Well trajectory design method for fracture-vug carbonate reservoir based on seismic response characteristics

Abstract

The present application relates to the technical field of oil and gas field development, in particular to a well trajectory design method for fracture-cave carbonate reservoirs based on seismic response characteristics, comprising: selecting a target area; judging the shape characteristics of seismic response and the combination modes of various seismic responses; establishing different well distribution modes according to the shape characteristics of seismic response and the combination modes; and establishing corresponding well trajectory design methods according to different well distribution modes. Through the well trajectory design method, the problem of low drilling success rate of fracture-cave carbonate reservoirs can be effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field development, in particular to a well trajectory design method for fracture-cave carbonate reservoir based on seismic response characteristics. BACKGROUND

[0002] Carbonate reservoirs occupy an important position in the world, and its oil and gas reserves account for about 50% of the total world oil and gas reserves, and its oil and gas production accounts for more than 60% of the total world oil and gas production. Fracture-cave carbonate reservoir is the main type of carbonate reservoir, and its reservoir types are diverse, including: pore type, cave type, fracture type, fracture-pore type, fracture-cave type and fracture-cave type. Different types of reservoirs have great differences in development location, scale and distribution characteristics, and the reservoirs have poor continuity, rapid change, strong heterogeneity and complex seismic response characteristics. At present, the characterization of domestic fracture-cave carbonate reservoir is mainly qualitative or semi-quantitative, and it is difficult to accurately depict the location, scale and spatial distribution of fracture-cave carbonate reservoir dominated by small-scale fracture-cave bodies, which makes it difficult to select well placement targets, design horizontal well trajectories, and drill wells with low success rate.

[0003] Through technical research, the current method for designing well trajectory of fracture-cave carbonate reservoir is mainly to arrange and design horizontal wells in the reservoir. Domestic and foreign experts and scholars have mostly analyzed and demonstrated the factors such as horizontal well location, horizontal section length and horizontal well azimuth. In the prior art, a Chinese patent for invention with publication number CN101936165A is proposed, and the technical solution disclosed in the patent document is as follows: upper and lower isochronous surfaces are selected near the time when the Caledonian tectonic movement ends and the Hercynian tectonic movement begins, the paleogeomorphology is reflected by the contour map as high in the west and low in the east, local development of residual hills and depressions, seismic data is collected, the small-amplitude structural form and evolution process are determined by inversion of profile and interwell seismic data, carbonate reservoir sedimentary subfacies and microfacies types are divided, favorable sedimentary microfacies are divided, the production of existing production wells and pressure measurement data are used to determine the reservoir connectivity of each well area, and the favorable area of well placement is divided and the well placement position is arranged in the area where the reservoir thickness is greater than 20m.

[0004] In the prior art, a Chinese patent for invention with publication number CN102042010A is proposed, and the technical solution disclosed in the patent document is as follows: a method for determining the development location of carbonate fracture-cave reservoir, which accurately predicts the development location of fracture-cave reservoir to guide the design of horizontal well trajectory, ensures that the horizontal well trajectory is at the top of the carbonate fracture-cave reservoir ±10m, avoids complex well conditions during drilling process, and achieves the purpose of efficient exploration and development.

[0005] In the prior art, a patent application file with the application number CN201710359995.4 is proposed, and the technical solution disclosed in the patent application file is as follows: a karst carbonate reservoir well arrangement method, the steps of the karst carbonate reservoir well arrangement method are as follows: (1) selecting an Ordovician karst reservoir as a well arrangement object; (2) extracting and screening a plurality of parameters sensitive to the karst carbonate reservoir response; (3) predicting the crack development density generated by multiple tectonic movements through strain analysis technology; (4) drawing an original Ordovician karst carbonate rock paleogeomorphic map; (5) determining the reservoir thickness and spatial distribution form of different lithologic sections of the Ordovician carbonate rock to determine a reasonable evaluation index, and the karst reservoir is consistent in a development zone through a plurality of information reflection; (6) selecting a favorable area with a high evaluation index to deploy a well site, effectively solving the problem of serious heterogeneity of the reservoir, providing a reliable basis for well site arrangement, and the well arrangement method is reasonable.

