The estimated ultimate recovery(EUR)of shale gas wells is influenced by many factors,and the accurate prediction still faces certain challenges.As an artificial intelligence algorithm,deep learning yields notable adva...The estimated ultimate recovery(EUR)of shale gas wells is influenced by many factors,and the accurate prediction still faces certain challenges.As an artificial intelligence algorithm,deep learning yields notable advantages in nonlinear regression.Therefore,it is feasible to predict the EUR of shale gas wells based on a deep-learning algorithm.In this paper,according to geological evaluation data,hydraulic fracturing data,production data and EUR evaluation results of 282 wells in the WY shale gas field,a deep-learning-based algorithm for EUR evaluation of shale gas wells was designed and realized.First,the existing EUR evaluation methods of shale gas wells and the deep feedforward neural network algorithm was systematically analyzed.Second,the technical process of a deep-learning-based algorithm for EUR prediction of shale gas wells was designed.Finally,by means of real data obtained from the WY shale gas field,several different cases were applied to testify the validity and accuracy of the proposed approach.The results show that the EUR prediction with high accuracy.In addition,the results are affected by the variety and number of input parameters,the network structure and hyperparameters.The proposed approach can be extended to other shale fields using the similar technic process.展开更多
This study was performed in two phases of work.In the first stage,four conventional first-order flotation kinetics models were fitted to the measured recoveries data and the best model were selected.In the second stag...This study was performed in two phases of work.In the first stage,four conventional first-order flotation kinetics models were fitted to the measured recoveries data and the best model were selected.In the second stage,influence of pH,solid concentration,water chemistry and the amount of collector dosage were investigated on kinetics parameters including flotation rate constant and ultimate recovery.The results indicated that that perfectly mixed reactor model and Kelsall model gave the best and the weakest fit to the experimental data,respectively.It was observed that flotation rate constant and ultimate recovery were strongly affected by chemical factors investigated especially water quality.The flotation rate constant decreased with increasing the solids content,while ultimate recovery increased to certain value and thereafter reduced.It was also found that the most values of flotation rate constant and ultimate recovery obtained in dosage of collector are 30 and 40 g/t,respectively.展开更多
Although carbon isotope reversal and its reasons in shale gas reservoirs have been widely recognized,the application of the reversal is yet to be investigated.A study on high-maturity shale from Wufeng and Longmaxi Fo...Although carbon isotope reversal and its reasons in shale gas reservoirs have been widely recognized,the application of the reversal is yet to be investigated.A study on high-maturity shale from Wufeng and Longmaxi Formations in the Sichuan Basin not only reveals the relationship between the degree of isotopes inversion and the production capacity(e.g.,estimated ultimate recovery(EUR))of the gas well but also indicates the preservation conditions of shale gas reservoirs.(1)Although there are differences in gas isotopes in different shale gas reservoirs,the isotope fractionation of shale gas is small during the production stage of gas wells,even when the wellbore pressure drops to zero.The main cause of the difference in carbon isotopes and their inversion degree can be the uplift time during the Yanshan period and the formation pressure relief degree of shale gas reservoirs in distinct structural positions.Thus,carbon isotope inversion is a good indicator of shale gas preservation condition and EUR of shale gas wells.(2)The degree of carbon isotope inversion correlates strongly with shale gas content and EUR.The calculation formula of shale-gas recoverable reserves was established using△δ^(13)C(δC_(1)-δC_(2))and EUR.(3)The gas loss rate and total loss amount can be estimated using the dynamic reserves and isotopic difference values of gas wells in various shale gas fields,which also reflects the current methane loss,thereby demonstrating great potential for evaluating global methane loss in shales.展开更多
This paper presents the development and application of a production data analysis software that can analyze and forecast the production performance and reservoir properties of shale gas wells.The theories used in the ...This paper presents the development and application of a production data analysis software that can analyze and forecast the production performance and reservoir properties of shale gas wells.The theories used in the study were based on the analytical and empirical approaches.Its reliability has been confirmed through comparisons with a commercial software.Using transient data relating to multi-stage hydraulic fractured horizontal wells,it was confirmed that the accuracy of the modified hyperbolic method showed an error of approximately 4%compared to the actual estimated ultimate recovery(EUR).On the basis of the developed model,reliable productivity forecasts have been obtained by analyzing field production data relating to wells in Canada.The EUR was computed as 9.6 Bcf using the modified hyperbolic method.Employing the Pow Law Exponential method,the EUR would be 9.4 Bcf.The models developed in this study will allow in the future integration of new analytical and empirical theories in a relatively readily than commercial models.展开更多
The Wufeng FormationeLongmaxi Formation in the Sichuan Basin in South China is the key stratum for shale gas exploration and pro-duction.To date,three national shale gas demonstration zones have been developed.Neverth...The Wufeng FormationeLongmaxi Formation in the Sichuan Basin in South China is the key stratum for shale gas exploration and pro-duction.To date,three national shale gas demonstration zones have been developed.Nevertheless,there are still some test wells that have not yet been commercialized.In this study,the geological characteristics of commercial and non-commercial zones are analyzed,as are the main controlling factors of high-producing wells(high estimated ultimate recovery;EUR),and the reasons for low-production wells(low EUR)by dissecting the three national shale gas demonstration zones and the main shale gas exploration wells.The results of this study indicate the following:(1)The black shale in the WF2-LM4 graptolite zone is deposited in the Craton depression on the Upper Yangtze plate,which provides a relatively stable tectonic environment for tectonic deformation and uplift destruction.The large shale thickness and weak tectonic activity jointly result in shale gas being enriched mainly in the deep-water shelf.