Quantitative evaluation method and device for connectivity of stratums between horizontal wells

Abstract

The invention relates to the field of shale gas reservoir horizontal well geological development, in particular to a quantitative evaluation method and device for connectivity of stratums between horizontal wells, and the method comprises the following steps: determining a common drilling geological interval of a first horizontal well and a second horizontal well; calculating a connectivity index between the first horizontal well and the second horizontal well according to the sweep range of the common drilling geological interval; and quantitatively evaluating the inter-well stratum connectivity of the first horizontal well and the second horizontal well according to the connectivity index. According to the method, a fluctuation connectivity index (size index parameters of connectivity of the same layer between two wells) calculation method is developed, and a horizontal well stratum intra-layer connectivity quantitative technology is realized, so that the maximum possibility of inter-well connectivity is provided, a reference basis is provided for a process transformation process, the risk of pressure channeling (even casing deformation) is reduced, and the working efficiency is improved. Quantitative geological parameters can be provided for prevention and treatment of inter-well interference in the shale gas well development process, and the inter-well interference is effectively reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of horizontal well geological development of shale gas reservoirs, and in particular to a method and device for quantitatively evaluating stratum connectivity between horizontal wells. Background Art

[0002] In recent years, with increasing awareness and technological advancements, shale gas has become a new highlight in global oil and gas exploration and development, becoming one of the most important areas of oil and gas exploration and development today. my country boasts abundant shale gas resources, with enormous resource potential and exploration prospects. After more than a decade of exploration and development, my country has achieved significant success in the Silurian Longmaxi Formation shale in southern Sichuan, becoming the world's second-largest shale gas producer and ushering in a period of rapid development for my country's shale gas industry.

[0003] The rapid development of shale gas exploration and development has also brought numerous new problems and challenges. The widespread occurrence of casing deformation, pressure channeling, and inter-well interference in production wells is a major problem during development, severely negatively impacting shale gas development and directly affecting shale gas production growth. Analysis reveals that one of the primary causes of casing deformation, pressure channeling, and inter-well interference is formation connectivity, including vertical connectivity between faults and fractures, as well as connectivity within the formation (intra-layer). This impact is particularly severe in shale formations with well-developed lamellation.

[0004] Existing solutions for evaluating formation connectivity problems are mainly focused on vertical wells, while no solutions for horizontal well formation connectivity problems have been found. Problems with current methods include:

[0005] (1) Interwell comparison is mainly performed between vertical wells. Through interwell stratigraphic comparison, it is easy to determine whether a set of reservoirs are distributed simultaneously in two vertical wells and the difference in distribution position, so as to determine whether the reservoirs are connected. However, it is difficult to determine whether the same set of reservoirs are encountered and connected in two horizontal wells.

[0006] (2) Existing technologies are mostly qualitative, with little quantitative analysis. Multi-well comparisons between vertical wells are primarily based on qualitative identification. Reservoirs with two wells simultaneously are considered connected. Current methods rarely address quantitative evaluation. Summary of the Invention

[0007] The present disclosure aims to solve at least one of the technical problems in the above-mentioned technologies to a certain extent. To this end, a method for quantitatively evaluating the connectivity of formations between horizontal wells is proposed, comprising:

[0008] Determine the geological interval encountered in common by the first horizontal well and the second horizontal well;

[0009] Calculating a connectivity index between the first horizontal well and the second horizontal well according to the sweep range of the common drilled geological interval;

[0010] The connectivity between the first horizontal well and the second horizontal well is quantitatively evaluated according to the connectivity index.

[0011] Preferably, the connectivity index includes: segment-to-segment connectivity index, segment-to-well connectivity index, and well-to-well connectivity index.

[0012] Preferably, the inter-well formation connectivity evaluation between the first horizontal well and the second horizontal well includes: segment-to-segment connectivity evaluation, segment-to-well connectivity evaluation, and well-to-well connectivity evaluation.

[0013] Preferably, the segment-to-segment connectivity index corresponds to a calculation formula including:

[0014] G=(H0 / H N )·S N

[0015] Wherein, G represents the connectivity index between the segments; H0 represents the designed well spacing between the first horizontal well and the second horizontal well; H N represents the actual well spacing between the first horizontal well and the second horizontal well; S N The affected range of the target layer segment in the first horizontal well and the target layer segment in the second horizontal well; N represents the layer segment number.

[0016] Preferably, the segment-well connectivity index corresponds to a calculation formula including:

[0017] G SW =(H0 / H N )·(S N11 +S N12 +…+S N1i )

[0018] Among them, G SW represents the connectivity index between the segment and the well; S N1i It represents the affected range of the target layer segment in the first horizontal well and the i-th layer segment in the second horizontal well.

