Circulating injection and production method for improving recovery ratio of remaining oil in oil and gas reservoir type gas storage

Abstract

The invention relates to a circulating injection and production method for improving the recovery ratio of remaining oil in an oil and gas reservoir type gas storage, and belongs to the technical field of oil and gas production. The method specifically comprises the following steps: deploying a gas injection and production well for gas injection and production in a gas enrichment area of the oil and gas reservoir type gas storage, and deploying a producing well for crude oil production in an oil ring remaining oil enrichment area; natural gas from a pipe network is pressurized by a compressor and then injected into a stratum through a gas injection-production well, a mixture of oil, water and gas is produced through a production well in a self-spraying mode, the mixture enters a gas production treatment system of a gas storage through a gas production pipeline to be subjected to natural gas purification treatment, and the treated natural gas is converged with the natural gas from the pipe network and then injected into the stratum through the compressor. The treated oil-water mixture enters a crude oil treatment system to obtain crude oil and sewage, and the process is repeated. The continuous circulating injection-production process can greatly improve the crude oil yield and the residual crude oil recovery rate.

Description

Technical Field

[0001] The invention relates to a cyclic injection and production method for improving the recovery rate of residual oil in an oil and gas reservoir type gas storage, and belongs to the technical field of oil and gas production. Background Art

[0002] Underground gas storage (abbreviated as "gas storage") is the best supplement to ensure the smooth supply of gas to natural gas users. It has the advantages of large storage capacity, high safety, long service life, and economical and easy operation. It is currently a more commonly used natural gas storage facility. A gas storage is an artificial gas field or gas reservoir formed by re-injecting commercial natural gas transported by long-distance pipelines into underground space. It is generally built near downstream natural gas user cities. The operation of gas storage is based on an annual cycle. "Gas extraction in winter and spring, gas injection in summer and autumn" is the operating process of my country's gas storage.

[0003] Many natural gas users have a large difference in gas consumption between winter and summer. Generally, winter consumption is higher than summer consumption. In extreme cases, winter consumption can be 6 to 10 times that of summer. Seasonal peak regulation must be carried out through gas storage, that is, when the market gas consumption in summer is lower than the pipeline gas transmission capacity, the surplus gas is stored in the underground gas storage. When the user's gas consumption in winter is greater than the pipeline transmission capacity, natural gas is extracted from the underground gas storage to supply gas to the user. In addition, the gas consumption at different times of the day will also be different, and gas storage is also required for peak regulation, which is called daily peak regulation. While playing the role of seasonal peak regulation, it can also serve as an emergency backup gas source when a sudden major natural disaster or pipeline leakage occurs in the gas transmission trunk line, causing a short-term interruption of gas supply, greatly improving the reliability of gas supply.

[0004] At present, the natural gas underground storage facilities that have been successfully applied in the world are mainly distributed in developed regions such as the United States, Russia and Europe. There are four typical types of natural gas underground storage facilities in the world: depleted oil and gas reservoir storage, aquifer storage, salt cavern storage, and abandoned mine storage. In the late stage of development, the formation energy of oil and gas reservoir blocks is generally insufficient, the crude oil recovery rate is only about 30%, the gas well production is also significantly reduced, and the entire block is almost exhausted and scrapped. This type of depleted oil and gas reservoir is converted into an underground gas storage facility to play the role of seasonal peak regulation, emergency and strategic reserve. Traditional gas storage facilities in China only deploy injection and production wells and monitoring wells, and use injection and production wells to inject gas in summer (April-October) and produce gas in winter (November to March of the following year). During the winter gas production period, some crude oil and condensate near the injection and production wells can be produced with natural gas, but the production volume is limited and shows a rapid decreasing trend. A large amount of crude oil in the remaining oil-rich area cannot be used for production, and it is difficult to significantly increase the crude oil recovery rate and crude oil production of the gas reservoir. Summary of the invention

[0005] The invention discloses a cyclic injection and production method for improving the recovery rate of residual oil in oil and gas reservoir type gas storage, which can solve the technical problems that the recovery rate of residual crude oil in traditional gas storage cannot be effectively improved and is difficult to mobilize, and can greatly improve the crude oil recovery rate and crude oil output.

