Shale gas deployment well horizontal section length setting method based on risk evaluation

Abstract

The invention relates to the technical field of shale gas development, in particular to a shale gas deployment well horizontal section length setting method based on risk evaluation, comprising: acquiring geological parameters of a horizontal well deployment area; calculating and determining a regional stress state through crustal stress data; calculating characteristic parameter coefficients according to geological parameters of the horizontal well deployment area; calculating a regional stratum risk coefficient according to the characteristic parameter coefficient; and calculating the proper length of the horizontal section of the horizontal well in the deployment area by combining a risk index standard. According to the method, the formation deformation risk of the shale gas development area can be predicted, the proper length of the horizontal section of the well is preferably deployed in combination with the risk evaluation result, and an effective method is provided for preferably selecting the proper length of the horizontal section of the shale gas horizontal well.

Description

Technical Field

[0001] This invention relates to the field of shale gas development technology, specifically to a method for setting the horizontal section length of shale gas deployment wells based on risk assessment. Background Technology

[0002] With the continuous advancement of unconventional oil and gas development technologies, shale gas development has entered a rapid production construction phase and is one of the main areas for increasing natural gas reserves and production in the future. Shale gas development includes well site deployment, feasibility studies, and implementation. The deployment phase is the crucial stage, guiding subsequent stages. The horizontal section length designed during deployment is generally the final implemented horizontal section length. Theoretically, increasing the horizontal section length results in a larger controlled storage volume and better production performance for shale gas wells. Currently, the horizontal section length of shale gas wells is usually determined through a comprehensive analysis of technical conditions and economic benefits, without considering the impact of geological characteristics on the horizontal section. From the current state of shale gas development, some shale gas wells experience casing deformation during implementation, affecting wellbore integrity and consequently impacting well stimulation and production efficiency. This leads to problems such as insufficient fracturing stimulation and inability to fully utilize the production capacity of the stimulated section. The impact is even greater for excessively long horizontal sections due to casing deformation, resulting in even worse economic returns.

[0003] Shale gas horizontal well casing deformation is caused by formation deformation and slippage, and the probability of formation deformation and slippage varies under different geological characteristics. Therefore, it is necessary to establish a method for predicting and setting the length of the horizontal section of shale gas wells, taking into account regional geological characteristics. Thus, a more reasonable technical solution needs to be proposed to address the technical problems existing in current technologies. Summary of the Invention

[0004] To overcome at least one of the aforementioned defects, this invention proposes a method for setting the length of the horizontal section of a shale gas deployment well based on risk assessment, taking into account the geological characteristics of the shale gas development area. This method evaluates the risk of formation deformation and slippage, predicts the risk of casing deformation in the deployed horizontal well, and then optimizes the length of the horizontal section.

[0005] To achieve the above objectives, the method for setting the horizontal section length of a shale gas deployment well disclosed in this invention can adopt the following technical solution:

[0006] A method for setting the horizontal section length of shale gas deployment wells based on risk assessment, comprising:

[0007] Step 1: Obtain geological parameters of the horizontal well deployment area;

[0008] Step 2: Calculate and determine the regional stress state using geostress data;

[0009] Step 3: Calculate the characteristic parameter coefficients based on the geological parameters of the horizontal well deployment area;

[0010] Step 4: Calculate the regional stratigraphic risk coefficient F based on the characteristic parameter coefficients:

[0011] F = Q × [A × S] 地应力 +B×S 夹角 +C×S 地层 +D×S 缝险 +E×S 缝密

[0012] +F×S 缝长 +G×S 矿物 +H×S 含水 ]

[0013] Where F is the formation risk coefficient; Q is the geostress state coefficient, with a value of 1 for strike-slip stress state and 0.8 for non-strike-slip stress state; A, B, C, D, E, F, G, and H are the influence factors of each characteristic parameter coefficient, with values ​​of 0.1 for A, 0.2 for B, 0.1 for C, 0.2 for D, 0.1 for E, 0.1 for F, 0.1 for G, and 0.1 for H.

[0014] Step 5: Based on the risk index standard, calculate the appropriate length L of the horizontal section of the horizontal well in the deployment area. 适 :

[0015]

[0016] Among them, L 标 The standard horizontal section length is determined based on the existing horizontal sections of shale gas wells in the large area, or it can be the length of the main horizontal sections implemented by shale gas wells in the large area.

