Quantitative evaluation method for water invasion influence degree of water production gas well

Abstract

The invention relates to the technical field of oil and gas reservoir development, in particular to a quantitative evaluation method for the influence degree of water invasion of a water-producing gas well, which comprises the following steps of: performing secondary pressure recovery test on the water-producing gas well which is subjected to overpressure recovery test in an oil testing period, performing superposition comparison on double logarithmic curves of the two pressure recovery tests, analyzing the radius of a water invasion gas layer, and evaluating the influence degree of water invasion of the water-producing gas well. The water volume of the invaded gas layer is calculated according to the radius of the water invaded gas layer, and finally the water body size and the water invasion replacement coefficient are calculated according to the water volume of the invaded gas layer. Through the method, the water invasion influence degree of the water production gas well can be more accurately and quantitatively evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas reservoir development, and in particular to a quantitative evaluation method for the influence degree of water invasion on water-producing gas wells. Background Art

[0002] my country has abundant natural gas resources with various types. Most of them are water-filled gas reservoirs with different degrees of activity, among which more than half are gas reservoirs with active edge and bottom water. According to incomplete statistics of more than 500 gas reservoirs in production in my country, water-driven gas reservoirs account for more than 80%, and most of them have entered the stage of water-carrying development. Water intrusion into gas reservoirs has a great impact on development. On the one hand, water will flow along high permeability zones and large fractures, forming closed gas in the reservoir, increasing the abandonment pressure and greatly reducing the final recovery rate. On the other hand, water production in gas wells will increase the difficulty of gas well lifting and increase the mining cost. This phenomenon is particularly prominent in the Sichuan Basin and the Tarim Basin. Therefore, it is particularly important to quantitatively evaluate the degree of water intrusion in water-producing gas wells and take reasonable water control measures to improve the recovery rate of gas wells and maximize the benefits of gas reservoir development. The quantitative evaluation of the degree of water intrusion in water-producing gas wells mainly includes the calculation of water intrusion replacement coefficient and water body size, and the core of calculating water intrusion replacement coefficient and water body size is to calculate the amount of water intrusion in water-producing gas wells.

[0003] Through relevant literature surveys conducted on platforms such as CNKI, Founder Data, and VIP Data, Chinese and foreign scholars have conducted a lot of research on the calculation of water intrusion. Among them, the common calculation methods are the water body compression coefficient method, the Schilthuis steady-state method, the Hurst modified steady-state method, and the Van Everdingen-Hurst unsteady-state method. The water body compression coefficient method is the simplest method for calculating water intrusion. It assumes that the water body is relatively small, the reservoir permeability is good, and the pressure drop of the gas reservoir can be quickly transmitted to the water body and quickly reach equilibrium. In other words, the pressure drop of the water body is consistent with the pressure drop of the gas reservoir, and the water intrusion is equal to the elastic expansion of the water body caused by the pressure drop. This method is suitable for the calculation of water intrusion in water-limited water bodies.

[0004] The Schilthuis steady-state method assumes that when the flow in the water body is in a stable state, the water invasion speed is proportional to the pressure drop. This method adopts a steady-state method and only considers the effect of pressure drop on water invasion, without considering the unstable flow state of the water body and the effect of the outer boundary of the water body. Overall, the later calculation results are too high.

[0005] The improvement of the Hurst modified steady-state method over the Schilthuis steady-state method is that it takes into account the pressure disturbance in the water area during water intrusion, which causes the outer boundary of the stable discharge area to expand outward, and is closer to the actual situation. However, it is still based on the theoretical model of stable seepage at constant pressure on the outer boundary, and has obvious application limitations.

[0006] The Van Everdingen-Hurst unsteady-state method does not take into account the heterogeneity of the physical properties of the water layer, and there is still the problem that the theoretical method is limited by applicable conditions.