[0006] The technical scheme adopted by the present invention is: a cyclic injection and production method for improving the recovery rate of residual oil in an oil and gas reservoir type gas storage reservoir, which is specifically as follows: gas injection and production wells are deployed in the gas-rich area of ​​the oil and gas reservoir type gas storage reservoir for gas injection and gas production, and oil production wells are deployed in the residual oil enrichment area of ​​the oil ring for crude oil production; during the gas injection period of the gas storage reservoir, natural gas from the pipeline network is pressurized by a compressor and then injected into the formation through the gas injection and production wells, and under the drive of the high-pressure natural gas, a mixture of oil, water and gas is produced by self-flowing from the oil production wells, and the mixture of oil, water and gas enters the gas production processing system of the gas storage reservoir through the gas production pipeline for natural gas purification treatment, and the treated natural gas is re-injected into the formation through the compressor after merging with the natural gas from the pipeline network, and the treated oil and water mixture enters the crude oil processing system to obtain crude oil and sewage, and the cycle is repeated.

[0007] Furthermore, the wellbore structure, cementing quality and pressure bearing capacity of the oil production well are consistent with those of the gas injection and production well.

[0008] Furthermore, the gas production and processing system includes a pre-separator, a production separator, a coiled heat exchanger, a JT valve, and a low-temperature separator; wherein the pre-separator, the production separator, and the low-temperature separator are used for gas-liquid separation; the gas phase outlet end of the pre-separator is connected to the gas phase inlet end of the production separator, the gas outlet end of the production separator is connected to the wet gas inlet end of the coiled heat exchanger, the wet gas outlet end of the coiled heat exchanger is connected to the JT valve, the other end of the JT valve is connected to the low-temperature separator, and the gas outlet end of the low-temperature separator is connected to the dry gas inlet end of the coiled heat exchanger.

[0009] Furthermore, the natural gas purification process of the gas production and processing system is as follows: first, the oil, gas and water mixture enters the pre-separator for the first gas-liquid two-phase separation; the wet natural gas separated by the pre-separator enters the production separator for the second gas-liquid two-phase separation; the wet natural gas separated by the production separator enters the coiled heat exchanger, and exchanges heat with the low-temperature dry natural gas inside the coiled heat exchanger. The wet natural gas whose temperature drops after the heat exchange continues to drop after passing through the JT valve, and then enters the low-temperature separator for the third gas-liquid two-phase separation. The low-temperature dry natural gas separated by the low-temperature separator enters the coiled heat exchanger for heat exchange with the high-temperature wet natural gas, and the purified natural gas after the heat exchange enters the pipeline network.

[0010] Furthermore, the purified natural gas is combined with the natural gas from the pipeline network and injected into the formation again through a compressor.

[0011] Furthermore, the pre-separator, production separator and low-temperature separator separate the oil-water mixture, and the oil-water mixture enters the crude oil processing system to obtain crude oil and sewage.

[0012] Furthermore, the crude oil is stored in a crude oil storage tank through a pipeline, and the sewage is transported to a sewage tank through a pipeline.

[0013] The present invention discloses a cyclic injection and production method for improving the recovery rate of residual oil in an oil and gas reservoir type gas storage reservoir. The beneficial effect is that compared with the prior art, during the gas injection period of the gas storage reservoir, the oil production well continuously produces an oil-gas-water mixture driven by high-pressure natural gas in the formation through the cyclic injection and production method, and obtains the oil-water mixture and purified natural gas after being processed by a gas production system. The purified natural gas is combined with natural gas from a pipeline network and is injected into the formation again through an injection compressor. Natural gas is used as a driving source for injection and production to obtain a continuous supply of crude oil and natural gas, which are reciprocated and recycled. This continuous cyclic injection and production process can greatly improve the crude oil output and the recovery rate of residual crude oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 Shown is a schematic diagram of the process of Example 1.

[0016] As shown in the figure:

[0017] 1. Gas injection and production wells; 2. Oil production wells; 3. Pipeline network; 4. Compressor; 5. Gas production pipeline; 6. Gas production processing system; 7. Crude oil processing system; 8. Crude oil storage tanks; 9. Sewage tanks.