(2)The regional fault has a destructive effect on shale gas preservation,and the shale gas reservoir is likely to be destroyed.In the areas close to the regional fault,multiple fracture-fluid migration activities caused by multistage tectonic movements are also detrimental to shale gas preservation.Conversely,shale gas is generally well preserved in areas far from regional faults.(3)The black shale thickness in the WF2-LM4 graptolite zone in the deep-water shelf area controls the shale gasfield distribution.Furthermore,the horizontal well trajectory in the WF2-LM4 graptolite zone determines the shale gas well test production and EUR.The results of this work will provide a reference for shale gas exploration and development of the Wufeng FormationeLongmaxi Formation in the Sichuan Basin,as well as the Silurian strata in other parts of the world.展开更多
The marine shale gas resource in South China is abundant,but the existing conventional methods cannot meet the needs of predicting the future production development of shale gas.With the marine shale of the Lower Silu...The marine shale gas resource in South China is abundant,but the existing conventional methods cannot meet the needs of predicting the future production development of shale gas.With the marine shale of the Lower Silurian Longmaxi Fm in this region as an example and based on its development potential,the development features of the existing shale gas resources were analyzed.It is considered that the Longmaxi shale gas accumulation zones in the Sichuan Basin and its neighboring areas contain resources of about 17.4×10^(12)m^(3)and recoverable resources of about 2.9×10^(12)m^(3).In particular,the shale gas above 3500 m underground is the main body for recent development targets,with a potential production scale about 300×10^(8)m^(3).On this basis,the development features of foreign and domestic shale gas wells were studied and the drilling workload analytical method for the prediction of shale gas production was established:(1)the initial production of a single well can be used to characterize the productivity of the shale gas well,and its test production is approximate to its initial production.Due to the similarity of decline rate among shale gas wells,the single-well estimated ultimate recovery(EUR)value of a single well can be roughly speculated from its initial production,thus the production scale of a shale gasfield can be speculated according to the analysis of drilling workload;(2)currently,the expected test production of South China marine shale gas is 17.6104 m^(3)/d,and the predicted single-well EUR value is roughly 1.5108 m^(3).It is concluded that the marine shale gas in South China represents high initial production of a single well,high declining rate,longer production cycle and the drilling workload is closely related with the production of a shale gasfield.Therefore,the analysis of drilling workload shows better applicability to the evaluation of shale gas production.Based on this method,the shale gas production of the Sichuan Basin and its neighboring area in 2020 was estimated to be about 200×10^(8)m^(3).展开更多
There is a need to increase ultimate recovery from petroleum reservoirs. In order to guarantee efficient resource extraction from reservoirs, primary recovery methods cannot be relied on throughout the life of a well....There is a need to increase ultimate recovery from petroleum reservoirs. In order to guarantee efficient resource extraction from reservoirs, primary recovery methods cannot be relied on throughout the life of a well. There is a time in the life of a reservoir when the primary energy will not be sufficient to ensure economic recovery. Complete abandonment of the reservoir at this point may not be a sound engineering decision given the huge investments in developing the asset. Secondary recovery methods present potentials for the recovery of the other trapped resources. The choice of the secondary recovery means depends on the reservoir and geologic conditions and should be determined by modeling and simulation. In this work, a simulation study is conducted for Niger Delta Field ABX2 to determine the performance of water-flooding and gas injection in the recovery of the asset after the primary recovery stage. ECLIPSE Blackoil simulator was used for the modeling and simulation. An equal reservoir rectangular grid block was designed for both the waterflooding and water injection comprising a total of 750 grid cells. Water and gas were injected in both cases at an injection rate of 11,000 stb/d and 300,000 scf/d for waterflooding and gas injection respectively. From the results of the simulation, it was realized that waterflooding gave a higher total oil recovery than gas injection. The difference in oil recovery from water-flooding and gas injection amounted to 0.08 MMstb/d. The Field Oil Recovery Efficiency (FOE) for waterflooding and gas injection was 38% and 16% respectively giving a difference of 22%. The waterflooding method was troubled with excessive water cuts due to water breakthroughs. Waterflooding was chosen against gas injection to be applied to Field ABX2 to improve recovery after primary production ceased.展开更多
基金supported by the funding of National Science and Technology Major Projects of China(2016ZX05037-006-005,2016ZX05037-006,2016ZX05035-004)。
文摘The estimated ultimate recovery(EUR)of shale gas wells is influenced by many factors,and the accurate prediction still faces certain challenges.As an artificial intelligence algorithm,deep learning yields notable advantages in nonlinear regression.Therefore,it is feasible to predict the EUR of shale gas wells based on a deep-learning algorithm.In this paper,according to geological evaluation data,hydraulic fracturing data,production data and EUR evaluation results of 282 wells in the WY shale gas field,a deep-learning-based algorithm for EUR evaluation of shale gas wells was designed and realized.First,the existing EUR evaluation methods of shale gas wells and the deep feedforward neural network algorithm was systematically analyzed.Second,the technical process of a deep-learning-based algorithm for EUR prediction of shale gas wells was designed.Finally,by means of real data obtained from the WY shale gas field,several different cases were applied to testify the validity and accuracy of the proposed approach.The results show that the EUR prediction with high accuracy.In addition,the results are affected by the variety and number of input parameters,the network structure and hyperparameters.The proposed approach can be extended to other shale fields using the similar technic process.