[0007] In summary, the existing water intrusion calculation methods have overly idealized assumptions, complicated calculations, and limited practicality. Summary of the invention

[0008] In order to solve the above technical problems, the present invention proposes a quantitative evaluation method for the degree of water invasion of water-producing gas wells. By conducting a secondary pressure recovery test on the water-producing gas wells that have been subjected to a pressure recovery test during the oil test, the double logarithmic curves of the two pressure recovery tests are superimposed and compared, and the radius of water invasion into the gas layer is analyzed. The water invasion amount calculated is more accurate, and the calculation method has a wide range of applications and is simpler. The water invasion amount calculated by this method is used to calculate the water body size and the water invasion replacement coefficient, which can more accurately and quantitatively evaluate the degree of water invasion of water-producing gas wells.

[0009] The present invention is achieved by adopting the following technical solutions:

[0010] A quantitative evaluation method for the degree of water invasion of a water-producing gas well comprises the following steps:

[0011] Step S1. During the oil test period and after water invasion of the water-producing gas well, pressure recovery well test is performed to obtain corresponding bottom hole pressure data;

[0012] Step S2. Using the bottom hole pressure data, combined with the basic physical property parameters of the gas well during logging interpretation, and through the well testing software, obtain the corresponding double logarithmic curve of pressure recovery during the oil test and the double logarithmic curve of pressure recovery after water invasion test, and interpret and obtain the reservoir parameters, including formation pressure;

[0013] Step S3. Superimpose and compare the double logarithmic curve of pressure recovery during oil testing and the double logarithmic curve of pressure recovery after water invasion test to determine the radius of water invasion into the gas layer;

[0014] Step S4. Calculate the amount of water invading the gas layer using basic physical property parameters and water invading formation radius:

[0015]

[0016] Where: W ea Indicates the amount of water invading the air layer; R a represents the radius of the gas layer into which formation water invades; h represents the effective thickness; φ represents the effective porosity; S ew Indicates water saturation;

[0017] Step S5. Calculate the water body size and water invasion replacement coefficient according to the amount of water invading the gas layer calculated in step S4.

[0018] The method for determining the radius of water intrusion into the gas layer in step S3 is: finding the maximum separation point of the two superimposed double logarithmic pressure recovery curves and the coincidence point when the two double logarithmic pressure recovery curves gradually overlap, and obtaining the radius R of formation water intrusion into the gas layer corresponding to the maximum separation point. a1 And the radius R of the formation water intrusion gas layer corresponding to the coincidence point a2 .

[0019] The specific method for calculating the amount of water invading the gas layer in step S4 is:

[0020]

[0021] Where W ea Indicates the amount of water invading the air layer; R a1 R represents the radius of formation water invading the gas layer corresponding to the maximum separation point; a2 S represents the radius of the gas layer invaded by formation water corresponding to the coincidence point; ew Indicates the radius R a1 Water saturation in the corresponding area; S ew ' represents the radius R a1 and radius R a2 The water saturation in the corresponding area.

[0022] The water body size N w The calculation method is:

[0023]

[0024] Where W ea Indicates the amount of water invading the gas layer, G w represents the cumulative water production of the gas well; Δp represents the formation pressure difference between the oil test period and after water invasion; B w Indicates the volume coefficient of formation water under current formation pressure; B wi Represents the original volume coefficient of formation water; C f Indicates the effective compression coefficient of rock; C w Represents the effective compressibility of formation water.

[0025] B w , B wi , C f and C w In order to utilize the bottom hole pressure data, basic physical property parameters and corresponding laboratory measured data, it is obtained by fitting through well testing software.

[0026] The calculation method of the water invasion replacement coefficient is:

[0027]

[0028] Where, I represents the water intrusion replacement coefficient; W ea Indicates the amount of water invading the air layer; G p Indicates the cumulative gas production of the gas well; B gi Represents the original volume coefficient of natural gas.

