Flue gas fooding is one of the important technologies to improve oil recovery and achieve greenhouse gas storage.In order to study multicomponent fue gas storage capacity and enhanced oil recovery(EOR)performance of f...Flue gas fooding is one of the important technologies to improve oil recovery and achieve greenhouse gas storage.In order to study multicomponent fue gas storage capacity and enhanced oil recovery(EOR)performance of fue gas water-alternating gas(fue gas-WAG)injection after continuous waterfooding in an oil reservoir,a long core fooding system was built.The experimental results showed that the oil recovery factor of fue gas-WAG fooding was increased by 21.25%after continuous waterfooding and fue gas-WAG fooding could further enhance oil recovery and reduce water cut signifcantly.A novel material balance model based on storage mechanism was developed to estimate the multicomponent fue gas storage capacity and storage capacity of each component of fue gas in reservoir oil,water and as free gas in the post-waterfooding reservoir.The ultimate storage ratio of fue gas is 16%in the fue gas-WAG fooding process.The calculation results of fue gas storage capacity showed that the injection gas storage capacity mainly consists of N_(2) and CO_(2),only N_(2) exists as free gas phase in cores,and other components of injection gas are dissolved in oil and water.Finally,injection strategies from three perspectives for fue gas storage,EOR,and combination of fue gas storage and EOR were proposed,respectively.展开更多
Gas injection serves as a main enhanced oil recovery(EOR)method in fractured-vuggy carbonate reservoir,but its effect differs among single wells and multi-well groups because of the diverse fractured-vuggy configurati...Gas injection serves as a main enhanced oil recovery(EOR)method in fractured-vuggy carbonate reservoir,but its effect differs among single wells and multi-well groups because of the diverse fractured-vuggy configuration.Many researchers conducted experiments for the observation of fluid flow and the evaluation of production performance,while most of their physical models were fabricated based on the probability distribution of fractures and caves in the reservoir.In this study,a two-dimensional physical model of the karst fault system was designed and fabricated based on the geological model of TK748 well group in the seventh block of the Tahe Oilfield.The fluid flow and production performance of primary gas flooding were discussed.Gas-assisted gravity flooding was firstly introduced to take full use of gas-oil gravity difference,and its feasibility in the karst fault system was examined.Experimental results showed that primary gas flooding created more flow paths and achieved a remarkable increment of oil recovery compared to water flooding.Gas injection at a lower location was recommended to delay gas breakthrough.Gas-assisted gravity flooding achieved more stable gas-displacing-oil because oil production was at a lower location,and thus,the oil recovery was further enhanced.展开更多
The recovery factor from tight gas reservoirs is typically less than 15%, even with multistage hydrauhc tractunng stimulation. Such low recovery is exacerbated in tight gas condensate reservoirs, where the depletion o...The recovery factor from tight gas reservoirs is typically less than 15%, even with multistage hydrauhc tractunng stimulation. Such low recovery is exacerbated in tight gas condensate reservoirs, where the depletion of gas leaves the valuable condensate behind. In this paper, three enhanced gas recovery （EGR） methods including produced gas injection, CO2 injection and water injection are investigated to increase the well productivity for a tight gas condensate reservoir in the Montney Formation, Canada. The production performance of the three EGR methods is compared and their economic feasibility is evaluated. Sensitivity analysis of the key factors such as primary production duration, bottom-hole pressures, and fracture conductivity is conducted and their effects on the well production performance are analyzed. Results show that, compared with the simple depletion method, both the cumulative gas and condensate production increase with fluids injected. Produced gas injection leads to both a higher gas and condensate production compared with those of the CO2 injection, while waterflooding suffers from injection difficulty and the corresponding low sweep efficiency. Meanwhile, the injection cost is lower for the produced gas injection due to the on-site available gas source and minimal transport costs, gaining more economic benefits than the other EGR methods.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
