and low efficiency wells;novel wellsite environmental protection technology;surface process based on integrated equipments;and C_(3)^(+)mixed hydrocarbon recovery technology.It provides technically reliable support for the development of tight sandstone gas reservoirs in the Sulige Gasfield during the 13th Five-Year Plan.展开更多
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
In the course of completion of an ultra-deep well newly drilled in the Yuanba Gasfield,Sichuan Basin,long-section and large-scale deformation occurred in the heavy casing section and nickel base alloy casing section o...In the course of completion of an ultra-deep well newly drilled in the Yuanba Gasfield,Sichuan Basin,long-section and large-scale deformation occurred in the heavy casing section and nickel base alloy casing section of the sealing Triassic limestone interval,so a new hole had to be sidetracked,which impels us to rediscover the applicability of conventional drilling and completion technology in ultra-deep wells.In this paper,based on the borehole condition and field operation data of this well,the borehole pressure field variation initiated by lost circulation in the low-pressure formation was analyzed from the perspective of dynamics,then,the variation pattern of differential pressure inside and outside the well bore at different time intervals was depicted,and the primary cause of such complication was theoretically revealed,i.e.,the pressure wave generated by instant lost circulation in low-pressure formation would result in redistribution of pressure inside the downhole confined space,and then the crush of casing in the vicinity of local low-pressure areas.Pertinent proposals for avoiding these kinds of engineering complexities were put forward:①when downhole sealing casing operation is conducted in open hole completion,liner completion or perforated hole,the potential damage of lost circulation to casing should be considered;②the downhole sealing point and sealing mode should be selected cautiously:the sealing point had better be selected in the section with good cementing quality or as close to the casing shoe as possible,and the sealing mode can be either cement plug or mechanical bridge plug.This paper finally points out that good cementing quality plays an important role in preventing this type of casing deformation.展开更多
By virtue of unique technical and economical advantages,horizontal well development has become a key technology in the high-efficiency development of tight gas reservoirs,however,this has worked unsatisfactorily in un...By virtue of unique technical and economical advantages,horizontal well development has become a key technology in the high-efficiency development of tight gas reservoirs,however,this has worked unsatisfactorily in unstratified gas reservoirs.In this paper,the orientation and coverage of gas-bearing sand bodies(in isolated distribution)of Member 8 of Permian Lower Shihezi Fm in the Sulige Gasfield were analyzed by means of outcrop analogy,geostatistical analysis and pilot tests of dense well patterns.Then,four gas-bearing sand distribution patterns suitable for the deployment of horizontal wells in Member 8 were proposed according to the precise geological anatomy results of dense well patterns.These patterns include thick massive isolated pattern,vertically superimposed pattern with physical interlayers,vertically superimposed pattern with argillaceous interlayers and lateral sugar-coated haw string pattern.Based on the statistics on gas-bearing sand bodies drilled by horizontal well drilling,the drilled gas-bearing sand bodies are 670-1300 m long.Based on production data correction,numerical simulation and economic evaluation,the length of rational horizontal sections were optimized by performing a case study of the vertically superimposed reservoirs with physical interlayers in the typical well group SuX-18-36 of Su-X Block.It is indicated that the rational horizontal well length within 1200 m in the Sulige Gasfield under current economic and technical conditions.This paper provides a technical support for the highefficiency development of the Sulige Gasfield in the future.展开更多
In the Anyue Gasfield,Sichuan Basin,the Lower Cambrian Longwangmiao Fm gas reservoir in Moxi Block has enormous natural gas reserves,and it is a typical three-high(high temperature,high pressure,and high flow rate)sou...In the Anyue Gasfield,Sichuan Basin,the Lower Cambrian Longwangmiao Fm gas reservoir in Moxi Block has enormous natural gas reserves,and it is a typical three-high(high temperature,high pressure,and high flow rate)sour gas field.Its ground engineering project(with the designed gas processing capacity of 60×10^(8)m^(2)/a)is characterized by high processing rate of each unit,complex process control,large construction load,restricted construction site and tight schedule.Based on the traditional engineering construction mode,however,it is difficult to complete the project design and construction within 16 months.In view of this,the design concept of unit large-scale modularization was introduced to implement“normalized design,scale purchase,factory-like prefabrication and modularized construction”and develop the modularization technology of large-scale surface engineering construction.This modularizationtechnology is performed as follows.First,the modularized units are laid out reasonably according to the technological