[0029] The pressure recovery well test specifically includes the following steps:

[0030] Step S 11 .Static pressure gradient test: In the shut-in state, the pressure gauge is used to test the static pressure gradient;

[0031] Step S 12 .Stable production: carry out artificial drainage to achieve a stable drainage production state;

[0032] Step S 13 .Pressure recovery test;

[0033] Step S 14 .Lift the pressure gauge and test the static pressure gradient again.

[0034] The step S 11 The medium static pressure gradient test specifically refers to: when the well is shut in, the pressure gauge is used to test the static pressure gradient, with a stop point test every 500m and a stay time of more than 10 minutes; within 500m of the predetermined final stay depth, the test is stopped every 100m; after the pressure gauge is lowered to the predetermined depth at the bottom of the well, the bottom hole static pressure is monitored for more than 12 hours.

[0035] The step S 12 In this context, stable production specifically refers to: carrying out artificial drainage to achieve a stable drainage production state, with output fluctuations less than 5%, and continuous stable production for more than 24 hours.

[0036] The step S 13 The medium pressure recovery test specifically refers to: instantaneous well shut-in, lasting more than 72 hours.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. The present invention can accurately and intuitively determine the radius of water intrusion into the gas layer by superimposing the double logarithmic curve of pressure recovery during oil testing and after water invasion according to the characteristics of the curve.

[0039] 2. The present invention uses bottom hole pressure data, basic physical property parameters and water invasion radius to calculate the amount of water invading the gas layer, the size of the water body of the water-producing gas well and the water invasion replacement coefficient. The calculation method is simple and has high accuracy.

[0040] 3. In the analysis of pressure recovery test data, the present invention fully considers the influence of water production in gas wells on test data. Gas well test interpretation usually adopts gas phase interpretation. In this method, water phase interpretation is adopted for the well test interpretation after water production in gas wells.

[0041] 4. The present invention fully considers the problems of water-producing gas wells during the pressure recovery test, optimizes and adjusts the well test process, and adopts artificial drainage before shutting down the well for pressure recovery to achieve a stable drainage production state, thereby ensuring accurate data collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, wherein:

[0043] Figure 1 It is a schematic diagram for determining the radius of water intrusion into the air layer in the present invention;

[0044] Figure 2 This is a double logarithmic curve fitting analysis diagram of the pressure recovery of the L2 well during the oil test of the present invention;

[0045] Figure 3 This is a double logarithmic curve fitting analysis diagram of the pressure recovery of the L2 well after water invasion in the present invention;

[0046] Figure 4 It is a schematic diagram of the superposition of two double logarithmic curves in the present invention. DETAILED DESCRIPTION

[0047] Example 1

[0048] As a basic implementation mode of the present invention, the present invention includes a method for quantitatively evaluating the degree of water invasion in a water-producing gas well, comprising the following steps:

[0049] Step S1. During the oil test period and after water invasion of the water-producing gas well, a pressure recovery well test is performed to obtain corresponding bottom hole pressure data.

[0050] Step S2. Using the bottom hole pressure data, combined with the basic physical property parameters of the gas well during logging interpretation, the corresponding double logarithmic curve of pressure recovery during oil testing and the double logarithmic curve of pressure recovery after water invasion test are obtained through well testing software, and reservoir parameters are obtained through interpretation, including formation pressure, skin coefficient, permeability, formation coefficient and other parameters. Among them, the basic physical property parameters include parameters such as medium depth of the production layer, effective thickness h and effective porosity φ.

[0051] Step S3: Superimpose and compare the double logarithmic curve of pressure recovery during oil testing and the double logarithmic curve of pressure recovery after water invasion to determine the radius of water invasion into the gas layer.

[0052] Step S4. Calculate the amount of water invading the gas layer using basic physical property parameters and water invading formation radius:

[0053]

[0054] Where: W ea Indicates the amount of water invading the air layer; R a represents the radius of the gas layer into which formation water invades; h represents the effective thickness; φ represents the effective porosity; S ew Indicates water saturation.