[0018] Specific implementation methods

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0020] The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] like Figure 1 As shown, this embodiment provides a cyclic injection and production method for improving the recovery rate of residual oil in an oil and gas reservoir type gas storage, which is specifically as follows: in addition to deploying an injection and production gas well 1 in a gas-rich area of ​​the oil and gas reservoir type gas storage for gas injection and production, an oil production well 2 is deployed in the residual oil enrichment area of ​​the oil ring for crude oil production; during the gas injection period of the gas storage, natural gas from the pipeline 3 is pressurized by a compressor 4 and then injected into the formation through the injection and production gas well 1, and the formation pressure gradually increases. Because the formation is interconnected, under the drive of high-pressure natural gas, a mixture of oil, water and gas is produced by self-flowing from the oil production well 2, and the mixture enters the gas production processing system 6 of the gas storage through a gas production pipeline 5 for natural gas purification treatment. The treated natural gas is re-injected into the formation through the compressor 4 after merging with the natural gas from the pipeline 3, and the treated oil and water mixture enters the crude oil processing system 7 to obtain crude oil and sewage, and the cycle is repeated.

[0023] The wellbore structure, cementing quality and pressure bearing capacity of the oil production well 2 are consistent with those of the gas injection and production well 1.

[0024] The gas production and processing system 6 includes a pre-separator, a production separator, a coiled heat exchanger, a JT valve, and a low-temperature separator; wherein the pre-separator, the production separator, and the low-temperature separator are all gas-liquid two-phase separators for gas-liquid separation; the gas phase outlet of the pre-separator is connected to the gas phase inlet of the production separator, the gas outlet of the production separator is connected to the wet gas inlet of the coiled heat exchanger, the wet gas outlet of the coiled heat exchanger is connected to the JT valve, the other end of the JT valve is connected to the low-temperature separator, and the gas outlet of the low-temperature separator is connected to the dry gas inlet of the coiled heat exchanger. The low-temperature separator separates dry natural gas to meet the re-injection requirements.

[0025] The natural gas purification process of the gas production and processing system 6 is as follows: first, the oil, gas and water mixture enters the pre-separator for the first gas-liquid two-phase separation; the separated wet natural gas enters the production separator for the second gas-liquid two-phase separation; the separated wet natural gas enters the coiled heat exchanger, and exchanges heat with the low-temperature dry natural gas inside the coiled heat exchanger. The wet natural gas whose temperature drops after the heat exchange continues to drop after passing through the JT valve, and then enters the low-temperature separator for the third gas-liquid two-phase separation. The separated low-temperature dry natural gas enters the coiled heat exchanger for heat exchange with the high-temperature wet natural gas, and the purified natural gas after the heat exchange enters the pipeline network.

[0026] The purified natural gas is combined with the natural gas from the pipeline network 3 and injected into the formation again through the compressor 4 to continue to increase the formation pressure and the gas storage capacity.

[0027] The pre-separator, production separator and low-temperature separator separate the oil and water mixture, and the oil and water mixture enters the crude oil processing system 7 to obtain crude oil and sewage. The crude oil is stored in the crude oil storage tank 8 through the pipeline, and the sewage is transported to the sewage tank 9 through the pipeline.