BACKGROUND Persistent vegetative state(PVS)is a devastating and long-lasting clinical condition with high morbidity and mortality;currently,there are no available effective interventions.CASE SUMMARY We report the cas...BACKGROUND Persistent vegetative state(PVS)is a devastating and long-lasting clinical condition with high morbidity and mortality;currently,there are no available effective interventions.CASE SUMMARY We report the case of an 11-year-old boy with PVS caused by severe intracerebral bleeding in the left hemisphere following anticoagulation treatment.The patient’s PVS severity showed no notable improvement after 2-mo neuroprotective treatment and rehabilitation,including nerve growth factor and baclofen,hyperbaric oxygen,and comprehensive bedside rehabilitation therapies.Daily inhalation treatment(4-6 h)of high-concentration hydrogen(H2)gas(66.6%H2+33.3%O2)was provided.Surprisingly,the patient’s orientation,consciousness,ability to speak,facial expressions,and locomotor function were significantly restored,along with improvements in essential general health status,after H2 gas inhalation treatment,which was consistent with stabilized neuropathology in the left hemisphere and increased Hounsfield unit values of computed tomography in the right hemisphere.The patient finally recovered to a near normal conscious state with a Coma Recovery Scale-Revised Score of 22 from his previous score of 3.CONCLUSION Phase 1 clinical trials are needed to explore the safety and efficacy of H2 gas inhalation in patients with PVS.展开更多
Gas injection is the second largest enhanced oil recovery process, next only to the thermal method used in heavy oil fields. To increase the extent of the reservoir contacted by the injected gas, the gas is generally ...Gas injection is the second largest enhanced oil recovery process, next only to the thermal method used in heavy oil fields. To increase the extent of the reservoir contacted by the injected gas, the gas is generally injected intermittently with water. This mode of injection is called water-alternating-gas (WAG). This study deals with a new immiscible water alternating gas (IWAG) EOR technique, “hot IWAG” which includes combination of thermal, solvent and sweep techniques. In the proposed method CO2 will be superheated above the reservoir temperature and instead of normal temperature water, hot water will be used. Hot CO2 and hot water will be alternatively injected into the sand packs. A laboratory test was conducted on the fractured and conventional sand packs. Slugs of water and CO2 with a low and constant rate were injected into the sand packs alternatively; slug size was 0.05 PV. Recovery from each sand pack was monitored and after that hot water and hot CO2 were injected alternatively under the same conditions and increased oil recovery from each sand pack and breakthrough were measured. Experimental results showed that the injection of hot WAG could significantly recover residual oil after WAG injection in conventional and fractured sand packs.展开更多
technique.However,the main challenge in this process is the high minimum miscibility pressure(MMP)between natural gas and crude oil,which limits its application and recovery factor,especially in hightemperature reserv...technique.However,the main challenge in this process is the high minimum miscibility pressure(MMP)between natural gas and crude oil,which limits its application and recovery factor,especially in hightemperature reservoirs.Therefore,we present a novel investigation to quantify the effect of chemicalassisted MMP reduction on the oil recovery factor.Firstly,we measured the interfacial tension(IFT)of the methane-oil system in the presence of chemical or CO_(2) to calculate the MMP reduction at a constant temperature(373K)using the vanishing interfacial tension(VIT)method.Afterwards,we performed three coreflooding experiments to quantify the effect of MMP reduction on the oil recovery factor under different injection scenarios.The interfacial tension measurements show that adding a small fraction(1.5 wt%)of the tested surfactant(SOLOTERRA ME-6)achieved 9%of MMP reduction,while adding 20 wt%of CO_(2) to the methane yields 13%of MMP reduction.Then,the coreflooding results highlight the significance of achieving miscibility during gas injection,as the ultimate recovery factor increased from 65.5%under immiscible conditions to 77.2%using chemical-assisted methane,and to 79%using gas mixture after achieving near miscible condition.The results demonstrate the promising potential of the MMP reduction to signifi-cantly increase the oil recovery factor during gas injection.Furthermore,these results will likely expand the application envelop of the miscible gas injection,in addition to the environmental benefits of utilizing the produced gas by re-injection/recycling instead of flaring which contributes to reducing the greenhouse gas emissions.展开更多
In this work,using fractured shale cores,isothermal adsorption experiments and core flooding tests were conducted to investigate the performance of injecting different gases to enhance shale gas recovery and CO_(2)geo...In this work,using fractured shale cores,isothermal adsorption experiments and core flooding tests were conducted to investigate the performance of injecting different gases to enhance shale gas recovery and CO_(2)geological storage efficiency under real reservoir conditions.The adsorption process of shale to different gases was in agreement with the extended-Langmuir model,and the adsorption capacity of CO_(2)was the largest,followed by CH_(4),and that of N_(2)was the smallest of the three pure gases.In addition,when the CO_(2)concentration in the mixed gas exceeded 50%,the adsorption capacity of the mixed gas was greater than that of CH4,and had a strong competitive adsorption effect.For the core flooding tests,pure gas injection showed that the breakthrough time of CO_(2)was longer than that of N_(2),and the CH_(4)recovery factor at the breakthrough time(Rch,)was also higher than that of N_(2).The RcH of CO_(2)gas injection was approximately 44.09%,while the RcH,of N_(2)was only 31.63%.For CO_(2)/N_(2)mixed gas injection,with the increase of CO_(2)concentration,the RcH,increased,and the RcH,for mixed gas CO_(2)/N_(2)=8:2 was close to that of pure CO_(2),about 40.24%.Moreover,the breakthrough time of N_(2)in mixed gas was not much different from that when pure N_(2)was injected,while the breakthrough time of CO_(2)was prolonged,which indicated that with the increase of N_(2)concentration in the mixed gas,the breakthrough time of CO_(2)could be extended.Furthermore,an abnormal surge of N_(2)concentration in the produced gas was observed after N_(2)breakthrough.In regards to CO_(2)storage efficiency(S_(Storage-CO_(2)),as the CO_(2)concentration increased,S storage-co_(2)also increased.The S storage-co_(2),of the pure CO_(2)gas injection was about 35.96%,while for mixed gas CO_(2)/N_(2)=8:2,S sorage-co,was about 32.28%.展开更多