[0055] Step S5. Calculate the water body size and water invasion replacement coefficient according to the amount of water invading the gas layer calculated in step S4.

[0056] Example 2

[0057] As a preferred embodiment of the present invention, this embodiment is based on the above-mentioned embodiment 1, and further supplements and explains the method for determining the radius of water invading the air layer and the corresponding method for calculating the amount of water invading the air layer.

[0058] Refer to the instruction manual Figure 1 In order to make the calculation of the amount of water invading the gas layer more accurate, in this embodiment, the radius of water invading the gas layer includes R a1 and R a2 Specifically, the determination method is: find the maximum separation point of the two superimposed double logarithmic pressure recovery curves and the coincidence point when the two double logarithmic pressure recovery curves gradually overlap, and obtain the formation water invasion gas layer radius R corresponding to the maximum separation point a1 And the radius R of the formation water intrusion gas layer corresponding to the coincidence point a2 .

[0059] Correspondingly, the calculation method of the amount of water invading the gas layer is specifically as follows:

[0060]

[0061] Where W ea Indicates the amount of water invading the air layer, in units of 10 4 m 3 ; R a1 Indicates the radius of formation water invading the gas layer corresponding to the maximum separation point, in meters; R a2 represents the radius of the gas layer into which the formation water intrudes corresponding to the coincidence point, in m; h represents the effective thickness, in m; φ represents the effective porosity, in decimals; S ew Indicates the radius R a1 The water saturation in the corresponding area, in decimal units; S ew ' represents the radius R a1 and radius R a2The water saturation in the corresponding area between the two, in decimals.

[0062] Example 3

[0063] As another preferred embodiment of the present invention, this embodiment further supplements and explains the method for calculating the size of a water body in detail based on the above-mentioned embodiment 1 or embodiment 2.

[0064] The size of the water body is calculated based on the material balance equation of the water zone, combined with the physical parameters of the formation water and rock:

[0065]

[0066] Where W ea Indicates the amount of water invading the air layer, in units of 10 4 m 3 ; G w Indicates the cumulative water production of the gas well, in units of 10 4 m 3 ; Δp represents the formation pressure difference between the oil test period and after water invasion, in MPa; B w Indicates the volume coefficient of formation water at the current formation pressure, dimensionless; B wi Represents the original volume coefficient of formation water, dimensionless; C f Indicates the effective compression coefficient of rock, in MPa -1 ; C w Indicates the effective compressibility of formation water, in MPa -1 .

[0067] Among them, B w , B wi , C f and C w The bottom hole pressure data, basic physical property parameters and corresponding laboratory measured data are obtained by fitting through well testing software. The well testing software can be panSystem, Saphir and other well testing software.

[0068] Example 4

[0069] As another preferred embodiment of the present invention, this embodiment further supplements and explains the calculation method of the water invasion replacement coefficient on the basis of the above-mentioned embodiment 3.

[0070] The water invasion replacement coefficient is calculated based on the amount of water invading the gas layer and the cumulative gas production of the gas well G p , the volume coefficient B of the gas in its original state measured by the laboratory high-pressure physical property experiment gi Specifically, the calculation method of the water invasion replacement coefficient is:

[0071]

[0072] Where I represents the water intrusion replacement coefficient, which is dimensionless; W ea Indicates the amount of water invading the air layer, in units of 10 4 m 3 ; G p Indicates the cumulative gas production of the gas well, in units of 10 4 m 3 ; B gi Represents the original volume coefficient of natural gas, dimensionless.

[0073] Example 5

[0074] As another preferred embodiment of the present invention, this embodiment is a further detailed supplement and elaboration of the pressure recovery well test based on any of the above embodiments.

