A method for draining gas from a gas reservoir

Abstract

The application discloses a gas reservoir drainage gas production method, according to the type of the gas reservoir, if the type of the gas reservoir is a layered edge water gas reservoir, or the block bottom water gas reservoir is determined to have a characteristic performance of the layered edge water, then the gas reservoir is subjected to fine reservoir description, the strata are compared according to the fine reservoir description, and the high-permeability strips of the gas reservoir and single well are determined according to the strata comparison and dynamic monitoring; the high-permeability strip drainage is implemented for the water breakthrough well in the low position, if the drainage horizon is not the high-permeability horizon, then the non-high-permeability horizon is blocked by mechanical blocking or cement injection, the high-permeability horizon of the well is subjected to drainage, the gas reservoir is subjected to fine drainage by the method, and the purpose of improving the recovery of the gas reservoir is achieved, and a good foundation is laid for efficient development of the gas reservoir.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, and specifically relates to a gas reservoir drainage and gas production method. Background Technology

[0002] Natural gas, like crude oil, is buried in closed geological structures underground. Some are stored in the same strata as crude oil, while others exist separately. Natural gas stored in the same strata as crude oil is extracted along with the crude oil. Natural gas reservoirs containing only single-phase gas are called gas reservoirs, and their extraction methods are very similar to those for crude oil, but also have their own unique features.

[0003] Natural gas extraction also has its own unique characteristics. Firstly, like crude oil, natural gas is often stored within a reservoir system containing bottom or edge water. During the extraction process, the elastic energy of the water body drives it to infiltrate the gas reservoir along high-permeability zones. In this situation, due to the hydrophilicity of the rock itself and the effect of capillary pressure, the intrusion of water does not effectively displace the gas, but rather seals the gas trapped in fissures or pores, forming a dead gas zone. This high-pressure gas trapped in the water-intruded zone can amount to 30%–50% of the rock's pore volume, significantly reducing the final recovery rate of the gas reservoir. Secondly, after water production occurs in the gas well, the seepage resistance to gas flowing into the bottom of the well increases, and the total energy consumption of the gas-liquid two-phase flow upwards along the well pipe will increase significantly. As the impact of water intrusion intensifies, the gas production rate of the reservoir decreases, the self-flowing capacity of the gas well weakens, and the production of a single well rapidly declines until severe water accumulation at the bottom of the well leads to production shutdown.

[0004] Currently, the main approaches to managing water hazards in gas reservoirs are twofold: drainage and water blocking.

[0005] Water shut-off involves using methods such as mechanical plugging and chemical sealing to separate the gas-producing and water-producing zones, or to establish a water barrier within the reservoir. Currently, there are many drainage methods, the main principle of which is to remove water accumulated in the wellbore, i.e., drainage gas production.

[0006] For gas reservoirs that are extremely thick, abnormally high-pressure, and contain water, with a reservoir thickness of 300–400 m, and whose physical properties are mainly medium-porosity and high-permeability reservoirs, the reservoirs are highly heterogeneous, with well-developed high-permeability bands and fractures within the reservoir. Based on abundant production logging data (saturation and production profile tests) and geological understanding, the gas field generally suffers from non-uniform water flooding due to the influence of high-permeability bands. Low-permeability reservoirs have poor reserve utilization, severely impacting gas reservoir development. The gas field urgently needs adjustment. The heterogeneity of the thick, water-bearing gas reservoir and the prevalence of high-permeability bands lead to non-uniform reservoir production. Later, water intrusion along these high-permeability bands reduces the water drive sweep efficiency, ultimately reducing the gas recovery rate. Summary of the Invention

[0007] The purpose of this invention is to provide a gas reservoir drainage and gas production method to overcome the shortcomings of the prior art.

[0008] A gas reservoir drainage and gas production method includes the following steps:

[0009] S1, determine the gas reservoir type. If the gas reservoir type is a layered edge water gas reservoir, proceed to S2. If the gas reservoir type is a blocky bottom water gas reservoir, determine the characteristics of the blocky bottom water gas reservoir as layered edge water based on the properties of the bottom water body and the development of interlayers. Proceed to S2.

[0010] S2. Based on the gas reservoir type, perform detailed reservoir description of the gas reservoir, perform stratigraphic correlation based on the detailed reservoir description, and determine the high-permeability strips of the gas reservoir and individual wells based on stratigraphic correlation and dynamic monitoring; implement high-permeability strip drainage for water-bearing wells in low-level locations; if the drainage layer is not a high-permeability layer, seal the non-high-permeability layer by mechanical sealing or cement injection, and drain the high-permeability layer of the well.

