Water invasion influence degree quantitative evaluation method for water-gas well

Abstract

The present application relates to the technical field of oil and gas reservoir development, in particular to a kind of water invasion influence degree quantitative evaluation method of water production gas well, through the overpressure recovery test carried out during oil testing to water production gas well, carry out secondary pressure recovery test, the double logarithmic curve of two pressure recovery tests is superimposed and compared, water invasion into gas layer radius is analyzed, water invasion into gas layer water volume is calculated according to water invasion into gas layer radius, finally, water body size and water invasion replacement coefficient are calculated according to water invasion into gas layer water volume. Through the method, the influence degree of water invasion of water production gas well can be more accurately quantitatively evaluated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas reservoir development, in particular to a quantitative evaluation method for water invasion influence degree of water-producing gas well. BACKGROUND

[0002] China is rich in natural gas resources, and there are various types, most of which are water gas reservoirs with different activity levels, among which more than half of the gas reservoirs are active with edge and bottom water. According to the incomplete statistics of more than 500 gas reservoirs in production in China, more than 80% of the gas reservoirs are water-driven, and most of the gas reservoirs have entered the water development stage. Water invasion into gas reservoirs has a great impact on development. On the one hand, water will flow along the high-permeability zone and large cracks, forming a closed gas in the reservoir, increasing the abandonment pressure and greatly reducing the ultimate recovery. On the other hand, water production in gas wells will increase the difficulty of gas well lifting and increase the cost of exploitation. This phenomenon is particularly prominent in the Sichuan Basin and the Tarim Basin. Therefore, it is particularly important to quantitatively evaluate the water invasion influence degree of water-producing gas wells and take reasonable water control measures to improve the recovery of gas wells and maximize the development benefit of gas reservoirs. The quantitative evaluation of the water invasion influence degree of water-producing gas wells mainly includes the calculation of water invasion replacement coefficient and water body size, and the core of the calculation of water invasion replacement coefficient and water body size is the calculation of the size of water invasion amount of water-producing gas wells.

[0003] Through the platform of China Knowledge Network, Founder Data, and VIP Data, relevant literature research is carried out, and scholars at home and abroad have done a lot of research on the calculation of water invasion amount. The common calculation methods are water body compression coefficient method, Schilthuis steady-state method, Hurst modified steady-state method and Van Everdingen-Hurst unsteady-state method. The water body compression coefficient method is the simplest method for calculating water invasion amount, which assumes that the water body is relatively small and the reservoir permeability is good, and the pressure drop of the gas reservoir can quickly spread to the water body and quickly reach equilibrium. That is, the pressure drop of the water body is consistent with the pressure drop of the gas reservoir, and the water invasion amount is equal to the elastic expansion of the water body caused by the pressure drop. This method is suitable for the calculation of water invasion amount of water-limited water body.

[0004] Schilthuis steady-state method considers that the flow in the water body is in a stable state, and the water invasion speed is proportional to the pressure drop. This method uses a steady-state method and only considers the influence of pressure drop on water invasion amount, without considering the unsteady flow state of the water body and the influence of the outer boundary of the water body. Overall, the later calculation result is high.

[0005] The improvement of Hurst modified steady-state method over Schilthuis steady-state method is that it considers the expansion of the outer boundary of the stable drainage area caused by the pressure disturbance of the water invasion process, which is closer to the actual situation. However, it is still based on the steady-state seepage theory model with a fixed outer boundary, and the application limitation is obvious.

[0006] The Van Everdingen-Hurst unsteady method does not consider the heterogeneity of the water layer properties, and the theoretical method is still limited by the applicable conditions.

[0007] In summary, the existing water invasion amount calculation method has idealized assumptions, is complicated to calculate, and has limited practicality. SUMMARY

[0008] To solve the above technical problems, the present application provides a quantitative evaluation method for the degree of water invasion in a water-producing gas well, which comprises the following steps:

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

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

[0011] Step S1. During the oil testing of the water-producing gas well and after the water invasion, pressure recovery testing is carried out respectively 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 well logging interpretation, the pressure recovery double logarithmic curve during the oil testing and the pressure recovery double logarithmic curve after the water invasion test are obtained through the well testing software, and the reservoir parameters, including the formation pressure, are interpreted;

[0013] Step S3. The pressure recovery double logarithmic curve during the oil testing and the pressure recovery double logarithmic curve after the water invasion test are superimposed and compared to determine the water invasion radius into the gas layer;

[0014] Step S4. Using the basic physical property parameters and the water invasion radius into the formation, the water amount invading into the gas layer is calculated:

[0015]

