Air injection technique for developing shale oil has gained significant attention. However, the ability of the heat front to consistently propagate within the shale during air injection remains uncertain. To address t...Air injection technique for developing shale oil has gained significant attention. However, the ability of the heat front to consistently propagate within the shale during air injection remains uncertain. To address this, we investigated the heat front propagation within oil-detritus mixtures, shale cores, and fractured shale cores using a self-designed combustion tube(CT) and experimental schemes. By integrating the results obtained from high-pressure differential scanning calorimetry and CT, we developed a comprehensive reaction kinetics model to accurately analyze the main factors influencing the heat front propagation within fractured shale. The findings revealed that in the absence of additional fractures, the heat front failed to propagate within the tight shale. The flow of gases and liquids towards the shale core was impeded, resulting in the formation of a high-pressure zone at the front region of the shale. This pressure buildup significantly hindered air injection, leading to inadequate oxygen supply and the extinguishment of the heat front. However, the study demonstrated the stable propagation of the heat front within the oil-detritus mixtures, indicating the good combustion activity of the shale oil.Furthermore, the heat front successfully propagated within the fractured shale, generating a substantial amount of heat that facilitated the creation of fractures and enhanced gas injection and shale oil flow. It was important to note that after the heat front passed through the shale, the combustion intensity decreased. The simulation results indicated that injecting air into the main fracturing layers of the shale oil reservoir enabled the establishment of a stable heat front. Increasing the reservoir temperature(from 63 to 143℃) and oxygen concentration in the injected gas(from 11% to 21%) promoted notable heat front propagation and increased the average temperature of the heat front. It was concluded that temperature and oxygen concentration had the most important influence on the heat front propagation, followed by pressure and oil saturation.展开更多
Nowadays,enhanced oil recovery(EOR)methods have been evaluated both for onshore and offshore oilfields.However,the conditions for using EOR methods in offshore fields are more complex due to the unique features of the...Nowadays,enhanced oil recovery(EOR)methods have been evaluated both for onshore and offshore oilfields.However,the conditions for using EOR methods in offshore fields are more complex due to the unique features of the infrastructure,transportation facilities and geological conditions.The experience gained from offshore gas EOR(gEOR)pilot projects has shown effective methods for increasing oil production at a later stage of field development.The technical knowledge base gained has been analyzed in this paper,which includes an analysis of the advantages and disadvantages of offshore projects and operational experience with gas and water-gas flooding in offshore environments.A history of implemented EOR projects in offshore oil fields from 1970 to the present and an evaluation of the application of different injection methods with hydrocarbon gas,CO_(2)and nitrogen is presented sequentially.展开更多
Accelerating mass exchange between matrix and fractures is the essence of enhanced oil recovery(EOR)in tight formations after natural depletion.Low salinity water(LSW)injection has been commerciallyproven in conventio...Accelerating mass exchange between matrix and fractures is the essence of enhanced oil recovery(EOR)in tight formations after natural depletion.Low salinity water(LSW)injection has been commerciallyproven in conventional reservoirs EOR,with scale projects in progress worldwide.There is,however,a lack of understanding of the EOR effect in tight formations.Therefore,in this work,we introduced LSWEOR to a target tight formation using huff-puff mode.Spontaneous imbibition(SI)tests were firstly performed on homogenous Berea sandstone cores with decreasing salinity brine to observe the production response.The results indicated that the oil recovery of the tight rock was boosted by tuning brine salinity.Of all the used brines with salinity ranging from 0.021%to 2.1%TDS(total dissolved salinity),the 0.21%TDS brine showed a rapid increase in oil production over imbibing time,which finally led to an incremental oil recovery of 4.5%OOIP(original oil in place).Core-scale modeling was conducted by history-matching the oil recovery dynamics of the SI results through modifying capillary pressure and relative permeability.A full-scale reservoir model was constructed using micro-seismic data to model fracture geometry combing fracturing results and scaling parameters obtained from core scale historymatching.It is proven that LSW huff-n-puff stimulated the oil production after natural depletion and improved MEE(mass exchange efficiency)of the target formation,but the EOR benefit was not comparable to CO2 and surfactant-assisted water huff-puff methods.展开更多
