CN104879167A - Method for rebuilding gas storage and layered injection and production system thereof - Google Patents

Abstract

The invention discloses a method for rebuilding a gas storage and a layered injection-production system. The method for rebuilding a gas storage includes: obtaining formation parameters of oil and gas reservoirs; respectively setting gas injection and production wells and observation wells on the oil and gas reservoirs; Run a layered drainage pipe string in the observation well, and perforate in sections on the layered drainage pipe string according to the formation parameters of the oil and gas reservoir to form a perforation section; Injecting the gas injection and production string for gas injection; performing sub-layer testing in the observation well to obtain sub-layer test results; determining the gas-producing layer according to the sub-layer test results and closing it. The method for rebuilding the gas storage and the layered injection-production system described in the invention can effectively reduce the remaining water content in the oil and gas reservoir and increase the storage capacity of the gas storage.

Description

Method for rebuilding gas storage and its layered injection-production system

technical field

The invention relates to the field of oil and gas reservoir reconstruction and development of a gas storage, in particular to a method for rebuilding a gas storage and a layered injection-production system.

Background technique

Underground gas storage is a way to store natural gas. Generally, the underground gas storage is to find a completely closed structure in the deep underground, and pump the natural gas into the structure on the ground for storage. When needed, the natural gas is extracted to the ground through production wells and delivered to users. Underground gas storage has the advantages of large gas storage capacity; high safety factor, not easy to cause fire and explosion; good economic benefits, and low gas storage cost compared with metal gas tanks. In addition, underground gas storage can coordinate the relationship between supply and demand and peak shaving, implement strategic reserves, ensure the reliability and continuity of gas supply, and help optimize the operation of production systems and gas pipeline networks. Use is extremely important. In the existing field of rebuilding gas storages, a common way is to transform abandoned oil and gas reservoirs into gas storages.

Generally, the development of formations is often uneven, and the parameters such as permeability and porosity in the vertical reservoirs of abandoned oil and gas reservoirs are quite different. Usually, there are aquifers in the vertical reservoirs of abandoned oil and gas reservoirs, such as the typical edge-bottom water reservoir, etc. For oil and gas reservoirs in such aquifers, the existing reconstruction methods are mainly to arrange multiple gas injection and production wells in the formation near the top boundary of the oil layer, arrange observation wells at the edge of the formation, inject gas through the top, and drain the edge. Inject the water into the water layer, squeeze the water to the edge with natural gas, and make the natural gas occupy the reservoir space, so as to realize the expansion demand of the reconstruction of the underground gas storage.

However, due to the inhomogeneity of formation development, especially the flow of gas in the oil layer tends to move toward the position with better permeability, when injecting natural gas into the injection-production gas well, it is likely that most of the effective gas will enter the aquifer in the formation Below, gas coning is caused, thereby not only wasting natural gas, and the water in the middle of the formation cannot be driven to the edge, and the expected set storage capacity cannot be achieved. Correspondingly, during the drainage process of the observation wells at the edge, the phenomenon of gas and water co-production often occurs in the observation wells, or even only gas is produced but not water, which eventually leads to the continuous high pressure of the gas injection and production wells that cannot be effectively injected, and the observation wells at the edge only produce gas and water. Gas production without water production cannot achieve the purpose of effective capacity expansion.

Contents of the invention

The object of the present invention is to provide a method for rebuilding a gas storage and a layered injection-production system, which can effectively reduce the remaining water content in the oil and gas reservoir and increase the storage capacity of the gas storage.

Above-mentioned purpose of the present invention can adopt following technical scheme to realize:

A method for rebuilding a gas storage, comprising:

Obtain formation parameters of oil and gas reservoirs;

Setting injection-production gas wells and observation wells on the oil and gas reservoirs;

Running a layered drainage string into the observation well, and perforating the layered drainage string in sections according to the formation parameters of the oil and gas reservoir to form a perforation section;

Lowering the gas injection and production string into the gas injection and production well for gas injection;

Carrying out sub-layer testing in the observation well to obtain sub-layer testing results;

According to the test results of the sub-layers, the gas-producing layers are determined and closed.

