Well optical fiber and ground node combined microseism monitoring device and method

Abstract

The invention provides an in-well optical fiber and ground node combined micro-seismic monitoring device and method, and belongs to the technical field of seismic exploration and acquisition. The monitoring device comprises optical fiber monitoring wells arranged on at least one side of a fractured well, and optical fibers are arranged in the optical fiber monitoring wells; and the ground node acquisition assembly is arranged right above the fractured well. The optical fiber enters the horizontal section to obtain more microseism events, and a small number of ground node detectors are utilized to assist the optical fiber to realize accurate positioning, so that the number of effective microseism events can be increased, and the problem that optical fiber microseism monitoring cannot realize accurate positioning is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of seismic exploration and acquisition, and in particular relates to a microseismic monitoring device and method combining an optical fiber in a well with a ground node. Background Art

[0002] At present, conventional microseismic monitoring methods mainly include well monitoring and ground monitoring. The disadvantage of well monitoring is that the well detector can only be placed in the vertical section and cannot enter the horizontal section, and the number of acquisition levels is relatively small (usually only a dozen to a hundred channels). As the horizontal section becomes longer and longer, the number of fracturing events at the bottom of the well gradually decreases due to signal attenuation problems, and the effect of microseismic monitoring is greatly reduced. The disadvantages of ground monitoring are that a large number of ground detectors are required, the layout area is large, and the construction is difficult in mountainous areas. During the acquisition process, there are problems such as data loss due to accidental disconnection of the line. In recent years, distributed fiber optic sensing technology, as a disruptive technology, has tended to replace conventional detectors for seismic data acquisition. At present, it is mainly restricted by the inability to achieve three-component acquisition, resulting in the inability to achieve accurate positioning when locating microseismic events. The current monitoring distance of fiber optic monitoring is shorter than that of well detectors, but the optical fiber can enter the horizontal section to carry out data collection, and the straight-line distance from the microseismic event is shorter (usually only a few hundred meters). Therefore, the number of microseismic events obtained by optical fiber is greater than that of conventional ground monitoring and well monitoring. As long as the problem of accurate positioning is solved, the quality and effect of microseismic monitoring can be better improved. Summary of the invention

[0003] The purpose of the present invention is to solve the difficulties existing in the above-mentioned prior art, and to provide a microseismic monitoring device and method combining optical fiber in a well and ground nodes, which uses optical fiber to enter the horizontal section to obtain more microseismic events, and then uses a small number of ground node detectors to assist the optical fiber in achieving precise positioning, effectively solving the problems of optical fiber in the actual application of microseismic monitoring.

[0004] One of the purposes of the present invention is to provide a microseismic monitoring device combining an optical fiber in a well and a ground node;

[0005] A second object of the present invention is to provide a microseismic monitoring method combining optical fiber in a well with ground nodes.

[0006] The present invention is achieved through the following technical solutions:

[0007] The first aspect of the present invention provides a microseismic monitoring device combining an optical fiber in a well and a ground node, comprising:

[0008] An optical fiber monitoring well is arranged on at least one side of the fracturing well, wherein an optical fiber is arranged in the optical fiber monitoring well;

[0009] The ground node acquisition component is set directly above the fracturing well.

[0010] Using optical fiber to enter the horizontal section to obtain more microseismic events, and then using the ground node acquisition components to assist the optical fiber in achieving precise positioning, can increase the number of effective microseismic events and solve the problem that optical fiber microseismic monitoring cannot accurately locate.

[0011] A further improvement of the present invention is:

[0012] The optical fiber monitoring wells are located on both sides or one side of the fracturing well, and the optical fiber in the optical fiber monitoring well is laid out in a continuous oil pipe with optical fiber or an optoelectronic composite cable inside the casing, a permanent laying outside the casing, and other optical fiber laying methods.

[0013] There is no special requirement for the optical fiber structure, and it can be ordinary optical fiber, fiber grating, spiral optical fiber or any other optical fiber.

