A gas reservoir recovery model construction method and system

Abstract

The application provides a gas reservoir recovery ratio model construction method and system, and comprises the following steps: obtaining a pure gas area recovery ratio based on macroscopic and microscopic heterogeneity characteristics of the gas reservoir; obtaining a water invasion area recovery ratio based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir; and constructing a gas reservoir recovery ratio model based on the pure gas area recovery ratio and the water invasion area recovery ratio. The recovery ratio model comprehensively considers the macroscopic and microscopic heterogeneity characteristics of the gas reservoir, can more carefully and comprehensively reflect a key index system affecting the gas reservoir recovery ratio, has strong operability, and also provides a basis for formulating a targeted gas reservoir recovery ratio improvement technical countermeasure.

Description

Technical Field

[0001] This invention belongs to the field of natural gas reservoir development technology, specifically relating to a method and system for constructing a gas reservoir recovery rate model. Background Technology

[0002] Natural gas reservoir development differs from oil reservoir development. Oil reservoir development has clearly defined primary, secondary, and tertiary recovery stages, while natural gas development lacks distinct phases due to the development method. For oil development, reservoir recovery rate is the product of sweep efficiency and wash efficiency, making its calculation relatively simple. However, for natural gas development, regardless of whether it's a gas field or a water field reservoir, a medium-to-high permeability or low-permeability tight gas reservoir, or a conventional or unconventional reservoir, the development method primarily employs depletion-based development. Due to the strong heterogeneity of reservoir development and the degree of water intrusion, calculating natural gas reservoir recovery rate is relatively complex. Currently, different methods for calculating gas reservoir recovery rate have emerged based on different reservoir types. The main methods for calculating natural gas recovery rate include the following three: The first method, primarily for depleted gas reservoirs in pure gas zones, uses the volumetric method to calculate reserves and applies the mass balance principle to obtain the reservoir recovery rate. (P is the formation pressure, Z is the natural gas deviation coefficient, and i and a represent the original and abandoned states.)

[0003] The second method, to account for changes in gas saturation during the development of gas reservoirs in water-rich areas, modifies the formula for calculating gas recovery rate. (P is the formation pressure, Z is the natural gas deviation coefficient,) (where i represents the gas saturation level and a represents the original and discarded states).

[0004] The third method, which comprehensively considers gas depletion, reservoir compression, and water intrusion, provides a formula for calculating the recovery rate of natural gas reservoirs: ( It is relative pressure, It is the reservoir volume coefficient, It is the water intrusion volume coefficient.

[0005] Based on the three methods for calculating recovery rate mentioned above, different recovery rate measures are also proposed. Generally speaking, the first two methods do not consider all factors, only targeting depleted gas fields or water-rich gas reservoirs, and provide formulas for calculating reservoir recovery rate. The last method (the third method) considers relatively comprehensive factors, taking into account both the compressibility of the storage and seepage media during natural gas development and the changes in gas saturation during water-rich processes. Although this formula is a quantitative evaluation formula for recovery rate, it shows that only three factors affect the recovery rate. Considering the increasing complexity of natural gas development targets, this method for calculating reservoir recovery rate suffers from insufficiently detailed parameter systems and weak practical operability.

[0006] As natural gas development targets shift towards deep, ultra-deep, and unconventional gas reservoirs, the problems of non-uniform water intrusion in water-bearing gas reservoirs and non-equilibrium utilization in waterless gas reservoirs are becoming increasingly serious. This leads to increasingly enhanced macroscopic and microscopic heterogeneity of natural gas development targets, resulting in greater gas-water distribution and higher risks and intensity of water intrusion. Consequently, gas reservoir recovery rates are generally low. Therefore, it is necessary to reconstruct a calculation model for gas reservoir recovery rates based on actual gas reservoir development processes. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a method and system for constructing a gas reservoir recovery model.

[0008] This invention is achieved through the following technical solution: This invention provides a method for constructing a gas reservoir recovery model, comprising the following steps: Based on the macroscopic and microscopic heterogeneous characteristics of gas reservoirs, the recovery rate of pure gas areas is obtained; Based on the macroscopic and microscopic heterogeneous characteristics of gas reservoirs, the recovery rate in water-swept areas is obtained; Based on the recovery rates in the pure gas zone and the water-swept zone, a gas reservoir recovery rate model is constructed.