The technique of Enhanced Gas Recovery by CO_(2) injection(CO_(2)-EGR)into shale reservoirs has brought increasing attention in the recent decade.CO_(2)-EGR is a complex geophysical process that is controlled by sever...The technique of Enhanced Gas Recovery by CO_(2) injection(CO_(2)-EGR)into shale reservoirs has brought increasing attention in the recent decade.CO_(2)-EGR is a complex geophysical process that is controlled by several parameters of shale properties and engineering design.Nevertheless,more challenges arise when simulating and predicting CO_(2)/CH4 displacement within the complex pore systems of shales.Therefore,the petroleum industry is in need of developing a cost-effective tool/approach to evaluate the potential of applying CO_(2) injection to shale reservoirs.In recent years,machine learning applications have gained enormous interest due to their high-speed performance in handling complex data and efficiently solving practical problems.Thus,this work proposes a solution by developing a supervised machine learning(ML)based model to preliminary evaluate CO_(2)-EGR efficiency.Data used for this work was drawn across a wide range of simulation sensitivity studies and experimental investigations.In this work,linear regression and artificial neural networks(ANNs)implementations were considered for predicting the incremental enhanced CH4.Based on the model performance in training and validation sets,our accuracy comparison showed that(ANNs)algorithms gave 15%higher accuracy in predicting the enhanced CH4 compared to the linear regression model.To ensure the model is more generalizable,the size of hidden layers of ANNs was adjusted to improve the generalization ability of ANNs model.Among ANNs models presented,ANNs of 100 hidden layer size gave the best predictive performance with the coefficient of determination(R2)of 0.78 compared to the linear regression model with R2 of 0.68.Our developed MLbased model presents a powerful,reliable and cost-effective tool which can accurately predict the incremental enhanced CH4 by CO_(2) injection in shale gas reservoirs.展开更多
Miscible CO_(2)injection appears to be an important enhanced oil recovery technique for improving sweep efficiency and eliminating CO_(2)-oil interfacial tension resulting in up to 10%higher oil recovery compared to i...Miscible CO_(2)injection appears to be an important enhanced oil recovery technique for improving sweep efficiency and eliminating CO_(2)-oil interfacial tension resulting in up to 10%higher oil recovery compared to immiscible flooding,in addition to the environmental benefits of reducing greenhouse gas emissions through carbon capturing utilising and storage(CCUS).Moreover,this technique could be similarly applicable to natural gas and nitrogen projects to increase oil recovery and to reduce the associated gas flaring.However,miscible displacement may not be achievable for all reservoirs,in particular,reservoirs with high temperature where high injection pressure would be needed to reach miscibility which likely exceeds the formation fracture pressure.Therefore,to further achieve reservoirs’potential,there is a pressing need to explore a viable means to decrease the miscibility pressure,and thus expand the application envelop of miscible gas injection in reservoirs with high temperatures.In this work,we aim to provide insights into minimum miscibility pressure(MMP)reduction by adding chemicals into CO_(2)phase during injection.We achieved this objective by performing a comprehensive review on chemical-assisted MMP reduction using different chemical additives(e.g.,alcohols,fatty acids,surfactants)and different experimental methodologies.Previous experimental studies have shown that a fraction of chemical additives can yield up to 22%of MMP reduction in CO_(2)-oil system.Based on results analysis,surfactant based chemicals were found to be more efficient compared to alcohol based chemicals in reducing the interfacial tension in the CO_(2)-oil system.Based on the current experimental results,adding chemicals to improve the miscibility and reduce the MMP in the CO_(2)-oil system appears to be a promising technique to increase oil recovery while reducing operating cost.Selection of the effective chemical additives may help to expand the application of miscible gas injection to shallow and high temperature reservoirs.Furthermore,our review provides an overall framework to screen potential chemical additives and an injection strategy to be used for miscible displacement in CO_(2)and/or gas systems.展开更多