[0006] The above-mentioned patent represents the existing carbonate reservoir well trajectory design method, which mainly determines the position of the reservoir development and designs the horizontal well trajectory. Due to the poor continuity, rapid change, strong heterogeneity, complex seismic response characteristics of the reservoir, and various spatial combination characteristics of the fracture-cave type carbonate reservoir, the existing well trajectory design method for high-quality reservoirs is prone to cause serious drilling loss or emptying, and the drilling is completed in advance, which cannot achieve the purpose of drilling geological design, the drilling success rate is low, and the development effect is poor. SUMMARY

[0007] To solve the above technical problems, the present application proposes a fracture-cave type carbonate reservoir well trajectory design method based on seismic response characteristics, which can effectively solve the problem of low drilling success rate of the fracture-cave type carbonate reservoir.

[0008] The present application is realized by adopting the following technical solutions:

[0009] The fracture-cave type carbonate reservoir well trajectory design method based on seismic response characteristics comprises the following steps:

[0010] S1. Selecting a target area;

[0011] S2. Judging the shape characteristics of the seismic response and the combination mode of various seismic responses;

[0012] S3. Establishing different well arrangement modes according to the shape characteristics of the seismic response and the combination mode;

[0013] S4. Establishing corresponding well trajectory design methods according to different well arrangement modes.

[0014] Step S1 refers to selecting a target area according to the seismic data plane amplitude attribute.

[0015] Step S1 specifically refers to: according to the planar amplitude attribute of the seismic data, a strong amplitude development area is selected as a target area.

[0016] The morphological characteristics of the seismic response in step S2 include "bead-like" response, "sheet-like" response and weak reflection response.

[0017] The morphological characteristics of the seismic response are obtained by classifying the strong amplitude reflection on the seismic profile of the target area according to the morphology.

[0018] The combination mode of each type of seismic response specifically refers to: according to the characteristics of different karst fracture-cave bodies in different karst areas, the connectivity between each fracture-cave body and the internal structure of the fracture-cave body are analyzed, the fracture-cave body space is combined in three-dimensional space, and the longitudinal and lateral combination modes of each type of seismic response are established.

[0019] The well pattern includes isolated large fracture-cave type reservoir vertical well pattern, bedding multi-fracture-cave type reservoir horizontal well pattern, multi-layer multi-fracture-cave type reservoir high-angle well pattern, bedding hole type + fracture-cave type reservoir horizontal well pattern, and bedding fracture-hole type reservoir horizontal well pattern.

[0020] Step S3 specifically refers to:

[0021] If the morphological characteristics of the seismic response are "bead-like" response, and the lateral and vertical are discontinuous, then the isolated large fracture-cave type reservoir vertical well pattern is established;

[0022] If the morphological characteristics of the seismic response are "bead-like" response, the lateral is continuous with multiple "bead-like" responses, and the vertical is discontinuous, then the bedding multi-fracture-cave type reservoir horizontal well pattern is established;

[0023] If the morphological characteristics of the seismic response are "bead-like" response, multiple "bead-like" responses are continuously distributed in the lateral and vertical directions, then the multi-layer multi-fracture-cave type reservoir high-angle well pattern is established;

[0024] If the morphological characteristics of the seismic response are "bead-like" and "sheet-like" responses, which are continuous in the lateral direction and discontinuous in the vertical direction, then the bedding hole type + fracture-cave type reservoir horizontal well pattern is established;

[0025] If the morphological characteristics of the seismic response are "sheet-like" response or weak reflection response, which are continuous in the lateral direction and discontinuous in the vertical direction, then the bedding fracture-hole type reservoir horizontal well pattern is established.

[0026] Step S4 specifically refers to:

[0027] If it is an isolated large fracture-cave type reservoir vertical well pattern, then a vertical well is deployed, and the well trajectory is drilled from the middle of the reservoir, and the strong drilling is controlled when the leakage or emptying occurs.

[0028] If the horizontal well drilling mode is for the bedding multi-fractured cave type reservoir, a horizontal well is deployed, and the horizontal well trajectory is controlled to pass through from 10m above the top of the reservoir;

[0029] If the high angle well drilling mode is for the multi-layer multi-fractured cave type reservoir, a high angle well is deployed, and the horizontal well trajectory is controlled to pass through from 10m above the top of each fractured cave body obliquely;

[0030] If the horizontal well drilling mode is for the bedding hole type + fractured cave type reservoir, a horizontal well is deployed, and the horizontal well trajectory is controlled to drill into the middle of the hole type reservoir with the seismic "sheet-like" response, and drill into the fractured cave type reservoir with the "bead" response at the end, and when drilling in the fractured cave type reservoir, strong drilling is performed when leakage or emptying occurs.

