Well diameter logging instrument, data acquisition method and stratum ground stress determination method

Abstract

The invention belongs to the technical field of well logging in oil exploration, and particularly relates to a well diameter logging instrument, a data acquisition method and a stratum ground stress determination method. The hole diameter logging instrument comprises a hole diameter logging instrument body and a well deviation instrument connected with the hole diameter logging instrument body, and is characterized in that the hole diameter logging instrument body comprises a shell, and four measuring arms are arranged on the shell; and the four measuring arms are distributed along the circumference of the shell in an array manner. One measuring arm is additionally arranged on the basis of an original three-arm hole diameter logging instrument, the four measuring arms are distributed in a cross shape, the direction measured by a well deviation instrument is consistent with the direction of one measuring arm of the hole diameter logging instrument during data collection, two pieces of independent hole diameter data in the vertical direction can be provided, and then the maximum hole diameter data and the minimum hole diameter data are determined; and the borehole shape is determined, so that the crustal stress direction can be determined.

Description

Technical Field

[0001] The present invention belongs to the technical field of well logging in oil exploration, and specifically relates to a borehole diameter logging instrument, a data acquisition method, and a formation in-situ stress determination method. Background Art

[0002] The Tarim Basin is the carbonate rock fracture-vug and fault-controlled reservoir basin with the largest reserves in China. Its oil reservoirs are affected by karst, tectonics, etc., and important storage spaces such as caves, fractures, and faults are developed. One of the important ways to obtain production capacity from ancient carbonate reservoirs is acid fracturing, and the determination of the stress direction is one of the key information for acid fracturing design.

[0003] In-situ stress is a mechanical parameter that causes response deformation inside the medium when the solid medium of the earth is affected by gravity, various earth tectonic dynamics, astronomical dynamics, and additional actions. Due to the complex and variable causes and influencing factors of in-situ stress, it is difficult to calculate the magnitude and direction of in-situ stress by means of mathematical calculation and theoretical derivation. Therefore, measurement methods are often used. The direct measurement method can only obtain the stress at a certain point of the lithology, and the measured data is limited. Therefore, another method for obtaining in-situ stress data has emerged, such as calculating in-situ stress using well logging data. In the Shunbei Oilfield, due to the deep burial of the reservoir and the bottom hole temperature reaching above 180 degrees, the use cost of imaging logging and its application under ultra-deep and ultra-high temperature conditions are greatly limited. Therefore, it is difficult to obtain well logging data and thus unable to accurately determine the in-situ stress orientation.

[0004] The prior art CN115563822A discloses a comprehensive evaluation method for in-situ stress anisotropy with multiple factors. Through the calculation of rock mechanics parameters and in-situ stress logging, combined with rock triaxial mechanical experiments, the mechanical properties of ultra-deep reservoirs, the magnitude and direction of present-day in-situ stress are determined. Using the finite element method, a continuous geological mechanics model of the entire formation system in the study area is established, and the three-dimensional distribution of present-day in-situ stress is accurately predicted; the in-situ stress anisotropy index is used to reveal the mechanism of present-day in-situ stress anisotropy from aspects such as tectonic location, burial depth, fracture, stress-fracture angle, and rock heterogeneity. Although the accuracy of determining the in-situ stress direction by this evaluation method is high, it requires the use of electrical imaging data, and the acquisition cost is still relatively high.

[0005] Therefore, there is an urgent need to provide a borehole diameter logging instrument, a data acquisition method, and a formation in-situ stress determination method to determine the wellbore of the well logging and the direction of the maximum in-situ stress without the need for electrical imaging data. Summary of the Invention

[0006] To solve the above technical problems existing in the prior art, the present invention provides a caliper logging instrument, a data acquisition method, and a formation in-situ stress determination method. The aim is to attach azimuth information to the caliper data by modifying the connection method between the four-arm caliper instrument and the well inclination instrument, and to write the ground control software for the combined recording of the caliper and well inclination instruments, so as to determine and interpret the in-situ stress direction of carbonate reservoirs, make up for the lack and insufficiency of stress direction data in ultra-deep carbonate reservoirs, and provide technical support for reservoir stimulation, completion plan formulation, and reservoir geological research.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A caliper logging instrument includes a caliper logging tool and a well inclination instrument connected to the caliper logging tool. The caliper logging tool includes a housing, and four measuring arms are arranged on the housing; the four measuring arms are circumferentially arrayed along the housing.

[0009] Further, the azimuth of the well inclination instrument is kept consistent with the azimuth of one of the measuring arms.

[0010] Further, the included angle between adjacent measuring arms is 90°.

