Vast amounts of world oil reservoirs are in natural fractured reservoirs. There are different methods for increasing recovery from fractured reservoirs. Miscible injection of water alternating CO2?is a good choice amo...Vast amounts of world oil reservoirs are in natural fractured reservoirs. There are different methods for increasing recovery from fractured reservoirs. Miscible injection of water alternating CO2?is a good choice among EOR methods. In this method, water and CO2?slugs are injected alternatively in reservoir as miscible agent into reservoir. This paper studies water injection scenario and miscible injection of water and CO2?in a two dimensional, inhomogeneous fractured reservoir. The results show that miscible water alternating CO2?gas injection leads to 3.95% increase in final oil recovery and total water production decrease of 3.89% comparing to water injection scenario.展开更多
In view of high water cut and low oil recovery caused by the unidirectional flow in linear pattern of horizontal wells for the carbonate reservoirs in the Middle East,this paper provides a novel approach to improve oi...In view of high water cut and low oil recovery caused by the unidirectional flow in linear pattern of horizontal wells for the carbonate reservoirs in the Middle East,this paper provides a novel approach to improve oil recovery by converting linear water injection to cyclic alternating water injection patterns including cyclic alternating water injection with apparent inverted seven-spot pattern or apparent five-spot pattern and cyclic differential alternating water injection.The main advantage of using this strategy is that the swept efficiency is improved by changing injection-production streamlines and displacement directions,which means displacement from two different direction for the same region during a complete cycle.This technology is effective in increasing the swept efficiency and tapping the remaining oil,thus resulting in higher oil recovery.Field application with three new patterns in a carbonate reservoir in the Middle East is successful.By optimizing injection and production parameters based on the cyclic alternating well pattern,the test well group had a maximum increase of daily oil production per well of 23.84 m^(3) and maximum water cut drop of 18%.By further optimizing the distance(keep a long distance)between the heels of injection and production wells,the waterflooding performance could be better with water cut decreasing and oil production increasing.展开更多
The purpose of this study is to optimize the existing carbon dioxide （CO2） flood in deep dolomite formations by improving oil sweep efficiency of miscible CO2 floods and enhancing the conformance control. A full com...The purpose of this study is to optimize the existing carbon dioxide （CO2） flood in deep dolomite formations by improving oil sweep efficiency of miscible CO2 floods and enhancing the conformance control. A full compositional simulation model using a detailed geologic characterization was built to optimize the injection pattern. The model is a quarter of an inverted nine-spot and covers 20 acres of field formation. Geologic description was used to construct the simulation grids. The simulation layers represent actual flow units and resemble the large variation of reservoir properties. History match was performed to validate the model. Several sensitivity runs were made to improve the CO2 sweep efficiency and increase the oil recovery. Finally, the optimum CO2 injection rate for dolomite formations was determined approximately. Simulation results also indicate that a water-alternating-gas （WAG） ratio of 1：1 along with an ultimate CO2 slug of 100% hydrocarbon pore volume （HCPV） will allow an incremental oil recovery of 18%. The additional recovery increases to 34% if a polymer is injected as a conformance control agent during the course of the WAG process at a ratio of 1：1. According to the results, a pattern reconfiguration change from the nine spot to staggered line drive would represent an incremental oil recovery of 26%.展开更多
In this paper, we have studied hot carrier injection （HCI） different degradations are obtained from the experiment results. under alternant stress. Under different stress modes, The different alternate stresses can ...In this paper, we have studied hot carrier injection （HCI） different degradations are obtained from the experiment results. under alternant stress. Under different stress modes, The different alternate stresses can reduce or enhance the HC effect, which mainly depends on the latter condition of the stress cycle. In the stress mode A （DC stress with electron injection）, the degradation keeps increasing. In the stress modes B （DC stress and then stress with the smMlest gate injection） and C （DC stress and then stress with hole injection under Vg = 0 V and Vd = 1.8 V）, recovery appears in the second stress period. And in the stress mode D （DC stress and then stress with hole injection under Vg = -1.8 V and Vd = 1.8 V）, as the traps filled in by holes can be smaller or greater than the generated interface states, the continued degradation or recovery in different stress periods can be obtained.展开更多
A dynamic transient flow analysis method considering complex factors such as the cyclic injection and production history in a gas field storage facility was established in view of the limitations of the existing metho...A dynamic transient flow analysis method considering complex factors such as the cyclic injection and production history in a gas field storage facility was established in view of the limitations of the existing methods for transient flow analysis and the characteristics of the injection-production operation of strongly heterogeneous gas reservoirs, and the corresponding theoretical charts were drawn. In addition, an injection-production dynamic transient flow analysis model named "three points and two stages" suitable for an underground gas storage(UGS) well with alternate working conditions was proposed. The "three points" refer to three time points during cyclic injection and production, namely, the starting point of gas injection for UGS construction, the beginning and ending points of the injection-production analysis stage;and the "two stages" refer to historical flow stage and injection-production analysis stage. The study shows that the dimensionless pseudo-pressure and dimensionless pseudo-pressure integral curves of UGS well flex downward in the early stage of the injection and production process, and the dimensionless pseudo-pressure integral derivative curve is convex during the gas production period and concave during the gas injection period, and the curves under different flow histories have atypical features. The new method present in this paper can analyze transient flow of UGS accurately. The application of this method to typical wells in Hutubi gas storage shows that the new method can fit the pressure history accurately, and obtain reliable parameters and results.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
文摘Vast amounts of world oil reservoirs are in natural fractured reservoirs. There are different methods for increasing recovery from fractured reservoirs. Miscible injection of water alternating CO2?is a good choice among EOR methods. In this method, water and CO2?slugs are injected alternatively in reservoir as miscible agent into reservoir. This paper studies water injection scenario and miscible injection of water and CO2?in a two dimensional, inhomogeneous fractured reservoir. The results show that miscible water alternating CO2?gas injection leads to 3.95% increase in final oil recovery and total water production decrease of 3.89% comparing to water injection scenario.