Regarding the enormous demands of numerous industries to fossil fuels,it is essential to select the proper enhanced oil recovery approaches for vertical and horizontal wells to supply the demands with the optimum expe...Regarding the enormous demands of numerous industries to fossil fuels,it is essential to select the proper enhanced oil recovery approaches for vertical and horizontal wells to supply the demands with the optimum expenditure.Water and gas injectivity as the secondary enhanced oil recovery techniques would be preferentially considered regarding their low costs of performances rather than chemical recovery and thermal techniques.Injected gas tends to push oil through pores or cracks in the matrix block and lead them to the production well.Therefore,injection of gas may significantly increase the recovery factor in these reservoirs.In this research,different injection scenarios in a fractured carbonate reservoir in the west of Iran are being simulated by the PVT modules of Eclipse software.The purpose of this research is to analyze the possibility of gradually increasing the extent of recovery by injecting carbon dioxide,methane,and water,and different injectivity patterns are considered in this research.The selection of injectivity patterns is severely based on the highest recycling rate of gas injection on different injection scenarios,and the injectivity scenarios were being compared with the natural depletion scenario.Consequently,Co2 injection(about 60%)had the highest oil recovery factor and CH4 and TB(about 54%and 53%)injectivity scenarios had the second and third highest rate of the oil recovery factor.展开更多
Nowadays,the non-hydrocarbon gases are the main sources for gas injection projects in different countries.The main advantages of the flue gas injection are low cost,readily available sources(which consists mainly of N...Nowadays,the non-hydrocarbon gases are the main sources for gas injection projects in different countries.The main advantages of the flue gas injection are low cost,readily available sources(which consists mainly of N2 and CO2)and low compressibility in comparison with other gases like CO2 or CH4(for a given volume at the same conditions).In addition,it occupies more space in the reservoir and it is an appropriate way for CO2 sequestering and consequently reducing greenhouse gases.In the aforementioned method,N2 and/or CO2 is injected into the oil reservoir for miscible and/or immiscible displacement of remaining oil.Moreover,a key parameter in the designing of a gas injection project is the minimum miscibility pressure(MMP)which is commonly calculated by running simulation case or implementing conventional correlations.From technical viewpoints,the lower MMP values are more flavor for miscible gas injection process due to lower injection pressure and consequently lower maintenance and lower injection costs.The main aim of this research is to investigate various gas injection methods(N2,CO2,produced reservoir gas,and flue gas)in one of the northern Persian gulf oil fields by a numerical simulation method.Moreover,for each scenario of gas injection technical and economical considerations are took into account.Finally,an economic analysis is implemented to compare the net present value(NPV)of the different gas injection scenarios in the aforementioned oil field.展开更多
This paper presents the effectiveness of the CO_(2) injection process at different periods during gascondensate reservoir development.Taking a real gas-condensate reservoir located in China's east region as an exa...This paper presents the effectiveness of the CO_(2) injection process at different periods during gascondensate reservoir development.Taking a real gas-condensate reservoir located in China's east region as an example,first,we conducted experiments of constant composition expansion(CCE),constant volume depletion(CVD),saturation pressure determination,and single flash.Next,a series of water/CO2 flooding experiments were been investigated,including water flooding at present pressure 15 MPa,CO_(2) flooding at 25.53 MPa,15 MPa,which repents initial pressure and present pressure respectively.Finally,the core flooding numerical model was constructed using a generalized equation-of-state model reservoir simulator(GEM)to reveal miscible flooding mechanism and the seepage flow characteristics in the condensate gas reservoir with CO2 injection.A desirable agreement achieved in experimental results and predicted pressure volume temperature(PVT)properties by the modified equation of state(EOS)in the CVD and CCE tests indicated that the proposed recombination method can successfully produce a fluid with the same phase behavior of initial reservoir fluid with an acceptable accuracy.The modeling results confirm the experimental results,and both methods indicate that significant productivity loss can occur in retrograde gas condensate reservoirs when the flowing bottom-hole pressure falls below dew point pressure.Moreover,the results show that CO_(2) treatment can improve gas productivity by a factor of about 1.39 compared with the water flooding mode.These results may help reservoir engineers and specialists to restore the lost productivity of gas condensate.展开更多
基金This work was supported by the Department of Science and Technology of Sichuan Province(2019YFG0457)the National Natural Science Foundation of China(5183000045)+1 种基金the National Major Science and Technology Project of CNPC"Research and Application of Key Technologies for Beneft Development of Volcanic Rock Reservoirs”(2017E-04-05)the PetroChina Major Science and Technology Project(2018E-1805).