In a preferred embodiment, the gas injection and production well is arranged in the middle of the oil and gas reservoir; the observation well is arranged at the edge of the oil and gas reservoir, and is located around the gas injection and production well.

In a preferred embodiment, the gas injection and production wells are horizontal wells, which are distributed at intervals along the gravity direction according to the formation parameters of the oil and gas reservoir.

In a preferred embodiment, the perforated section of the layered drainage pipe string communicates with a small layer satisfying predetermined permeability and porosity.

In a preferred embodiment, the sublayer testing method includes:

Opening the perforation section in sections, so that the layered drainage pipe string is connected with the predetermined small layer;

Obtaining a sample of stratified inflow in the stratified drainage column;

According to the properties of the sample, the test results of the sub-layers are obtained to determine whether to close or open the corresponding sub-layers.

A layered injection-production system for the method of rebuilding a gas storage, which includes an injection-production gas string for gas injection and gas production and a layered drainage string for observation and drainage,

The gas injection and production string is arranged in the gas injection and production well, which includes a vertical well section and a horizontal section, the first casing is arranged in the vertical well section, the first oil pipe arranged in the first casing, and the The downhole safety valve, sliding sleeve, packer, and plug on the first tubing are located on the short circuit and the test site short circuit, and the plug is located on the first oil pipe between the short circuit site and the test site short circuit a plurality of through holes are provided;

The layered drainage pipe string is set in the observation well, which includes a second casing, a second oil pipe arranged in the second casing, and a downhole safety valve and at least one sliding pipe arranged in sequence on the second oil pipe. The casing, at least one packer, the stopper is short-circuited, and the test is short-circuited. The second casing is provided with a perforation section, and the position of the perforation section is connected to a predetermined small layer.

In a preferred embodiment, both ends of the downhole safety valve are provided with flow shorts, and the flow shorts are variable diameter joints, one end with a larger diameter is connected to the tubing, and the end with a smaller diameter is connected to the downhole Safety valve connection.

In a preferred embodiment, the oil and gas reservoir is divided into more than two layers, and the number of packers and sliding sleeves on the layered drainage string is consistent with the number of layers of the oil and gas reservoir.

In a preferred embodiment, the second oil pipe between two adjacent packers is provided with the sliding sleeve, and by opening the sliding sleeve, the layered drainage string can be connected to a predetermined small layer. connected.

In a preferred embodiment, a bell mouth is provided at the lower end of the first oil pipe near the horizontal section.

The characteristics and advantages of the present invention are: the present invention provides a method for rebuilding a gas storage and a layered injection-production system. The method for rebuilding a gas storage combines the stratum parameters of the oil and gas reservoir to lower the layers into the observation well. Drainage string, and according to the stratum parameters of the oil and gas reservoir, perforate in sections on the layered drainage string to form a perforation section; and perform a sublayer test in the observation well to obtain a sublayer test result; According to the test results of the sub-layers, the gas-producing layers are determined and closed. The method can specifically reduce the remaining water content in the oil reservoir, effectively increase the storage capacity of the gas storage, and through the small-layer test, can improve the utilization rate of the injected natural gas in the injection-production gas well, so that in the limited reservoir space It is especially suitable for aquifer reservoirs such as edge-bottom water reservoirs and high water-cut reservoirs.

Description of drawings

Fig. 1 is a flow chart of a method for rebuilding a gas storage in an embodiment of the present invention;

Fig. 2 is a schematic diagram of well pattern distribution of a rebuilt gas storage in an embodiment of the present invention;

Fig. 3 is a flow chart of small-layer testing in a method for rebuilding a gas storage in an embodiment of the present invention;

Fig. 4 is a structural schematic diagram of a gas injection and production string in a gas injection and production well in an embodiment of the present invention;

Fig. 5 is a schematic structural view of a layered drainage pipe column in an observation well in an embodiment of the present invention.