[0017] The aforementioned method for setting the horizontal section length of deployment wells takes into account the deformation of shale gas horizontal well casing caused by formation deformation and sliding. The probability of formation deformation and sliding varies under different geological characteristics. Combined with regional formation deformation and sliding risk assessment and regional gas well implementation analysis, the method determines the horizontal section length of shale gas horizontal wells in the region, which is conducive to determining a more reasonable horizontal section length.

[0018] Furthermore, in this invention, the regional geological parameters include multiple components: at least in-situ stress parameters, fracture parameters, stratigraphic attitude parameters, clay mineral parameters, and water saturation parameters. Adopting this approach allows for a more comprehensive evaluation of the impact of environmental factors on casing deformation and a more accurate simulation of casing deformation in real-world environments.

[0019] Furthermore, in this invention, the regional stress state is determined as follows: combining the triaxial principal stresses, the regional stress state is divided into strike-slip stress state and non-strike-slip stress state; if δ h-max >δ v This is the strike-slip stress state, if δ v >δ h-max This is a non-strike-slip stress state, δ h-max It is the maximum horizontal principal stress, δ v It is the vertical principal stress, and the unit is MPa.

[0020] Furthermore, when calculating the characteristic parameter coefficients, the geostress parameter S 地应力 Calculated and determined as follows:

[0021]

[0022] Where, δ h-max It is the maximum horizontal principal stress, δ h-min Minimum horizontal principal stress, in MPa.

[0023] Furthermore, when calculating the characteristic parameter coefficients, the coefficient S of the maximum horizontal principal stress angle of the crack is... 夹角 Determined as follows: When the angle between the crack direction and the maximum horizontal principal stress is between 0° and 30°, S 夹角 The value is 2; the angle between the crack direction and the maximum horizontal principal stress is between 30° and 60°, S 夹角 The value is taken as 1.3; the angle between the crack direction and the maximum horizontal principal stress is between 60° and 90°, S 夹角 The value is 0.7.

[0024] Furthermore, when calculating the characteristic parameter coefficients, the formation dip angle variation coefficient S 地层 Determine using the following method:

[0025]

[0026] Where k is the change angle of the formation dip angle every 30m along the trajectory of the horizontal well in the deployment area; K is the standard value of the formation dip angle change, which is 3, and the unit is ° / 30m.

[0027] Furthermore, when calculating the characteristic parameter coefficients, the crack risk coefficient S is mainly determined. 缝险 Crack development density coefficient S 缝密 and crack development length coefficient S 缝长 .

[0028] Crack risk coefficient S 缝险 The area where the risk of natural fractures in the target layer reaches the first level is determined using the following method: S 缝险The value is 2; in areas where the risk of natural fractures in the target layer reaches the second level, S 缝险 The value is 1.3; in areas where the risk of natural fractures in the target layer reaches level three, S 缝险 The value is 0.7, and it gradually decreases from the first level to the third level;

[0029] Crack development density coefficient S 缝密 The following method is used to determine S: When the fracture development density of the target formation is between 0 and 2 fractures / km along the direction of the deployed horizontal well trajectory, S is... 缝密 The value is taken as 0.7; the crack development density is between 2 and 4 cracks / km, S 缝密 The value is 1.3; the crack development density is greater than 4 cracks / km, S 缝密 The value is 2;

[0030] Crack development length coefficient S 缝长 The following method was used to determine the average crack length in the deployment area, which ranged from 0 to 2 km. 缝长 The value is taken as 0.7; the average crack length is between 2 and 4 km, S 缝长 The value is 1.3; the average crack length is greater than 4km, S 缝长 The value is 2.

[0031] Furthermore, in determining the crack risk coefficient S 缝险 At that time, the risk of natural fractures in the target layer was predicted using geophysical methods, where curvature bodies represent fractures with a risk level of 1, likelihood bodies represent fractures with a risk level of 2, and ant bodies represent fractures with a risk level of 3.

[0032] Furthermore, when calculating the characteristic parameter coefficients, the clay mineral abundance coefficient S is determined according to the following method. 矿物 :

[0033]

[0034] Among them, W 黏土 It is the clay mineral content of the deployment area, W 标 This is the standard value for clay mineral content, taken as 30%, in percentage form.

[0035] Furthermore, when calculating the characteristic parameter coefficients, the water saturation coefficient S is determined as follows: 含水 :

[0036]

[0037] in, It refers to the water saturation level of the deployment area. This is the standard value for water saturation, taken as 30%, in percentages (%).