文摘Flue gas fooding is one of the important technologies to improve oil recovery and achieve greenhouse gas storage.In order to study multicomponent fue gas storage capacity and enhanced oil recovery(EOR)performance of fue gas water-alternating gas(fue gas-WAG)injection after continuous waterfooding in an oil reservoir,a long core fooding system was built.The experimental results showed that the oil recovery factor of fue gas-WAG fooding was increased by 21.25%after continuous waterfooding and fue gas-WAG fooding could further enhance oil recovery and reduce water cut signifcantly.A novel material balance model based on storage mechanism was developed to estimate the multicomponent fue gas storage capacity and storage capacity of each component of fue gas in reservoir oil,water and as free gas in the post-waterfooding reservoir.The ultimate storage ratio of fue gas is 16%in the fue gas-WAG fooding process.The calculation results of fue gas storage capacity showed that the injection gas storage capacity mainly consists of N_(2) and CO_(2),only N_(2) exists as free gas phase in cores,and other components of injection gas are dissolved in oil and water.Finally,injection strategies from three perspectives for fue gas storage,EOR,and combination of fue gas storage and EOR were proposed,respectively.
基金the financial support from National Natural Science Foundation of China(51504268)National Technology Major Project of China(2016ZX05014).
文摘Gas injection serves as a main enhanced oil recovery(EOR)method in fractured-vuggy carbonate reservoir,but its effect differs among single wells and multi-well groups because of the diverse fractured-vuggy configuration.Many researchers conducted experiments for the observation of fluid flow and the evaluation of production performance,while most of their physical models were fabricated based on the probability distribution of fractures and caves in the reservoir.In this study,a two-dimensional physical model of the karst fault system was designed and fabricated based on the geological model of TK748 well group in the seventh block of the Tahe Oilfield.The fluid flow and production performance of primary gas flooding were discussed.Gas-assisted gravity flooding was firstly introduced to take full use of gas-oil gravity difference,and its feasibility in the karst fault system was examined.Experimental results showed that primary gas flooding created more flow paths and achieved a remarkable increment of oil recovery compared to water flooding.Gas injection at a lower location was recommended to delay gas breakthrough.Gas-assisted gravity flooding achieved more stable gas-displacing-oil because oil production was at a lower location,and thus,the oil recovery was further enhanced.
基金funding from Natural Sciences and Engineering Research Council of Canada (NSERC) for this researchsupport from the University of Calgary Beijing Research Site, a research initiative associated with the University of Calgary Global Research Initiative in Sustainable Low Carbon Unconventional Resources, the Kerui Group, and the Mitacs Accelerate program
文摘The recovery factor from tight gas reservoirs is typically less than 15%, even with multistage hydrauhc tractunng stimulation. Such low recovery is exacerbated in tight gas condensate reservoirs, where the depletion of gas leaves the valuable condensate behind. In this paper, three enhanced gas recovery （EGR） methods including produced gas injection, CO2 injection and water injection are investigated to increase the well productivity for a tight gas condensate reservoir in the Montney Formation, Canada. The production performance of the three EGR methods is compared and their economic feasibility is evaluated. Sensitivity analysis of the key factors such as primary production duration, bottom-hole pressures, and fracture conductivity is conducted and their effects on the well production performance are analyzed. Results show that, compared with the simple depletion method, both the cumulative gas and condensate production increase with fluids injected. Produced gas injection leads to both a higher gas and condensate production compared with those of the CO2 injection, while waterflooding suffers from injection difficulty and the corresponding low sweep efficiency. Meanwhile, the injection cost is lower for the produced gas injection due to the on-site available gas source and minimal transport costs, gaining more economic benefits than the other EGR methods.