[0009] Furthermore, the recovery rate of the pure gas zone is specifically obtained through the following formula:

[0010] in, This indicates the recovery rate in the pure gas zone. Indicates the voltage drop sweep coefficient. Indicates the current pressure exhaustion efficiency. This represents the current water intrusion sweep coefficient.

[0011] Furthermore, the recovery rate of the water-swept area is specifically obtained through the following formula:

[0012] in, Indicates the recovery rate in the flooded area. Indicates the voltage drop sweep coefficient. This indicates the macroscopic efficiency of water-driven gas transmission. This represents the current water intrusion sweep coefficient.

[0013] Furthermore, the construction of a gas reservoir recovery rate model based on the recovery rate in the pure gas zone and the recovery rate in the water-swept zone specifically includes: The degree of gas reservoir recovery is obtained based on the recovery rate of the pure gas zone and the recovery rate of the water-swept zone. The degree of gas reservoir recovery under abandoned formation pressure is taken as the gas reservoir recovery rate.

[0014] Furthermore, the degree of gas reservoir recovery is obtained based on the recovery rate in the pure gas zone and the recovery rate in the water-swept zone, specifically constructed using the following formula:

[0015]

[0016] in, Indicates the degree of gas reservoir recovery. This indicates the recovery rate of the pure gas zone. This indicates the recovery rate of the water-swept area.

[0017] Furthermore, the current pressure exhaustion efficiency Specifically, it is calculated using the following formula:

[0018] in, Indicates the original gas reservoir pressure. Indicates the original natural gas deviation coefficient. This indicates the current gas reservoir pressure. This indicates the current natural gas deviation coefficient.

[0019] Furthermore, the voltage drop sweep coefficient Specifically, it is calculated using the following formula:

[0020] in, To dynamically control the geological reserves of gas reservoirs, This represents the original geological reserves.

[0021] Furthermore, the current water intrusion sweep efficiency... Specifically, it is calculated using the following formula:

[0022] Where We represents the cumulative water intrusion, and Wp represents the sum of the cumulative water production and discharge. Indicates the formation water volume factor. This indicates the dynamic control of geological reserves in a gas reservoir. Indicates the original volume factor. This indicates the efficiency of microscopic water-driven gas.

[0023] Furthermore, the microscopic water-driven gas efficiency Specifically, it is calculated using the following formula:

[0024] in, Indicates the initial water saturation. This indicates the residual gas saturation in the water-inundated area.

[0025] Furthermore, the macroscopic water-driven gas efficiency Specifically, it is calculated using the following formula:

[0026] in, Indicates the original gas reservoir pressure. This is the original natural gas deviation coefficient. Given the current gas reservoir pressure, This represents the current natural gas deviation coefficient. Indicates the initial water saturation. This indicates the residual gas saturation in the water-inundated area.

[0027] Furthermore, Specifically, it is obtained in the following way: Substituting the natural gas state equation Obtained; in, Indicates the current remaining geological reserves. Indicates original geological reserves, Indicates the original volume factor. Indicates the initial water saturation. Indicates the residual gas saturation in the flooded area. This represents the current natural gas volume factor.

[0028] Furthermore, the remaining geological reserves Specifically, it is calculated using the following formula:

[0029] in, Indicates the remaining geological reserves in the un-water-inundated area. This indicates the remaining geological reserves in the flooded area.

[0030] Furthermore, the remaining geological reserves in the un-water-inundated area Specifically, it is calculated using the following formula:

[0031] in, Indicates the original volume factor. This represents the current natural gas volume factor.

[0032] Furthermore, the remaining geological reserves in the water-inundated area Specifically, it is calculated using the following formula:

[0033] in, Indicates the original volume factor. This represents the current natural gas volume factor. Indicates the initial water saturation. This indicates the residual gas saturation in the water-inundated area.

[0034] Furthermore, when the gas reservoir is a water-free gas reservoir, the water intrusion sweep efficiency is... =0, At this point, the degree of gas reservoir recovery .

