The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle m...The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle model. With the new model, the statistical correspondence between the production decline stage and the reserve-production imbalance is clarified,and the correlation of water cut with the recovery percent of recoverable reserves is discussed, providing quantitative basis of reservoir engineering for dividing development stages of oilfield and defining mature oilfields. According to the statistics of oilfields in eastern China, the time point corresponding to the reserve-production balance coefficient dropping to less than 1dramatically is well correlated the beginning point of production decline, thus the time when the reserve-production balance coefficient drops dramatically can be taken as the initiation point of production decline stage. The research results show that the water cut and the recovery percent of recoverable reserves have a good statistical match in the high water cut stage, and it is more rational to take both the start point of production decline stage and the water cut of 90%(or the recovery percent of recoverable reserves of 80%) as the critical criteria for defining a mature oilfield. Five production evolution patterns can be summarized as follows: growth–peak plateau–stepped decline, growth–stepped stabilizing–stepped decline, growth–stepped stabilizing–rapid decline, growth–peak plateau–rapid decline, and growth–continuous decline.展开更多
The oil production predicted by means of the conventional water-drive characteristic curve is typically affected by large deviations with respect to the actual value when the so-called high water-cut stage is entered....The oil production predicted by means of the conventional water-drive characteristic curve is typically affected by large deviations with respect to the actual value when the so-called high water-cut stage is entered.In order to solve this problem,a new characteristic relationship between the relative permeability ratio and the average water saturation is proposed.By comparing the outcomes of different matching methods,it is verified that it can well reflect the variation characteristics of the relative permeability ratio curve.Combining the new formula with a reservoir engineering method,two new formulas are derived for the water flooding characteristic curve in the high water-cut stage.Their practicability is verified by using the production data of Mawangmiao and Xijiakou blocks.The results show that the error between the predicted cumulative oil production and production data of the two new water drive characteristic curves is less than the error between the B-type water drive characteristic curve and the other two water drive characteristic curves.It is concluded that the two new characteristic curves can be used to estimate more accurately the recoverable reserves,the final recovery and to estimate the effects of water flooding.展开更多
This study analyzes the status-quo of the proved oil/gas initially-in-place and its variation trend,the proved undeveloped oil/gas initially-in-place,and the remaining proved technically recoverable reserves(TRR)of oi...This study analyzes the status-quo of the proved oil/gas initially-in-place and its variation trend,the proved undeveloped oil/gas initially-in-place,and the remaining proved technically recoverable reserves(TRR)of oil/gas in China as of 2020 based on statistics.As shown by the results,the proved oil initially-in-place(OIIP),the proved undeveloped OIIP,and the remaining proved TRR of oil in China are mainly distributed in the Bohai Bay,Ordos and Songliao Basins,and those of free gas are mainly in the Ordos,Sichuan,and Tarim Basins.From 2011 to 2020,the largest increment in the proved OIIP,the proved undeveloped OIIP and the remaining proved TRR of oil occurred in the Ordos Basin,followed by the Bohai Bay Basin,while that in the proved gas initially-in-place(GIIP),the proved undeveloped GIIP,and the remaining proved TRR of gas occurred in the Ordos Basin,followed by the Sichuan Basin.In addition,a comprehensive analysis reveals that the petroliferous basins in China with the potential of reserve addition and production growth include the Ordos Basin,the Bohai Bay Basin,the Sichuan Basin,and the Tarim Basin.展开更多
By reviewing the challenges in the development of oilfields in China under low oil prices,this study analyzes the root causes of cost rising,put forwards the low cost oilfield development strategy and specific paths t...By reviewing the challenges in the development of oilfields in China under low oil prices,this study analyzes the root causes of cost rising,put forwards the low cost oilfield development strategy and specific paths to realize the strategy,and predicts the development potential and prospect of oilfields in China.In addition to the low grade of the reservoir and high development maturation,the fundamental reasons of development full cost rising of oilfields in China are as follows:(1)Facing the problem of resources turning poorer in quality,we have built production capacity at a pace too fast before making enough technical and experimental preparation;(2)technical engineering service model leads to high service cost;(3)team of oil development expertise and matched engineering system cannot satisfy the technical requirements of stabilizing oil production,controlling water cut and fine development.To realize development at low cost,the core is to increase economic recoverable reserves.The concrete paths include:(1)to explore the"Daqing oilfield development culture",improve the ability of leaders in charge of development,and inspire potential of staff;(2)to improve the ability of reservoir dynamics control,and implement precise development by following scientific principles;(3)to speed up integration of water flooding and enhanced oil recovery(EOR)and technological upgrading in order to enhance oil recovery;(4)to innovate key techniques in gas flooding and accelerate the industrial popularization of gas flooding;(5)to break the related transaction barriers and create new management models;and(6)to collaboratively optimize strategic layout and cultivate key oil bases.Although oilfield development in China faces huge challenges in cost,the low-cost development strategy will succeed as long as strategic development of mature and new oil fields is well planned.The cores to lower cost are to control decline rate and enhance oil recovery in mature oil fields,and increase single well productivity through technical innovation and improve engineering service efficiency through management innovation in new oil fields.展开更多