[0016] In the formula, W represents the water amount invading into the gas layer; R represents the radius of the formation water invading into the gas layer; h represents the effective thickness; φ represents the effective porosity; S represents the water saturation; ea In the formula, W represents the water amount invading into the gas layer; R represents the radius of the formation water invading into the gas layer; h represents the effective thickness; φ represents the effective porosity; S represents the water saturation; a In the formula, W represents the water amount invading into the gas layer; R represents the radius of the formation water invading into the gas layer; h represents the effective thickness; φ represents the effective porosity; S represents the water saturation; ew In the formula, W represents the water amount invading into the gas layer; R represents the radius of the formation water invading into the gas layer; h represents the effective thickness; φ represents the effective porosity; S represents the water saturation;

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

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

[0019] The calculation method of the water invasion gas layer amount in the step S4 is specifically:

[0020]

[0021] In the formula, W ea represents the water invasion gas layer amount; R a1 represents the formation water invasion gas layer radius corresponding to the maximum separation point; R a2 represents the formation water invasion gas layer radius corresponding to the overlapping point; S ew represents the water saturation in the area corresponding to the radius R a1 ; S ew ' represents the water saturation in the area corresponding to the radius R a1 and the radius R a2 .

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

[0023]

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

[0025] B w , B wi , C f and C w are obtained by using the bottom hole pressure data, basic physical parameters and corresponding laboratory measured data, and through the well test software fitting.

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

[0027]

[0028] In the formula, I represents a water invasion replacement coefficient; W ea represents the water volume of the invaded gas layer; G p represents the cumulative gas production of the gas well; B gi represents the original volume coefficient of natural gas.

[0029] The pressure buildup well testing test specifically comprises the following steps:

[0030] Step S 11 . Static pressure gradient test: in the closed state, the static pressure gradient is tested by a downhole pressure gauge;

[0031] Step S 12 . Stable production: artificial drainage is carried out to reach a stable drainage production state;

[0032] Step S 13 . Pressure buildup test;

[0033] Step S 14 . The pressure gauge is pulled up, and the static pressure gradient is tested again.

[0034] The static pressure gradient test in the step S 11 specifically refers to that in the closed state, the static pressure gradient is tested by a downhole pressure gauge, and the test is carried out once every 500 m, and the pressure gauge is kept for more than 10 minutes; when the depth is within 500 m of the predetermined final depth, the test is carried out once every 100 m; after the pressure gauge is lowered to the predetermined depth of the well bottom, the static pressure of the well bottom is monitored for more than 12 hours.

[0035] In the step S 12 , the stable production specifically refers to that artificial drainage is carried out to reach a stable drainage production state, the yield fluctuation change is less than 5%, and the stable production is maintained for more than 24 hours.

[0036] In the step S 13 , the pressure buildup test specifically refers to that the well is closed instantaneously, and the closure is maintained for more than 72 hours.

[0037] Compared with the prior art, the beneficial effects of the present application are shown in:

[0038] 1. According to the pressure buildup double logarithmic curve during the superposition oil testing and after the water invasion, the water invasion radius of the gas layer can be accurately and intuitively determined according to the characteristics of the curve.

[0039] 2. The water volume of the invaded gas layer, the water body size of the water production gas well and the water invasion replacement coefficient are calculated by using the well bottom pressure data, basic physical parameters and water invasion radius, and the calculation method is simple and accurate.

[0040] 3、The present application fully considers the influence of water production on the test data in the analysis of pressure buildup test data, and the gas well test interpretation is usually performed by using gas phase, but in the present method, the test interpretation after water production is performed by using water phase.

[0041] 4、The present application fully considers the problems of water production gas well in the pressure buildup test process, optimizes and adjusts the test flow, and uses artificial drainage before shutting down for pressure buildup, so as to achieve stable drainage production state and ensure the accurate data acquisition. BRIEF DESCRIPTION OF DRAWINGS

[0042] The present application will be further described in detail below in combination with the drawings and specific embodiments, in which:

[0043] Figure 1 It is a schematic diagram for determining the water invasion radius into the gas layer in the present application.

[0044] Figure 2 It is a pressure buildup double logarithmic curve fitting analysis diagram of well L2 during the oil test in the present application.

[0045] Figure 3 It is a pressure buildup double logarithmic curve fitting analysis diagram of well L2 after water invasion in the present application.

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

[0047] Example 1

[0048] As a basic embodiment of the present application, the present application includes a quantitative evaluation method for the water invasion influence degree of water production gas well, which comprises the following steps:

[0049] Step S1. During the oil test of the water production gas well and after water invasion, pressure buildup test is respectively performed to obtain the corresponding bottom hole pressure data.