process.Second,the layout of modularized units is usually super-imposed in the multi-layer framework.Third,those equipments with the same or similar operational modes,medium properties,functional characteristics and installation requirements are concentrated in the pattem of a module.Fourth,escape passageway is specially set up.Fifth,room for installation,maintenance and repair of large equipments is reserved.And sixth,transportation and hoisting requirements of modules are taken into consideration sufficiently.This technology is contributive to the improvement of design quality,effective shortening of design period,reduction of field working load,decrease of safety management risk of on-site installation,increase of production efficiency,conservation of land occupation and diminishment of construction investment.It plays a reference role in the modularized construction of surface engineering of similar large projects.展开更多
The Yuanba Gasfield is another large gasfield with reserves of a hundred billion cubic meters that was discovered by Sinopec after the Puguang Gasfield in the Sichuan Basin.At present,it is the deepest marine carbonat...The Yuanba Gasfield is another large gasfield with reserves of a hundred billion cubic meters that was discovered by Sinopec after the Puguang Gasfield in the Sichuan Basin.At present,it is the deepest marine carbonate sour gasfield in China.Its principal reservoir,the Upper Permian Changxing Fm,is characterized by ultra depth,high temperature,high sulfur content,high CO_(2)content,and complex gasewater relationship.Therefore,well completion is faced with complicated engineering geological conditions,diverse well types and well completion modes and high-difficulty operation.In view of this,Sinopec Southwest Petroleum Engineering Co.,Ltd.carried out technical research and practice.As a result,a series of key well completion and commissioning technologies were developed,including well completion testing and ground control,in-depth acid fracturing stimulation,ultra-deep slim-hole wellbore processing,micro-tooth mark make-up and air tightness detection,and safety control.Based on these technologies,the worldwide technical difficulties of well completion and commissioning in the process of gasfield development are settled,such as string corrosion prevention,in-depth acid fracturing,high-yield testing,and safety control.These technologies have been applied successfully in nearly 40 wells,providing an important technical support for the realization of 34×10^(8)m^(3)annual gas production capacity construction in the Yuanba Gasfield.展开更多
Centralized and group well deployment and factory-like fracturing techniques are adopted for low-permeability tight sandstone reservoirs in the Sulige Gasfield,Ordos Basin,so as to realize its efficient and economic d...Centralized and group well deployment and factory-like fracturing techniques are adopted for low-permeability tight sandstone reservoirs in the Sulige Gasfield,Ordos Basin,so as to realize its efficient and economic development.However,environmental protection is faced with grim situations because fluid delivery rises abruptly on site in a short time due to centralized fracturing of the well group.Based on the characteristics of gas testing after fracturing in this gas field,a fracturing flowback fluid recovery and treatment method suitable for the Sulige Gasfield has been developed with the landform features of this area taken into account.Firstly,a high-efficiency well-to-well fracturing flowback fluid recovery and reutilization technique was developed with multi-effect surfactant polymer recoverable fracturing fluid system as the core,and in virtue of this technique,the treatment efficiency of conventional guar gum fracturing fluid system is increased.Secondly,for recovering and treating the end fluids on the well sites,a fine fracturing flowback fluid recovery and treatment technique has been worked out with“coagulation and precipitation,filtration and disinfection,and sludge dewatering”as the main part.Owing to the application of this method,the on-site water resource utilization ratio has been increased and environmental protection pressure concerned with fracturing operation has been relieved.In 2014,field tests were performed in 62 wells of 10 well groups,with 32980 m3 cumulative treated flowback fluid,17160 m3 reutilization volume and reutilization ratio over 70%.Obviously,remarkable social and economical benefits are thus realized.展开更多
The Yuanba Gasfield is a large gasfield discovered by Sinopec in the Sichuan Basin in recent years,and another main exploration area for natural gas reserves and production increase after the Puguang Gasfield.The ultr...The Yuanba Gasfield is a large gasfield discovered by Sinopec in the Sichuan Basin in recent years,and another main exploration area for natural gas reserves and production increase after the Puguang Gasfield.The ultra-deep sour gas reservoir in the Yuanba Gasfield is characterized by complicated geologic structure,deep reservoirs and complex drilled formation,especially in the continental deep strata which are highly abrasive with low ROP(rate of penetration)and long drilling period.After many years of drilling practice and technical research,the following six key drilling and completion technologies for this type reservoir are established by introducing new tools and technologies,developing specialized drill