[0019] Preferably, the well-to-well connectivity index corresponds to a calculation formula including: G WW =(H min / H0)·[(S N11 +S N12 +…+S N1i )+(S N21 +S N22 +…+S N2i )+…+

[0020] (S Nj1 +S Nj2 +…+S Nji )]

[0021] Among them, G WW H represents the well-to-well connectivity index; min Indicates the minimum well spacing between two wells; S Nji It represents the affected range of the i-th layer in the first horizontal well and the j-th layer in the second horizontal well.

[0022] Preferably, the affected range is the fluctuation area enclosed by a quadrilateral constructed with the length of the same small layer section encountered by the first horizontal well and the second horizontal well as the base.

[0023] The present disclosure also provides a shale gas horizontal well formation connectivity logging quantitative evaluation system, comprising:

[0024] A layer determination module, used to determine the geological layer commonly encountered by the first horizontal well and the second horizontal well;

[0025] An index calculation module, configured to calculate a connectivity index between the first horizontal well and the second horizontal well according to the sweep range of the common drilled geological interval;

[0026] A quantitative evaluation module is used to quantitatively evaluate the connectivity between the first horizontal well and the second horizontal well according to the connectivity index.

[0027] The present disclosure also provides an electronic device, including a memory and a processor, wherein the memory stores a computer program or instruction, and when the computer program or instruction is executed by the processor, it is at least used to implement the above method.

[0028] The present disclosure also provides a computer-readable storage medium, in which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, it is at least used to implement the above method.

[0029] Compared with the prior art, the beneficial effects of the present disclosure are: the present disclosure evaluates the intra-layer connectivity of the formation through the distribution of the small layers encountered by the horizontal well trajectory, including the similarities and differences of the geological small layers corresponding to the shortest distance between the two wells, and the position analysis of the same geological small layer encountered between the two wells. At the same time, an innovative calculation method for the fluctuation connectivity index (the size index parameter of the connectivity ability of the same layer between the two wells) is developed, which realizes the quantitative technology of the intra-layer connectivity of the horizontal well formation, and achieves the purpose of quantitatively characterizing the connectivity of the formation between wells on the basis of considering the influence of different well spacings and different reservoir fluid properties, thereby providing the maximum possibility of inter-well connectivity, providing a reference basis for the process transformation process, reducing the risk of pressure channeling (even casing change), and also providing quantitative geological parameters for the prevention and control of inter-well interference during shale gas well development, effectively reducing inter-well interference, and providing beneficial technical support for the efficient development of shale gas.

[0030] Other features and advantages of the present disclosure will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present disclosure. The purpose and other advantages of the present disclosure can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0031] The technical solution of the present disclosure is further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0033] Figure 1 Schematic diagram of a quantitative evaluation method for horizontal well-to-well formation connectivity given in an embodiment;

[0034] Figure 2 A flow chart of a method for quantitatively evaluating the connectivity of formations between horizontal wells provided in an embodiment;

[0035] Figure 3 A comparative analysis diagram of the sub-layers encountered by horizontal wells and their connectivity is provided in the embodiment;

[0036] Figure 4 Schematic diagram of the method for calculating the connectivity index using the quasi-wave method provided in the embodiment;

[0037] Figure 5 Schematic diagram of a method for calculating the connectivity index between drilled layers provided in an embodiment;

[0038] Figure 6 Schematic diagram of a quantitative evaluation system for horizontal well-to-well formation connectivity given in an embodiment;

[0039] Figure 7A schematic diagram of an electronic device provided in an embodiment;

[0040] Figure 8 A schematic diagram of a computer-readable storage medium according to an embodiment. DETAILED DESCRIPTION

[0041] The development of a quantitative evaluation method for shale gas horizontal well connectivity can quantitatively characterize and evaluate the stratigraphic connectivity between two or more different wells, accurately indicating the connectivity between different wells and providing a technical means for quantitatively evaluating stratigraphic connectivity in shale gas horizontal wells. Production practice has confirmed that the quantitative evaluation method provided in this disclosure can effectively evaluate the connectivity between wells on the same shale gas platform and between adjacent platforms, thereby providing basic data for the scale of fracturing stimulation, minimizing the possibility of inter-well pressure crosstalk (and even casing change), and achieving the goal of efficient development of shale gas horizontal well groups.

[0042] The present disclosure is described below in conjunction with the accompanying drawings. The preferred embodiments described herein are only used to illustrate and explain the present disclosure and are not used to limit the present disclosure.