基金Supported by the China National Science and Technology Major Project(2017ZX05030)。
文摘In view of high water cut and low oil recovery caused by the unidirectional flow in linear pattern of horizontal wells for the carbonate reservoirs in the Middle East,this paper provides a novel approach to improve oil recovery by converting linear water injection to cyclic alternating water injection patterns including cyclic alternating water injection with apparent inverted seven-spot pattern or apparent five-spot pattern and cyclic differential alternating water injection.The main advantage of using this strategy is that the swept efficiency is improved by changing injection-production streamlines and displacement directions,which means displacement from two different direction for the same region during a complete cycle.This technology is effective in increasing the swept efficiency and tapping the remaining oil,thus resulting in higher oil recovery.Field application with three new patterns in a carbonate reservoir in the Middle East is successful.By optimizing injection and production parameters based on the cyclic alternating well pattern,the test well group had a maximum increase of daily oil production per well of 23.84 m^(3) and maximum water cut drop of 18%.By further optimizing the distance(keep a long distance)between the heels of injection and production wells,the waterflooding performance could be better with water cut decreasing and oil production increasing.
文摘The purpose of this study is to optimize the existing carbon dioxide （CO2） flood in deep dolomite formations by improving oil sweep efficiency of miscible CO2 floods and enhancing the conformance control. A full compositional simulation model using a detailed geologic characterization was built to optimize the injection pattern. The model is a quarter of an inverted nine-spot and covers 20 acres of field formation. Geologic description was used to construct the simulation grids. The simulation layers represent actual flow units and resemble the large variation of reservoir properties. History match was performed to validate the model. Several sensitivity runs were made to improve the CO2 sweep efficiency and increase the oil recovery. Finally, the optimum CO2 injection rate for dolomite formations was determined approximately. Simulation results also indicate that a water-alternating-gas （WAG） ratio of 1：1 along with an ultimate CO2 slug of 100% hydrocarbon pore volume （HCPV） will allow an incremental oil recovery of 18%. The additional recovery increases to 34% if a polymer is injected as a conformance control agent during the course of the WAG process at a ratio of 1：1. According to the results, a pattern reconfiguration change from the nine spot to staggered line drive would represent an incremental oil recovery of 26%.
基金supported by the National Key Science and Technology Special Project,China (Grant No. 2008ZX01002-002)the grant from the Major State Basic Research Development Program of China (973 Program,No. 2011CB309606)the Fundamental Research Funds for the Central Universities (Grant No. JY10000904009)
文摘In this paper, we have studied hot carrier injection （HCI） different degradations are obtained from the experiment results. under alternant stress. Under different stress modes, The different alternate stresses can reduce or enhance the HC effect, which mainly depends on the latter condition of the stress cycle. In the stress mode A （DC stress with electron injection）, the degradation keeps increasing. In the stress modes B （DC stress and then stress with the smMlest gate injection） and C （DC stress and then stress with hole injection under Vg = 0 V and Vd = 1.8 V）, recovery appears in the second stress period. And in the stress mode D （DC stress and then stress with hole injection under Vg = -1.8 V and Vd = 1.8 V）, as the traps filled in by holes can be smaller or greater than the generated interface states, the continued degradation or recovery in different stress periods can be obtained.
基金Supported by the CNPC Major Scientific and Technological Project(2019B-3204)PetroChina Major Scientific and Technological Project(kt2020-16-01)。
文摘A dynamic transient flow analysis method considering complex factors such as the cyclic injection and production history in a gas field storage facility was established in view of the limitations of the existing methods for transient flow analysis and the characteristics of the injection-production operation of strongly heterogeneous gas reservoirs, and the corresponding theoretical charts were drawn. In addition, an injection-production dynamic transient flow analysis model named "three points and two stages" suitable for an underground gas storage(UGS) well with alternate working conditions was proposed. The "three points" refer to three time points during cyclic injection and production, namely, the starting point of gas injection for UGS construction, the beginning and ending points of the injection-production analysis stage;and the "two stages" refer to historical flow stage and injection-production analysis stage. The study shows that the dimensionless pseudo-pressure and dimensionless pseudo-pressure integral curves of UGS well flex downward in the early stage of the injection and production process, and the dimensionless pseudo-pressure integral derivative curve is convex during the gas production period and concave during the gas injection period, and the curves under different flow histories have atypical features. The new method present in this paper can analyze transient flow of UGS accurately. The application of this method to typical wells in Hutubi gas storage shows that the new method can fit the pressure history accurately, and obtain reliable parameters and results.
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.