bits and optimizing drilling design.They are:casing program optimization technology for ROP increasing and safe well completion;gas drilling technology for shallow continental strata and high-efficiency drilling technology for deep high-abrasion continental strata;drillingfluid support technologies of gaseliquid conversion,ultra-deep highly-deviated wells and horizontal-well lubrication and drag reduction,hole stability control and sour gas contamination prevention;well cementing technologies for gas medium,deep-well long cementing intervals and ultra-high pressure small space;horizontal-well trajectory control technologies for measuring instrument,downhole motor opti-mization and bottom hole assembly design;and liner completion modes and completion string optimization technologies suitable for this gas reservoir.Field application shows that these key technologies are contributive to ROP increase and efficiency improvement of 7000 m deep horizontal wells and to significant operational cycle shortening.展开更多
The Sulige Gas Field in the Ordos Basin is the largest tight gasfield in China,with proved reserves exceeding 2×10^(12)m^(3).As the main contributor to gas production in PetroChina Changqing Oilfield Company,The ...The Sulige Gas Field in the Ordos Basin is the largest tight gasfield in China,with proved reserves exceeding 2×10^(12)m^(3).As the main contributor to gas production in PetroChina Changqing Oilfield Company,The Sulige Gas Field is in the stage of stable production.Maximizing the stable production period is a focus and challenge for the gasfield now.To address a series of problems influencing the efficient development of Sulige gasfield,such as large-scale remaining gas reserves between wells/layers and low ratio of employed reserves,the main technologies for enhanced gas recovery(EGR)of tight gas reservoirs were developed by multidisciplinary research with respect to development geology,reservoir engineering,drilling and production process,and surface gathering and transportation.Experiments were conducted on reservoir description and remaining gas characterization,well pattern thickening optimization,vertical well separate-layer fracturing,horizontal-well multi-stage multi-cluster volume fracturing for their improvement and upgrading.The orientation of EGR for tight gas reservoirs is pro-posed.The following results are obtained.First,well pattern thickening optimization is the most important EGR method,which can increase the recovery rate by more than 6%.Second,based on continuous upgrading and promotion,either of reservoir stimulation technology and drainage gas recovery technology can increase the recovery rate by more than 2%.The gathering and transportation technology which further reduces the wellhead pressure can increase the recovery rate by about 1.5%.Third,the EGR technology should be oriented to maximize the quantity of employed reserves,especially by way of new technologies such asfine remaining gas characterization,well pattern/type optimization,cross-layer fracturing of a multi-thin-layer reservoir by horizontal wells,intelligent drainage gas recovery,and multi-stage pressurization.It is concluded that the development of key EGR technologies will help increase the recovery rate of The Sulige Gas Field by 10%e15%,and will provide an effective support for The Sulige Gas Field to maintain the production at 300108 m^(3)/a for a long term and for the Changqing gas province to increase the production to 500×10^(8)m^(3)/a,which will ultimately ensure the national energy security.展开更多
Taking advantage of the successful experience in exploring and discovering the Puguang Gasfield,and targeting the Changxing Formation-Feixianguan Formation organic reef and shoal lithological trap,SINOPEC drilled Well...Taking advantage of the successful experience in exploring and discovering the Puguang Gasfield,and targeting the Changxing Formation-Feixianguan Formation organic reef and shoal lithological trap,SINOPEC drilled Well Yuanba 1 in the Bazhong area in Northeast Sichuan in 2006,and discovered the Yuanba Gasfield with a high-production commercial gas flow of 503×10^(3) m^(3)/d.As a normal-pressured lithological gas reservoir with high H_(2)S content,Yuanba Gasfield is characterized by weak tectonic deformation and deep burial,with an average depth of 6,600 m in the central part of the gas reservoir,and is the deepest marine gas field in the Sichuan Basin.Yuanba Gasfield is dominated by large-scale reef-shoal reservoirs of Changxing Formation.The formation of the reservoirs was primarily controlled by early meteoric freshwater dissolution and dolomitization,and less affected by deep-burial dissolution and tectonic movement.A comparative analysis was made on the characteristics of deep reef-shoal reservoirs in the Yuanba and Puguang gas fields so as to explore their formation mechanisms.It is concluded that the reservoir size and early pore development was controlled by early depositional-diagenetic environment.Fracture formation and dissolution were controlled by structure-fluid coupling,pore reworking and preservation is determined by fluid-rock interaction.展开更多
基金National Science and Technology Major Project“Demonstration Project of Development of Large-Scale Low-Permeability Lithologic and Stratigraphic Reservoirs in the Ordos Basin”(No.2011ZX05044)Scientific Research and Technical Development Project of CNPC(No.2012E-1306).