[0031] If the horizontal well drilling mode is for the bedding fractured hole type reservoir, a horizontal well is deployed, and the horizontal well trajectory is controlled to drill into the middle of the fractured hole type reservoir with the seismic "sheet-like" response.

[0032] When the horizontal well drilling mode is for the bedding multi-fractured cave type reservoir or the high angle well drilling mode is for the multi-layer multi-fractured cave type reservoir, multiple fractured cave bodies can be communicated after acidizing or fracturing.

[0033] Compared with the prior art, the beneficial effects of the present application are as follows:

[0034] 1、The present application fully considers that the fractured hole type carbonate rock reservoir is various in type, greatly different in scale, extremely uneven in spatial distribution, extremely strong in reservoir heterogeneity, and different in seismic response form, therefore, the seismic reflection characteristics of various reservoirs in the target area are classified through the seismic response characteristics of various types of fractured hole type carbonate rock reservoirs. On this basis, a combination mode of various seismic responses is established, and a well trajectory is designed according to the form and combination mode of the seismic response. The present application focuses on the fractured hole type carbonate rock reservoir, finds the development position, scale and spatial distribution of the fractured hole type carbonate rock reservoir, combines with the current drilling engineering technology, uses the spatial combination mode of the fractured cave body, designs a complete set of well site deployment and well trajectory design mode, effectively guides the well site deployment and well trajectory design of the fractured hole type carbonate rock oil and gas reservoir, realizes the geological target of drilling, reduces the engineering difficulty, improves the drilling success rate, improves the single well productivity, and effectively fills the technical gap.

[0035] 2、The well trajectory design method in the present application guides the well site deployment and well trajectory design of the fractured hole type carbonate rock reservoir in Sichuan Basin, Tarim Basin and Ordos Basin, and the drilling success rate is improved from about 30% to about 97%.

[0036] The fractured-vuggy carbonate reservoir has large scale and great exploration and development potential. However, the well site deployment and well trajectory design are difficult due to strong heterogeneity. The present technology has wide application prospect. The present technology can also be applied to the well site deployment and well trajectory design in the fractured-vuggy and fault-controlled carbonate reservoirs abroad, and plays an important role in the exploration and development of the fractured-vuggy carbonate reservoir. BRIEF DESCRIPTION OF DRAWINGS

[0037] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Figure 1 The present application is a flowchart.

[0039] Figure 2 The present application is a well trajectory design mode under different reservoir types. DETAILED DESCRIPTION

[0040] Embodiment 1

[0041] As a basic embodiment of the present application, the present application includes a well trajectory design method for fractured-vuggy carbonate reservoir based on seismic response characteristics, comprising the following steps:

[0042] S1. Selecting a target area.

[0043] S2. Judging the morphological characteristics of seismic response and the combination modes of various seismic responses.

[0044] S3. Establishing different well deployment modes according to the morphological characteristics of seismic response and the combination modes.

[0045] S4. Establishing corresponding well trajectory design methods according to different well deployment modes.

[0046] Embodiment 2

[0047] As a preferred embodiment of the present application, the present application includes a well trajectory design method for fractured-vuggy carbonate reservoir based on seismic response characteristics, comprising the following steps:

[0048] S1. Selecting a target area: selecting a target area according to the planar amplitude attribute of seismic data.

[0049] S2. Judging the morphological characteristics of seismic response and the combination modes of various seismic responses. Specifically, the seismic reflection characteristics of various reservoirs in the target area are classified into "bead-like" response, "sheet-like" response and weak reflection response, etc. On this basis, the longitudinal and lateral combination modes of various seismic responses are established.

[0050] S3. According to the morphological characteristics of the seismic response and the combination mode, different well distribution modes are established, including the isolated large fracture-cave type reservoir vertical well distribution mode, the bedding multi-fracture-cave type reservoir horizontal well distribution mode, the multi-layer multi-fracture-cave type reservoir high angle well distribution mode, the bedding hole type + fracture-cave type reservoir horizontal well distribution mode and the bedding fracture-hole type reservoir horizontal well distribution mode.