[0028] like Figure 1 As shown, the process of the cyclic injection and production method is that during the gas injection period of the gas storage, the natural gas from the pipeline 3 is pressurized by the compressor 4 and then injected into the formation through the injection and production well 1. The formation pressure gradually increases. Because the formation is interconnected, under the drive of the high-pressure natural gas, the mixture of oil, water and gas is produced by the oil production well 2 through the self-flowing spray. The mixture enters the gas production processing system 6 of the gas storage through the gas production pipeline 5 for natural gas purification. The natural gas purification process of the gas production processing system 6 is as follows: First, the oil, gas and water mixture enters the pre-separator for the first gas-liquid two-phase separation; the separated wet natural gas enters the production separator for the second gas-liquid two-phase separation; the separated wet natural gas enters the coiled heat exchanger, and exchanges heat with the low-temperature dry natural gas inside the coiled heat exchanger. After the heat exchange, the temperature of the wet natural gas drops further after passing through the JT valve, and then enters the low-temperature separator for the third gas-liquid two-phase separation. The separated low-temperature dry natural gas enters the coiled heat exchanger for heat exchange with the high-temperature wet natural gas to obtain purified natural gas. The pre-separator, production separator and low temperature separator separate the oil and water mixture, which enters the crude oil processing system 7 to obtain crude oil and sewage. The crude oil is stored in the crude oil storage tank 8 through the pipeline, and the sewage is transported to the sewage tank 9 through the pipeline. The purified natural gas merges with the natural gas from the pipeline network 3 and is injected into the formation again through the compressor 4 to continue to increase the formation pressure and the capacity of the gas storage reservoir, and continuously produce the oil, gas and water mixture. This cycle is continuous, thereby improving the crude oil production and residual oil recovery rate of the oil and gas reservoir type gas storage reservoir; in addition, the wellbore structure, cementing quality and pressure bearing capacity of the oil production well 2 are consistent with those of the injection and production gas well 1, that is, when the residual oil enrichment area is produced to a certain extent and no oil is produced, the oil production well 2 can be used as the injection and production gas well 1.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage, characterized in that: In the gas-rich area of ​​the oil and gas reservoir type gas storage, a gas injection and production well (1) is deployed for gas injection and gas production, and at the same time, an oil production well (2) is deployed in the residual oil-rich area of ​​the oil ring for crude oil production. During the gas injection period of the gas storage, the natural gas from the pipeline (3) is pressurized by a compressor (4) and then injected into the formation through the gas injection and production well (1). Driven by the high-pressure natural gas, a mixture of oil, water and gas is produced by the oil production well (2) through spontaneous spraying. The mixture of oil, water and gas enters the gas production processing system (6) of the gas storage through a gas production pipeline (5) for natural gas purification. The treated natural gas is combined with the natural gas from the pipeline (3) and then re-injected into the formation through a compressor (4). The treated oil and water mixture enters the crude oil processing system (7) to obtain crude oil and sewage, and the cycle is repeated.

2. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage according to claim 1, characterized in that: The wellbore structure, cementing quality and pressure bearing capacity of the oil production well (2) are consistent with those of the gas injection and production well (1).

3. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage according to claim 1, characterized in that: The gas production and processing system (6) comprises a pre-separator, a production separator, a coiled heat exchanger, a JT valve and a low-temperature separator, wherein the pre-separator, the production separator and the low-temperature separator are used for gas-liquid separation; the gas phase outlet end of the pre-separator is connected to the gas phase inlet end of the production separator, the gas outlet end of the production separator is connected to the wet gas inlet end of the coiled heat exchanger, the wet gas outlet end of the coiled heat exchanger is connected to the JT valve, the other end of the JT valve is connected to the low-temperature separator, and the gas outlet end of the low-temperature separator is connected to the dry gas inlet end of the coiled heat exchanger.

4. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage according to any one of claims 1 or 3, characterized in that: The natural gas purification process of the gas production and processing system (6) is as follows: first, the oil, gas and water mixture enters the pre-separator for the first gas-liquid two-phase separation; the wet natural gas separated by the pre-separator enters the production separator for the second gas-liquid two-phase separation; the wet natural gas separated by the production separator enters the coiled heat exchanger, and exchanges heat with the low-temperature dry natural gas inside the coiled heat exchanger. After the heat exchange, the temperature of the wet natural gas drops further after passing through the JT valve. Subsequently, the wet natural gas with the lowered temperature enters the low-temperature separator for the third gas-liquid two-phase separation. The low-temperature dry natural gas separated by the low-temperature separator enters the coiled heat exchanger for heat exchange with the high-temperature wet natural gas. The purified natural gas after the heat exchange enters the pipeline network.

5. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage according to claim 4, characterized in that: The purified natural gas is combined with the natural gas from the pipeline network (3) and injected into the formation again through the compressor (4).

6. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage according to claim 4, characterized in that: The pre-separator, production separator and low-temperature separator separate the oil and water mixture, and the oil and water mixture enters the crude oil processing system (7) to obtain crude oil and sewage.

7. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage according to claim 6, characterized in that: The crude oil is stored in the crude oil storage tank (8) through a pipeline.

8. A cyclic injection and production method for improving the recovery rate of remaining oil in an oil and gas reservoir type gas storage according to claim 6, characterized in that: The sewage is transported to the sewage tank (9) through pipelines.

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