[0075] The pressure recovery well test specifically includes the following steps:

[0076] Step S 11 .Static pressure gradient test: When the well is shut in, lower the pressure gauge to test the static pressure gradient, stop every 500m and stay for more than 10 minutes; when approaching the predetermined final stay depth (within 500m), stop every 100m; after the pressure gauge is lowered to the predetermined depth at the bottom of the well, monitor the bottom hole static pressure for more than 12 hours.

[0077] Step S 12 .Stable production: Carry out artificial drainage to achieve a stable drainage production state; the output fluctuation is less than 5%, and stable production is maintained for more than 24 hours.

[0078] Step S 13 .Pressure recovery test: instant well shut-in, lasting more than 72 hours.

[0079] Step S 14 .Lift up the pressure gauge and test the static pressure gradient again. The test is complete.

[0080] The above tests require continuous recording of production during the well opening stage, and high-precision electronic pressure gauges are used to record bottom hole pressure and temperature change data during the well opening and closing stages. When conditions permit, wellhead pressure and temperature change data should be recorded at the same time. Due to differences in the geographical environment, wellbore conditions, and reservoir properties of each gas well, the actual test time is adjusted according to the actual situation of the gas well.

[0081] Example 6

[0082] This embodiment includes a method for quantitatively evaluating the degree of water invasion in a water-producing gas well, including the following steps:

[0083] Step S1. During the oil test period and after water invasion of the water-producing gas well, a pressure recovery well test is performed to obtain corresponding bottom hole pressure data.

[0084] Step S2. Using the bottom hole pressure data, combined with the basic physical property parameters of the gas well during logging interpretation, the corresponding double logarithmic curve of pressure recovery during oil testing and the double logarithmic curve of pressure recovery after water invasion test are obtained through well testing software, and the reservoir parameters, including formation pressure, are interpreted.

[0085] Specifically, this embodiment takes a water-producing gas well L2 in a reef-flat gas reservoir in the Sichuan Basin as an example. The well did not produce formation water in the oil test, and the test gas production was 156.02×10 4 m 3 / d. During the oil test, a pressure recovery test was conducted, and the double logarithmic curve of pressure recovery during the oil test was obtained using Saphir well testing software. The double logarithmic curve of pressure recovery during the oil test is shown in the attached manual. Figure 2 The formation pressure, skin coefficient, permeability, formation coefficient and other parameters are obtained through further interpretation, as shown in Table 1 below.

[0086] Table 1 Interpretation results of the pressure recovery test of Well L2 (during the oil test)

[0087] <![CDATA[Wellbore storage coefficient (m 3 / MPa)]]> 1.449 Skin Factor -0.46 Formation coefficient near wellbore area (Kh) (mD·m) 446.45 Gas permeability near wellbore area (I) (within a radius of 69.3049 m) (mD) 17.3319 Transition zone (Zone II) gas phase permeability (69.3049m~138m)(mD) 60.3442 Transition zone (Zone III) gas phase permeability (138m~225.513m)(mD) 4.4737 Gas permeability in the far well area (IV area) (225.513m away) (mD) 5.9791 Formation pressure at the middle depth of the measuring point (vertical depth 5969.27m) (MPa) 60.1506 Formation pressure at the middle depth of the producing layer (vertical depth 5977.13m) (MPa) 60.1702

[0088] The well is 90×10 4 m 3 / d was put into production, and the water output increased from 11.3m 3 / d rises to 197.99m 3 / d, gas production dropped to 43.79×10 4 m 3 / d, the well was forced to shut down because the surface gathering and transportation system could not handle the high-sulfur formation water. Several self-spraying drainage tests were carried out, but normal production could not be restored due to low pressure. The laboratory measured the chloride content of the produced water to be 25251mg / L at most, 3798mg / L at least, and 23233mg / L on average, which was formation water that invaded the gas layer.

[0089] In order to understand the dynamic characteristics of drainage, analyze the water energy in the well area, determine whether to continue drainage in the next step, and predict the drainage effect, it was decided to carry out a pressure recovery well test.