[0011] The present invention also provides a data acquisition method, which uses the above caliper logging instrument and includes:

[0012] S1. Fix the caliper logging instrument.

[0013] S2. Compile the ground computer acquisition control software module so that it can record the azimuth data of the measuring arm consistent with the azimuth of the well inclination instrument.

[0014] S3. Use the caliper logging instrument to collect multiple groups of target logging data.

[0015] Further, step S3 specifically includes: placing the caliper logging instrument at the bottom of the well, and then lifting the caliper logging instrument upward, and collecting multiple groups of target logging data during the lifting process.

[0016] Even further, use a cable to place the caliper logging instrument at the bottom of the well, and then lift the caliper logging instrument upward by lifting the cable upward.

[0017] Even further, during the lifting process, use the caliper logging tool to collect caliper data, use the well inclination instrument to collect azimuth data, establish the correlation between the caliper data and the azimuth data of each measuring point, and obtain multiple groups of target logging data.

[0018] Even further, the target logging data includes natural gamma curve, resistivity curve, acoustic wave, neutron curve, caliper curve, caliper, and azimuth data.

[0019] The present invention also provides a method for determining in-situ stress of a formation, using the data collected by the above data acquisition method, including: analyzing multiple groups of target logging data to obtain the borehole shape and the maximum in-situ stress direction of the current logging.

[0020] Further, the analysis specifically includes:

[0021] A1. Determine the stress concentration section according to the natural gamma curve, resistivity curve, acoustic wave, and neutron curve;

[0022] A2. Within the stress concentration section, select the enlarged hole section according to the collected caliper curve;

[0023] A3. Draw a caliper - azimuth cross - plot according to the caliper and azimuth data, and determine the azimuth of the enlarged hole section according to the caliper - azimuth cross - plot; within the enlarged hole section, determine the borehole shape according to the caliper data, and determine the minimum in-situ stress direction according to the borehole shape and azimuth data. The direction perpendicular to the minimum in-situ stress direction is the maximum in-situ stress direction.

[0024] Further, in step A2, within the stress concentration section, select the section with a caliper value greater than the bit diameter as the enlarged hole section according to the collected caliper curve.

[0025] Further, in step A3, draw a caliper - azimuth cross - plot in the XY plane. On the cross - plot, the scale value corresponding to the data point of the enlarged hole section on the azimuth axis is the azimuth of the enlarged hole section.

[0026] Further, in step A3, within the enlarged hole section, determine the elliptical borehole shape according to the caliper data in two perpendicular directions. The major axis azimuth of the elliptical borehole corresponds to the minimum in-situ stress direction.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The caliper logging instrument provided by the present invention adds a measuring arm on the basis of the original three - arm caliper logging tool, and the four measuring arms are distributed in a cross shape. When collecting data, the azimuth measured by the inclinometer is made consistent with the azimuth of one of the measuring arms of the caliper logging instrument. Compared with the three - arm caliper logging tool that can only measure the average caliper and cannot provide independent caliper data in two perpendicular X and Y directions, the caliper logging instrument of the present invention can provide independent caliper data in two perpendicular directions, thereby determining the maximum and minimum caliper data, determining the borehole shape, and further facilitating the determination of the in-situ stress direction.

[0029] The method for determining formation in-situ stress provided by the present invention, based on the caliper logging instrument provided by the present invention, utilizes the collected caliper data and azimuth data to determine the elliptical borehole shape according to the caliper data in two perpendicular directions. The major axis azimuth of the elliptical borehole corresponds to the minimum in-situ stress direction, and the direction perpendicular to the minimum in-situ stress direction is the maximum in-situ stress direction. It improves the evaluation ability of the in-situ stress direction of the reservoir, makes up for the problem that the in-situ stress direction cannot be determined due to the lack of imaging logging data in a large number of wells, provides important technical support for the acid fracturing of fractured reservoirs in the later stage and the borehole conditions of the completion plan, and makes the completion plan more targeted. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the caliper logging instrument of the present invention.

[0031] Figure 2 It is a flowchart of the data acquisition method of the present invention.

[0032] Figure 3 It is a flowchart of the method for determining formation in-situ stress of the present invention.

[0033] Figure 4 It is a schematic diagram for determining the in-situ stress direction in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The technical solutions of the present invention will be clearly described below in conjunction with the description of the drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps described in these embodiments and numerical expressions should not be construed as limiting the scope of the present invention.

[0036] The following description of the exemplary embodiments is merely illustrative and in no way restricts the present invention and its application or use. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail here, but when applicable, these technologies, methods, and devices should be regarded as part of this specification.