[0035] Correspondingly, the present invention also provides a gas reservoir recovery rate model construction system. It includes a first acquisition unit, a second acquisition unit, and a model building unit; The first acquisition unit is used to acquire the recovery rate of pure gas areas based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir; The second acquisition unit is used to acquire the recovery rate of the water-swept area based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir. The model building unit is used to construct a gas reservoir recovery rate model based on the recovery rate of the pure gas zone and the recovery rate of the water-swept zone.

[0036] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: This invention provides a method for constructing a gas reservoir recovery rate model. Based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir, the recovery rate of the pure gas zone is obtained, and based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir, the recovery rate of the water-swept zone is obtained. Based on the recovery rates of the pure gas zone and the water-swept zone, a gas reservoir recovery rate model is constructed. This recovery rate model comprehensively considers the macroscopic and microscopic heterogeneity characteristics of the gas reservoir, and can more meticulously and comprehensively reflect the key indicator system affecting the gas reservoir recovery rate. It is highly operable and also provides a basis for formulating targeted technical countermeasures to improve the gas reservoir recovery rate. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart illustrating the gas reservoir recovery model construction method of the present invention. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] In this document, the terms "first," "second," and other similar words are not intended to imply any order, quantity, or importance, but are merely used to distinguish different elements. The terms "one," "a," and other similar words are not intended to indicate the existence of only one of the stated things, but rather that the description refers only to one of the stated things, which may have one or more. The terms "comprising," "including," and other similar words are intended to indicate a logical relationship, not a spatial relationship. For example, "A includes B" means that logically B belongs to A, not that spatially B is located inside A. Furthermore, the meanings of the terms "comprising," "including," and other similar words should be considered open-ended, not closed. For example, "A includes B" means that B belongs to A, but B does not necessarily constitute all of A; A may also include other elements such as C, D, and E.

[0041] In this document, the terms "embodiment," "this embodiment," "preferred embodiment," and "one embodiment" do not imply that the description applies only to one specific embodiment, but rather that such description may also be applicable to one or more other embodiments. Those skilled in the art will understand that any description made herein with respect to one embodiment can be substituted, combined, or otherwise incorporated with the descriptions in one or more other embodiments. Such substitutions, combinations, or other incorporations resulting in new embodiments are readily conceived by those skilled in the art and fall within the scope of protection of this invention.

[0042] In this description, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0043] like Figure 1 As shown in the figure, this invention provides a method for constructing a gas reservoir recovery model, the overall concept of which is as follows: A gas reservoir recovery rate model is constructed based on the recovery rates in the pure gas zone and the water-swept zone.

[0044] Specifically, based on the recovery rate in the pure gas zone and the recovery rate in the water-swept zone, a gas reservoir recovery rate model is constructed, which includes the following steps: The degree of gas reservoir recovery is obtained based on the recovery rate in the pure gas zone and the recovery rate in the water-swept zone.

[0045] The degree of gas reservoir recovery under abandoned formation pressure is used as the gas reservoir recovery rate. Here, "abandoned formation pressure" refers to the formation pressure when the gas reservoir is abandoned during the natural gas extraction process.

[0046] The recovery rate of the pure gas zone is obtained based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir, specifically through the following formula:

[0047] in, This indicates the recovery rate in the pure gas zone.

[0048] This represents the pressure drop sweep coefficient.

[0049] This represents the current pressure decay efficiency, i.e., during natural gas extraction, the formation pressure decreases from the initial formation pressure P. i Pressure exhaustion efficiency when it drops to P.

[0050] This represents the current water sweep efficiency, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The water sweep efficiency when it drops to P.

[0051] The recovery rate in the water-swept area is obtained based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir, specifically through the following formula:

[0052] in, This indicates the recovery rate in the water-affected area.

[0053] This represents the pressure drop sweep coefficient.

[0054] This indicates the macroscopic efficiency of water-driven gas.

[0055] This represents the current water sweep efficiency, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction.i The water sweep efficiency when it drops to P.

[0056] The degree of gas reservoir recovery is obtained based on the recovery rate in the pure gas zone and the recovery rate in the water-swept zone, specifically constructed using the following formula:

[0057]

[0058] in, Indicates the degree of gas reservoir recovery. This indicates the recovery rate of the pure gas zone. This indicates the recovery rate in the water-swept area. Indicates the voltage drop sweep coefficient. This represents the current pressure decay efficiency, i.e., during natural gas extraction, the formation pressure decreases from the initial formation pressure P. i Pressure exhaustion efficiency when it drops to P. This represents the current water sweep efficiency, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The water sweep efficiency when it drops to P This indicates the macroscopic efficiency of water-driven gas.