[0011] Preferably, a layered edge-water gas reservoir refers to a gas reservoir where the reservoir thickness is less than the gas reservoir width, and a blocky bottom-water gas reservoir refers to a gas reservoir where the reservoir thickness is greater than the gas reservoir width.

[0012] Preferably, if the gas reservoir evaluation results show large permeability differences, strong heterogeneity, and well-developed high-velocity channels, then the water-bearing characteristic of this type of gas reservoir is that water is first encountered in wells at the structural periphery.

[0013] Preferably, the gas reservoir geological body is finely characterized by combining reservoir geological description and dynamic characteristics to achieve the description of the gas reservoir.

[0014] Preferably, the classification and comparison are carried out step by step according to the principles of equal sedimentary cycles and hierarchical control, with groups, segments, sand layers, and sub-layers.

[0015] Preferably, the current production status of the well is monitored by running instruments into the wellbore, including saturation testing and production profile, to determine the main producing layer, which is the high-permeability zone.

[0016] Preferably, the cumulative probability curve of gas reservoir well permeability and the statistical table of high permeability zones in each layer of the gas field are obtained. Based on the statistical table of high permeability zones in each layer of the gas field, the ratio of the average permeability of the relative high permeability zone to the average permeability of the reservoir is calculated, and the ratio of the average permeability of the relative high permeability zone to the average permeability of the surrounding rock is calculated.

[0017] High-permeability zones are divided into zones and segments. Through geological zoning and stratification statistics, and combined with dynamic monitoring data, a systematic analysis and demonstration are conducted to establish a standard for classifying high-permeability zones based on the cumulative probability curve of gas reservoir well permeability, the ratio of the average permeability of the high-permeability zone to the average permeability of the reservoir, and the ratio of the average permeability of the high-permeability zone to the average permeability of the surrounding rock.

[0018] The high-permeability zones of gas wells are effectively identified and divided according to the high-permeability zone classification standard.

[0019] Preferred criteria for classifying high-permeability zones:

[0020] 1) The cumulative probability curve has an inflection point;

[0021] 2)K 相对高渗带 >a×K P50 ;

[0022] 3)K 相对高渗带 >a×K 围岩 ;

[0023] Where a is a constant, K P50 K is the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the reservoir. 围岩 To calculate the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the surrounding rock.

[0024] Preferably, a is 3.

[0025] Preferably, the specific drainage process for a single well can be determined as follows: if the formation energy is sufficient, low-pressure drainage can be adopted; if low-pressure drainage cannot be adopted, electric pump drainage can be adopted for pure water wells, and coiled tubing gas lift can be adopted for other gas wells.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] This invention discloses a gas reservoir drainage and gas production method. Based on the gas reservoir type, if the gas reservoir is a layered edge-water gas reservoir, or if the blocky bottom-water gas reservoir is characterized by layered edge water, a detailed reservoir description is performed. Based on the detailed reservoir description, stratigraphic correlation is conducted. High-permeability zones in the gas reservoir and individual wells are identified based on stratigraphic correlation and dynamic monitoring. For water-bearing wells in lower locations, high-permeability zone drainage is implemented. If the drainage layer is not a high-permeability layer, the non-high-permeability layer is sealed by mechanical plugging or cement injection. The high-permeability layer of the well is then drained. This method of detailed drainage of the gas reservoir aims to improve the gas reservoir recovery rate, laying a solid foundation for the efficient development of this type of gas reservoir.

[0028] Preferably, based on stratigraphic correlation, the development characteristics of high-permeability zones are further characterized to provide geological basis for the study of water intrusion channels; based on stratigraphic correlation, physical property studies are conducted on each layer of each single well, and the permeability distribution law of vertical layers is studied. Due to the strong heterogeneity of reservoir physical properties, the relative high-permeability zone values ​​vary greatly in different well areas and different layers, so high-permeability strips need to be considered in different zones and segments. Attached Figure Description

[0029] Figure 1 This is a schematic diagram in an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram illustrating the relationship between the activity level of gas reservoir water and the water intrusion replacement coefficient in an embodiment of the present invention.

[0031] Figure 3 This is a graph showing the relationship between drainage volume and cumulative gas volume under different drainage conditions in this embodiment of the invention.