[0050] Step S2. By using the bottom hole pressure data, combining with the basic physical property parameters of the gas well in the well logging interpretation, the pressure buildup double logarithmic curve during the oil test and the pressure buildup double logarithmic curve after the test of water invasion are obtained by using the test software, and the reservoir parameters are obtained by interpretation, including the formation pressure, skin factor, permeability, formation coefficient and other parameters. The basic physical property parameters include the depth of production layer, effective thickness h and effective porosity φ and other parameters.

[0051] Step S3. The pressure buildup double logarithmic curve during the oil test and the pressure buildup double logarithmic curve after the test of water invasion are superimposed and compared to determine the water invasion radius into the gas layer.

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

[0053]

[0054] Where: W ea Indicates the amount of water invading the air layer; R a represents the radius of the gas layer where 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 based on 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 further supplements and elaborates on 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 based on the above embodiment 1.

[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 intrusion 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, the unit is 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 The radius of the gas layer corresponding to the coincidence point is expressed in meters; h is the effective thickness in meters; φ is the effective porosity in decimals; S ew Indicates 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 elaborates on the method for calculating the size of a water body 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 properties of the formation water and rock:

[0065]

[0066] Where W ea Indicates the amount of water invading the air layer, the unit is 10 4 m 3 ; G w Indicates the cumulative water production of the gas well, the unit is 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 compressibility 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 parameters and corresponding laboratory measured data are fitted by well testing software. The well testing software can be panSystem, Saphir or other well testing software.

[0068] Example 4

[0069] As another preferred embodiment of the present invention, this embodiment further supplements and elaborates on the calculation method of the water intrusion substitution coefficient based on 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 laboratory high-pressure physical property experiments gi Specifically, the calculation method of the water intrusion substitution coefficient is:

[0071]

[0072] In the formula, I represents a water invasion replacement coefficient, dimensionless; W ea represents the water volume of the invaded gas layer, in units of 10 4 m 3 ; G p represents 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] Embodiment 5

[0074] As another preferred embodiment of the present application, this embodiment is a further detailed supplement and elaboration of the pressure buildup test on the basis of any of the above embodiments.

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

[0076] Step S 11 Static pressure gradient test: in the closed state, the static pressure gradient is tested by a pressure gauge, and the test is performed once every 500 m of stopping point, and the stopping time is more than 10 minutes; when approaching the predetermined final stopping depth (within 500 m), the test is performed once every 100 m of stopping point; after the pressure gauge is lowered to the predetermined depth of the well bottom, the static pressure at the well bottom is monitored for more than 12 hours.

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

[0078] Step S 13 Pressure buildup test: instantaneous shut-in, and the duration is more than 72 hours.

[0079] Step S 14 The pressure gauge is lifted, the static pressure gradient is tested again, and the test is ended.

[0080] The above test requires continuous recording of the yield during the opening stage, and the high-precision electronic pressure gauge is used to record the well bottom pressure and temperature change data during the opening and closing stages, and the wellhead pressure and temperature change data are recorded at the same time if possible. Due to the differences in 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] Embodiment 6

[0082] This embodiment includes a quantitative evaluation method for the water invasion influence degree of a water-producing gas well, which includes the following steps:

[0083] Step S1. During the oil testing of the water production gas well and after water invasion, pressure recovery test is carried out respectively to obtain the corresponding bottom hole pressure data.

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

[0085] Specifically, the present embodiment takes a reef flat gas reservoir in Sichuan Basin as an example. The well L2 well is a water production gas well. The well testing test does not produce formation water, and the test gas production is 156.02x10 4 m 3 / d. And pressure recovery test is carried out during the oil testing, and the Saphir well testing software is used to obtain the pressure recovery double logarithmic curve during the oil testing, and the pressure recovery double logarithmic curve during the oil testing is shown in the description. Figure 2 The formation pressure, skin factor, permeability, formation coefficient and other parameters are interpreted, and the specific parameters are shown in Table 1.