文摘With the grade of hydrocarbon resources becoming poorer,tight sandstone gas reservoirs may serve as the key to the enhancement of both reserves and productivity.Accordingly,high efficient and sustainable development of the large and over-large tight sandstone reservoirs is very important.However,currently,there is no effective method available for macro-analysis.Based on the latest research findings from the Sulige Gasfield,the largest onshore tight sandstone gas reservoir in China,studies were conducted in five aspects,i.e.reserve scale,development scale,dynamic reserve evaluation,rules in production declines of gasfields and undeveloped resource evaluation,to identify challenges to the production stabilization of gas reservoirs.In addition,key evidences and constraints for the solutions to the difficulties in production stabilization were proposed to provide necessary technical supports for high-efficient development in later stages.Research results show that the major challenges to production stabilization include seven aspects,such as low development induced by improper allocation of well patterns,uneven declines in productivity induced by specific features of reservoir formations and fluids,difficulties in the development of some reserves due to complex gas/water correlation,and differences in production performances by using different production techniques.Finally,guided by the development principles of“promoting productivity by using innovative technologies in different spaces and time”,13 key technologies,such as comprehensive optimization of development well patterns,multi-dimensional matrix for gas well management and“positive”water discharging and gas production technologies,were proposed to further prolong peak production time and enhance the recovery rates of tight gas reservoirs.
基金Project supported by National Science and Technology Major Project“Demonstration Project of Fuling Shale Gas Development”(No.:2016ZX05060).
文摘For the sake of figuring out the influential mechanisms of structural characteristics on the productivity of shale gas wells,the structural characteristics of the Jiaoshiba Block in the Fuling shale gasfield,Sichuan Basin,were analyzed.Then,based on well test data of more than 190 horizontal wells,the effects of structures on shale gas well productivity were discussed systematically,and the main structural factors of different structural units in the Jiaoshiba Block that influence the productivity of shale gas wells were clarified.The following results were obtained.First,the structural units in the Jiaoshiba Block were obviously different in structural characteristics and their deformation strength is different.Second,the influence of structural characteristics on shale gas well productivity is directly manifested in gas-bearing property and fracturing effect.The stronger the structural deformation and the more developed the large faults and natural fractures,the more easily shale gas escapes and the poorer the gas bearing property will be,and vice versa.Third,The stronger the structural deformation,the more developed the fractures,the greater the burial depth and the higher the compressive stress of negative structures,the worse the fracturing effect will be,and vice versa.And fourth,Tectonics is the key factor controlling the difference of shale gas productivity between different structural units in the Jiaoshiba Block,but the main structural factors influencing the productivity are different in different structural units.
基金supported by the National Science and Technology Major Project in the 13th Five-Year Plan"High-efficiency development of ultra-deep bio-herm gas reservoirs with bottom water"(No.:2016ZX05017-005).
文摘Located in the Sichuan Basin,the Yuanba Gasfield is the deepest high-sulfur carbonate gasfield among those discovered in the world.Its biohermal gas reservoir of the Upper Permian Changxing Fm is characterized by ultra depth,multi-stage small and scattered reef,thin reservoir,poor physical properties,strong heterogeneity,complexfluid distribution,and low production of vertical wells.The development of the bio-hermal gas reservoir is subject to many difficulties.For example,it is necessary to deepen the studies on timeespace distribution laws of reef dolomite reservoirs;it is difficult to characterize small reefs precisely and predict thin reservoirs quantitatively;the deployment and optimization design of horizontal wells are influenced by multiple factors;and the difficulty for horizontal wells with long horizontal sections to run through high-quality thin reservoirs is high.In order to develop the Yuanba Gasfield efficiently,therefore,it is necessary to carry out a series of technical researches on the distribution laws and development models of biohermal reservoirs,precise characterization of small reefs,quantitative pre-diction of thin reservoirs,optimization design of horizontal wells in banded small reef gas reservoirs,and real-time trajectory optimization and adjustment of horizontal wells in ultra-deep thin reservoirs.These research results provide a powerful support for the development and con-struction of the Yuanba Gasfield.Based on these technologies,China'sfirst ultra-deep high-sulfur large biohermal gasfield was built with a mixed gas annual production capacity of 40108 m3.The successful commissioning of the Yuanba Gasfield lays a basis for the leading position of China in thefield of high-sulfur gasfield development.In addition,it is of great significance to the long-term stable gas supply in 70 cities of six provinces and two municipalities along the“Sichuan-to-East China Gas Transmission Pipeline”,as well as to the industrial structure adjustment in centralewestern China and the economic development along the Yangtze River.