To study the distribution law of remaining oil in a block, core analysis method, C/O test method, reservoir engineering method, dynamic analysis method, numerical simulation method, microscopic oil displacement experi...To study the distribution law of remaining oil in a block, core analysis method, C/O test method, reservoir engineering method, dynamic analysis method, numerical simulation method, microscopic oil displacement experiment method and other methods are mainly used. Finally, the distribution of remaining oil and remaining recoverable reserves from qualitative to quantitative, macroscopic to microscopic, and from small layer plane to longitudinal are deeply understood, and the potential of chemical flooding is analyzed.展开更多
The monitoring results of production logging show that almost one third of perforation clusters produce no or less gas after volumetric fracturing is initially applied in shale gas reservoirs.Besides,the production de...The monitoring results of production logging show that almost one third of perforation clusters produce no or less gas after volumetric fracturing is initially applied in shale gas reservoirs.Besides,the production decline after the commissioning is commonly faster.In this paper,a fracture network prediction model and a fracturing well productivity prediction model were established based on microseismic interpretation data and hydraulic fracture network propagation results.After petrophysics,microseism,production performance were taken into consideration comprehensively,shale re-fracturing development potential evaluation index(RDPEI)was proposed.Then,a re-fracturing design and evaluation method was developed and targeted interval selection and evaluation was realized and applied on site.And the following research results were obtained.First,due to the heterogeneity of natural fractures,hydraulic fracture networks are more different,so an obvious“dead gas zone”can be easily formed and its re-fracturing potential is high.Second,the initial hydraulic fracture network is more affected by natural fractures.The main part of a fracture network propagates along the direction of maximum horizontal major stress,the fractures in regional stimulated intervals propagate in the form of double wing,and the length of a liquid swept fracture network is 52e70%of seismic interpretation result.Third,the RDPEI model avoids the limitations of single factor analysis and realizes the quantitative prediction on three types of indexes of recoverability,compressibility and re-fracturing.Fourth,re-fracturing of the case well is remarkable in stimulation effect.Its shale gas productivity is increased by 38.9%,and its cumulative gas production in one year is increased by 62.5%.In conclusion,re-fracturing is an effective and feasible method for improving the single well ultimate recovery reserves of shale gas.This method provides a theoretical and technical support for the selection and effect evaluation of re-fracturing intervals in shale-gas horizontal wells.展开更多
After over 10 years'development of coalbed methane(CBM)industry in China,two industrial bases have been built,i.e.,the Qinshui Basin and the Ordos Basin.However,the biggest problem that restricts the high-efficien...After over 10 years'development of coalbed methane(CBM)industry in China,two industrial bases have been built,i.e.,the Qinshui Basin and the Ordos Basin.However,the biggest problem that restricts the high-efficiency development of CBM industry in China is that average single-well gas production rate is low.At present,the production of high-rank CBM accounts for more than 90%of total CBM production in China.In the future,the exploitation field of high-rank CBM resources will focus on the deep and medium reservoirs.The complex CBM occurrence and flow conditions(e.g.different tectonic field,stress field and fracture field)bring great challenges to the adaptability of existing engineering technologies to geological conditions.In this regard,this paper takes the research and practice of high-rank CBM technologies in the Qinshui Basin of PetroChina Huabei Oilfield Company as an example to analyze the“four low”(low effective reserve producing ratio,low remaining producible reserves,low single-well gas production rate and low exploitation profit)CBM exploitation phenomena and discuss the essence of CBM exploitation dialectically.And the following research results were obtained.First,current major problems in CBM exploitation include CBM reserve recoverability,geological difference,engineering technological adaptability and scientific drainage gas recovery.Second,the only way for scientific CBM exploitation is to break through the key bottlenecks under existing technical conditions,including control technology for reserve development,regional selection technology for economic productivity construction,engineering technology suitable for geological characteristics and top-level design technology for scheme preparation.Third,the exploitation practice achievements of high-rank CBM in the Mabidong Block and medium-rank CBM in the Dacheng uplift are realized by breaking the traditional geological cognitions and breaking through the restricted idea that the CBM below 800 m is not suitable to be developed.And it is demonstrated that burial depth is not the limitation condition to determine if CBM can be exploited and medium and deep reservoirs are not the forbidden areas of CBM exploitation.展开更多