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.
文摘BACKGROUND Persistent vegetative state(PVS)is a devastating and long-lasting clinical condition with high morbidity and mortality;currently,there are no available effective interventions.CASE SUMMARY We report the case of an 11-year-old boy with PVS caused by severe intracerebral bleeding in the left hemisphere following anticoagulation treatment.The patient’s PVS severity showed no notable improvement after 2-mo neuroprotective treatment and rehabilitation,including nerve growth factor and baclofen,hyperbaric oxygen,and comprehensive bedside rehabilitation therapies.Daily inhalation treatment(4-6 h)of high-concentration hydrogen(H2)gas(66.6%H2+33.3%O2)was provided.Surprisingly,the patient’s orientation,consciousness,ability to speak,facial expressions,and locomotor function were significantly restored,along with improvements in essential general health status,after H2 gas inhalation treatment,which was consistent with stabilized neuropathology in the left hemisphere and increased Hounsfield unit values of computed tomography in the right hemisphere.The patient finally recovered to a near normal conscious state with a Coma Recovery Scale-Revised Score of 22 from his previous score of 3.CONCLUSION Phase 1 clinical trials are needed to explore the safety and efficacy of H2 gas inhalation in patients with PVS.
文摘Gas injection is the second largest enhanced oil recovery process, next only to the thermal method used in heavy oil fields. To increase the extent of the reservoir contacted by the injected gas, the gas is generally injected intermittently with water. This mode of injection is called water-alternating-gas (WAG). This study deals with a new immiscible water alternating gas (IWAG) EOR technique, “hot IWAG” which includes combination of thermal, solvent and sweep techniques. In the proposed method CO2 will be superheated above the reservoir temperature and instead of normal temperature water, hot water will be used. Hot CO2 and hot water will be alternatively injected into the sand packs. A laboratory test was conducted on the fractured and conventional sand packs. Slugs of water and CO2 with a low and constant rate were injected into the sand packs alternatively; slug size was 0.05 PV. Recovery from each sand pack was monitored and after that hot water and hot CO2 were injected alternatively under the same conditions and increased oil recovery from each sand pack and breakthrough were measured. Experimental results showed that the injection of hot WAG could significantly recover residual oil after WAG injection in conventional and fractured sand packs.
基金supported by a joint project with Southwest Petroleum University (China)funded by Tarim Oilfield Company (PetroChina).
文摘technique.However,the main challenge in this process is the high minimum miscibility pressure(MMP)between natural gas and crude oil,which limits its application and recovery factor,especially in hightemperature reservoirs.Therefore,we present a novel investigation to quantify the effect of chemicalassisted MMP reduction on the oil recovery factor.Firstly,we measured the interfacial tension(IFT)of the methane-oil system in the presence of chemical or CO_(2) to calculate the MMP reduction at a constant temperature(373K)using the vanishing interfacial tension(VIT)method.Afterwards,we performed three coreflooding experiments to quantify the effect of MMP reduction on the oil recovery factor under different injection scenarios.The interfacial tension measurements show that adding a small fraction(1.5 wt%)of the tested surfactant(SOLOTERRA ME-6)achieved 9%of MMP reduction,while adding 20 wt%of CO_(2) to the methane yields 13%of MMP reduction.Then,the coreflooding results highlight the significance of achieving miscibility during gas injection,as the ultimate recovery factor increased from 65.5%under immiscible conditions to 77.2%using chemical-assisted methane,and to 79%using gas mixture after achieving near miscible condition.The results demonstrate the promising potential of the MMP reduction to signifi-cantly increase the oil recovery factor during gas injection.Furthermore,these results will likely expand the application envelop of the miscible gas injection,in addition to the environmental benefits of utilizing the produced gas by re-injection/recycling instead of flaring which contributes to reducing the greenhouse gas emissions.
基金the China National Petroleum Corporation South-west Oil and Gas Field Branch Shale Gas Research Institute(Grant No.JS-2020-42)for providing research funding.