Production prediction is crucial for the recovery of hydrocarbon resources.However,accurate and rapid production forecasting remains challenging for unconventional reservoirs due to the complexity of the percolation p...Production prediction is crucial for the recovery of hydrocarbon resources.However,accurate and rapid production forecasting remains challenging for unconventional reservoirs due to the complexity of the percolation process and the scarcity of available data.To address this problem,a novel model combining a long short-term memory network(LSTM)and support vector regression(SVR)was proposed to forecast tight oil production.Three variables,the tubing head pressure,nozzle size,and water rate were utilized as the inputs of the presented machine-learning workflow to account for the influence of operational parameters.The time-series response of tight oil production was the output and was predicted by the optimized LSTM model.An SVR-based residual correction model was constructed and embedded with LSTM to increase the prediction accuracy.Case studies were carried out to verify the feasibility of the proposed method using data from two wells in the Ma-18 block of the Xinjiang oilfield.Decline curve analysis(DCA)methods,LSTM and artificial neural network(ANN)models were also applied in this study and compared with the LSTM-SVR model to prove its superiority.It was demonstrated that introducing residual correction with the newly proposed LSTM-SVR model can effectively improve prediction performance.The LSTM-SVR model of Well A produced the lowest prediction root mean square error(RMSE)of 5.42,while the RMSE of Arps,PLE Duong,ANN,and LSTM were 5.84,6.65,5.85,8.16,and 7.70,respectively.The RMSE of Well B of LSTM-SVR model is 0.94,while the RMSE of ANN,and LSTM were 1.48,and 2.32.展开更多
Application of high resolution^(13)C nuclear magnetic resonance(NMR)spectroscopy to characterize crude oil was demonstrated.The chemical shifts of^(13)C NMR functional groups that determine the composition of the oil ...Application of high resolution^(13)C nuclear magnetic resonance(NMR)spectroscopy to characterize crude oil was demonstrated.The chemical shifts of^(13)C NMR functional groups that determine the composition of the oil sample were determined.Molar fractions of primary,secondary,quaternary,tertiary,aromatic groups,aromatic factor and average hydrocarbon chain length of aliphatic hydrocarbons of the oil sample according to^(13)C NMR spectra were determined.Detailed description of the^(13)C NMR spectra of the oil sample using a single consideration of three NMR spectra:^(13)C,^(13)C Attached Proton Test(APT),^(13)C with Gated Decoupling(GD)was performed.The different contribution of the studied oil sample in the aliphatic(10e75 ppm)and aromatic(115e165 ppm)areas of the^(13)C NMR spectra was determined.The presence of all major hydrocarbon components in the studied oil sample was established on the quantitative level,the aromaticity factor and the mean length of the hydrocarbon chain were evaluated.Quantitative fractions of aromatic molecules and functional groups constituting oil hydrocarbons were determined.In this work we demonstrate that the attached proton test and gated decoupling^(13)C NMR spectroscopy can afford all information to complete the chemical shift assignment of an oil sample,especially for determination of long range 1He^(13)C coupling constants and^(13)C multiplicity.展开更多
Application of high resolution^(13)C nuclear magnetic resonance(NMR)spectroscopy to characterize Cuba oil and oil-containing rock samples from Cuban basin was demonstrated.The chemical shifts of^(13)C NMR functional g...Application of high resolution^(13)C nuclear magnetic resonance(NMR)spectroscopy to characterize Cuba oil and oil-containing rock samples from Cuban basin was demonstrated.The chemical shifts of^(13)C NMR functional groups for later determination the composition of the oil and rock samples were determined.The different contribution of the studied samples in the aliphatic and aromatic areas was determined.Molar fractions of primary,secondary,quaternary,tertiary,aromatic groups,aromaticity factor and the mean length of hydrocarbon chain length of aliphatic hydrocarbons were estimated.Comparative analysis on the quantitative level for all major hydrocarbon components,the aromaticity factor and the mean length of the hydrocarbon chain were carried out.展开更多
基金supported by National Natural Science Foundation of China (No. 52204049)Natural Science Foundation of Sichuan Province (No. 2024NSFSC0960)Ministry of Science and Higher Education of the Russian Federation under Agreement No. 075-15-2022-299 within the Framework of the Development Program for a World-Class Research Center “Efficient development of the global liquid hydrocarbon reserves”。