[0014] A further improvement of the present invention is:

[0015] The distance between the optical fiber monitoring well and the fracturing well is maintained within 600m.

[0016] A further improvement of the present invention is:

[0017] The ground node acquisition array includes a plurality of node detectors arranged directly above the fracturing well.

[0018] A further improvement of the present invention is:

[0019] A plurality of node detectors are arranged around the fracturing section to form the surface node acquisition array.

[0020] A further improvement of the present invention is:

[0021] Directly above the fracturing well, a 300m×1200m rectangular ground node acquisition array is arranged with the fracturing section as the center. The single line is 300m along the well trajectory, with a line spacing of 20m, a total of 16 lines, and the line spacing perpendicular to the well trajectory is 50m, a total of 25 lines, requiring 16×25=400 node detectors.

[0022] A further improvement of the present invention is:

[0023] If an optical fiber monitoring well is set on one side of the fracturing well, the number of node detectors arranged on the ground on the other side will increase, preferably, the number of node detectors will be doubled.

[0024] A second aspect of the present invention provides a method for microseismic monitoring by combining an optical fiber in a well with a ground node, wherein the method uses the optical fiber in a well with a ground node to perform microseismic monitoring, and specifically comprises the following steps:

[0025] Step 1, using the optical fiber deployed in the optical fiber monitoring well to collect data in real time, and performing microseismic event identification and event determination through a preset algorithm, and if it is determined to be a valid event, sending a data return instruction to the ground node acquisition component;

[0026] Step 2: The ground node array adopts a blind sampling working mode. After receiving the data return instruction, the ground node uses the optical fiber microseismic event as the time reference point, intercepts and packages the data of the first 1 second + the last 10 seconds for return;

[0027] Step 3: Fusion processing and analysis of optical fiber data and ground node data.

[0028] A further improvement of the present invention is:

[0029] In step 3, the optical fiber data and the ground node data are integrated, processed and analyzed, specifically:

[0030] Intelligent event recognition is performed on the data sent back by the ground nodes, and microseismic events can be identified and combined with the optical fiber acquisition data for joint positioning;

[0031] If the data transmitted back by the ground node fails to identify microseismic events, the corresponding fiber optic acquisition data will be identified using artificial intelligence. The identification method combines the located strong energy events to determine the direction of fracture development and reduce multiple solutions, or combines the vertical well section fiber optic data for comprehensive analysis to perform positioning interpretation.

[0032] A further improvement of the present invention is:

[0033] The monitoring method further comprises:

[0034] If single-sided fiber optic monitoring is used, due to distance issues, no or very few microseismic signals may be detected by the fiber optic on the other side of the fracturing well, but the ground node array can receive them. In this case, the monitoring points on the other side should be encrypted when designing the ground node array. In subsequent processing, the ground node array should be fully recovered, and the ground node data should be intelligently identified for microseisms to increase the microseismic monitoring capabilities on the opposite side.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention uses optical fiber to enter the horizontal section to obtain more microseismic events, and then uses a small number of ground node detectors to assist the optical fiber in achieving precise positioning, which can increase the number of effective microseismic events and solve the problem that optical fiber microseismic monitoring cannot accurately locate. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention provides a structural schematic diagram of a microseismic monitoring device combining an optical fiber in a well and a ground node. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0039] [Example 1]

[0040] like Figure 1 As shown, this embodiment provides a microseismic monitoring device combining an optical fiber in a well and a ground node, including:

[0041] An optical fiber monitoring well is arranged on at least one side of the fracturing well, wherein an optical fiber is arranged in the optical fiber monitoring well for receiving downhole vibration signals;

[0042] The ground node acquisition array is set up directly above the fracturing well to receive ground vibration signals.