文摘In this work,using fractured shale cores,isothermal adsorption experiments and core flooding tests were conducted to investigate the performance of injecting different gases to enhance shale gas recovery and CO_(2)geological storage efficiency under real reservoir conditions.The adsorption process of shale to different gases was in agreement with the extended-Langmuir model,and the adsorption capacity of CO_(2)was the largest,followed by CH_(4),and that of N_(2)was the smallest of the three pure gases.In addition,when the CO_(2)concentration in the mixed gas exceeded 50%,the adsorption capacity of the mixed gas was greater than that of CH4,and had a strong competitive adsorption effect.For the core flooding tests,pure gas injection showed that the breakthrough time of CO_(2)was longer than that of N_(2),and the CH_(4)recovery factor at the breakthrough time(Rch,)was also higher than that of N_(2).The RcH of CO_(2)gas injection was approximately 44.09%,while the RcH,of N_(2)was only 31.63%.For CO_(2)/N_(2)mixed gas injection,with the increase of CO_(2)concentration,the RcH,increased,and the RcH,for mixed gas CO_(2)/N_(2)=8:2 was close to that of pure CO_(2),about 40.24%.Moreover,the breakthrough time of N_(2)in mixed gas was not much different from that when pure N_(2)was injected,while the breakthrough time of CO_(2)was prolonged,which indicated that with the increase of N_(2)concentration in the mixed gas,the breakthrough time of CO_(2)could be extended.Furthermore,an abnormal surge of N_(2)concentration in the produced gas was observed after N_(2)breakthrough.In regards to CO_(2)storage efficiency(S_(Storage-CO_(2)),as the CO_(2)concentration increased,S storage-co_(2)also increased.The S storage-co_(2),of the pure CO_(2)gas injection was about 35.96%,while for mixed gas CO_(2)/N_(2)=8:2,S sorage-co,was about 32.28%.
文摘The technique of Enhanced Gas Recovery by CO_(2) injection(CO_(2)-EGR)into shale reservoirs has brought increasing attention in the recent decade.CO_(2)-EGR is a complex geophysical process that is controlled by several parameters of shale properties and engineering design.Nevertheless,more challenges arise when simulating and predicting CO_(2)/CH4 displacement within the complex pore systems of shales.Therefore,the petroleum industry is in need of developing a cost-effective tool/approach to evaluate the potential of applying CO_(2) injection to shale reservoirs.In recent years,machine learning applications have gained enormous interest due to their high-speed performance in handling complex data and efficiently solving practical problems.Thus,this work proposes a solution by developing a supervised machine learning(ML)based model to preliminary evaluate CO_(2)-EGR efficiency.Data used for this work was drawn across a wide range of simulation sensitivity studies and experimental investigations.In this work,linear regression and artificial neural networks(ANNs)implementations were considered for predicting the incremental enhanced CH4.Based on the model performance in training and validation sets,our accuracy comparison showed that(ANNs)algorithms gave 15%higher accuracy in predicting the enhanced CH4 compared to the linear regression model.To ensure the model is more generalizable,the size of hidden layers of ANNs was adjusted to improve the generalization ability of ANNs model.Among ANNs models presented,ANNs of 100 hidden layer size gave the best predictive performance with the coefficient of determination(R2)of 0.78 compared to the linear regression model with R2 of 0.68.Our developed MLbased model presents a powerful,reliable and cost-effective tool which can accurately predict the incremental enhanced CH4 by CO_(2) injection in shale gas reservoirs.
基金by Petro China Tarim Oilfield Company(PetroChina).
文摘Miscible CO_(2)injection appears to be an important enhanced oil recovery technique for improving sweep efficiency and eliminating CO_(2)-oil interfacial tension resulting in up to 10%higher oil recovery compared to immiscible flooding,in addition to the environmental benefits of reducing greenhouse gas emissions through carbon capturing utilising and storage(CCUS).Moreover,this technique could be similarly applicable to natural gas and nitrogen projects to increase oil recovery and to reduce the associated gas flaring.However,miscible displacement may not be achievable for all reservoirs,in particular,reservoirs with high temperature where high injection pressure would be needed to reach miscibility which likely exceeds the formation fracture pressure.Therefore,to further achieve reservoirs’potential,there is a pressing need to explore a viable means to decrease the miscibility pressure,and thus expand the application envelop of miscible gas injection in reservoirs with high temperatures.In this work,we aim to provide insights into minimum miscibility pressure(MMP)reduction by adding chemicals into CO_(2)phase during injection.We achieved this objective by performing a comprehensive review on chemical-assisted MMP reduction using different chemical additives(e.g.,alcohols,fatty acids,surfactants)and different experimental methodologies.Previous experimental studies have shown that a fraction of chemical additives can yield up to 22%of MMP reduction in CO_(2)-oil system.Based on results analysis,surfactant based chemicals were found to be more efficient compared to alcohol based chemicals in reducing the interfacial tension in the CO_(2)-oil system.Based on the current experimental results,adding chemicals to improve the miscibility and reduce the MMP in the CO_(2)-oil system appears to be a promising technique to increase oil recovery while reducing operating cost.Selection of the effective chemical additives may help to expand the application of miscible gas injection to shallow and high temperature reservoirs.Furthermore,our review provides an overall framework to screen potential chemical additives and an injection strategy to be used for miscible displacement in CO_(2)and/or gas systems.