[0037] Embodiment 1

[0038] The present invention provides a caliper logging instrument, as Figure 1As shown in the figure, it includes a caliper logging tool 1 and an inclinometer 2 connected to the caliper logging tool. The caliper logging tool 1 includes a housing, and four measuring arms 3 are arranged on the housing; the four measuring arms 3 are arranged in a circumferential array along the housing. Among them, the caliper logging tool 1 is an improvement based on the existing three-arm caliper logging tool. The existing three-arm caliper logging tool is a 5700 series logging tool. One measuring arm 3 is added to the 5700 series logging tool, and the four measuring arms 3 are distributed in a cross shape, that is, the included angle between adjacent measuring arms 3 is 90°. Furthermore, two sets of opposite measuring arms 3 are used to measure the maximum diameter and the minimum diameter of the wellbore.

[0039] Connect the caliper logging tool 1 and the inclinometer 2 using the existing connection method. For example, insert one end of the housing of the caliper logging tool 1 into one end of the inclinometer 2, and use a positioning pin to connect the caliper logging tool 1 and the inclinometer 2.

[0040] The azimuth of the inclinometer is kept consistent with the azimuth of one of the measuring arms 3. Among them, the inclinometer 2 uses the existing inclinometer, so its specific structure will not be described in detail here.

[0041] In the present invention, one measuring arm is added on the basis of the original three-arm caliper logging tool, and the four measuring arms are distributed in a cross shape. When collecting data, the azimuth measured by the inclinometer is made consistent with the azimuth of one of the measuring arms of the caliper logging tool. Compared with the three-arm caliper logging tool that can only measure the average well diameter and cannot provide independent well diameter data in the X and Y vertical directions, the caliper logging instrument of the present invention can provide independent well diameter data in two vertical directions, and then determine the maximum and minimum well diameter data, determine the wellbore shape, and thus facilitate the determination of the in-situ stress direction.

[0042] Embodiment 2

[0043] The present invention also provides a data acquisition method, which uses the caliper logging instrument provided in Embodiment 1, as Figure 2 shown, including:

[0044] S1. Fix the caliper logging instrument; and ensure that the azimuth of the inclinometer is kept consistent with the azimuth of one of the measuring arms, and set the measuring arm consistent with the azimuth of the inclinometer as the No. 1 arm.

[0045] S2. Compile a ground computer acquisition control software module so that it can record the azimuth data of the measuring arm consistent with the azimuth of the inclinometer; since the No. 1 arm is consistent with the azimuth of the inclinometer, the azimuth data collected by the inclinometer is the same as the azimuth of the No. 1 arm, and the azimuths of other measuring arms can be calculated through the azimuth of the No. 1 arm.

[0046] S3. Use a caliper logging tool to collect multiple sets of target logging data. Preferably, place the caliper logging tool at the bottom of the well using a cable, and then lift the cable upward to lift the caliper logging tool upward. During the lifting process, use the caliper logging tool to collect caliper data and use an inclinometer to collect azimuth data, and establish the association between the caliper data and azimuth data at each measurement point to obtain multiple sets of target logging data.

[0047] The target logging data includes natural gamma curve, resistivity curve, acoustic wave, neutron curve, caliper curve, caliper, and azimuth data.

[0048] Embodiment III

[0049] The present invention also provides a method for determining formation in-situ stress. Using the data collected by the data acquisition method provided in Embodiment II, as Figure 3 shown, it includes: analyzing multiple sets of target logging data according to a pre-trained network model to obtain the wellbore shape and the maximum in-situ stress direction of the current logging.

[0050] The analysis specifically includes:

[0051] A1. Determine the stress concentration section according to the natural gamma curve, resistivity curve, acoustic wave, and neutron curve;

[0052] A2. In the stress concentration section, select the enlarged diameter well section according to the collected caliper curve; specifically, in the stress concentration section, select the well section with a caliper value greater than the bit diameter as the enlarged diameter well section according to the collected caliper curve.

[0053] A3. Draw a caliper-azimuth crossplot according to the caliper and azimuth data, and determine the azimuth of the enlarged diameter well section according to the caliper-azimuth crossplot; determine the wellbore shape according to the caliper data in the enlarged diameter well section, and determine the minimum in-situ stress direction according to the wellbore shape and azimuth data. The direction perpendicular to the minimum in-situ stress direction is the maximum in-situ stress direction.