[0059] It should be noted that when the gas reservoir is a water-free gas reservoir (i.e., a pure gas zone), the water sweep efficiency is... =0, At this point, the degree of gas reservoir recovery .

[0060] Specifically, the above It is obtained in the following way: Substituting the natural gas state equation The obtained equation of state for natural gas is: .

[0061] The specific methods for obtaining it are as follows: The natural gas volume factor is the volume of a unit volume of natural gas under standard surface conditions (20 degrees Celsius, 0.101 MPa) within the formation. Therefore, the natural gas volume factor is the ratio of the underground volume of natural gas to the volume of natural gas under standard surface conditions, i.e. ,in, Indicates the volume factor of natural gas. Indicates the underground volume of natural gas. This indicates the volume of natural gas under standard surface conditions.

[0062] therefore: From the equation of state of natural gas It can be seen that, (Mode ).

[0063] Assuming the gas reservoir temperature remains constant during development, the equation will be... Substitution .

[0064] in, This represents the current remaining geological reserves, i.e., the formation pressure during natural gas extraction, which changes from the original formation pressure P. i The remaining geological reserves when the temperature drops to P.

[0065] This represents the pressure drop sweep coefficient.

[0066] This represents the original geological reserves, i.e., the original formation pressure P. i Geological reserves below.

[0067] This represents the current water sweep efficiency, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The water sweep efficiency when it drops to P.

[0068] This represents the original volume factor, i.e., the original formation pressure P. i The volume coefficient below.

[0069] This represents the initial water saturation, i.e., the initial formation pressure P. i The water saturation level below.

[0070] This indicates the residual gas saturation in the water-inundated area.

[0071] This represents the current natural gas volume factor, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The volume factor of natural gas when it drops to P.

[0072] Among them, the current remaining geological reserves, i.e., the formation pressure during natural gas extraction, are changed from the original formation pressure P. i Remaining geological reserves when it drops to P Specifically, it is calculated using the following formula:

[0073] Indicates the remaining geological reserves in the un-water-inundated area. This indicates the remaining geological reserves in the flooded area.

[0074] Specifically, the remaining geological reserves in the un-water-inundated areas Specifically, it is calculated using the following formula:

[0075] in, This represents the original volume factor, i.e., the original formation pressure P. i The volume coefficient below.

[0076] This represents the current natural gas volume factor, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The volume factor of natural gas when it drops to P.

[0077] Indicates the original geological reserves.

[0078] This represents the current water sweep efficiency, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The water sweep efficiency when it drops to P.

[0079] Specifically, the remaining geological reserves in the flood-affected area Specifically, it is calculated using the following formula:

[0080] in, This represents the original volume factor, i.e., the original formation pressure P. i The volume coefficient below.

[0081] This represents the current natural gas volume factor, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The volume factor of natural gas when it drops to P.

[0082] Indicates the original geological reserves.

[0083] This represents the current water sweep efficiency, i.e., the change in formation pressure from the original formation pressure P during natural gas extraction. i The water sweep efficiency when it drops to P.

[0084] This represents the initial water saturation, i.e., the initial formation pressure P. i The water saturation level below.

[0085] This indicates the residual gas saturation in the water-inundated area.

[0086] Specifically, according to the mass balance equation, the above-mentioned current pressure decay efficiency It is calculated using the following formula:

[0087] in, Indicates the original gas reservoir pressure. Indicates the original natural gas deviation coefficient. This indicates the current gas reservoir pressure. This indicates the current natural gas deviation coefficient.

[0088] Specifically, based on the material balance equation for water-inundated gas reservoirs, the aforementioned current water inundation sweep efficiency... It is calculated using the following formula:

[0089] Where We represents the cumulative water intrusion, and Wp represents the sum of the cumulative water production and discharge. Indicates the formation water volume factor. This indicates the dynamic control of geological reserves in a gas reservoir. This represents the original volume factor, i.e., the original formation pressure P. i The volume factor below, This indicates the efficiency of microscopic water-driven gas.