文摘Air injection technique for developing shale oil has gained significant attention. However, the ability of the heat front to consistently propagate within the shale during air injection remains uncertain. To address this, we investigated the heat front propagation within oil-detritus mixtures, shale cores, and fractured shale cores using a self-designed combustion tube(CT) and experimental schemes. By integrating the results obtained from high-pressure differential scanning calorimetry and CT, we developed a comprehensive reaction kinetics model to accurately analyze the main factors influencing the heat front propagation within fractured shale. The findings revealed that in the absence of additional fractures, the heat front failed to propagate within the tight shale. The flow of gases and liquids towards the shale core was impeded, resulting in the formation of a high-pressure zone at the front region of the shale. This pressure buildup significantly hindered air injection, leading to inadequate oxygen supply and the extinguishment of the heat front. However, the study demonstrated the stable propagation of the heat front within the oil-detritus mixtures, indicating the good combustion activity of the shale oil.Furthermore, the heat front successfully propagated within the fractured shale, generating a substantial amount of heat that facilitated the creation of fractures and enhanced gas injection and shale oil flow. It was important to note that after the heat front passed through the shale, the combustion intensity decreased. The simulation results indicated that injecting air into the main fracturing layers of the shale oil reservoir enabled the establishment of a stable heat front. Increasing the reservoir temperature(from 63 to 143℃) and oxygen concentration in the injected gas(from 11% to 21%) promoted notable heat front propagation and increased the average temperature of the heat front. It was concluded that temperature and oxygen concentration had the most important influence on the heat front propagation, followed by pressure and oil saturation.
基金supported by the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2022-299 within the framework of the development program for a world-class Research Center«Efficient development of the global liquid hydrocarbon reserves».
文摘Nowadays,enhanced oil recovery(EOR)methods have been evaluated both for onshore and offshore oilfields.However,the conditions for using EOR methods in offshore fields are more complex due to the unique features of the infrastructure,transportation facilities and geological conditions.The experience gained from offshore gas EOR(gEOR)pilot projects has shown effective methods for increasing oil production at a later stage of field development.The technical knowledge base gained has been analyzed in this paper,which includes an analysis of the advantages and disadvantages of offshore projects and operational experience with gas and water-gas flooding in offshore environments.A history of implemented EOR projects in offshore oil fields from 1970 to the present and an evaluation of the application of different injection methods with hydrocarbon gas,CO_(2)and nitrogen is presented sequentially.
基金support of National Natural Science Foundation of China(51974265 and 51804264)Youth Science and Technology Innovation Team of SWPU(2017CXTD04)。
文摘Accelerating mass exchange between matrix and fractures is the essence of enhanced oil recovery(EOR)in tight formations after natural depletion.Low salinity water(LSW)injection has been commerciallyproven in conventional reservoirs EOR,with scale projects in progress worldwide.There is,however,a lack of understanding of the EOR effect in tight formations.Therefore,in this work,we introduced LSWEOR to a target tight formation using huff-puff mode.Spontaneous imbibition(SI)tests were firstly performed on homogenous Berea sandstone cores with decreasing salinity brine to observe the production response.The results indicated that the oil recovery of the tight rock was boosted by tuning brine salinity.Of all the used brines with salinity ranging from 0.021%to 2.1%TDS(total dissolved salinity),the 0.21%TDS brine showed a rapid increase in oil production over imbibing time,which finally led to an incremental oil recovery of 4.5%OOIP(original oil in place).Core-scale modeling was conducted by history-matching the oil recovery dynamics of the SI results through modifying capillary pressure and relative permeability.A full-scale reservoir model was constructed using micro-seismic data to model fracture geometry combing fracturing results and scaling parameters obtained from core scale historymatching.It is proven that LSW huff-n-puff stimulated the oil production after natural depletion and improved MEE(mass exchange efficiency)of the target formation,but the EOR benefit was not comparable to CO2 and surfactant-assisted water huff-puff methods.