[0038] Compared with the prior art, some of the beneficial effects of the technical solution disclosed in this invention include:

[0039] This invention can predict the formation deformation risk in shale gas development areas, and based on the risk assessment results, optimize the appropriate length of the horizontal section of the well, providing an effective method for optimizing the appropriate length of the horizontal section of shale gas horizontal wells. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram illustrating the process of setting the length of the horizontal section of the deployment well in this invention. Detailed Implementation

[0042] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0043] In view of the unreasonable setting of the horizontal section length in the existing technology of shale gas wells, the following embodiments are optimized and solve the defects existing in the existing technology.

[0044] Example

[0045] like Figure 1 As shown, this embodiment provides a method for setting the horizontal section length of shale gas deployment wells based on risk assessment, including:

[0046] Step 1: Obtain geological parameters of the horizontal well deployment area;

[0047] Step 2: Calculate and determine the regional stress state using geostress data;

[0048] Step 3: Calculate the characteristic parameter coefficients based on the geological parameters of the horizontal well deployment area;

[0049] Step 4: Calculate the regional stratigraphic risk coefficient F based on the characteristic parameter coefficients:

[0050] F = Q × [A × S] 地应力 +B×S 夹角 +C×S 地层 +D×S 缝险 +E×S 缝密

[0051] +F×S 缝长 +G×S 矿物 +H×S 含水 ]

[0052] Where F is the formation risk coefficient; Q is the geostress state coefficient, with a value of 1 for strike-slip stress state and 0.8 for non-strike-slip stress state; A, B, C, D, E, F, G, and H are the influence factors of each characteristic parameter coefficient, with values ​​of 0.1 for A, 0.2 for B, 0.1 for C, 0.2 for D, 0.1 for E, 0.1 for F, 0.1 for G, and 0.1 for H.

[0053] Step 5: Based on the risk index standard, calculate the appropriate length L of the horizontal section of the horizontal well in the deployment area. 适 :

[0054]

[0055] Among them, L 标 The standard horizontal section length is determined based on the existing horizontal sections of shale gas wells in the large area, or it can be the length of the main horizontal sections implemented by shale gas wells in the large area.

[0056] The method for setting the horizontal section length of the deployment well disclosed in this embodiment takes into account the deformation of the casing of the shale gas horizontal well caused by formation deformation and sliding. The probability of formation deformation and sliding varies under different geological characteristics. Combined with the regional formation deformation and sliding risk assessment and the regional gas well implementation analysis, the method determines the horizontal section length of the shale gas horizontal well in the region, which is conducive to determining a more reasonable horizontal section length.

[0057] In this embodiment, the regional geological parameters include several aspects: at least in-situ stress parameters, fracture parameters, stratigraphic attitude parameters, clay mineral parameters, and water saturation parameters. Adopting this approach allows for a more comprehensive evaluation of the impact of environmental factors on casing deformation and a more accurate simulation of casing deformation in real-world environments.

[0058] In this embodiment, the regional stress state is determined as follows: combining the triaxial principal stresses, the regional stress state is divided into strike-slip stress state and non-strike-slip stress state; if δ h-max >δ v This is the strike-slip stress state, if δ v >δ h-max This is a non-strike-slip stress state, δ h-max It is the maximum horizontal principal stress, δ v It is the vertical principal stress, and the unit is MPa.

[0059] In this embodiment, when calculating the characteristic parameter coefficients, the geostress parameter S... 地应力 Calculated and determined as follows:

[0060]

[0061] Where, δh-max It is the maximum horizontal principal stress, δ h-min Minimum horizontal principal stress, in MPa.

[0062] In this embodiment, when calculating the characteristic parameter coefficients, the crack maximum horizontal principal stress angle coefficient S is used. 夹角 Determined as follows: When the angle between the crack direction and the maximum horizontal principal stress is between 0° and 30°, S 夹角 The value is 2; the angle between the crack direction and the maximum horizontal principal stress is between 30° and 60°, S 夹角 The value is taken as 1.3; the angle between the crack direction and the maximum horizontal principal stress is between 60° and 90°, S 夹角 The value is 0.7.

[0063] In this embodiment, when calculating the characteristic parameter coefficients, the formation dip angle variation coefficient S is... 地层 Determine using the following method:

[0064]

[0065] Where k is the change angle of the formation dip angle every 30m along the trajectory of the horizontal well in the deployment area; K is the standard value of the formation dip angle change, which is 3, and the unit is ° / 30m.

[0066] In this embodiment, when calculating the characteristic parameter coefficients, the crack risk coefficient S is mainly determined. 缝险 Crack development density coefficient S 缝密 and crack development length coefficient S 缝长 .