Detailed ways

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. After reading the present invention, those skilled in the art Modifications to various equivalent forms of the present invention fall within the scope defined by the appended claims of the present application.

The object of the present invention is to provide a method for rebuilding a gas storage and a layered injection-production system, which can effectively reduce the remaining water content in the oil and gas reservoir and increase the storage capacity of the gas storage.

Please refer to FIG. 1 , which is a flowchart of a method for rebuilding a gas storage in an embodiment of the present invention. The method for rebuilding the gas storage according to the present invention comprises:

S1: Obtain formation parameters of oil and gas reservoirs;

S2: setting injection-production gas wells and observation wells on the oil and gas reservoirs;

S3: Running a layered drainage pipe string into the observation well, and perforating the layered drainage pipe string in sections according to the formation parameters of the oil and gas reservoir;

S4: Running a gas injection and production string into the gas injection and production well to perform gas injection;

S5: Perform sublayer testing in the observation well, and obtain sublayer test results;

S6: According to the test results of the sub-layer, determine the gas-producing layer and close it.

Since the formation development is often uneven, the vertical reservoirs of abandoned oil and gas reservoirs have large differences in parameters such as permeability and porosity. Usually, there are aquifers in the vertical reservoirs of abandoned oil and gas reservoirs. Therefore, before the transformation, it is necessary to obtain all Formation parameters of stimulated abandoned oil and gas reservoirs. The formation parameters include buried depth, thickness, porosity, permeability, temperature, pressure system, reservoir type, etc. of oil and gas reservoirs.

Please refer to FIG. 2 , which is a schematic diagram of well pattern distribution of a modified gas storage in an embodiment of the present invention. The gas injection and production well 1 is arranged in the middle of the oil and gas reservoir, and the observation well 2 is arranged at the edge of the oil and gas reservoir, and is located around the gas injection and production well 1 . The number of the gas injection and production wells 1 is generally multiple. The gas injection and production wells 1 are horizontal wells, which are distributed at intervals along the direction of gravity according to the formation parameters of the oil and gas reservoir. For example, according to parameters such as buried depth and thickness of the reservoir, the horizontal sections of the injection-production gas well 1 are distributed at predetermined depths.

Compared with existing vertical wells, horizontal wells for the injection and production gas wells 1 are more suitable for water-bearing reservoirs such as edge-bottom water reservoirs and high water-cut reservoirs. Taking edge-bottom water reservoirs as an example, when vertical wells are used for development, the initial production is relatively high. However, due to the severe water cone phenomenon and the rapid rise of water cut in the later stage, edge-bottom water reservoirs are active in edge-bottom water reservoirs, with high formation capacity and pressure drop. small, resulting in a significant reduction in oil recovery. When using horizontal wells for development, because horizontal wells can increase the production of oil wells by expanding the drainage area of oil layers, single well production can be greatly increased, high production with fewer wells can be achieved, and ultimate recovery of oil reservoirs can be improved, increasing recoverable reserves. In particular, in the process of exploiting edge-bottom water reservoirs using horizontal well technology, it can effectively control edge-bottom water to achieve efficient exploitation of such reservoirs.

The perforation section of the layered drainage pipe string is located on the sublayer satisfying the predetermined permeability and porosity, so that the perforation of the layered drainage pipe string can be connected with the small layer satisfying the predetermined permeability and porosity.

The specific location of the perforation of the layered drainage string is determined by the known formation parameters of the reservoir. Specifically, since the reservoir itself cannot be fully developed, there may be disconnected interlayers between oil layers, and perforation can be carried out in sections according to the interlayers.

The perforated section is isolated by setting a packer between the observation well 2 and the layered drainage pipe string inside. Correspondingly, at the position corresponding to the perforation section on the layered drainage string, there is provided a switch that can communicate the layered drainage string with the oil casing annulus of the observation well. The switch is usually a sliding sleeve connected to the oil pipe. The sliding sleeve can repeatedly open and close the oil sleeve annulus.