文摘Regarding the enormous demands of numerous industries to fossil fuels,it is essential to select the proper enhanced oil recovery approaches for vertical and horizontal wells to supply the demands with the optimum expenditure.Water and gas injectivity as the secondary enhanced oil recovery techniques would be preferentially considered regarding their low costs of performances rather than chemical recovery and thermal techniques.Injected gas tends to push oil through pores or cracks in the matrix block and lead them to the production well.Therefore,injection of gas may significantly increase the recovery factor in these reservoirs.In this research,different injection scenarios in a fractured carbonate reservoir in the west of Iran are being simulated by the PVT modules of Eclipse software.The purpose of this research is to analyze the possibility of gradually increasing the extent of recovery by injecting carbon dioxide,methane,and water,and different injectivity patterns are considered in this research.The selection of injectivity patterns is severely based on the highest recycling rate of gas injection on different injection scenarios,and the injectivity scenarios were being compared with the natural depletion scenario.Consequently,Co2 injection(about 60%)had the highest oil recovery factor and CH4 and TB(about 54%and 53%)injectivity scenarios had the second and third highest rate of the oil recovery factor.
文摘Nowadays,the non-hydrocarbon gases are the main sources for gas injection projects in different countries.The main advantages of the flue gas injection are low cost,readily available sources(which consists mainly of N2 and CO2)and low compressibility in comparison with other gases like CO2 or CH4(for a given volume at the same conditions).In addition,it occupies more space in the reservoir and it is an appropriate way for CO2 sequestering and consequently reducing greenhouse gases.In the aforementioned method,N2 and/or CO2 is injected into the oil reservoir for miscible and/or immiscible displacement of remaining oil.Moreover,a key parameter in the designing of a gas injection project is the minimum miscibility pressure(MMP)which is commonly calculated by running simulation case or implementing conventional correlations.From technical viewpoints,the lower MMP values are more flavor for miscible gas injection process due to lower injection pressure and consequently lower maintenance and lower injection costs.The main aim of this research is to investigate various gas injection methods(N2,CO2,produced reservoir gas,and flue gas)in one of the northern Persian gulf oil fields by a numerical simulation method.Moreover,for each scenario of gas injection technical and economical considerations are took into account.Finally,an economic analysis is implemented to compare the net present value(NPV)of the different gas injection scenarios in the aforementioned oil field.
文摘This paper presents the effectiveness of the CO_(2) injection process at different periods during gascondensate reservoir development.Taking a real gas-condensate reservoir located in China's east region as an example,first,we conducted experiments of constant composition expansion(CCE),constant volume depletion(CVD),saturation pressure determination,and single flash.Next,a series of water/CO2 flooding experiments were been investigated,including water flooding at present pressure 15 MPa,CO_(2) flooding at 25.53 MPa,15 MPa,which repents initial pressure and present pressure respectively.Finally,the core flooding numerical model was constructed using a generalized equation-of-state model reservoir simulator(GEM)to reveal miscible flooding mechanism and the seepage flow characteristics in the condensate gas reservoir with CO2 injection.A desirable agreement achieved in experimental results and predicted pressure volume temperature(PVT)properties by the modified equation of state(EOS)in the CVD and CCE tests indicated that the proposed recombination method can successfully produce a fluid with the same phase behavior of initial reservoir fluid with an acceptable accuracy.The modeling results confirm the experimental results,and both methods indicate that significant productivity loss can occur in retrograde gas condensate reservoirs when the flowing bottom-hole pressure falls below dew point pressure.Moreover,the results show that CO_(2) treatment can improve gas productivity by a factor of about 1.39 compared with the water flooding mode.These results may help reservoir engineers and specialists to restore the lost productivity of gas condensate.