[0090] (1) Determine the test content

[0091] The designed test content includes one pressure recovery test and a static pressure gradient test, and fluid sampling and analysis are carried out at the same time.

[0092] (2) Well testing steps

[0093] Step S 11 .Static pressure gradient test: When the well is shut in, lower the pressure gauge to below the perforation section to continuously measure the pressure. Test the static pressure gradient with a stop point every 500m for 10 minutes; stop every 100m after a depth of 5500m; monitor the bottom hole static pressure for 12 hours after the pressure gauge is lowered to the predetermined depth at the bottom of the well.

[0094] Step S 12 .Stabilize production: Carry out artificial drainage to achieve a stable drainage production state, which lasts for 24 hours before shutting down the well.

[0095] Step S 13 .Pressure recovery test: instant well shut-in, lasting 72 hours.

[0096] Step S 14 .Lift up the pressure gauge: lift the pressure gauge to test the static pressure gradient again, and the test is finished.

[0097] The above tests require continuous recording of production during the well opening stage, and the use of high-precision electronic pressure gauges to record bottom hole pressure and temperature change data during the well opening and closing stages, as well as the wellhead pressure and temperature change data.

[0098] (3) Test data analysis

[0099] The basic physical property parameters of L2 well were obtained through well logging interpretation, as shown in Table 2 below. The effective reservoir thickness is 26.1m (vertical thickness), and the average reservoir porosity is 9.5% weighted by the effective reservoir vertical thickness. Since L2 well is currently drained by gas lift, the fluid should be considered as water phase when interpreting formation parameters, and the water saturation is 100%.

[0100] Table 2 Well logging interpretation data table of L2 well

[0101] Medium depth of producing layer (m) 5983.73 (vertical depth: 5977.13) Wellbore radius of production layer (m) 0.0635 Relative density of natural gas 0.6521 Porosity of production layer (%) 9.5 Effective thickness of production layer (m) 26.1

[0102] Using its basic physical properties and bottom hole pressure test data, the Saphir well testing software was used to obtain the double logarithmic curve of pressure recovery after water invasion test, as shown in the attached manual. Figure 3 The formation pressure, skin factor, permeability, formation factor and other parameters are obtained through further interpretation, as shown in Table 3 below.

[0103] Table 3 Interpretation results of pressure recovery test of Well L2 (after water invasion)

[0104] <![CDATA[Wellbore storage coefficient (m 3 / MPa)]]> 4.2626 Skin Factor -5.27 Formation coefficient near wellbore area (Kh) (mD·m) 174.9496 Water phase permeability near the wellbore area (Zone I) (within a radius of 66.16 m) (mD) 6.7919 Transition zone (Zone II) water phase permeability (66.16m~512.36) (mD) 25.1124 Water phase permeability in the far well area (area III) (512.36 m away) (mD) 6.6903 Detection radius within 72h of effective shut-in test period (m) 508.6 Formation pressure at the middle depth of the measuring point (vertical depth 5969.27m) (MPa) 55.9255 Formation pressure at the middle depth of the producing layer (vertical depth 5977.13m) (MPa) 55.9885

[0105] Step S3. Overlay and compare the double logarithmic curve of pressure recovery during oil testing and the double logarithmic curve of pressure recovery after water invasion test, as shown in the attached manual. Figure 4 From the instruction manual Figure 4It can be seen that the two pressure derivative curves are far apart within 66.16m, indicating that this interval has been completely invaded by water. The pressure derivative curves gradually overlap between 66.16m and 210.8m. This area should belong to the gas-water coexistence zone. Beyond 210.8m, the two pressure derivative curves have completely overlapped. Therefore, we believe that this area is basically not affected by water invasion.

[0106] Therefore, the radius of water intrusion into the gas layer is determined, that is, the radius R of formation water intrusion into the gas layer corresponding to the maximum separation point. a1 It can be 66.16m, and the radius of formation water intrusion into the gas layer corresponding to the coincidence point is R a2 It can be 210.8m.