文摘This study was performed in two phases of work.In the first stage,four conventional first-order flotation kinetics models were fitted to the measured recoveries data and the best model were selected.In the second stage,influence of pH,solid concentration,water chemistry and the amount of collector dosage were investigated on kinetics parameters including flotation rate constant and ultimate recovery.The results indicated that that perfectly mixed reactor model and Kelsall model gave the best and the weakest fit to the experimental data,respectively.It was observed that flotation rate constant and ultimate recovery were strongly affected by chemical factors investigated especially water quality.The flotation rate constant decreased with increasing the solids content,while ultimate recovery increased to certain value and thereafter reduced.It was also found that the most values of flotation rate constant and ultimate recovery obtained in dosage of collector are 30 and 40 g/t,respectively.
基金supported by the National Natural Science Foundation of China(Grant No.41872124,42202175&No.42130803)。
文摘Although carbon isotope reversal and its reasons in shale gas reservoirs have been widely recognized,the application of the reversal is yet to be investigated.A study on high-maturity shale from Wufeng and Longmaxi Formations in the Sichuan Basin not only reveals the relationship between the degree of isotopes inversion and the production capacity(e.g.,estimated ultimate recovery(EUR))of the gas well but also indicates the preservation conditions of shale gas reservoirs.(1)Although there are differences in gas isotopes in different shale gas reservoirs,the isotope fractionation of shale gas is small during the production stage of gas wells,even when the wellbore pressure drops to zero.The main cause of the difference in carbon isotopes and their inversion degree can be the uplift time during the Yanshan period and the formation pressure relief degree of shale gas reservoirs in distinct structural positions.Thus,carbon isotope inversion is a good indicator of shale gas preservation condition and EUR of shale gas wells.(2)The degree of carbon isotope inversion correlates strongly with shale gas content and EUR.The calculation formula of shale-gas recoverable reserves was established using△δ^(13)C(δC_(1)-δC_(2))and EUR.(3)The gas loss rate and total loss amount can be estimated using the dynamic reserves and isotopic difference values of gas wells in various shale gas fields,which also reflects the current methane loss,thereby demonstrating great potential for evaluating global methane loss in shales.
基金supported by the Energy Efficiency&Resources Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)granted financial resource from the Ministry of Trade,Industry&Energy,Republic of Korea(No.20172510102090).
文摘This paper presents the development and application of a production data analysis software that can analyze and forecast the production performance and reservoir properties of shale gas wells.The theories used in the study were based on the analytical and empirical approaches.Its reliability has been confirmed through comparisons with a commercial software.Using transient data relating to multi-stage hydraulic fractured horizontal wells,it was confirmed that the accuracy of the modified hyperbolic method showed an error of approximately 4%compared to the actual estimated ultimate recovery(EUR).On the basis of the developed model,reliable productivity forecasts have been obtained by analyzing field production data relating to wells in Canada.The EUR was computed as 9.6 Bcf using the modified hyperbolic method.Employing the Pow Law Exponential method,the EUR would be 9.4 Bcf.The models developed in this study will allow in the future integration of new analytical and empirical theories in a relatively readily than commercial models.