基金support of National Natural Science Foundation of China(52274041 and 51974265)Sichuan science fund for distinguished Young Scholars(2023NSFSC1954)+3 种基金the Ministry of Science and Higher Education of the Russian Federation under Agreement No.075-15-2022-299 within the framework of the development program for a worldclass Research Center“Efficient development of the global liquid hydrocarbon reserves”,Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202201510)Natural Science Foundation of Chongqing(CSTB2022NSCQMSX0403)Chongqing Municipal Support Program for Overseas Students Returning for Entrepreneurship and Innovation(2205012980950154)Scientific Research Funding Project of Chongqing University of Science and Technology(ckrc2021040)。
文摘Production prediction is crucial for the recovery of hydrocarbon resources.However,accurate and rapid production forecasting remains challenging for unconventional reservoirs due to the complexity of the percolation process and the scarcity of available data.To address this problem,a novel model combining a long short-term memory network(LSTM)and support vector regression(SVR)was proposed to forecast tight oil production.Three variables,the tubing head pressure,nozzle size,and water rate were utilized as the inputs of the presented machine-learning workflow to account for the influence of operational parameters.The time-series response of tight oil production was the output and was predicted by the optimized LSTM model.An SVR-based residual correction model was constructed and embedded with LSTM to increase the prediction accuracy.Case studies were carried out to verify the feasibility of the proposed method using data from two wells in the Ma-18 block of the Xinjiang oilfield.Decline curve analysis(DCA)methods,LSTM and artificial neural network(ANN)models were also applied in this study and compared with the LSTM-SVR model to prove its superiority.It was demonstrated that introducing residual correction with the newly proposed LSTM-SVR model can effectively improve prediction performance.The LSTM-SVR model of Well A produced the lowest prediction root mean square error(RMSE)of 5.42,while the RMSE of Arps,PLE Duong,ANN,and LSTM were 5.84,6.65,5.85,8.16,and 7.70,respectively.The RMSE of Well B of LSTM-SVR model is 0.94,while the RMSE of ANN,and LSTM were 1.48,and 2.32.
基金the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2020-931 within the framework of the development program for a world-class Research Center"Efficient development of the global liquid hydrocarbon reserves.".
文摘Application of high resolution^(13)C nuclear magnetic resonance(NMR)spectroscopy to characterize crude oil was demonstrated.The chemical shifts of^(13)C NMR functional groups that determine the composition of the oil sample were determined.Molar fractions of primary,secondary,quaternary,tertiary,aromatic groups,aromatic factor and average hydrocarbon chain length of aliphatic hydrocarbons of the oil sample according to^(13)C NMR spectra were determined.Detailed description of the^(13)C NMR spectra of the oil sample using a single consideration of three NMR spectra:^(13)C,^(13)C Attached Proton Test(APT),^(13)C with Gated Decoupling(GD)was performed.The different contribution of the studied oil sample in the aliphatic(10e75 ppm)and aromatic(115e165 ppm)areas of the^(13)C NMR spectra was determined.The presence of all major hydrocarbon components in the studied oil sample was established on the quantitative level,the aromaticity factor and the mean length of the hydrocarbon chain were evaluated.Quantitative fractions of aromatic molecules and functional groups constituting oil hydrocarbons were determined.In this work we demonstrate that the attached proton test and gated decoupling^(13)C NMR spectroscopy can afford all information to complete the chemical shift assignment of an oil sample,especially for determination of long range 1He^(13)C coupling constants and^(13)C multiplicity.
基金supported by the Ministry of Science and Higher Education of the Russian Federation under agreement No.075-15-2020-931 within the framework of the development program for a world-class Research Center“Efficient development of the global liquid hydrocarbon reserves.”。
文摘Application of high resolution^(13)C nuclear magnetic resonance(NMR)spectroscopy to characterize Cuba oil and oil-containing rock samples from Cuban basin was demonstrated.The chemical shifts of^(13)C NMR functional groups for later determination the composition of the oil and rock samples were determined.The different contribution of the studied samples in the aliphatic and aromatic areas was determined.Molar fractions of primary,secondary,quaternary,tertiary,aromatic groups,aromaticity factor and the mean length of hydrocarbon chain length of aliphatic hydrocarbons were estimated.Comparative analysis on the quantitative level for all major hydrocarbon components,the aromaticity factor and the mean length of the hydrocarbon chain were carried out.