[0032] Figure 4 This is a curve showing the effect of daily drainage volume on the recovery rate in an embodiment of the present invention.

[0033] Figure 5 This is a structural diagram of the eastern part of gas field A in an embodiment of the present invention.

[0034] Figure 6 This is a comparative log chart of production logging data for well A10 over the years, as shown in this embodiment of the invention.

[0035] Figure 7 The figures show the drainage volume of the two eastern wells and the chloride ion variation curve of well A1 in this embodiment of the invention.

[0036] Figure 8 This is a comparison chart of production logging data for well A1 over the years in an embodiment of the present invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] This invention discloses a gas reservoir drainage and gas production method, which improves gas reservoir recovery rate by carrying out precise drainage of the gas reservoir. The method specifically includes the following steps:

[0040] S1, determine the gas reservoir type. If the gas reservoir type is a layered edge water gas reservoir, proceed to S2. If the gas reservoir type is a blocky bottom water gas reservoir, determine the characteristics of the blocky bottom water gas reservoir as layered edge water based on the properties of the bottom water body and the development of interlayers. Proceed to S2.

[0041] Layered edge-water gas reservoirs refer to gas reservoirs where the reservoir thickness is less than the gas reservoir width, while massive bottom-water gas reservoirs refer to gas reservoirs where the reservoir thickness is greater than the gas reservoir width.

[0042] This invention determines the type of water-driven gas reservoir by the reservoir type. It is applicable to layered edge-water gas reservoirs. For blocky bottom-water gas reservoirs, due to the poor physical properties of the bottom water and the development of interlayers, the bottom water rises slowly. The development process mainly relies on edge-water propulsion. This method is also applicable to this type of gas reservoir.

[0043] Evaluation of the water transgression replacement coefficient of gas reservoirs:

[0044] ω=(W e -W p B w ) / (G p B gi );

[0045] W e —Water intrusion volume, ×10 4 m 3 W p —Cumulative water production, ×10 8 m 3 ;

[0046] B w — Formation water volume coefficient, dimensionless;

[0047] B gi —Primary natural gas volume coefficient, dimensionless G p —Cumulative natural gas production, 10 8 m 3

[0048] ω—Water transgression replacement coefficient, dimensionless; corresponds to the activity level of the water body in the gas reservoir, such as... Figure 2 As shown.

[0049] S2. Based on the gas reservoir type, perform detailed reservoir description of the gas reservoir, perform stratigraphic correlation based on the detailed reservoir description, and determine the high-permeability strips of the gas reservoir and individual wells based on stratigraphic correlation and dynamic monitoring; implement high-permeability strip drainage for water-bearing wells in low-level locations; if the drainage layer is not a high-permeability layer, seal the non-high-permeability layer by mechanical sealing or cement injection, and drain the high-permeability layer of the well.

[0050] If the gas reservoir evaluation results show that the permeability difference is large, the heterogeneity is strong, and high-velocity channels (high-permeability strips or faults) are developed, then the water-bearing characteristics of this type of gas reservoir are that water is first encountered in wells at the structural edge (lower part), and the water-bearing characteristics of a single well are that water is successively encountered in the high-permeability strips of the perforated section, and water production is mainly in a few high-permeability strips in the perforated section, rather than water production in the entire well section.

[0051] By combining reservoir geological description and dynamic characteristics, the geological body of the gas reservoir is finely characterized, thus achieving the description of the gas reservoir.

[0052] Stratigraphic correlation of reservoirs: According to the principle of equal sedimentary cycles and hierarchical control, the formation-section-sand layer-sublayer are divided and correlated step by step.

[0053] This application selects well A2, an exploration well in the eastern part of a gas reservoir with relatively complete drilling strata and obvious electrical logging characteristics, as a standard well. Simultaneously, wells A01 in the central part of the gas reservoir and A03 in the western part are selected as standard wells for comparison with well A2. Based on these three standard wells, repeated comparisons are conducted with adjacent wells. The principles and basis for stratigraphic division and correlation, and marker beds are determined. On this basis, further subdivision and stratigraphic correlation are carried out.

[0054] The current production status of the well is monitored by running instruments into the wellbore, including saturation testing (water intrusion characteristics of the test layer) and production profile (production status of the test layer, including gas production and liquid production), and the main producing layer is identified as the high-permeability zone.