[0051] S4. According to different well distribution modes, corresponding well trajectory design methods are established.

[0052] Embodiment 3

[0053] As another preferred embodiment of the present application, the present application comprises a fracture-cave type carbonate reservoir well trajectory design method based on seismic response characteristics, comprising the following steps:

[0054] S1. Selecting a target target area.

[0055] S2. Judging the morphological characteristics of the seismic response and the combination mode of various seismic responses. Among them, the combination mode of the seismic response also refers to the spatial distribution of the fracture-cave body. Among them, the morphological characteristics of the seismic response include "bead-like" response, "sheet-like" response and weak reflection response.

[0056] S3. According to the morphological characteristics of the seismic response and the combination mode, different well distribution modes are established, including the isolated large fracture-cave type reservoir vertical well distribution mode, the bedding multi-fracture-cave type reservoir horizontal well distribution mode, the multi-layer multi-fracture-cave type reservoir high angle well distribution mode, the bedding hole type + fracture-cave type reservoir horizontal well distribution mode and the bedding fracture-hole type reservoir horizontal well distribution mode.

[0057] S4. According to different well distribution modes, corresponding well trajectory design methods are established. Specifically: if it is the isolated large fracture-cave type reservoir vertical well distribution mode, a vertical well is deployed, and the well trajectory is controlled to drill from the middle of the reservoir, and to drill strongly when leaking or emptying; if it is the bedding multi-fracture-cave type reservoir horizontal well distribution mode, a horizontal well is deployed, and the horizontal well trajectory is controlled to pass through within 10m above the top of the reservoir; if it is the multi-layer multi-fracture-cave type reservoir high angle well distribution mode, a high angle well is deployed, and the horizontal well trajectory is controlled to pass through obliquely within 10m above the top of each fracture-cave body; if it is the bedding hole type + fracture-cave type reservoir horizontal well distribution mode, a horizontal well is deployed, and the horizontal well trajectory is controlled to drill from the middle of the seismic "sheet-like" response hole type reservoir, and to drill into the "bead-like" response fracture-cave type reservoir at the end, and to drill strongly when leaking or emptying in the fracture-cave type reservoir; if it is the bedding fracture-hole type reservoir horizontal well distribution mode, a horizontal well is deployed, and the horizontal well trajectory is controlled to drill from the middle of the seismic "sheet-like" response fracture-hole type reservoir.

[0058] Embodiment 4

[0059] As the best mode of the present application, with reference to the description and drawings Figure 1 The present application comprises a well trajectory design method for fracture-vug carbonate reservoirs based on seismic response characteristics, comprising the following steps:

[0060] S1. Selecting a preferred target area: selecting a strong amplitude development area as the target area according to the planar amplitude attribute of seismic data.

[0061] S2. Judging the morphological characteristics of seismic response and the combination mode of various types of seismic response.

[0062] The morphological characteristics of seismic response specifically refer to: classifying the strong amplitude reflection on the seismic profile of the target area according to the morphology, which can be divided into "bead-like" response, "sheet-like" response and weak reflection response.

[0063] The combination mode of various types of seismic response specifically refers to: analyzing the connectivity between various karst fracture-vug bodies and the internal structure of the fracture-vug bodies according to the characteristics of different karst fracture-vug bodies in different karst areas, performing spatial combination of the fracture-vug bodies in three-dimensional space, and establishing the longitudinal and lateral combination modes of various types of seismic response to provide spatial combination of the fracture-vug bodies for well deployment.

[0064] S3. Establishing different well deployment modes according to the morphological characteristics and combination mode of seismic response. Specifically:

[0065] If the morphological characteristics of seismic response are "bead-like" response, and the horizontal and vertical directions are discontinuous, this type is an isolated large fracture-cave reservoir, and a straight well deployment mode for isolated large fracture-cave reservoirs is established.

[0066] If the morphological characteristics of seismic response are "bead-like" response, the horizontal direction is continuous with multiple "bead-like" responses, and the vertical direction is discontinuous, this type is a bedding multi-fracture-cave reservoir, and a horizontal well deployment mode for bedding multi-fracture-cave reservoirs is established.