[0107] Step S4: Calculate the amount of water invading the gas layer.

[0108] As shown in Table 4, the volumetric method and two well test interpretations were used to calculate that the water volume in the L2 well gas layer within 66.16 m is 3.41×10 4 m 3 The water volume within 66.16m~210.8m is 15.6×10 4 m 3 The amount of water invading the gas layer was determined to be 19.01×10 4 m 3 .

[0109] Table 4 Size of water bodies within a certain radius in the gas layer of Well L2

[0110]

[0111] Step S5. Calculate the water body size and water invasion replacement coefficient according to the amount of water invading the gas layer calculated in step S4.

[0112] The formation pressure difference obtained by the pressure recovery test after oil testing and water production is 4.1817MPa. The volume coefficient B of the formation water under the current formation pressure is calculated using Saphir well testing software. w is 1.05951, the original volume coefficient of formation water B wi is 1.05874, the effective compressibility coefficient of formation water C w 0.000448MPa -1 , the effective compression coefficient of rock C f 0.00072MPa -1 , the field production data shows that the cumulative water production of this well is 3.1609×10 4 m 3 , substituting into the following formula, the water body size is 3757.78×10 4 m 3 .

[0113]

[0114] Where N w Indicates the size of the water body; W ea Indicates the amount of water invading the air layer; G w represents the cumulative water production of the gas well; Δp represents the formation pressure difference between the oil test period and after water invasion; B w Indicates the volume coefficient of formation water under current formation pressure; B wi Represents the original volume coefficient of formation water; C f Indicates the effective compression coefficient of rock; C w Represents the effective compressibility of formation water.

[0115] According to the on-site production data, the cumulative gas production of this well is 8229×10 4 m 3 The original volume coefficient of natural gas measured in the laboratory is B gi is 0.00305. Substituting it into the following formula, the water invasion replacement coefficient of well L2 is 0.77.

[0116]

[0117] Where, I represents the water intrusion replacement coefficient; W ea Indicates the amount of water invading the air layer; G p Indicates the cumulative gas production of the gas well; B gi Represents the original volume coefficient of natural gas.

[0118] According to the judgment basis of water body activity in the "Calculation Method of Recoverable Natural Gas Reserves" of the Petroleum and Natural Gas Industry Standard of the People's Republic of China, when the water invasion replacement coefficient I≧0.4, it indicates that the water body is large and active. The water invasion replacement coefficient of Well L2 is 0.77, which is much greater than 0.4, indicating that the water body of the well is active. Under the current economic and technical conditions, Well L2 is not worth developing.

[0119] In summary, after reading the present invention document, ordinary technicians in this field can make various other corresponding transformation schemes based on the technical scheme and technical concept of the present invention without creative mental labor, which all fall within the scope of protection of the present invention.

Claims

1. A quantitative evaluation method for the degree of water intrusion in a water-producing gas well, characterized by: The following steps are involved: Step S1. During the oil test period and after water invasion of the water-producing gas well, pressure recovery well test is performed to obtain corresponding bottom hole pressure data; Step S2. Using the bottom hole pressure data, combined with the basic physical property parameters of the gas well during logging interpretation, and through the well testing software, obtain the corresponding double logarithmic curve of pressure recovery during the oil test and the double logarithmic curve of pressure recovery after water invasion test, and interpret and obtain the reservoir parameters, including formation pressure; Step S3. Superimpose and compare the double logarithmic curve of pressure recovery during oil testing and the double logarithmic curve of pressure recovery after water invasion test to determine the radius of water invasion into the gas layer; Step S4. Calculate the amount of water invading the gas layer using basic physical property parameters and water invading formation radius: Where: W ea Indicates the amount of water invading the air layer; R a represents the radius of the gas layer invaded by formation water; h represents the effective thickness; φ represents the effective porosity; S ew Indicates water saturation; Step S5. Calculate the water body size and water invasion replacement coefficient according to the amount of water invading the gas layer calculated in step S4.