[0055] Based on stratigraphic correlation, the development characteristics of high-permeability zones will be further characterized to provide geological basis for the study of water intrusion channels. Based on stratigraphic correlation, physical property studies will be conducted on each layer of individual wells, and the permeability distribution law of vertical layers will be studied. Due to the strong heterogeneity of reservoir physical properties, the relative high-permeability zone values ​​vary greatly in different well areas and different layers, so high-permeability strips need to be considered in different zones and segments.

[0056] The identification of high-permeability zones in gas reservoirs includes the following steps:

[0057] Obtain the cumulative probability curve of gas reservoir well permeability and the statistical table of high permeability zones in each layer of the gas field. Calculate the ratio of the average permeability of the relative high permeability zone to the average permeability of the reservoir based on the statistical table of high permeability zones in each layer of the gas field. Calculate the ratio of the average permeability of the relative high permeability zone to the average permeability of the surrounding rock.

[0058] High-permeability zones are divided into zones and segments. Through geological zoning and stratification statistics, and combined with dynamic monitoring data, a systematic analysis and demonstration are conducted to establish a standard for classifying high-permeability zones based on the cumulative probability curve of gas reservoir well permeability, the ratio of the average permeability of the high-permeability zone to the average permeability of the reservoir, and the ratio of the average permeability of the high-permeability zone to the average permeability of the surrounding rock.

[0059] The high-permeability zones of gas wells are effectively identified and divided according to the high-permeability zone classification standard.

[0060] High-permeability zone classification criteria:

[0061] 1) The cumulative probability curve has an inflection point;

[0062] 2)K 相对高渗带 >a×K P50 ;

[0063] 3)K 相对高渗带 >a×K 围岩 ;

[0064] Where a is a constant, K P50 K is the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the reservoir. 围岩 To calculate the ratio of average permeability of the relatively high-permeability zone to average permeability of the surrounding rock;

[0065] A is 3.

[0066] To effectively identify high-permeability zones in gas wells based on the high-permeability zone classification criteria, the criteria are determined by three conditions that must be met simultaneously.

[0067] A system for identifying high-permeability strips in a gas reservoir includes an acquisition and calculation module, a standard establishment module, and an identification module.

[0068] The calculation module is used to acquire the cumulative probability curve of gas reservoir well permeability and the statistical table of high permeability zones in each layer of the gas field. Based on the statistical table of high permeability zones in each layer of the gas field, it calculates the ratio of the average permeability of the relative high permeability zone to the average permeability of the reservoir, and calculates the ratio of the average permeability of the relative high permeability zone to the average permeability of the surrounding rock.

[0069] The standard establishment module is used to divide high-permeability zones into sections. Through geological zoning and stratification statistics, and combined with dynamic monitoring data, a systematic analysis and demonstration are conducted to establish a standard for classifying high-permeability zones based on the cumulative probability curve of gas reservoir well permeability, the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the reservoir, and the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the surrounding rock.

[0070] The identification module is used to effectively identify high-permeability zones in gas wells based on the relative high-permeability zone classification criteria.

[0071] The criteria for defining relatively high permeability zones in the standard establishment module include:

[0072] 1) The cumulative probability curve has an inflection point;

[0073] 2)K 相对高渗带 >a×K P50 ;

[0074] 3)K 相对高渗带 >a×K 围岩 ;

[0075] Where a is a constant, K P50 K is the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the reservoir. 围岩 To calculate the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the surrounding rock, 'a' is set to 3.

[0076] The identification module effectively identifies high-permeability zones in gas wells based on the relative high-permeability zone classification standard by simultaneously meeting three conditions of the relative high-permeability zone classification standard.

[0077] The gas reservoir drainage and gas production method of this invention verifies the specific drainage volume and drainage period. It is demonstrated through detailed numerical simulation of specific gas reservoirs. Economic factors (including drilling, reinjection, surface support, and management) should be fully considered. Economic benefits are the primary factor in determining whether to drain gas. The designed drainage volume must be profitable before it can be applied.

[0078] Regarding the determination of the specific drainage process for a single well, if the formation energy is sufficient, i.e., low-pressure drainage is required, low-pressure drainage can be adopted; if low-pressure drainage cannot be adopted, electric pump drainage is used for pure water wells, and coiled tubing gas lift is used for other gas wells.