文摘Mixed deposition is a sedimentary phenomenon of special significance to the tectonic movement, material supply, sea level change, andpaleoclimate of the sedimentary environment. The sediments of the Late Carboniferous-Early Permian System in the North China Craton, whichare composed of clastic rock and limestone, are mixed clastic-platform carbonate sediments in the epicontinental sea. Based on the geologicaland well logging data of nearly 100 exploratory wells and hundreds of development wells in the region, the lithologic association and cyclefeatures of the Upper Carboniferous-Lower Permian were determined. From this data, the Benxi Formation and the Taiyuan Formation of theDaniudi Gasfield are considered to belong to a mixed clastic coastline-carbonate platform sedimentary system and coastal plain sedimentarysystem in the epicontinental sea. Based on the six transgressions and regressions during the Late Carboniferous-Early Permian epochs in theregion, combined with the regional evolution history, this study analyzed the sedimentary evolution history of the Daniudi Gasfield from the LateCarboniferous to the Early Permian.
文摘World Bank offered 255 million RMB Yuan bank loan and 10 million RMB Yuan donation in equivalent US dollars to"Sichuan Natural Gas Development and Energy-saving Project".This project includes evaluation and development of 13 gasfields and gas-bearing structures in the east-ern Sichuan,reformation of low-permeability gas fields,reformation and expanding of gas pipeline system and related environmental protection in Moxi,Bajiaocang in Middle Sichuan,technical assistance and personnel training,etc.The loan period is limited to 20 years,including five years of extension period.
基金CNPC Project“Research and Application of Key Development Technologies in Turkmenistan Amu Darya Right Bank 16.5 Billion Cubic Meters Natural Gas Production Enhancement”(No.2011E-2505)National Key S&T Project“Natural Gas Development Demonstration Project in the Middle Area of Amu Darya Right Bank”(No.2011ZX05059).
文摘With complicated formation mechanisms,liquid loading in gas wells during gasfield development may significantly affect the productivity of gas wells and the ultimate recovery rate.Dynamic monitoring data of the Samandepe Gasfield in Turkmenistan shows that liquid loading can be found extensively in gas wells.Their formation mechanisms and negative impacts on gasfield development severely restrict the productivity enhancement of this gasfield.With their origins taken into consideration,liquid loads in gas wells were classified into three types:formation water,condensed liquid,and external liquid.By using the hydrostatic pressure gradient method and through PLT monitoring,properties of liquid loads in the Samandepe Gasfield were determined.In addition,formation mechanisms related to liquid loading in gas wells were obtained through analyses of critical fluid-carrying capacities and by using gas-reservoir production data.The following findings were obtained.Liquid loading was commonly found in this gas well with majority of reservoir formations in lower well intervals flooded.However,the formation mechanisms for these liquid loads are different from those of other gasfields.Due to long-term shut-down of gas wells,killing fluids precipitated and pores in lower reservoir formations were plugged.As a result,natural gas had no access to boreholes,killing fluids were impossibly carried out of the borehole.Instead,the killing fluid was detained at the bottomhole to generate liquid load and eliminate the possibility of formation water coning.Moreover,since the gasfield was dominated by block reservoirs with favorable physical properties and connectivity,impacts of liquid load on gasfield development were insignificant.Thus,to enhance the recovery rate of the Samandepe Gasfield significantly,it is necessary to expand the gasfield development scale and strengthen the development of marginal gas reservoirs.
基金Project supported by the National Major Scientific and Technological Project,“Demonstration Project of Large Low-permeability Lithologic-stratigraphic Oil and Gas Reservoirs in Ordos Basin”(Grant No.2011ZX05044)the CNPC Scientific Research and Technical Development Project,“Major Engineering Technologies for Development of Tight Gas Reservoirs”(Grant No.2012E-1306).