[0043] Figure 1 The quantitative evaluation method for the connectivity of formations between horizontal wells provided in this disclosure includes:

[0044] S101. Determine a geological interval commonly encountered by the first horizontal well and the second horizontal well;

[0045] S102. Calculating a connectivity index between the first horizontal well and the second horizontal well based on the range of the common drilled geological interval;

[0046] S103. Quantitatively evaluate the connectivity of the formations in the first horizontal well and the second horizontal well according to the connectivity index.

[0047] Figure 2 The quantitative evaluation method for horizontal well-to-well formation connectivity provided in the embodiment of the present disclosure includes the following steps:

[0048] (1) Identification of substrata encountered by horizontal wells and identification of connectivity of specific substrata encountered by horizontal wells

[0049] Fundamentally speaking, the stratigraphic connectivity between horizontal wells is completely consistent with that between vertical wells. As long as it is determined that the layer section encountered by a horizontal well is the same as the formation encountered by another horizontal well, then the two sections of the formation are considered to be connected. Therefore, the identification of the connectivity of the sub-layers encountered by horizontal wells is mainly to determine whether the two wells have encountered the same geological sub-layer. In some embodiments of the present disclosure, the identification of the connectivity of the sub-layers encountered by horizontal wells is first based on a horizontal wellbore drilling formation identification method disclosed in ZL201511009649.0, and the sub-layers encountered by the horizontal wells are finely identified and divided. If both wells have encountered the same geological sub-layer, it is determined that the sub-layer is connected in the two wells. Figure 3 The comparative analysis of sublayers encountered by horizontal wells and their connectivity is shown in the figure. In the figure, A and B represent two horizontal wells. AL31 is a drilled layer (sublayer 3) in horizontal well A and is connected to the same sublayer (sublayer 3) encountered by BL31, BL32, and BL3 in horizontal well B. H11, H12, and H13 respectively represent the distances between the AL31 layer in horizontal well A and BL31, BL32, and BL3 in horizontal well B. Similarly, AL32 is a drilled layer (sublayer 3) in horizontal well A and is connected to the same sublayer (sublayer 3) encountered by BL31, BL32, and BL3 in horizontal well B. H21, H22, and H23 respectively represent the distances between the AL32 layer in horizontal well A and BL31, BL32, and BL3 in horizontal well B.

[0050] (2) Calculation method of connectivity index of small layers encountered by horizontal wells

[0051] First, the definition of the connectivity index G is given. The connectivity index G represents the size index parameter of the corresponding layer connectivity between horizontal wells. It is proportional to the swept range (area) of the corresponding layer and inversely proportional to the swept distance. Its expression is:

[0052] G=(H0 / H N )·S N

[0053] Among them, H0 is the design well spacing between comparison wells, H N is the actual well distance between the comparison layers (N is the small layer number), S N is the affected range (area) of the comparison layer (N is the small layer number); H0 is the drilling design content, H N It can be obtained from the identification results of the small layer encountered by the horizontal well, but the affected range (area) S of the small layer encountered by the horizontal well is difficult to determine.

[0054] In view of the characteristics of shale gas horizontal wells, this paper adopts the pseudo-wave method to calculate the affected range (area). This method is based on the propagation characteristics of waves and believes that the degree of connectivity within the formation can be characterized by the area covered by the maximum distance of the wave front. The connectivity between two horizontal wells is determined by the wave area enclosed by a quadrilateral constructed with the length of the same small layer section encountered by the two wells as the base. The calculation method of the pseudo-wave method connectivity index is as follows: Figure 4 As shown, Figure 4 It can be seen that the closest small layer in the two wells has the largest fluctuation area, and the drilling length (L Ni ) is larger, the fluctuation area is larger, and the connectivity is better (such as Figure 4 Medium L N1 -L N4 On the contrary, the connectivity is poor (such as Figure 4 Medium L N3 -L N6 between small layers).

[0055] Assuming the fluctuation radius R of the well area, using the general form of well connectivity ( Figure 4 Medium L N3 -L N6 Small layer) to deduce the connectivity of two horizontal well sections, such as Figure 5 As shown. According to the definition of connectivity index, L N3 -L N6 The connectivity of the small layer is determined by the fluctuating area enclosed by the trapezoid ABCD, that is, the irregular shape ABGF and the irregular shape CDEH. Figure 5 It can be seen that AB and CD are the known lengths of the drilled layers. At the same time, the positions of points A, B, C, and D can be easily determined based on the drilling depths of the two wells. The lengths of line segments CJ and DI are also known, making it easy to calculate angles θ1, θ2, θ3, and θ4. It is also easy to calculate the areas S of ΔOAF, ΔOBG, ΔO'CH, and ΔO'DE. ΔOAF 、S ΔOBG 、S ΔO'CH 、S ΔO'DE , and the central angles of sectors OFG and O'EH can be obtained, and finally S 扇形OFG 、S 扇形O'EH .