[0067] If the morphological characteristics of seismic response are "bead-like" response, multiple "bead-like" responses are continuously distributed in the horizontal and vertical directions, and are in a "bead-like" oblique column distribution mode. This type is a multi-layer multi-fracture-cave reservoir, and a high-angle well deployment mode for multi-layer multi-fracture-cave reservoirs is established.

[0068] If the morphological characteristics of seismic response are "bead-like" and "sheet-like" responses, which are continuous in the horizontal direction and discontinuous in the vertical direction, this type is a bedding pore + fracture-cave reservoir, and a horizontal well deployment mode for bedding pore + fracture-cave reservoirs is established.

[0069] If the morphological characteristics of seismic response are "sheet-like" response or weak reflection response, which are continuous in the horizontal direction and discontinuous in the vertical direction, this is a bedding developed fracture-pore reservoir, and a horizontal well deployment mode for bedding fracture-pore reservoirs is established.

[0070] S4. According to different well pattern, refer to the description attached Figure 2 , to establish the corresponding well trajectory design method. Specifically:

[0071] If it is a large isolated fracture-cave type reservoir straight well well pattern, then deploy straight well, and control the well trajectory to drill from the middle of the reservoir, and strongly drill when leaking or emptying, and try to increase the drainage area.

[0072] If it is a bedding multi-fracture-cave type reservoir horizontal well well pattern, then deploy horizontal well, and control the horizontal well trajectory to pass through within 10m above the top of the reservoir to avoid serious drilling leakage or emptying. After acidizing or fracturing, multiple fracture-cave bodies can be connected to realize high yield of horizontal well.

[0073] If it is a multi-layer multi-fracture-cave type reservoir high angle well well pattern, then deploy high angle well, and control the horizontal well trajectory to pass through within 10m above the top of each fracture-cave body to avoid serious drilling leakage or emptying. After acidizing or fracturing, multiple fracture-cave bodies can be connected to realize high yield of high angle well.

[0074] If it is a bedding pore type + fracture-cave type reservoir horizontal well well pattern, then deploy horizontal well, and control the horizontal well trajectory to drill from the middle of the "sheet-like" response pore type reservoir, and drill into the "bead-like" response fracture-cave type reservoir at the end. When drilling in the fracture-cave type reservoir, strongly drill when leaking or emptying to try to increase the drainage area.

[0075] If it is a bedding fracture-pore type reservoir horizontal well well pattern, then deploy horizontal well, and control the horizontal well trajectory to drill from the middle of the "sheet-like" response fracture-pore type reservoir to improve the drilling rate of horizontal well in the reservoir.

[0076] This embodiment fully considers the response characteristics of fracture-cave type carbonate reservoir on the earthquake, predicts the development position, scale and distribution of fracture-cave body. On this basis, the combination mode of seismic response of fracture-cave type reservoir and five well patterns are established, which not only realizes the geological target, but also greatly reduces the occurrence of engineering complex situation, and significantly improves the drilling success rate. The method has been widely applied in Taizhong fracture-cave type condensate gas reservoir, Penglaizhuang Dengying group fracture-cave type carbonate gas reservoir in Sichuan, and subsalt carbonate gas reservoir in the right bank of Amu Darya in Turkmenistan, which improves the drilling rate of the above-mentioned reservoirs, realizes single well high yield and stable yield, and saves a lot of funds.

[0077] In summary, after reading the present invention document, according to the technical solution and technical concept of the present invention, various corresponding transformation schemes made by ordinary skilled in the art without creative mental effort are within the scope of the present invention.