A sublayer test is performed in the observation well 2 to obtain a sublayer test result. Specifically, please refer to FIG. 3 , which is a flow chart of small-layer testing in a method for rebuilding a gas storage in an embodiment of the present invention. Described small layer test method comprises:

S51: Open the perforation section in sections, so that the layered drainage pipe string is connected to a predetermined sublayer;

S52: Obtain a sample of stratified inflow in the stratified drainage column;

S53: According to the properties of the sample, obtain the test results of the sub-layers, so as to determine whether to close or open the corresponding sub-layers.

If the sample is mainly water, keep the layered drainage pipe column in communication with the predetermined small layer, so as to facilitate the water in the oil reservoir to be discharged from the observation well, so as to effectively expand the capacity of the gas storage Storage capacity. When the sample is mainly gas, the sliding sleeve is closed to isolate the layered drainage string from the predetermined sublayer, thereby saving the natural gas injected from the injection-production gas well and improving its utilization rate.

The present invention also correspondingly proposes a layered injection-production system used in the method for rebuilding a gas storage, which includes an injection-production gas string for gas injection and gas production and layered drainage for observation and drainage pipe string.

Please refer to FIG. 4 , which is a schematic structural diagram of a gas injection and production string in a gas injection and production well in an embodiment of the present invention. The gas injection and production string is a downhole string designed to ensure normal gas injection and gas production for the gas storage.

The injection-production gas string is set in the injection-production gas well 1, which includes a vertical well section 10 and a horizontal section 101. The first casing 1A is arranged in the vertical well section 10, and the first casing 1A is arranged in the first casing 1A. The oil pipe 1B, and the flow short 11, downhole safety valve 12, sliding sleeve 13, packer 14, plugger seat short 15, and test seat short 17 arranged on the first oil pipe 1B in sequence. A plurality of through-holes 16 are provided on the first oil pipe 1B between the tester short-circuit 15 and the test short-circuit 17 .

The flow short 11 can specifically be a variable diameter joint. It can be arranged at both ends of the downhole safety valve 12 , with one end connected to the oil pipe and the other end connected to the downhole safety valve 12 . The end connected to the downhole safety valve 12 has a smaller inner diameter than the end connected to the first oil pipe 1B, which can prevent the downhole safety valve 12 from being eroded under the action of diameter reduction, thereby protecting the downhole safety valve. 12. Extend its service life.

The downhole safety valve 12 is an automatic downhole shut-in device controlled by the hydraulic control pipeline 120, which can realize automatic well shut-in when the gas well produces abnormal pressure and needs to be shut down.

The sliding sleeve 13 is a tool for opening the oil jacket annulus formed by the first casing 1A and the first oil pipe 1B, so as to facilitate running in the oil jacket annulus; The inner circulation of the annulus is replaced by the casing protection fluid; or the upper string needs to be replaced in the later stage to carry out the killing circulation operation. The sliding sleeve 13 can be a circulating sliding sleeve, which can repeatedly open or close the annulus of the oil sleeve.

The packer 14 is a downhole tool for preventing the oil casing annulus above the packer 14 from being subjected to high pressure. Specifically, the packer 14 is an optional packer.

The plug is located on the short-circuit 15, which is a downhole tool for the auxiliary packer 14 to pressurize and set. Specifically, it is a downhole tool with an inner stepped surface for matching with a plug. When pressing and setting the seal, the plug is thrown onto the short connection 15 of the plug to close the oil pipe for pressing.

The test sits short 17 for placing test tools downhole. Specifically, it is a downhole tool with an inner stepped surface, and the stepped surface is used to match with the testing tool.

When carrying out production testing, it is necessary to put downhole pressure testing tools on the test set short-circuit 17 for a long time. An oil pipe 1B is provided with a plurality of through holes 16 as backup production channels.