[0090] Among them, microscopic water-driven gas efficiency Specifically, it is calculated using the following formula:

[0091] in, This represents the initial water saturation, i.e., the initial formation pressure P. i The water saturation level below This indicates the residual gas saturation in the water-inundated area.

[0092] Specifically, in the development of oil and gas reservoirs, the geological reserves within the affected volume are the foundation of oil and gas production. Natural gas has low viscosity and good fluidity; it can flow wherever there is a pressure drop. Therefore, the aforementioned pressure drop sweep efficiency... It is calculated using the following formula:

[0093] in, To dynamically control the geological reserves of gas reservoirs, This represents the original geological reserves.

[0094] Specifically, the aforementioned macroscopic water-driven gas efficiency Specifically, it is calculated using the following formula:

[0095] in, Indicates the original gas reservoir pressure. This is the original natural gas deviation coefficient. Given the current gas reservoir pressure, This represents the current natural gas deviation coefficient. This represents the initial water saturation, i.e., the initial formation pressure P. i The water saturation level below This indicates the residual gas saturation in the water-inundated area.

[0096] The following examples further illustrate the method for constructing the gas reservoir recovery model described above: Example 1 The recovery rate calculation of waterless gas reservoirs (i.e., depleted gas reservoirs in pure gas zones) is based on the typical well group Suligesu 36-11 as an example.

[0097] The original formation pressure in this block The pressure in the abandoned formation is 32 MPa. The original natural gas deviation coefficient is 5 MPa. The deviation coefficient of natural gas at the time of disposal is 1.01. The dynamic control geological reserves of the gas reservoir in this well group are 0.957. It is 3.66 × 10⁸ m 3 Original geological reserves It is 6.4 × 10⁸ m 3 .

[0098] Based on the recovery rate formula under pure gas conditions, the degree of gas reservoir recovery is... Pressure drop sweep coefficient of well group Pressure exhaustion efficiency Therefore, under the existing well network conditions, when gas reservoir development reaches the abandoned formation pressure, the degree of gas reservoir recovery is... .

[0099] Example 2 The recovery rate of water-bearing gas reservoirs is calculated using the M gas field in the Sichuan Basin as an example.

[0100] The original formation pressure of the gas field The pressure in the abandoned formation is 75.72 MPa. The original natural gas deviation coefficient is 15.03 MPa. The deviation coefficient of natural gas at the time of abandonment is 1.3604. The cumulative water intrusion was 0.9595. It is 5897.65×10 4 m 3 The sum of cumulative water production and discharge 1458.72×10 4 m 3 Formation water volume coefficient The value is 1.025, and the exploitable geological reserves of the gas reservoir are 2338.86 × 10⁻⁶. 8 m3 Dynamic control of gas reservoir geological reserves 1734×10 8 m 3 The original volume factor of natural gas The initial water saturation was 0.00257. The residual gas saturation in the water-swept area is 0.154. The pressure decay efficiency is 0.54 when the gas reservoir is abandoned. Microscopic water-driven gas efficiency Water intrusion sweep coefficient =0.2731, voltage drop sweep coefficient Macroscopic water-driven gas efficiency When a gas reservoir is abandoned, the degree of gas recovery is... %.

[0101] Correspondingly, embodiments of the present invention also provide a gas reservoir recovery rate model construction system, the system including a first acquisition unit, a second acquisition unit, and a model construction unit.

[0102] The first acquisition unit is used to acquire the recovery rate of pure gas areas based on the macroscopic and microscopic heterogeneous characteristics of the gas reservoir.

[0103] The second acquisition unit is used to acquire the recovery rate of the water-swept area based on the macroscopic and microscopic heterogeneous characteristics of the gas reservoir. The model building unit is used to construct a gas reservoir recovery rate model based on the recovery rate of the pure gas zone and the recovery rate of the water-swept zone.