Claims

1. A method for designing a well trajectory in a fractured-vuggy carbonate reservoir based on seismic response characteristics, characterized in that: The method comprises the following steps: S1. selecting a target target area; S2. judging the shape characteristics of the seismic response and the combination mode of various types of seismic responses; wherein the shape characteristics of the seismic response include "bead-like" response, "sheet-like" response and weak reflection response; the judgment of the combination mode of various types of seismic responses specifically refers to: according to the characteristics of different karst fracture-cave bodies in different karst areas, analyzing the connectivity between the fracture-cave bodies and the internal structure of the fracture-cave bodies, carrying out the spatial grouping of the fracture-cave bodies in three-dimensional space, and establishing the longitudinal and lateral combination mode of various types of seismic responses; S3. According to the shape characteristics of the seismic response and the combination mode of various types of seismic responses, different well arrangement modes are established; the well arrangement mode includes in-seam hole type + fracture-cave type reservoir horizontal well arrangement mode and in-seam fracture-hole type reservoir horizontal well arrangement mode; if the shape characteristics of the seismic response are "bead-like" response and "sheet-like" response, which are continuous in the lateral direction and discontinuous in the vertical direction, the in-seam hole type + fracture-cave type reservoir horizontal well arrangement mode is established; if the shape characteristics of the seismic response are "sheet-like" response or weak reflection response, which are continuous in the lateral direction and discontinuous in the vertical direction, the in-seam fracture-hole type reservoir horizontal well arrangement mode is established; S4. According to different well arrangement modes, corresponding well trajectory design methods are established.

2. The method for seismic response feature based fracture-cave carbonate reservoir well trajectory design according to claim 1, characterized in that: Step S1 refers to selecting a target target area according to the plane amplitude attribute of seismic data.

3. The method for seismic response feature based fracture-cave carbonate reservoir well trajectory design according to claim 2, characterized in that: Step S1 specifically refers to selecting a strong amplitude development area as a target target area according to the plane amplitude attribute of seismic data.

4. The method for seismic response feature based fracture-cave carbonate reservoir well trajectory design according to claim 1, characterized in that: The shape characteristics of the seismic response are classified according to the shape of the strong amplitude reflection on the seismic profile of the target target area.

5. The method for seismic response feature based fracture-cave carbonate reservoir well trajectory design according to claim 1, characterized in that: The well arrangement mode also includes isolated large fracture-cave type reservoir vertical well arrangement mode, in-seam multi-fracture-cave type reservoir horizontal well arrangement mode and multi-layer multi-fracture-cave type reservoir high-angle well arrangement mode.

6. The method for seismic response feature based fracture-cave carbonate reservoir well trajectory design according to claim 5, characterized in that: Step S3 further includes: If the shape characteristics of the seismic response are "bead-like" response and the lateral and vertical directions are discontinuous, the isolated large fracture-cave type reservoir vertical well arrangement mode is established; if the shape characteristics of the seismic response are "bead-like" response, the lateral direction is continuous with multiple "bead-like" responses, and the vertical direction is discontinuous, the in-seam multi-fracture-cave type reservoir horizontal well arrangement mode is established; if the shape characteristics of the seismic response are "bead-like" response, multiple "bead-like" responses are continuously distributed in the lateral and vertical directions, the multi-layer multi-fracture-cave type reservoir high-angle well arrangement mode is established.

7. The method for seismic response feature based fracture-cave carbonate reservoir well trajectory design according to claim 6, characterized in that: Step S4 specifically refers to: if it is isolated large fracture-cavity type reservoir straight well well pattern, then deploy straight well, and control well trajectory from the middle of the reservoir, strong drilling when leakage or empty; if it is along the layer multi-fracture cavity type reservoir horizontal well well pattern, then deploy horizontal well, and control horizontal well trajectory from the top of the reservoir within 10m; if it is multi-layer multi-fracture cavity type reservoir high angle deviated well well pattern, then deploy high angle deviated well, and control horizontal well trajectory from the top of each fracture-cavity within 10m; if it is along the layer hole type + fracture-cavity type reservoir horizontal well well pattern, then deploy horizontal well, and control horizontal well trajectory from the middle of the hole type reservoir of seismic "sheet" response, drill into the "bead" response of fracture-cavity type reservoir at the end, and strong drilling when leakage or empty in the fracture-cavity type reservoir; if it is along the layer fracture-hole type reservoir horizontal well well pattern, then deploy horizontal well, and control horizontal well trajectory from the middle of the fracture-hole type reservoir of seismic "sheet" response.

8. The method for seismic response feature based fracture-cave carbonate reservoir well trajectory design according to claim 7, characterized in that: When it is along the layer multi-fracture cavity type reservoir horizontal well well pattern or multi-layer multi-fracture cavity type reservoir high angle deviated well well pattern, acidizing or fracturing can communicate multiple fracture-cavity.

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