There are abundant high-rank coal bed methane(CBM)resources in China,accounting for one third of total CBM resources.Its efficient development and utilization is of great significance to guarantee the national energy ...There are abundant high-rank coal bed methane(CBM)resources in China,accounting for one third of total CBM resources.Its efficient development and utilization is of great significance to guarantee the national energy strategic security,diminish the hidden danger of coal mine production and reduce carbon dioxide emission.In order to solve the"four lows"problem(i.e.,low effective utilization ratio of proved reserves,low productivity targeting ratio,low single-well production rate and low development profit)restricting the development of high-rank CBM industry in China,this paper deeply analyzes the core problems restricting the development of high-rank CBM.Based on this,several new methods of production control,area selection and evaluation are put forward by taking multiple measures,such as paying the same attention on theoretical research and technological research&development,carrying out laboratory research and field test in parallel and conducting large scale construction and benefit development simultaneously.And the following research results are obtained.First,the geological difference between CBM and coal mine,the difference in reserves recoverability,the adaptability of engineering technology and the scientificity of production are the main factors restricting CBM development effect.Second,"Four-element"production control theory,methane-leading en gineering transformation method and methane-leading production control theory are proposed,which provides guidance for the development of a series of technologies for the efficient development of high-rank CBM.Third,in practice,the control degree of quality reserves is increased from 32%to 80%,the success ratio of development wells is increased from 60%to 95%,the average single-well daily gas production of vertical wells is increased by about 1100 m^(3),the drilling cost of horizontal wells is reduced by 50%,and the operation cost per cubic meter of gas is reduced by 24%.In conclusion,the established technology series for the efficient development of high-rank CBM actively promote the efficient CBMdevelopment in the Qinshui Basin.The yearly CBM production of PetroChina Huabei Oilfield Company is expected to reach 20108 m^(3) in the middle of the"14th Five-Year Plan",which promotes the strategic development of CBM industry in China.展开更多
基金Supported by the National Natural Science Foundation of China (72088101)。
文摘The continuous growth of recoverable reserves in a waterflooding oilfield has a significant impact on the patterns of production evolution. A new production evolution model is established by improving the Weng Cycle model. With the new model, the statistical correspondence between the production decline stage and the reserve-production imbalance is clarified,and the correlation of water cut with the recovery percent of recoverable reserves is discussed, providing quantitative basis of reservoir engineering for dividing development stages of oilfield and defining mature oilfields. According to the statistics of oilfields in eastern China, the time point corresponding to the reserve-production balance coefficient dropping to less than 1dramatically is well correlated the beginning point of production decline, thus the time when the reserve-production balance coefficient drops dramatically can be taken as the initiation point of production decline stage. The research results show that the water cut and the recovery percent of recoverable reserves have a good statistical match in the high water cut stage, and it is more rational to take both the start point of production decline stage and the water cut of 90%(or the recovery percent of recoverable reserves of 80%) as the critical criteria for defining a mature oilfield. Five production evolution patterns can be summarized as follows: growth–peak plateau–stepped decline, growth–stepped stabilizing–stepped decline, growth–stepped stabilizing–rapid decline, growth–peak plateau–rapid decline, and growth–continuous decline.
基金It is supported by the National Natural Science Foundation of China(No.51404037)supported by the Scientific and Technological Research Project of Sinopec Jianghan Oilfield Branch Company(No.ZKK0220006).
文摘The oil production predicted by means of the conventional water-drive characteristic curve is typically affected by large deviations with respect to the actual value when the so-called high water-cut stage is entered.In order to solve this problem,a new characteristic relationship between the relative permeability ratio and the average water saturation is proposed.By comparing the outcomes of different matching methods,it is verified that it can well reflect the variation characteristics of the relative permeability ratio curve.Combining the new formula with a reservoir engineering method,two new formulas are derived for the water flooding characteristic curve in the high water-cut stage.Their practicability is verified by using the production data of Mawangmiao and Xijiakou blocks.The results show that the error between the predicted cumulative oil production and production data of the two new water drive characteristic curves is less than the error between the B-type water drive characteristic curve and the other two water drive characteristic curves.It is concluded that the two new characteristic curves can be used to estimate more accurately the recoverable reserves,the final recovery and to estimate the effects of water flooding.