[0056] Therefore, the stratigraphic connectivity between the two horizontal segments can be calculated as G SS =(H0 / H N )·(S ΔOAF +S ΔOBG +S ΔO'CH +S ΔO'DE +S 扇形OFG +S 扇形O'EH ).

[0057] (3) Quantitative evaluation of horizontal well connectivity

[0058] Horizontal well connectivity includes three forms: between sections, between sections and wells, and between wells.

[0059] a. Segment-to-segment connectivity index G SS

[0060] The connectivity index between segments refers to the connectivity index between a specific sub-layer segment drilled in horizontal well A and a specific sub-layer segment drilled in horizontal well B, which can be calculated using the calculation formula of G derived above.

[0061] b. Connectivity index G between segments and wells SW

[0062] The connectivity index between sections and wells refers to the connectivity index of a certain section (N1) of well A to all sections of the same layer in well B, that is, the sum of the connectivity indices between section N1 of well A and the sections drilled in the same layer in well B. The corresponding calculation formula is:

[0063] G SW =(H0 / H N )·(S N11 +S N12 +…+S N1i )

[0064] Among them, G SW represents the connectivity index between the target interval in the first horizontal well and all intervals in the second horizontal well; S N1i It represents the affected range of the target layer (Nth layer) in the first horizontal well and the i-th layer in the second horizontal well (N represents the small layer number).

[0065] c. Connectivity index G between wells WW

[0066] Well-to-well connectivity refers to the connectivity index of all drilled sections of a certain layer in well A to all drilled sections of the same layer in well B, that is, the sum of the connectivity indices between all drilled sections of N small layers drilled by well A and all drilled sections of N small layers drilled by well B. The corresponding formula is:

[0067] G WW =(H min / H0)·[(S N11 +S N12 +…+S N1i )+(S N21 +S N22 +…+S N2i )

[0068] +…+(S Nj1 +S Nj2 +…+S Nji)]

[0069] Among them, G WW represents the connectivity index between the first horizontal well and the second horizontal well; H min Indicates the minimum well spacing between two wells; S Nji It represents the affected range of the i-th layer in the first horizontal well and the j-th layer in the second horizontal well.

[0070] According to some embodiments of the present disclosure, after quantitatively calculating the connectivity index between segments, a comprehensive evaluation and classification of connectivity can be performed. Figure 1 Connectivity index and evaluation results of the 3# layer encountered in the two wells:

[0071] Table 1

[0072]

[0073] The table indicates that between sections, the AL of horizontal well A 31 BL with B horizontal well 31 The connectivity index of the segment is the largest, the connectivity is the best, and the evaluation result is Class I connectivity. 31 The connectivity index with the 3# layer of horizontal well B is AL 31 With BL 31 BL 32 BL 31 The sum of the segment connectivity index is 6122m 2 The connectivity index of the 3# layer between horizontal well A and horizontal well B is the sum of the connectivity indices of all 3# layers, which is 11451m 2 .

[0074] Based on the same inventive concept, Figure 6 As shown, the present disclosure also provides a shale gas horizontal well formation connectivity logging quantitative evaluation system, including: a layer determination module 201, used to determine the common drilling geological layer segment of the first horizontal well and the second horizontal well; an index calculation module 202, used to calculate the connectivity index between the first horizontal well and the second horizontal well according to the scope of the common drilling geological layer segment; a quantitative evaluation module 203, used to quantitatively evaluate the formation connectivity in the first horizontal well and the second horizontal well according to the connectivity index.

[0075] like Figure 7 As shown, the present disclosure provides an electronic device 1000, which includes a memory 1002 and a processor 1001. The memory 1002 stores a computer program or instruction. When the computer program or instruction is executed by the processor 1001, it is at least used to implement the above method. Figure 8As shown, the present disclosure provides a computer-readable storage medium 1100 , in which a computer program or instruction is stored. When the computer program or instruction is executed by a processor, it is at least used to implement the above method.