[0086] Table 1 Well L2 pressure recovery well testing interpretation results (during oil testing)

[0087] Wellbore storage coefficient (m 3 / MPa)]]> 1.449 Skin factor -0.46 Formation coefficient (Kh) in near wellbore region (mD-m) 446.45 Gas phase permeability in near wellbore region (I) (within radius 69.3049 m) (mD) 17.3319 Gas phase permeability in transition zone (II region) (69.3049 m ~ 138 m) (mD) 60.3442 Gas phase permeability in transition zone (III region) (138 m ~ 225.513 m) (mD) 4.4737 Gas phase permeability in far wellbore region (IV region) (outside 225.513 m) (mD) 5.9791 Formation pressure at middle depth of measuring point (vertical depth 5969.27 m) (MPa) 60.1506 Formation pressure at middle depth of producing zone (vertical depth 5977.13 m) (MPa) 60.1702

[0088] The well is produced with 90x10 4 m 3 / d, and the water production increases from 11.3m 3 / d to 197.99m 3 / d after one month of production, and the gas production decreases to 43.79x10 4 m 3 / d, because the surface gathering system cannot handle the high sulfur formation water, the well is forced to shut down. Many self-flowing drainage tests are carried out, but all of them cannot restore normal production due to low pressure. Laboratory tests show that the maximum chloride content of the produced water is 25251mg / L, the minimum is 3798mg / L, and the average is 23233mg / L, which belongs to the formation water invading the gas layer.

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

[0090] (1) Determine the test content

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

[0092] (2) Well testing test steps

[0093] Step S 11 . Static pressure gradient test: in the closed state, the lower pressure gauge is continuously measured below the perforation section, the lower pressure gauge is tested for static pressure gradient, and it is tested once every 500m stop point, and stays for 10 minutes; every 100m stop point after 5500m depth; after the pressure gauge is lowered to the predetermined depth of the bottom of the well, the static pressure of the bottom of the well is monitored for 12 hours.

[0094] Step S 12 . Stable production: carry out artificial drainage, reach stable drainage production state, last for 24 hours, and then shut down.

[0095] Step S 13 . Pressure recovery test: instantaneous shut-in, last for 72 hours.

[0096] Step S 14 . Pressure gauge is lifted: the pressure gauge is tested again for static pressure gradient, and the test is ended.

[0097] The above test requires continuous recording of production during the open well stage, and high-precision electronic pressure gauges are used to record the bottom hole pressure and temperature change data, as well as the wellhead pressure and temperature change data during the open and shut-in stages.

[0098] (3) Test data analysis

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

[0100] Table 2 Well L2 well logging interpretation data

[0101] Middle depth of producing zone (m) 5983.73 (vertical depth: 5977.13) Borehole radius of producing zone (m) 0.0635 Relative density of natural gas 0.6521 Porosity of producing zone (%) 9.5 Effective thickness of producing zone (m) 26.1

[0102] Using its basic physical property parameters and bottom hole pressure test data, the Saphir (Saphir) well testing software is used to obtain the pressure recovery double logarithmic curve of the test after water invasion, as shown in the accompanying drawings of the specification. Figure 3 The formation pressure, skin factor, permeability, and formation coefficient parameters are obtained by interpretation, as shown in Table 3 below.

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

[0104] Wellbore storage coefficient (m 3 / MPa) 4.2626 Skin factor -5.27 Formation coefficient (Kh) in near wellbore region (mD-m) 174.9496 Water phase permeability in near wellbore region (I region) (within radius 66.16 m) (mD) 6.7919 Water phase permeability in transition zone (II region) (66.16 m ~ 512.36) (mD) 25.1124 Water phase permeability in far wellbore region (III region) (outside 512.36 m) (mD) 6.6903 Detection radius within effective testing period of 72 h after shut-in (m) 508.6 Formation pressure at middle depth of measuring point (vertical depth 5969.27 m) (MPa) 55.9255 Formation pressure at middle depth of producing zone (vertical depth 5977.13 m) (MPa) 55.9885

[0105] Step S3. The pressure recovery double logarithmic curve during the oil test and the pressure recovery double logarithmic curve of the test after water invasion are superimposed and compared, as shown in the accompanying drawings of the specification. Figure 4 Figure 4 ​It can be seen that the two pressure derivative curves are far apart within 66.16m, indicating that water has completely invaded this interval. 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 intrusion.

[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 The radius of the 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 below, the volumetric method and two well test interpretations were used to calculate the water volume within 66.16 m in the L2 well gas layer to be 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 Water body size within a certain radius in the L2 well gas layer

[0110]

[0111] Step S5. Calculate the water body size and water invasion replacement coefficient based on 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 The original volume coefficient of formation water is 1.05951, B wi The effective compressibility coefficient of formation water is 1.05874, C w 0.000448MPa -1 , the effective compression coefficient C of rock f 0.00072MPa -1 The on-site production data shows that the cumulative water production of this well is 3.1609×10 4 m 3 , the water body size is calculated as 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 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 Indicates the original volume coefficient of formation water; C f Indicates the effective compression coefficient of rock; C w Indicates the effective compressibility of formation water.