文摘This study analyzes the status-quo of the proved oil/gas initially-in-place and its variation trend,the proved undeveloped oil/gas initially-in-place,and the remaining proved technically recoverable reserves(TRR)of oil/gas in China as of 2020 based on statistics.As shown by the results,the proved oil initially-in-place(OIIP),the proved undeveloped OIIP,and the remaining proved TRR of oil in China are mainly distributed in the Bohai Bay,Ordos and Songliao Basins,and those of free gas are mainly in the Ordos,Sichuan,and Tarim Basins.From 2011 to 2020,the largest increment in the proved OIIP,the proved undeveloped OIIP and the remaining proved TRR of oil occurred in the Ordos Basin,followed by the Bohai Bay Basin,while that in the proved gas initially-in-place(GIIP),the proved undeveloped GIIP,and the remaining proved TRR of gas occurred in the Ordos Basin,followed by the Sichuan Basin.In addition,a comprehensive analysis reveals that the petroliferous basins in China with the potential of reserve addition and production growth include the Ordos Basin,the Bohai Bay Basin,the Sichuan Basin,and the Tarim Basin.
文摘By reviewing the challenges in the development of oilfields in China under low oil prices,this study analyzes the root causes of cost rising,put forwards the low cost oilfield development strategy and specific paths to realize the strategy,and predicts the development potential and prospect of oilfields in China.In addition to the low grade of the reservoir and high development maturation,the fundamental reasons of development full cost rising of oilfields in China are as follows:(1)Facing the problem of resources turning poorer in quality,we have built production capacity at a pace too fast before making enough technical and experimental preparation;(2)technical engineering service model leads to high service cost;(3)team of oil development expertise and matched engineering system cannot satisfy the technical requirements of stabilizing oil production,controlling water cut and fine development.To realize development at low cost,the core is to increase economic recoverable reserves.The concrete paths include:(1)to explore the"Daqing oilfield development culture",improve the ability of leaders in charge of development,and inspire potential of staff;(2)to improve the ability of reservoir dynamics control,and implement precise development by following scientific principles;(3)to speed up integration of water flooding and enhanced oil recovery(EOR)and technological upgrading in order to enhance oil recovery;(4)to innovate key techniques in gas flooding and accelerate the industrial popularization of gas flooding;(5)to break the related transaction barriers and create new management models;and(6)to collaboratively optimize strategic layout and cultivate key oil bases.Although oilfield development in China faces huge challenges in cost,the low-cost development strategy will succeed as long as strategic development of mature and new oil fields is well planned.The cores to lower cost are to control decline rate and enhance oil recovery in mature oil fields,and increase single well productivity through technical innovation and improve engineering service efficiency through management innovation in new oil fields.
文摘To study the distribution law of remaining oil in a block, core analysis method, C/O test method, reservoir engineering method, dynamic analysis method, numerical simulation method, microscopic oil displacement experiment method and other methods are mainly used. Finally, the distribution of remaining oil and remaining recoverable reserves from qualitative to quantitative, macroscopic to microscopic, and from small layer plane to longitudinal are deeply understood, and the potential of chemical flooding is analyzed.
基金supported by the National Major Science and Technology Project“Optimization system of horizontal well fracturing design”(No.:2016ZX05023-001).
文摘The monitoring results of production logging show that almost one third of perforation clusters produce no or less gas after volumetric fracturing is initially applied in shale gas reservoirs.Besides,the production decline after the commissioning is commonly faster.In this paper,a fracture network prediction model and a fracturing well productivity prediction model were established based on microseismic interpretation data and hydraulic fracture network propagation results.After petrophysics,microseism,production performance were taken into consideration comprehensively,shale re-fracturing development potential evaluation index(RDPEI)was proposed.Then,a re-fracturing design and evaluation method was developed and targeted interval selection and evaluation was realized and applied on site.And the following research results were obtained.First,due to the heterogeneity of natural fractures,hydraulic fracture networks are more different,so an obvious“dead gas zone”can be easily formed and its re-fracturing potential is high.Second,the initial hydraulic fracture network is more affected by natural fractures.The main part of a fracture network propagates along the direction of maximum horizontal major stress,the fractures in regional stimulated intervals propagate in the form of double wing,and the length of a liquid swept fracture network is 52e70%of seismic interpretation result.Third,the RDPEI model avoids the limitations of single factor analysis and realizes the quantitative prediction on three types of indexes of recoverability,compressibility and re-fracturing.Fourth,re-fracturing of the case well is remarkable in stimulation effect.Its shale gas productivity is increased by 38.9%,and its cumulative gas production in one year is increased by 62.5%.In conclusion,re-fracturing is an effective and feasible method for improving the single well ultimate recovery reserves of shale gas.This method provides a theoretical and technical support for the selection and effect evaluation of re-fracturing intervals in shale-gas horizontal wells.