[0067] Crack risk coefficient S 缝险 The area where the risk of natural fractures in the target layer reaches the first level is determined using the following method: S 缝险 The value is 2; in areas where the risk of natural fractures in the target layer reaches the second level, S 缝险 The value is 1.3; in areas where the risk of natural fractures in the target layer reaches level three, S 缝险 The value is 0.7, and it gradually decreases from the first level to the third level;

[0068] Crack development density coefficient S 缝密 The following method is used to determine S: When the fracture development density of the target formation is between 0 and 2 fractures / km along the direction of the deployed horizontal well trajectory, S is... 缝密 The value is taken as 0.7; the crack development density is between 2 and 4 cracks / km, S 缝密 The value is 1.3; the crack development density is greater than 4 cracks / km, S 缝密 The value is 2;

[0069] Crack development length coefficient S 缝长The following method was used to determine the average crack length in the deployment area, which ranged from 0 to 2 km. 缝长 The value is taken as 0.7; the average crack length is between 2 and 4 km, S 缝长 The value is 1.3; the average crack length is greater than 4km, S 缝长 The value is 2.

[0070] This embodiment determines the crack risk coefficient S. 缝险 At that time, the risk of natural fractures in the target layer was predicted using geophysical methods, where curvature bodies represent fractures with a risk level of 1, likelihood bodies represent fractures with a risk level of 2, and ant bodies represent fractures with a risk level of 3.

[0071] In this embodiment, the clay mineral abundance coefficient S is determined according to the following method when calculating the characteristic parameter coefficients. 矿物 :

[0072]

[0073] Among them, W 黏土 It is the clay mineral content of the deployment area, W 标 This is the standard value for clay mineral content, taken as 30%, in percentage form.

[0074] In this embodiment, the water saturation coefficient S is determined according to the following method when calculating the characteristic parameter coefficients. 含水 :

[0075]

[0076] in, It refers to the water saturation level of the deployment area. This is the standard value for water saturation, taken as 30%, in percentages (%).

[0077] Based on the information disclosed above, a real-world example will be provided for illustration.

[0078] Case 1

[0079] Taking Block ① of a shale gas development zone as an example, the scheme disclosed in this embodiment is described in detail:

[0080] (1) Obtain the geological parameters of ① the area. The specific parameters are shown in Table 1.

[0081]

[0082] (2) ① δ of the community h-max >δ v , which is the maximum principal stress, belongs to the strike-slip stress state.

[0083] (3) Based on the geological parameters of the area in ①, calculate the characteristic parameter coefficients, where:

[0084] 1) Substitute the maximum and minimum horizontal principal stress values ​​of cell ① into the formula to calculate the result.

[0085]

[0086] 2) ① The angle between the direction of the crack in the residential area and the direction of the maximum horizontal principal stress is 40°, which is between 30° and 60°. 夹角 The value is 1.3.

[0087] 3) Substitute the change in formation dip angle every 30m along the trajectory of the deployed horizontal well in area ① into the formula to calculate the result.

[0088]

[0089] 4) ① The prediction results for natural cracks in the community are mainly based on likelihood, with a medium risk, S 缝险 The value is 1.3.

[0090] 5) ① Along the trajectory of the deployed horizontal wells, the fracture development density at the target stratum is 1.5 fractures / km, ranging from 0 to 2 fractures / km. 缝密 The value is 0.7.

[0091] 6) ① The average length of cracks in the deployment area of ​​the community is 2.5km, ranging from 2 to 4km, S 缝密 The value is 1.3.

[0092] 7) Substitute the clay mineral content of plot ① into the formula to calculate the result.

[0093]

[0094] 8) Substitute the water saturation of plot ① into the formula to calculate the result.

[0095]

[0096] (4) Substitute the characteristic parameter coefficients of the plot into the formula for calculating the formation risk coefficient:

[0097] F=1×[0.1×1.01+0.2×1.3+0.1×0.444+0.2×1.3+0.1

[0098] [×0.7+0.1×1.3+0.1×1.17+0.1×1]=1.0824

[0099] (5) Substitute the geological risk coefficient of the ① area into the formula for calculating the appropriate length of the horizontal section:

[0100]

[0101] L标 The length of the horizontal section of the main shale gas well in Block A is 2000m.

[0102] Therefore, based on the geological characteristics analysis, ① the appropriate length of the main horizontal section of the community is 1847m.

[0103] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments under the guidance of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be defined in the claims.