[0054] Specifically: Draw a caliper-azimuth crossplot in the XY plane. On the crossplot, the scale value on the azimuth axis corresponding to the data point of the enlarged diameter well section is the azimuth of the enlarged diameter well section. In the enlarged diameter well section, determine the elliptical wellbore shape according to the caliper data in two perpendicular directions. The major axis azimuth of the elliptical wellbore corresponds to the minimum in-situ stress direction, as Figure 4 shown, where the curve with triangular discrete points is the azimuth line, the 2-4 curve represents the caliper curve collected by the 2nd arm - 4th arm (the four measurement arms are numbered in sequence), the 1-3 curve represents the caliper curve collected by the 1st arm - 3rd arm, and the wellbore break section and azimuth can be determined through the two caliper curves. The range delimited by the horizontal dashed line in the figure is the break section.

[0055] The present invention has been applied to ultra-deep carbonate reservoirs in areas such as Tarim, improving the evaluation ability of the in-situ stress direction of ultra-deep carbonate reservoirs in areas such as Tarim, making up for the problem that the in-situ stress direction cannot be determined due to the lack of imaging logging data in a large number of wells, providing important technical support for the acid fracturing transformation of fractured reservoirs and the wellbore conditions of completion programs in the later stage, making the completion program more targeted and generating greater economic benefits.

[0056] The above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A borehole diameter logging instrument, comprising a borehole diameter logging tool and an inclinometer connected to the borehole diameter logging tool, characterized in that, The caliper logging tool includes a housing, and four measuring arms are arranged on the housing; the four measuring arms are arranged in a circumferential array along the housing.

2. The borehole diameter logging instrument according to claim 1, characterized in that, The azimuth of the inclinometer is consistent with the azimuth of one of the measuring arms.

3. The borehole diameter logging instrument according to claim 1, characterized in that, The included angle between adjacent measuring arms is 90°.

4. A data acquisition method, using the borehole diameter logging instrument according to any one of claims 1-3, characterized in that, It includes: S1. Fix the caliper logging tool. S2. Compile a ground computer acquisition control software module so that it can record the azimuth data of the measuring arm consistent with the azimuth of the inclinometer. S3. Use the caliper logging tool to acquire multiple groups of target logging data.

5. The data acquisition method according to claim 4, characterized in that, Step S3 specifically includes: placing the caliper logging tool at the bottom of the well, and then lifting the caliper logging tool upward, and acquiring multiple groups of target logging data during the lifting process.

6. The data acquisition method according to claim 5, characterized in that, Use a cable to place the caliper logging tool at the bottom of the well, and then lift the caliper logging tool upward by lifting the cable upward.

7. The data acquisition method according to claim 6, characterized in that, During the lifting process, use the caliper logging tool to acquire caliper data, use the inclinometer to acquire azimuth data, establish the association between the caliper data and the azimuth data of each measuring point, and obtain multiple groups of target logging data.

8. The data acquisition method according to claim 7, characterized in that, The target logging data includes natural gamma curve, resistivity curve, acoustic wave, neutron curve, caliper curve, caliper, and azimuth data.

9. A method for determining formation in-situ stress, using the data collected by the data acquisition method according to any one of claims 4-8, characterized in that, It includes: Analyze multiple groups of target logging data to obtain the wellbore shape and the direction of the maximum in-situ stress of the current logging.

10. The method for determining formation in-situ stress according to claim 9, characterized in that, The specific analysis includes: A1. Determine the stress concentration section according to the natural gamma curve, resistivity curve, acoustic wave, and neutron curve. A2. In the stress concentration section, select the enlarged hole section according to the acquired caliper curve. A3. Draw a caliper-azimuth crossplot according to the caliper and azimuth data, and determine the azimuth of the enlarged hole section according to the caliper-azimuth crossplot; in the enlarged hole section, determine the wellbore shape according to the caliper data, and determine the direction of the minimum in-situ stress according to the wellbore shape and azimuth data. The direction perpendicular to the minimum in-situ stress direction is the direction of the maximum in-situ stress.

11. The method for determining formation in-situ stress according to claim 10, characterized in that, In step A2, in the stress concentration section, select the section with a caliper value greater than the bit diameter as the enlarged hole section according to the acquired caliper curve.

12. The method for determining formation in-situ stress according to claim 10, characterized in that, In step A3, draw a caliper-azimuth crossplot in the XY plane. On the crossplot, the scale value corresponding to the data point of the enlarged hole section on the azimuth axis is the azimuth of the enlarged hole section.

13. The method for determining formation in-situ stress according to claim 12, characterized in that, In step A3, in the enlarged hole section, determine the elliptical wellbore shape according to the caliper data in two perpendicular directions. The major axis azimuth of the elliptical wellbore corresponds to the direction of the minimum in-situ stress.

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