[0115] The cumulative gas production of this well is 8229×10 4 m 3 , the original volume coefficient of natural gas B measured in the laboratory gi 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 gas 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 criteria for determining water activity in the "Method for Calculating Recoverable Natural Gas Reserves," a water intrusion replacement coefficient (I) ≥ 0.4, indicating a large and active water body. Well L2's water intrusion replacement coefficient is 0.77, significantly greater than 0.4, indicating active water. Under current economic and technical conditions, Well L2 is not currently 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 solutions and technical concepts of the present invention without creative mental work, which all fall within the scope of protection of the present invention.

Claims

1. A method for quantitatively evaluating the degree of water invasion influence of a water-gas well, characterized in that: Comprise the following steps: Step S1, during the oil test of the water production gas well and after water invasion, respectively, carry out pressure recovery well test test, obtain corresponding bottom hole pressure data; Step S2, using bottom hole pressure data, combining with the basic physical parameters of gas well in well logging interpretation, through well test software, obtain corresponding pressure recovery double logarithmic curve during oil test and pressure recovery double logarithmic curve after test of water invasion, and obtain reservoir parameters including formation pressure through interpretation; Step S3, superimposing and comparing the pressure recovery double logarithmic curves during the oil testing and the pressure recovery double logarithmic curves after the water invasion testing to determine the water invasion radius of the gas layer; the method for determining the water invasion radius of the gas layer in the step S3 is: finding the maximum separation point of the superimposed two pressure recovery double logarithmic curves and the coincidence point when the two pressure recovery double logarithmic curves gradually coincide together, and obtaining the formation water invasion radius of the gas layer corresponding to the maximum separation point R a1 and the formation water invasion radius of the gas layer corresponding to the coincidence point R a2 ; Step S4, using the basic physical parameters and the water invasion formation radius, calculate the water amount of invaded gas layer: wherein W ea represents the water influx from the formation into the gas reservoir; R a1 represents the radius of the formation water influx into the gas reservoir corresponding to the maximum separation point; R a2 represents the radius of the formation water influx into the gas reservoir corresponding to the coincidence point; S ew represents the radius R a1 corresponding to the area between the radius a1 and the radius R a2 corresponding to the area between the radius R a1 0>and the radius h represents the effective thickness; represents the effective porosity; Step S5, according to the water amount of invaded gas layer calculated in step S4, calculate the water body size and water invasion replacement coefficient.

2. The method according to claim 1, characterized in that: The water body size N w The calculation method is: wherein, W ea represents the water volume of the invaded gas zone; G w represents the cumulative water volume of the gas well; Δp represents the difference between the formation pressure during the oil test and after water invasion; B w represents the volume factor of the formation water at the current formation pressure; B wi represents the original volume factor of the formation water; C f represents the effective compressibility of the rock; C w represents the effective compressibility of the formation water.

3. The method according to claim 2, characterized in that: B w 、 B wi 、C f and C w For the use of bottom hole pressure data, basic physical parameters and corresponding laboratory measured data, through the well test software fitting.

4. The method according to claim 3, characterized in that: The well test software is panSystem or Saphir.

5. The method according to claim 1 or 2, characterized in that: The calculation method of the water invasion replacement coefficient is: In the formula, I represents the water influx replacement coefficient; W ea represents the water content of the invaded gas layer; G p represents the cumulative gas production of the gas well; B gi represents the original volume coefficient of natural gas.

6. The method according to claim 5, characterized in that: Natural gas original volume factor B gi Data measured in the laboratory.

7. The method according to claim 1, characterized in that: The pressure recovery well test test specifically comprises the following steps: Step S 11 Static pressure gradient test: In the closed well state, the lower pressure gauge tests the static pressure gradient; Step S 12 Stable production: Artificial drainage is carried out to achieve stable drainage production state; Step S 13 , pressure build-up test; Step S 14 The static pressure gradient was again tested with the uphole pressure gauge.

8. The method according to claim 7, characterized in that: The step S 11 The static pressure gradient test in particular refers to: in the closed state, a static pressure gradient is tested by a pressure gauge, and a stop point is tested every 500 m, and the stop lasts for more than 10 minutes; a stop point is tested every 100 m within 500 m close to a predetermined final stop depth; and after the pressure gauge is lowered to a predetermined depth of the well bottom, the static pressure of the well bottom is monitored for more than 12 hours.

9. The method according to claim 7, characterized in that: The step S 12 In the step S, the stable production specifically refers to: carrying out artificial drainage to reach a stable drainage production state, with a yield fluctuation change of less than 5%, and a continuous stable production of more than 24 hours.

10. The method according to claim 7, characterized in that: The step S 13 The middle pressure recovery test specifically refers to instantaneous shut-in for more than 72 hours.

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