[0079] This invention enables precise drainage of water-bearing wells at the edge of gas reservoirs, effectively draining water from high-permeability strips along high-speed water intrusion channels. Numerical simulations demonstrate that this method effectively slows down the inrush of high-permeability layers, delays the water-bearing time of gas wells in the central and high-permeability areas, achieves more uniform water intrusion, and effectively improves gas reservoir recovery. The method of this invention is effective.

[0080] like Figure 1 As shown in the comparison chart of gas extraction effects before and after drainage, the drainage volume is analyzed, and the results show that the larger the drainage volume, the better the effect. Figure 4 As shown.

[0081] When designing drainage capacity, economic factors (including drilling, reinjection, surface infrastructure, and management) should be fully considered. Economic efficiency is the primary factor in determining whether to drain water. For example, draining 10,000 cubic meters of water results in a loss if 300,000 cubic meters of gas is added, breaking even with 1 million cubic meters, and a profit if 3 million cubic meters is added. Figure 3 As shown.

[0082] The specific drainage process for a single well can be determined by the formation energy. If the formation energy is sufficient, low-pressure drainage can be adopted. If low-pressure drainage cannot be adopted, electric pump drainage can be adopted for pure water wells, and coiled tubing gas lift can be adopted for other gas wells.

[0083] Numerical simulations were used to demonstrate the effectiveness of the research and development of a numerical model that incorporates actual production conditions. The top production layer is a high-permeability layer. By comparing the top high-permeability layer with and without drainage, the results show that drainage delays the water breakthrough time of the adjacent well PROD3 by 1.9 years, promotes more uniform water intrusion, increases the water drive sweep efficiency, and improves the recovery rate by 1%.

[0084] This invention relates to the implementation of two high-permeability strip drainage wells (Well A10 and Well A204) in the eastern part of a gas field. Initially, drainage from Well A10 resulted in a decrease in chloride ion in the adjacent Well A1. Drainage from Well A204 also showed signs of a decrease in chloride ion in Well A1.

[0085] Therefore, increasing the drainage volume of the high-permeability layer further demonstrates its effectiveness in delaying water intrusion into the central well. Furthermore, drainage in the eastern section showed that it took 1.5 years for water to be encountered in the high-permeability strips at the bottom and top of the perforated section of well A10 to reach the top. Three years after water was encountered at the bottom of the perforated section of well A1, the top was still producing gas normally, further demonstrating the effectiveness of the drainage. Practice has proven the validity of this innovative research result, its strong operability, and its effective promotion and application.

[0086] Taking the Tarim A gas reservoir as an example for analysis, the water drive index of this gas reservoir is 0.34, which is an active water drive gas reservoir with a large water volume ratio (14 times). The heterogeneity between the reservoir units of this gas field is serious, with a large permeability difference (114-121627) and a coefficient of variation of 0.8 to 3.4.

[0087] This gas reservoir is a massive bottom-water reservoir, but it has two stable strata at the bottom, and the bottom water layer has poor physical properties, resulting in a slow bottom water uplift rate (approximately 10m per year on average). The water volume ratio in the eastern part reaches 11 times, exhibiting characteristics of a layered edge-water gas reservoir during development. Furthermore, the eastern part suffers the most severe non-uniform water flooding. Taking well A10 in the eastern part of the reservoir as an example... Figure 5 The well's historical saturation and production profile, such as Figure 6 By combining detailed stratigraphic correlation, it can be found that the water-bearing layer of this well corresponds well with the high-permeability band, and the high-permeability band extends well into the middle and high parts of the gas reservoir.

[0088] Therefore, this paper proposes to drain the high-permeability strips of the perforated sections of wells A10 and A204 in the eastern part of the active water-driven gas reservoir with strong water bodies, so as to slow down the water invasion rate and degree of water invasion in well A1 in the middle and high parts. By draining, the water invasion rate and non-uniform advancement can be effectively slowed down, thereby improving the gas reservoir recovery rate.

[0089] Drainage layer: Due to well condition issues, production profile testing could not be performed on well A204. Well A10 is in good condition. The drainage layer will be evaluated through production profile testing of well A10. Figure 6As shown, the well is also affected by the high-permeability strips during drainage. The high-permeability strips at the top and bottom of the producing layer are the main producing layers. Therefore, there is no need to treat the well shaft, which achieves the purpose of drainage of the high-permeability strips of the edge-flooded gas well designed by the well.