The lower end of the first oil pipe 1B near the horizontal section 101 is provided with a bell mouth 18 . The diameter of the bell mouth 18 gradually becomes larger along the direction of gravity. When the gas is injected downward through the first oil pipe 1B, it has a larger contact area with the water in the lower part, which is beneficial to better transport the water along the direction of gravity. The horizontal section 101 advances toward the observation well 2.

Please refer to FIG. 5 , which is a schematic structural diagram of a layered drainage pipe column in an observation well in an embodiment of the present invention. The observation well 2 is arranged at the boundary of the gas storage, and the layered drainage pipe string is set in the observation well 2, which can not only be used for monitoring pressure and performing drainage and capacity expansion in the later stage, but also has some functions of gas injection and production wells.

The layered drainage string is set in the observation well 2, which includes a second casing 2A, a second oil pipe 2B arranged in the second casing 2A, and a second oil pipe 2B arranged in turn on the second oil pipe 2B. Flow short 11, downhole safety valve 12, at least one sliding sleeve 13, at least one packer 14, plugging short 15, testing short 17, the second casing 2A is provided with a perforation section, The position of the perforation section communicates with a predetermined sublayer.

The flow short 11, downhole safety valve 12, sliding sleeve 13, packer 14, stopper short 15, and test short 17 on the second oil pipe 2B have the same structure and function as the first oil pipe 1B. same as above.

The pressure gauge holder 19 can be used to monitor the pressure and temperature in the wellbore during later testing and production.

Generally, the oil and gas reservoir is divided into more than two layers, and the number of packers and sliding sleeves on the layered drainage string is consistent with the number of layers of the oil and gas reservoir. As shown in FIG. 5 , when the oil and gas reservoir is divided into two layers, that is, the predetermined small layer 3 includes: a first oil and gas layer 31 and a second oil and gas layer 32 . Correspondingly, the sliding sleeve 13 includes a first sliding sleeve 131 and a second sliding sleeve 132; the packer 14 includes: a first packer 141 and a second packer 142 arranged up and down. The second oil pipe 2B between two adjacent packers 14 is provided with the second sliding sleeve 132. By opening the second sliding sleeve 132, the layered drainage string can be aligned with a predetermined small Layer 3 is connected.

When expanding capacity, perform gas injection in the injection-production gas well 1; perform sub-layer testing in the observation well 2 to obtain sub-layer test results, determine the gas-producing layer according to the sub-layer test results, and place its off. Specifically, the second oil and gas layer 32 is kept connected in the layered drainage column, and the substances flowing into the layered drainage column are sampled and analyzed. If the obtained sample is water, then keep the second oil and gas layer 32 in communication with the layered drainage column; if the obtained sample is mainly gas, the lower layer can be closed by dropping a plug so that the second There is no communication between the oil and gas layer 32 and the layered drainage pipe string.

If water is produced in the second oil and gas layer 32, a plug is put into the layered drainage column so that it sits on the short-circuit 15 of the plug so that the layered drainage pipe The column does not communicate with the second oil and gas layer 32 .

Open the second sliding sleeve 132 to make the layered drainage pipe column communicate with the first oil and gas layer 31, and obtain the sample of stratified inflow in the layered drainage pipe column; Samples in the drainage column are sampled and analyzed, if the obtained sample is water, then keep the first oil and gas layer 31 in communication with the layered drainage column; if the obtained sample is mainly gas, then close the The second sliding sleeve 132 is used to prevent communication between the second oil and gas layer 32 and the layered drainage pipe column.

The invention provides a method for rebuilding a gas storage and a layered injection-production system. The method for rebuilding a gas storage combines the stratum parameters of oil and gas reservoirs, and runs a layered drainage string in the observation well, and according to the Formation parameters of oil and gas reservoirs, perforating in sections on the layered drainage pipe string to form perforation sections; and performing sub-layer testing in the observation well to obtain sub-layer test results; according to the sub-layer test results, Identify gas-producing horizons and close them. The method can specifically reduce the remaining water content in the oil reservoir, effectively increase the storage capacity of the gas storage, and through the small-layer test, can improve the utilization rate of the injected natural gas in the injection-production gas well, so that in the limited reservoir space It is especially suitable for aquifer reservoirs such as edge-bottom water reservoirs and high water-cut reservoirs.