Claims

1. A method for setting the horizontal section length of a shale gas deployment well based on risk assessment, characterized in that, include: Step 1: Obtain geological parameters of the horizontal well deployment area; Step 2: Calculate and determine the regional stress state using geostress data; Step 3: Calculate the characteristic parameter coefficients based on the geological parameters of the horizontal well deployment area; Step 4: Calculate the regional stratigraphic risk coefficient F based on the characteristic parameter coefficients: F=Q×[A×S 地应力 +B×S 夹角 +C×S 地层 +D×S 缝险 +E×S 缝密 +F×S 缝长 +G×S 矿物 +H×S 含水 ] Where F is the formation risk coefficient; Q is the geostress state coefficient, with a value of 1 for strike-slip stress state and 0.8 for non-strike-slip stress state; A, B, C, D, E, F, G, and H are the influence factors of each characteristic parameter coefficient, with values ​​of 0.1 for A, 0.2 for B, 0.1 for C, 0.2 for D, 0.1 for E, 0.1 for F, 0.1 for G, and 0.1 for H. Step 5: Based on the risk index standard, calculate the appropriate length L of the horizontal section of the horizontal well in the deployment area. 适 : Among them, L 标 The standard horizontal section length is determined based on the existing horizontal sections of shale gas wells in the large area, or it can be the length of the main horizontal sections implemented by shale gas wells in the large area.

2. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that: Regional geological parameters include at least in-situ stress parameters, fracture parameters, stratigraphic occurrence parameters, clay mineral parameters, and water saturation parameters.

3. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that, The stress state of the region shall be determined as follows: Based on the triaxial principal stresses, the stress state of the region is divided into strike-slip stress state and non-strike-slip stress state; if δ h-max >δ v This is the strike-slip stress state, if δ v >δ h-max This is a non-strike-slip stress state, δ h-max It is the maximum horizontal principal stress, δ v It is the vertical principal stress.

4. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that, When calculating the characteristic parameter coefficients, the geostress parameter S 地应力 Calculated and determined as follows: Where, δ h-max It is the maximum horizontal principal stress, δ h-min Minimum horizontal principal stress.

5. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that, When calculating the characteristic parameter coefficients, the crack maximum horizontal principal stress angle coefficient S 夹角 Determined as follows: When the angle between the crack direction and the maximum horizontal principal stress is between 0° and 30°, S 夹角 The value is 2; the angle between the crack direction and the maximum horizontal principal stress is between 30° and 60°, S 夹角 The value is taken as 1.3; the angle between the crack direction and the maximum horizontal principal stress is between 60° and 90°, S 夹角 The value is 0.

7.

6. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that, When calculating the characteristic parameter coefficients, the formation dip angle variation coefficient S 地层 Determine using the following method: Where k is the change angle of the formation dip angle every 30m along the trajectory of the deployed horizontal well in the deployment area; K is the standard value of the formation dip angle change, which is 3.

7. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that, When calculating the coefficients of the characteristic parameters: Crack risk factor S 缝险 The area where the risk of natural fractures in the target layer reaches the first level is determined using the following method: S 缝险 The value is 2; in areas where the risk of natural fractures in the target layer reaches the second level, S 缝险 The value is 1.3; In areas where the risk of natural fractures in the target layer reaches level three, S 缝险 The value is 0.7, and it gradually decreases from the first level to the third level; Crack development density coefficient S 缝密 The following method is used to determine S: When the fracture development density of the target formation is between 0 and 2 fractures / km along the direction of the deployed horizontal well trajectory, S is... 缝密 The value is taken as 0.7; the crack development density is between 2 and 4 cracks / km, S 缝密 The value is 1.3; the crack development density is greater than 4 cracks / km, S 缝密 The value is 2; Crack development length coefficient S 缝长 The following method was used to determine the average crack length in the deployment area, which ranged from 0 to 2 km. 缝长 The value is taken as 0.7; the average crack length is between 2 and 4 km, S 缝长 The value is 1.3; the average crack length is greater than 4km, S 缝长 The value is 2.

8. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 7, characterized in that: Geophysical prediction of the risk of natural fractures in the target layer is used, where curvature bodies represent fractures with a risk level of 1, likelihood bodies represent fractures with a risk level of 2, and ant bodies represent fractures with a risk level of 3.

9. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that, When calculating the characteristic parameter coefficients, the clay mineral abundance coefficient S is determined as follows: 矿物 : Among them, W 黏土 It is the clay mineral content of the deployment area, W 标 It is the standard value for clay mineral content, which is 30.

10. The method for setting the horizontal section length of shale gas deployment wells based on risk assessment according to claim 1, characterized in that, When calculating the characteristic parameter coefficients, the water saturation coefficient S is determined as follows: 含水 : in, It refers to the water saturation level of the deployment area. It is the standard value for water saturation, which is 30.

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