[0104] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A method for constructing a gas reservoir recovery model, characterized in that, Includes the following steps: Based on the macroscopic and microscopic heterogeneous characteristics of gas reservoirs, the recovery rate of pure gas areas is obtained; The recovery rate of the pure gas zone is obtained using the following formula: in, Indicates the recovery rate in the pure gas zone. Indicates the voltage drop sweep coefficient. Indicates the current pressure exhaustion efficiency. This indicates the current water intrusion sweep efficiency; Based on the macroscopic and microscopic heterogeneous characteristics of gas reservoirs, the recovery rate in water-swept areas is obtained; The recovery rate of the water-swept area is obtained using the following formula: in, Indicates the recovery rate in the flooded area. Indicates the voltage drop sweep coefficient. This indicates the macroscopic efficiency of water-driven gas extraction. This indicates the current water intrusion sweep efficiency; Based on the recovery rates in the pure gas zone and the water-swept zone, a gas reservoir recovery rate model is constructed, specifically including: Based on the recovery rates in the pure gas zone and the water-swept zone, the degree of gas reservoir recovery is obtained, specifically constructed using the following formula: in, Indicates the degree of gas reservoir recovery. This indicates the recovery rate of the pure gas zone. This indicates the recovery rate in the water-swept area; The degree of gas reservoir recovery under abandoned formation pressure is taken as the gas reservoir recovery rate. The current pressure exhaustion efficiency Specifically, it is calculated using the following formula: in, Indicates the original gas reservoir pressure. Indicates the original natural gas deviation coefficient. This indicates the current gas reservoir pressure. This indicates the current natural gas deviation coefficient; The pressure drop and the coefficient Specifically, it is calculated using the following formula: in, To dynamically control the geological reserves of gas reservoirs, Original geological reserves; The current water intrusion sweep coefficient Specifically, it is calculated using the following formula: Where We represents the cumulative water intrusion, and Wp represents the sum of the cumulative water production and discharge. Indicates the formation water volume factor. This indicates the dynamic control of geological reserves in a gas reservoir. Indicates the original volume factor. This indicates the efficiency of microscopic water-driven gas.

2. The method for constructing a gas reservoir recovery model according to claim 1, characterized in that, The microscopic water-driven gas efficiency Specifically, it is calculated using the following formula: in, Indicates the initial water saturation. This indicates the residual gas saturation in the water-inundated area.

3. The method for constructing a gas reservoir recovery model according to claim 1, characterized in that, The macroscopic water drive gas efficiency Specifically, it is calculated using the following formula: in, Indicates the original gas reservoir pressure. This is the original natural gas deviation coefficient. Given the current gas reservoir pressure, This represents the current natural gas deviation coefficient. Indicates the initial water saturation. This indicates the residual gas saturation in the water-inundated area.

4. The method for constructing a gas reservoir recovery model according to claim 1, characterized in that, Specifically, it is obtained in the following way: Substituting the natural gas state equation Obtained; in, Indicates the current remaining geological reserves. Indicates original geological reserves, Indicates the original volume factor. Indicates the initial water saturation. Indicates the residual gas saturation in the flooded area. This represents the current natural gas volume factor.

5. The method for constructing a gas reservoir recovery model according to claim 4, characterized in that, The remaining geological reserves Specifically, it is calculated using the following formula: in, Indicates the remaining geological reserves in the un-water-inundated area. This indicates the remaining geological reserves in the flooded area.

6. The method for constructing a gas reservoir recovery model according to claim 5, characterized in that, Remaining geological reserves in the un-water-inundated area Specifically, it is calculated using the following formula: in, Indicates the original volume factor. This represents the current natural gas volume factor.

7. The method for constructing a gas reservoir recovery model according to claim 5, characterized in that, The remaining geological reserves in the flooded area Specifically, it is calculated using the following formula: in, Indicates the original volume factor. This represents the current natural gas volume factor. Indicates the initial water saturation. This indicates the residual gas saturation in the water-inundated area.

8. The method for constructing a gas reservoir recovery model according to claim 1, characterized in that, When the gas reservoir is a water-free gas reservoir, the water sweep efficiency is... =0, At this point, the degree of gas reservoir recovery .

9. A gas reservoir recovery rate model construction system, used to implement the gas reservoir recovery rate model construction method according to any one of claims 1-8, characterized in that, It includes a first acquisition unit, a second acquisition unit, and a model building unit; The first acquisition unit is used to acquire the recovery rate of pure gas areas based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir; The second acquisition unit is used to acquire the recovery rate of the water-swept area based on the macroscopic and microscopic heterogeneity characteristics of the gas reservoir. The model building unit is used to construct a gas reservoir recovery rate model based on the recovery rate of the pure gas zone and the recovery rate of the water-swept zone.

Images