文摘Based on the exploration and development achievements of the Sulige Gasfield in the Ordos Basin,tight sandstone gas yield has been increased essentially in China.Recovery enhancement is always the core subject in researches.In this paper,the development history of the Sulige Gasfield was reviewed focusing on the technological progress in single well production enhancement.Then,the technical ideas on and countermeasures for transforming the traditional development modes and increasing recovery factor were discussed.It is shown that the development technologies in the evaluation and the production enhancement and stabilization of giant tight sandstone gas reservoirs are changed progressively.The fast increase of gas production in this field is made possible by well location arrangement technology based on sweep spot screening,horizontal well development technology,well type and well pattern optimization technology,fast drilling technology,reservoir stimulation technology,drainage gas recovery technology and integrated construction mode.And finally,the technical ideas of recovery enhancement during the 13th Five-Year Plan were proposed in nine aspects,including gas field development,planning and evaluation technology based on single-well life cycle analysis;dynamic evaluation and infilling technology for mixed well patterns targeting recovery enhancement;one-shot recovery enhancement technology for a new areal pattern area with integrated multiple well patterns and multiple series of strata;reserve evaluation model based on risk and benefit evaluation;gas-well precise management technology with multi-dimensional matrix;potential tapping technology for low production and low efficiency wells;novel wellsite environmental protection technology;surface process based on integrated equipments;and C_(3)^(+)mixed hydrocarbon recovery technology.It provides technically reliable support for the development of tight sandstone gas reservoirs in the Sulige Gasfield during the 13th Five-Year Plan.
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In the course of completion of an ultra-deep well newly drilled in the Yuanba Gasfield,Sichuan Basin,long-section and large-scale deformation occurred in the heavy casing section and nickel base alloy casing section of the sealing Triassic limestone interval,so a new hole had to be sidetracked,which impels us to rediscover the applicability of conventional drilling and completion technology in ultra-deep wells.In this paper,based on the borehole condition and field operation data of this well,the borehole pressure field variation initiated by lost circulation in the low-pressure formation was analyzed from the perspective of dynamics,then,the variation pattern of differential pressure inside and outside the well bore at different time intervals was depicted,and the primary cause of such complication was theoretically revealed,i.e.,the pressure wave generated by instant lost circulation in low-pressure formation would result in redistribution of pressure inside the downhole confined space,and then the crush of casing in the vicinity of local low-pressure areas.Pertinent proposals for avoiding these kinds of engineering complexities were put forward:①when downhole sealing casing operation is conducted in open hole completion,liner completion or perforated hole,the potential damage of lost circulation to casing should be considered;②the downhole sealing point and sealing mode should be selected cautiously:the sealing point had better be selected in the section with good cementing quality or as close to the casing shoe as possible,and the sealing mode can be either cement plug or mechanical bridge plug.This paper finally points out that good cementing quality plays an important role in preventing this type of casing deformation.
基金Project supported by the National Major Scientific and Technological Project,“Key Development Technologies for Natural Gas”(Grant No.2011ZX05015).
文摘By virtue of unique technical and economical advantages,horizontal well development has become a key technology in the high-efficiency development of tight gas reservoirs,however,this has worked unsatisfactorily in unstratified gas reservoirs.In this paper,the orientation and coverage of gas-bearing sand bodies(in isolated distribution)of Member 8 of Permian Lower Shihezi Fm in the Sulige Gasfield were analyzed by means of outcrop analogy,geostatistical analysis and pilot tests of dense well patterns.Then,four gas-bearing sand distribution patterns suitable for the deployment of horizontal wells in Member 8 were proposed according to the precise geological anatomy results of dense well patterns.These patterns include thick massive isolated pattern,vertically superimposed pattern with physical interlayers,vertically superimposed pattern with argillaceous interlayers and lateral sugar-coated haw string pattern.Based on the statistics on gas-bearing sand bodies drilled by horizontal well drilling,the drilled gas-bearing sand bodies are 670-1300 m long.Based on production data correction,numerical simulation and economic evaluation,the length of rational horizontal sections were optimized by performing a case study of the vertically superimposed reservoirs with physical interlayers in the typical well group SuX-18-36 of Su-X Block.It is indicated that the rational horizontal well length within 1200 m in the Sulige Gasfield under current economic and technical conditions.This paper provides a technical support for the highefficiency development of the Sulige Gasfield in the future.