基金funded by National Natural Science Foundation of China Project“Evolution Mechanism and Evaluation Method of Wufeng-Longmaxi Formation Shale Gas Reservoir in Sichuan Basin”(No.41872124)“Large-scale enrichment effect of oil and gas in one-way splitcon-vergence of continents in the Tethys region(No.91755211)”。
文摘The Wufeng FormationeLongmaxi Formation in the Sichuan Basin in South China is the key stratum for shale gas exploration and pro-duction.To date,three national shale gas demonstration zones have been developed.Nevertheless,there are still some test wells that have not yet been commercialized.In this study,the geological characteristics of commercial and non-commercial zones are analyzed,as are the main controlling factors of high-producing wells(high estimated ultimate recovery;EUR),and the reasons for low-production wells(low EUR)by dissecting the three national shale gas demonstration zones and the main shale gas exploration wells.The results of this study indicate the following:(1)The black shale in the WF2-LM4 graptolite zone is deposited in the Craton depression on the Upper Yangtze plate,which provides a relatively stable tectonic environment for tectonic deformation and uplift destruction.The large shale thickness and weak tectonic activity jointly result in shale gas being enriched mainly in the deep-water shelf.(2)The regional fault has a destructive effect on shale gas preservation,and the shale gas reservoir is likely to be destroyed.In the areas close to the regional fault,multiple fracture-fluid migration activities caused by multistage tectonic movements are also detrimental to shale gas preservation.Conversely,shale gas is generally well preserved in areas far from regional faults.(3)The black shale thickness in the WF2-LM4 graptolite zone in the deep-water shelf area controls the shale gasfield distribution.Furthermore,the horizontal well trajectory in the WF2-LM4 graptolite zone determines the shale gas well test production and EUR.The results of this work will provide a reference for shale gas exploration and development of the Wufeng FormationeLongmaxi Formation in the Sichuan Basin,as well as the Silurian strata in other parts of the world.
基金supported by the National Key Basic Rescarch Program of China(973 Program)(No.:2012CB214700).
文摘The marine shale gas resource in South China is abundant,but the existing conventional methods cannot meet the needs of predicting the future production development of shale gas.With the marine shale of the Lower Silurian Longmaxi Fm in this region as an example and based on its development potential,the development features of the existing shale gas resources were analyzed.It is considered that the Longmaxi shale gas accumulation zones in the Sichuan Basin and its neighboring areas contain resources of about 17.4×10^(12)m^(3)and recoverable resources of about 2.9×10^(12)m^(3).In particular,the shale gas above 3500 m underground is the main body for recent development targets,with a potential production scale about 300×10^(8)m^(3).On this basis,the development features of foreign and domestic shale gas wells were studied and the drilling workload analytical method for the prediction of shale gas production was established:(1)the initial production of a single well can be used to characterize the productivity of the shale gas well,and its test production is approximate to its initial production.Due to the similarity of decline rate among shale gas wells,the single-well estimated ultimate recovery(EUR)value of a single well can be roughly speculated from its initial production,thus the production scale of a shale gasfield can be speculated according to the analysis of drilling workload;(2)currently,the expected test production of South China marine shale gas is 17.6104 m^(3)/d,and the predicted single-well EUR value is roughly 1.5108 m^(3).It is concluded that the marine shale gas in South China represents high initial production of a single well,high declining rate,longer production cycle and the drilling workload is closely related with the production of a shale gasfield.Therefore,the analysis of drilling workload shows better applicability to the evaluation of shale gas production.Based on this method,the shale gas production of the Sichuan Basin and its neighboring area in 2020 was estimated to be about 200×10^(8)m^(3).
文摘There is a need to increase ultimate recovery from petroleum reservoirs. In order to guarantee efficient resource extraction from reservoirs, primary recovery methods cannot be relied on throughout the life of a well. There is a time in the life of a reservoir when the primary energy will not be sufficient to ensure economic recovery. Complete abandonment of the reservoir at this point may not be a sound engineering decision given the huge investments in developing the asset. Secondary recovery methods present potentials for the recovery of the other trapped resources. The choice of the secondary recovery means depends on the reservoir and geologic conditions and should be determined by modeling and simulation. In this work, a simulation study is conducted for Niger Delta Field ABX2 to determine the performance of water-flooding and gas injection in the recovery of the asset after the primary recovery stage. ECLIPSE Blackoil simulator was used for the modeling and simulation. An equal reservoir rectangular grid block was designed for both the waterflooding and water injection comprising a total of 750 grid cells. Water and gas were injected in both cases at an injection rate of 11,000 stb/d and 300,000 scf/d for waterflooding and gas injection respectively. From the results of the simulation, it was realized that waterflooding gave a higher total oil recovery than gas injection. The difference in oil recovery from water-flooding and gas injection amounted to 0.08 MMstb/d. The Field Oil Recovery Efficiency (FOE) for waterflooding and gas injection was 38% and 16% respectively giving a difference of 22%. The waterflooding method was troubled with excessive water cuts due to water breakthroughs. Waterflooding was chosen against gas injection to be applied to Field ABX2 to improve recovery after primary production ceased.