[0076] The working principle and beneficial effects of the above technical scheme: The present invention aims to evaluate the intra-layer connectivity of the formation through the adjacent or similar logging data in the horizontal well group in shale gas development, and the distribution of the small layers encountered by the horizontal well trajectory, including the similarities and differences of the geological small layers corresponding to the shortest distance between the two wells, and the position analysis of the same geological small layer encountered between the two wells. At the same time, an innovative calculation method for the fluctuation connectivity index (the size index parameter of the connectivity ability of the same layer between two wells) is developed to realize the quantitative technology of the intra-layer connectivity of the horizontal well formation, and on the basis of considering the influence of different well spacings and different reservoir fluid properties, the purpose of quantitatively characterizing the connectivity of the formations between wells is achieved, thereby providing the maximum possibility of inter-well connectivity, providing a reference basis for the process transformation process, reducing the risk of pressure channeling (even casing change), and also providing quantitative geological parameters for the prevention and control of inter-well interference during shale gas well development, effectively reducing inter-well interference, and providing beneficial technical support for the efficient development of shale gas.

[0077] It is obvious that those skilled in the art may make various changes and modifications to the present disclosure without departing from the spirit and scope of the present disclosure. Thus, if such changes and modifications of the present disclosure fall within the scope of the claims of the present disclosure and their equivalents, the present disclosure is intended to include such changes and modifications.

Claims

1. A method for quantitatively evaluating the connectivity of formations between horizontal wells, characterized in that: include: Determine the geological interval encountered in common by the first horizontal well and the second horizontal well; Calculating a connectivity index between the first horizontal well and the second horizontal well according to the sweep range of the common drilled geological interval; The connectivity between the first horizontal well and the second horizontal well is quantitatively evaluated according to the connectivity index.

2. The method for quantitatively evaluating the connectivity of formations between horizontal wells according to claim 1, wherein: The connectivity index includes: segment-to-segment connectivity index, segment-to-well connectivity index, and well-to-well connectivity index.

3. The method for quantitatively evaluating the connectivity of formations between horizontal wells according to claim 2, wherein: The inter-well formation connectivity evaluation between the first horizontal well and the second horizontal well includes: segment-to-segment connectivity evaluation, segment-to-well connectivity evaluation, and well-to-well connectivity evaluation.

4. The method for quantitatively evaluating the connectivity of formations between horizontal wells according to claim 2, wherein: The segment-to-segment connectivity index corresponds to a calculation formula including: G=(H0 / H N )·S N Wherein, G represents the connectivity index between the segments; H0 represents the designed well spacing between the first horizontal well and the second horizontal well; H N represents the actual well spacing between the first horizontal well and the second horizontal well; S N The affected range of the target layer segment in the first horizontal well and the target layer segment in the second horizontal well; N represents the layer segment number.

5. The method for quantitatively evaluating the connectivity of formations between horizontal wells according to claim 4, wherein: The calculation formula for the segment-well connectivity index includes: G SW =(H0 / H N )·(S N11 +S N12 +…+S N1i ) Among them, G SW represents the connectivity index between the segment and the well; S N1i It represents the affected range of the target layer segment in the first horizontal well and the i-th layer segment in the second horizontal well.

6. The method for quantitatively evaluating the connectivity of formations between horizontal wells according to claim 5, wherein: The calculation formula for the well-to-well connectivity index includes: G WW =(H min / H0)·[(S N11 +S N12 +…+S N1i )+(S N21 +S N22 +…+S N2i )+…+(S Nj1 +S Nj2 +…+S Nji )] Among them, G WW H represents the well-to-well connectivity index; min Indicates the minimum well spacing between two wells; S Nji It represents the affected range of the i-th layer in the first horizontal well and the j-th layer in the second horizontal well.

7. The method for quantitatively evaluating the connectivity of formations between horizontal wells according to any one of claims 4 to 6, wherein: The affected range is the fluctuation area enclosed by a quadrilateral constructed with the length of the same small layer section encountered by the first horizontal well and the second horizontal well as the base.

8. A shale gas horizontal well formation connectivity logging quantitative evaluation system, characterized in that: include: A layer determination module, used to determine the geological layer commonly encountered by the first horizontal well and the second horizontal well; An index calculation module, configured to calculate a connectivity index between the first horizontal well and the second horizontal well according to the sweep range of the common drilled geological interval; A quantitative evaluation module is used to quantitatively evaluate the connectivity between the first horizontal well and the second horizontal well according to the connectivity index.

9. An electronic device comprising a memory and a processor, characterized in that: The memory stores a computer program or instruction, which, when executed by the processor, is used to at least implement the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program or instructions, which, when executed by a processor, are used to at least implement the method according to any one of claims 1 to 7.

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