文摘In the Anyue Gasfield,Sichuan Basin,the Lower Cambrian Longwangmiao Fm gas reservoir in Moxi Block has enormous natural gas reserves,and it is a typical three-high(high temperature,high pressure,and high flow rate)sour gas field.Its ground engineering project(with the designed gas processing capacity of 60×10^(8)m^(2)/a)is characterized by high processing rate of each unit,complex process control,large construction load,restricted construction site and tight schedule.Based on the traditional engineering construction mode,however,it is difficult to complete the project design and construction within 16 months.In view of this,the design concept of unit large-scale modularization was introduced to implement“normalized design,scale purchase,factory-like prefabrication and modularized construction”and develop the modularization technology of large-scale surface engineering construction.This modularizationtechnology is performed as follows.First,the modularized units are laid out reasonably according to the technological process.Second,the layout of modularized units is usually super-imposed in the multi-layer framework.Third,those equipments with the same or similar operational modes,medium properties,functional characteristics and installation requirements are concentrated in the pattem of a module.Fourth,escape passageway is specially set up.Fifth,room for installation,maintenance and repair of large equipments is reserved.And sixth,transportation and hoisting requirements of modules are taken into consideration sufficiently.This technology is contributive to the improvement of design quality,effective shortening of design period,reduction of field working load,decrease of safety management risk of on-site installation,increase of production efficiency,conservation of land occupation and diminishment of construction investment.It plays a reference role in the modularized construction of surface engineering of similar large projects.
基金supported by the Sinopec Technology Development Project Pilot on Acid Frcturing Technology of Ultn-deep Marine Horizontal Wells in Yuanba Gasfiel"(No.:GJ-258-1254)SinopecTechnology Application Project"Optimization Design for the Testing of High-Pressure High-Yield Acid Gas Wells in Northeast Sichuan Basin"(No.:JPO8001)Technical Pillot Experiment Project of Sinopec Petroleum Engincering Company(No.SG1314-03K).
文摘The Yuanba Gasfield is another large gasfield with reserves of a hundred billion cubic meters that was discovered by Sinopec after the Puguang Gasfield in the Sichuan Basin.At present,it is the deepest marine carbonate sour gasfield in China.Its principal reservoir,the Upper Permian Changxing Fm,is characterized by ultra depth,high temperature,high sulfur content,high CO_(2)content,and complex gasewater relationship.Therefore,well completion is faced with complicated engineering geological conditions,diverse well types and well completion modes and high-difficulty operation.In view of this,Sinopec Southwest Petroleum Engineering Co.,Ltd.carried out technical research and practice.As a result,a series of key well completion and commissioning technologies were developed,including well completion testing and ground control,in-depth acid fracturing stimulation,ultra-deep slim-hole wellbore processing,micro-tooth mark make-up and air tightness detection,and safety control.Based on these technologies,the worldwide technical difficulties of well completion and commissioning in the process of gasfield development are settled,such as string corrosion prevention,in-depth acid fracturing,high-yield testing,and safety control.These technologies have been applied successfully in nearly 40 wells,providing an important technical support for the realization of 34×10^(8)m^(3)annual gas production capacity construction in the Yuanba Gasfield.
文摘Centralized and group well deployment and factory-like fracturing techniques are adopted for low-permeability tight sandstone reservoirs in the Sulige Gasfield,Ordos Basin,so as to realize its efficient and economic development.However,environmental protection is faced with grim situations because fluid delivery rises abruptly on site in a short time due to centralized fracturing of the well group.Based on the characteristics of gas testing after fracturing in this gas field,a fracturing flowback fluid recovery and treatment method suitable for the Sulige Gasfield has been developed with the landform features of this area taken into account.Firstly,a high-efficiency well-to-well fracturing flowback fluid recovery and reutilization technique was developed with multi-effect surfactant polymer recoverable fracturing fluid system as the core,and in virtue of this technique,the treatment efficiency of conventional guar gum fracturing fluid system is increased.Secondly,for recovering and treating the end fluids on the well sites,a fine fracturing flowback fluid recovery and treatment technique has been worked out with“coagulation and precipitation,filtration and disinfection,and sludge dewatering”as the main part.Owing to the application of this method,the on-site water resource utilization ratio has been increased and environmental protection pressure concerned with fracturing operation has been relieved.In 2014,field tests were performed in 62 wells of 10 well groups,with 32980 m3 cumulative treated flowback fluid,17160 m3 reutilization volume and reutilization ratio over 70%.Obviously,remarkable social and economical benefits are thus realized.