基金Project supported by National Major Science and Technology Project“High efficiency development demonstration project of high-rank CBM in the Qinshui Basin”(No.:2017ZX05064)PetroChina Major Science and Technology Project“Study on the production-increase technology of highrank CBM development”(No.:2017E-1404).
文摘After over 10 years'development of coalbed methane(CBM)industry in China,two industrial bases have been built,i.e.,the Qinshui Basin and the Ordos Basin.However,the biggest problem that restricts the high-efficiency development of CBM industry in China is that average single-well gas production rate is low.At present,the production of high-rank CBM accounts for more than 90%of total CBM production in China.In the future,the exploitation field of high-rank CBM resources will focus on the deep and medium reservoirs.The complex CBM occurrence and flow conditions(e.g.different tectonic field,stress field and fracture field)bring great challenges to the adaptability of existing engineering technologies to geological conditions.In this regard,this paper takes the research and practice of high-rank CBM technologies in the Qinshui Basin of PetroChina Huabei Oilfield Company as an example to analyze the“four low”(low effective reserve producing ratio,low remaining producible reserves,low single-well gas production rate and low exploitation profit)CBM exploitation phenomena and discuss the essence of CBM exploitation dialectically.And the following research results were obtained.First,current major problems in CBM exploitation include CBM reserve recoverability,geological difference,engineering technological adaptability and scientific drainage gas recovery.Second,the only way for scientific CBM exploitation is to break through the key bottlenecks under existing technical conditions,including control technology for reserve development,regional selection technology for economic productivity construction,engineering technology suitable for geological characteristics and top-level design technology for scheme preparation.Third,the exploitation practice achievements of high-rank CBM in the Mabidong Block and medium-rank CBM in the Dacheng uplift are realized by breaking the traditional geological cognitions and breaking through the restricted idea that the CBM below 800 m is not suitable to be developed.And it is demonstrated that burial depth is not the limitation condition to determine if CBM can be exploited and medium and deep reservoirs are not the forbidden areas of CBM exploitation.
基金Scientific and Technological Project of China National Petroleum Exploration and Production Corporation"Research on North China Coalbed Methane Reserve Utilization and Beneficial Development Technology"(kt2021-10-07)China National Petroleum North China Technology Project of Oilfield Company"Geological Design Technology of High Coalbed Methane Horizontal Well and Implementation Tracking Research"(2022-HB-M03).
文摘There are abundant high-rank coal bed methane(CBM)resources in China,accounting for one third of total CBM resources.Its efficient development and utilization is of great significance to guarantee the national energy strategic security,diminish the hidden danger of coal mine production and reduce carbon dioxide emission.In order to solve the"four lows"problem(i.e.,low effective utilization ratio of proved reserves,low productivity targeting ratio,low single-well production rate and low development profit)restricting the development of high-rank CBM industry in China,this paper deeply analyzes the core problems restricting the development of high-rank CBM.Based on this,several new methods of production control,area selection and evaluation are put forward by taking multiple measures,such as paying the same attention on theoretical research and technological research&development,carrying out laboratory research and field test in parallel and conducting large scale construction and benefit development simultaneously.And the following research results are obtained.First,the geological difference between CBM and coal mine,the difference in reserves recoverability,the adaptability of engineering technology and the scientificity of production are the main factors restricting CBM development effect.Second,"Four-element"production control theory,methane-leading en gineering transformation method and methane-leading production control theory are proposed,which provides guidance for the development of a series of technologies for the efficient development of high-rank CBM.Third,in practice,the control degree of quality reserves is increased from 32%to 80%,the success ratio of development wells is increased from 60%to 95%,the average single-well daily gas production of vertical wells is increased by about 1100 m^(3),the drilling cost of horizontal wells is reduced by 50%,and the operation cost per cubic meter of gas is reduced by 24%.In conclusion,the established technology series for the efficient development of high-rank CBM actively promote the efficient CBMdevelopment in the Qinshui Basin.The yearly CBM production of PetroChina Huabei Oilfield Company is expected to reach 20108 m^(3) in the middle of the"14th Five-Year Plan",which promotes the strategic development of CBM industry in China.