2. The method for quantitatively evaluating the degree of water intrusion in a water-producing gas well according to claim 1, characterized in that: The method for determining the radius of water intrusion into the gas layer in step S3 is: finding the maximum separation point of the two superimposed double logarithmic pressure recovery curves and the coincidence point when the two double logarithmic pressure recovery curves gradually overlap, and obtaining the radius R of formation water intrusion into the gas layer corresponding to the maximum separation point. a1 And the radius R of the formation water intrusion gas layer corresponding to the coincidence point a2 .

3. A quantitative evaluation method for water intrusion in water-producing gas wells according to claim 2, characterized in that: The specific method for calculating the amount of water invading the gas layer in step S4 is: Where W ea Indicates the amount of water invading the air layer; R a1 R represents the radius of formation water invading the gas layer corresponding to the maximum separation point; a2 S represents the radius of the gas layer invaded by formation water corresponding to the coincidence point; ew Indicates the radius R a1 Water saturation in the corresponding area; S ew ' represents the radius R a1 and radius R a2 The water saturation in the corresponding area.

4. A quantitative evaluation method for water intrusion in water-producing gas wells according to claim 3, characterized in that: The water body size N w The calculation method is: Where W ea Indicates the amount of water invading the gas layer, G w Indicates the cumulative water production of the gas well; Δp represents the formation pressure difference between the oil test period and after water invasion; B w Indicates the volume coefficient of formation water under current formation pressure; B wi Represents the original volume coefficient of formation water; C f Indicates the effective compression coefficient of rock; C w Represents the effective compressibility of formation water.

5. A quantitative evaluation method for water intrusion in water-producing gas wells according to claim 4, characterized in that: B w , B wi , C f and C w In order to utilize the bottom hole pressure data, basic physical property parameters and corresponding laboratory measured data, it is obtained by fitting through well testing software.

6. A quantitative evaluation method for water invasion impact degree of water-producing gas wells according to claim 3 or 4, characterized in that: The calculation method of the water invasion replacement coefficient is: Where, I represents the water intrusion replacement coefficient; W ea Indicates the amount of water invading the gas layer; G p Indicates the cumulative gas production of the gas well; B gi Represents the original volume coefficient of natural gas.

7. The method for quantitatively evaluating the degree of water intrusion in a water-producing gas well according to claim 1, characterized in that: The pressure recovery well test specifically includes the following steps: Step S 11 .Static pressure gradient test: In the shut-in state, the pressure gauge is used to test the static pressure gradient; Step S 12 .Stable production: carry out artificial drainage to achieve a stable drainage production state; Step S 13 .Pressure recovery test; Step S 14 .Lift the pressure gauge and test the static pressure gradient again.

8. A quantitative evaluation method for water intrusion in water-producing gas wells according to claim 7, characterized in that: The step S 11 The medium static pressure gradient test specifically refers to: when the well is shut in, the pressure gauge is used to test the static pressure gradient, with a stop point test every 500m and a stay time of more than 10 minutes; within 500m of the predetermined final stay depth, the test is stopped every 100m; after the pressure gauge is lowered to the predetermined depth of the well bottom, the bottom hole static pressure is monitored for more than 12 hours.

9. A quantitative evaluation method for water invasion impact degree of water-producing gas wells according to claim 7, characterized in that: The step S 12 In this context, stable production specifically refers to: carrying out artificial drainage to achieve a stable drainage production state, with output fluctuations less than 5%, and continuous stable production for more than 24 hours.

10. A quantitative evaluation method for water invasion impact degree of water-producing gas wells according to claim 7, characterized in that: The step S 13 The medium pressure recovery test specifically refers to: instantaneous well shut-in, lasting more than 72 hours.

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