The above descriptions are only a few embodiments of the present invention. Although the disclosed embodiments of the present invention are as above, the content described above is only for the convenience of understanding the present invention, and is not intended to limit the present invention. Any person skilled in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention is Still, the scope defined by the appended claims shall prevail.

Claims (10)

1. A method for rebuilding a gas storage, characterized in that it comprises: Obtain formation parameters of oil and gas reservoirs; Setting injection-production gas wells and observation wells on the oil and gas reservoirs; Running a layered drainage string into the observation well, and perforating the layered drainage string in sections according to the formation parameters of the oil and gas reservoir to form a perforation section; Lowering the gas injection and production string into the gas injection and production well for gas injection; Carrying out sub-layer testing in the observation well to obtain sub-layer testing results; According to the test results of the sub-layers, the gas-producing layers are determined and closed. 2. The method for rebuilding a gas storage as claimed in claim 1, characterized in that: the gas injection well is arranged in the middle of the oil and gas reservoir; around. 3. The method for rebuilding a gas storage according to claim 2, characterized in that: the gas injection and production wells are horizontal wells, which are distributed along the direction of gravity at intervals according to the formation parameters of the oil and gas reservoir. 4. The method for rebuilding a gas storage according to claim 1, characterized in that: the perforated section of the layered drainage pipe string communicates with a small layer satisfying predetermined permeability and porosity. 5. The method for rebuilding a gas storage as claimed in claim 1, wherein said sublayer testing method comprises: Opening the perforation section in sections, so that the layered drainage pipe string is connected with the predetermined small layer; Obtaining a sample of stratified inflow in the stratified drainage column; According to the properties of the sample, the test results of the sub-layers are obtained to determine whether to close or open the corresponding sub-layers. 6. A layered injection-production system for the method for rebuilding a gas storage as claimed in claim 1, characterized in that: it includes an injection-production gas string for gas injection and gas production and an injection-production gas string for observation and drainage layered drainage strings, The gas injection and production string is arranged in the gas injection and production well, which includes a vertical well section and a horizontal section, the first casing is arranged in the vertical well section, the first oil pipe arranged in the first casing, and the The downhole safety valve, sliding sleeve, packer, and plug on the first tubing are located on the short circuit and the test site short circuit, and the plug is located on the first oil pipe between the short circuit site and the test site short circuit a plurality of through holes are provided; The layered drainage string is set in the observation well, which includes a second casing, a second oil pipe arranged in the second casing, and a downhole safety valve and at least one sliding pipe arranged in turn on the second oil pipe. The sleeve, at least one packer, the stopper is short-circuited, and the test is short-circuited. The second casing is provided with a perforation section, and the position of the perforation section is connected to a predetermined sublayer. 7. The layered injection-production system as claimed in claim 6, characterized in that: the two ends of the downhole safety valve are provided with flow shorts, the flow shorts are variable diameter joints, and the end with a larger diameter is connected to the The tubing is connected, and the end with a smaller diameter is connected with the downhole safety valve. 8. The layered injection-production system as claimed in claim 6, characterized in that: the oil and gas reservoirs are divided into more than two layers, and the number of packers and sliding sleeves on the layered drainage string is related to the number of oil and gas reservoir layers. unanimous. 9. The layered injection-production system according to claim 7, characterized in that: the second oil pipe between two adjacent packers is provided with the sliding sleeve, by opening the sliding sleeve, it can The layered drainage column is connected with the predetermined sublayer. 10. The layered injection-production system according to claim 6, characterized in that: the lower end of the first oil pipe near the horizontal section is provided with a bell mouth.