[0090] like Figure 7 As shown in the comparison curves of the drainage volume of the two eastern wells and the chloride ion change of well A1, it can be seen that when well A10 was initially drained, the chloride ion in the adjacent well A1 decreased. Drainage from well A204 also showed signs of a decrease in chloride ion in well A1. Therefore, increasing the drainage volume in the high-permeability layer further demonstrates its effectiveness in delaying water intrusion into the central wells.

[0091] like Figure 8 As shown, the drainage in the eastern part of the A10 well was effective. It took one and a half years for the high-permeability strip at the bottom of the perforated section to see water, and for the top of the A1 well to see water, the top of the perforated section was still producing gas normally three years after the bottom of the perforated section saw water. This further demonstrates that the drainage was effective. Practice has proven that this innovative research result is valid and highly operable, and can be effectively promoted and applied.

Claims

1. A method for gas reservoir drainage and gas production, characterized in that, Includes the following steps: S1, determine the gas reservoir type. If the gas reservoir type is a layered edge water gas reservoir, proceed to S2. If the gas reservoir type is a blocky bottom water gas reservoir, determine the characteristics of the blocky bottom water gas reservoir as layered edge water based on the properties of the bottom water body and the development of interlayers. Proceed to S2. S2. Based on the gas reservoir type, perform detailed reservoir description of the gas reservoir, perform stratigraphic correlation based on the detailed reservoir description, and determine the high-permeability strips of the gas reservoir and individual wells based on stratigraphic correlation and dynamic monitoring; implement high-permeability strip drainage for water-bearing wells in low-level locations; if the drainage layer is not a high-permeability layer, seal the non-high-permeability layer by mechanical sealing or cement injection, and drain the high-permeability layer of the well. Layered edge water gas reservoirs refer to gas reservoirs where the reservoir thickness is less than the gas reservoir width, while massive bottom water gas reservoirs refer to gas reservoirs where the reservoir thickness is greater than the gas reservoir width. Obtain the cumulative probability curve of gas reservoir well permeability and the statistical table of high permeability zones in each layer of the gas field. Calculate the ratio of the average permeability of the relative high permeability zone to the average permeability of the reservoir based on the statistical table of high permeability zones in each layer of the gas field. Calculate the ratio of the average permeability of the relative high permeability zone to the average permeability of the surrounding rock. High-permeability zones are divided into zones and segments. Through geological zoning and stratification statistics, and combined with dynamic monitoring data, a systematic analysis and demonstration are conducted to establish a standard for classifying high-permeability zones based on the cumulative probability curve of gas reservoir well permeability, the ratio of the average permeability of the high-permeability zone to the average permeability of the reservoir, and the ratio of the average permeability of the high-permeability zone to the average permeability of the surrounding rock. Effective identification and division of high-permeability zones in gas wells based on high-permeability zone classification standards; High-permeability zone classification criteria: 1) The cumulative probability curve has an inflection point; 2)K 相对高渗带 >a×K P50 ; 3)K 相对高渗带 >a×K 围岩 ; Where a is a constant, K P50 K is the ratio of the average permeability of the relatively high-permeability zone to the average permeability of the reservoir. 围岩 To calculate the ratio of average permeability of the relatively high-permeability zone to average permeability of the surrounding rock, a is taken as 3.

2. The gas reservoir drainage and gas production method according to claim 1, characterized in that, If the gas reservoir evaluation results show large permeability differences, strong heterogeneity, and well-developed high-velocity channels, then the water-bearing characteristic of the gas reservoir is that water is first encountered in wells at the structural periphery.

3. The gas reservoir drainage and gas production method according to claim 1, characterized in that, By combining reservoir geological description and dynamic characteristics, the geological body of the gas reservoir is finely characterized, thus achieving the description of the gas reservoir.

4. A gas reservoir drainage and gas production method according to claim 1, characterized in that, Based on the principles of equal sedimentary cycles and hierarchical control, the formation, section, sand layer, and sub-layer were progressively divided and compared.

5. A gas reservoir drainage and gas production method according to claim 1, characterized in that, By lowering instruments into the wellbore to monitor and obtain the current production status of the wellbore, including saturation testing and production profiles, the main producing layer is identified as the high-permeability zone.

6. A gas reservoir drainage and gas production method according to claim 1, characterized in that, The specific drainage process for a single well is determined as follows: if the formation energy is sufficient, low-pressure drainage is adopted; if low-pressure drainage cannot be adopted, electric pump drainage is adopted for pure water wells, and coiled tubing gas lift is adopted for other gas wells.

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