文摘The Yuanba Gasfield is a large gasfield discovered by Sinopec in the Sichuan Basin in recent years,and another main exploration area for natural gas reserves and production increase after the Puguang Gasfield.The ultra-deep sour gas reservoir in the Yuanba Gasfield is characterized by complicated geologic structure,deep reservoirs and complex drilled formation,especially in the continental deep strata which are highly abrasive with low ROP(rate of penetration)and long drilling period.After many years of drilling practice and technical research,the following six key drilling and completion technologies for this type reservoir are established by introducing new tools and technologies,developing specialized drill bits and optimizing drilling design.They are:casing program optimization technology for ROP increasing and safe well completion;gas drilling technology for shallow continental strata and high-efficiency drilling technology for deep high-abrasion continental strata;drillingfluid support technologies of gaseliquid conversion,ultra-deep highly-deviated wells and horizontal-well lubrication and drag reduction,hole stability control and sour gas contamination prevention;well cementing technologies for gas medium,deep-well long cementing intervals and ultra-high pressure small space;horizontal-well trajectory control technologies for measuring instrument,downhole motor opti-mization and bottom hole assembly design;and liner completion modes and completion string optimization technologies suitable for this gas reservoir.Field application shows that these key technologies are contributive to ROP increase and efficiency improvement of 7000 m deep horizontal wells and to significant operational cycle shortening.
基金supported by CNPC Scientific Research and Tech-nology Development Project"Enhanced gas Recovery Method Research and Pilot Test for Developed Gas Fields"(No.:2022KT0901).
文摘The Sulige Gas Field in the Ordos Basin is the largest tight gasfield in China,with proved reserves exceeding 2×10^(12)m^(3).As the main contributor to gas production in PetroChina Changqing Oilfield Company,The Sulige Gas Field is in the stage of stable production.Maximizing the stable production period is a focus and challenge for the gasfield now.To address a series of problems influencing the efficient development of Sulige gasfield,such as large-scale remaining gas reserves between wells/layers and low ratio of employed reserves,the main technologies for enhanced gas recovery(EGR)of tight gas reservoirs were developed by multidisciplinary research with respect to development geology,reservoir engineering,drilling and production process,and surface gathering and transportation.Experiments were conducted on reservoir description and remaining gas characterization,well pattern thickening optimization,vertical well separate-layer fracturing,horizontal-well multi-stage multi-cluster volume fracturing for their improvement and upgrading.The orientation of EGR for tight gas reservoirs is pro-posed.The following results are obtained.First,well pattern thickening optimization is the most important EGR method,which can increase the recovery rate by more than 6%.Second,based on continuous upgrading and promotion,either of reservoir stimulation technology and drainage gas recovery technology can increase the recovery rate by more than 2%.The gathering and transportation technology which further reduces the wellhead pressure can increase the recovery rate by about 1.5%.Third,the EGR technology should be oriented to maximize the quantity of employed reserves,especially by way of new technologies such asfine remaining gas characterization,well pattern/type optimization,cross-layer fracturing of a multi-thin-layer reservoir by horizontal wells,intelligent drainage gas recovery,and multi-stage pressurization.It is concluded that the development of key EGR technologies will help increase the recovery rate of The Sulige Gas Field by 10%e15%,and will provide an effective support for The Sulige Gas Field to maintain the production at 300108 m^(3)/a for a long term and for the Changqing gas province to increase the production to 500×10^(8)m^(3)/a,which will ultimately ensure the national energy security.
基金This study was supported by China Geological Survey(Zi[2012]02-029-006).
文摘Taking advantage of the successful experience in exploring and discovering the Puguang Gasfield,and targeting the Changxing Formation-Feixianguan Formation organic reef and shoal lithological trap,SINOPEC drilled Well Yuanba 1 in the Bazhong area in Northeast Sichuan in 2006,and discovered the Yuanba Gasfield with a high-production commercial gas flow of 503×10^(3) m^(3)/d.As a normal-pressured lithological gas reservoir with high H_(2)S content,Yuanba Gasfield is characterized by weak tectonic deformation and deep burial,with an average depth of 6,600 m in the central part of the gas reservoir,and is the deepest marine gas field in the Sichuan Basin.Yuanba Gasfield is dominated by large-scale reef-shoal reservoirs of Changxing Formation.The formation of the reservoirs was primarily controlled by early meteoric freshwater dissolution and dolomitization,and less affected by deep-burial dissolution and tectonic movement.A comparative analysis was made on the characteristics of deep reef-shoal reservoirs in the Yuanba and Puguang gas fields so as to explore their formation mechanisms.It is concluded that the reservoir size and early pore development was controlled by early depositional-diagenetic environment.Fracture formation and dissolution were controlled by structure-fluid coupling,pore reworking and preservation is determined by fluid-rock interaction.