[0043] The present invention uses optical fiber to enter the horizontal section to obtain more microseismic events, and then uses the ground node acquisition component to assist the optical fiber to achieve precise positioning, which can increase the number of effective microseismic events and solve the problem that optical fiber microseismic monitoring cannot accurately locate.

[0044] Furthermore, the optical fiber monitoring well is located on both sides or one side of the fracturing well, and the optical fiber in the optical fiber monitoring well can be laid out in the casing with a continuous tubing with optical fiber or an optoelectronic composite cable, permanently laid out of the casing, or in other optical fiber laying methods. The fracturing well can be laid with an optical fiber outside the casing or without an optical fiber.

[0045] There is no special requirement for the optical fiber structure, and it can be ordinary optical fiber, fiber grating, spiral optical fiber or any other optical fiber.

[0046] The distance between the fiber optic monitoring well and the fracturing well should be kept within 600m as much as possible.

[0047] Furthermore, the surface node acquisition array includes a plurality of node detectors arranged directly above the fracturing well, and the plurality of node detectors are arranged around the fracturing section to form the surface node acquisition array. Preferably, the plurality of node detectors cover 100m before and after the fracturing section along the well direction, and cover above the adjacent well or 600m above the adjacent well perpendicular to the well section direction. Try not to exceed the adjacent well.

[0048] For example, in this embodiment, a 300m×1200m rectangular ground node acquisition array is arranged with the fracturing section as the center, directly above the fracturing well. The single line is along the well trajectory direction (300m), with a line spacing of 20m, a total of 16 lines, and the line spacing perpendicular to the well trajectory direction is 50m, a total of 25 lines, requiring 16×25=400 node detectors.

[0049] Track spacing and line spacing can be increased or decreased based on comprehensive consideration of factors such as actual vertical well depth, horizontal well group spacing, and surface geological conditions.

[0050] If a fiber optic monitoring well is set up on one side of the fracturing well and optical fiber is laid in the fiber optic monitoring well, the number of node detectors laid on the ground on the other side will increase, for example, the number of node detectors can be doubled.

[0051] When the fracturing section starts to move forward from the bottom of the well, the ground node monitors the length of the fracturing section each time it moves forward. For example, if each section is 100m, the entire arrangement moves forward 100m. A rolling arrangement or other methods may be used.

[0052] The present invention takes advantage of the fact that optical fiber can enter the horizontal section, making the distance between the acquisition equipment and the actual microseismic event shorter, thereby acquiring more microseismic events, and then using a small number of ground node detectors to achieve rolling deployment along with the fracturing section, effectively reducing costs while assisting the optical fiber to achieve precise positioning.

[0053] [Example 2]

[0054] This embodiment provides a method for microseismic monitoring of a well optical fiber and a ground node, which uses a well optical fiber and a ground node combined with a microseismic monitoring device to perform microseismic monitoring.

[0055] The structure of the monitoring device is as follows Figure 1 As shown, including:

[0056] An optical fiber monitoring well is arranged on at least one side of the fracturing well, wherein an optical fiber is arranged in the optical fiber monitoring well for receiving downhole vibration signals;

[0057] The ground node acquisition array is set up directly above the fracturing well to receive ground vibration signals.

[0058] The present invention uses optical fiber to enter the horizontal section to obtain more microseismic events, and then uses the ground node acquisition component to assist the optical fiber to achieve precise positioning, which can increase the number of effective microseismic events and solve the problem that optical fiber microseismic monitoring cannot accurately locate.

[0059] Furthermore, the optical fiber monitoring well is located on both sides or one side of the fracturing well, and the optical fiber in the optical fiber monitoring well can be laid out in the casing with a continuous tubing with optical fiber or an optoelectronic composite cable, permanently laid out of the casing, or in other optical fiber laying methods. The fracturing well can be laid with an optical fiber outside the casing or without an optical fiber.

[0060] There is no special requirement for the optical fiber structure, and it can be ordinary optical fiber, fiber grating, spiral optical fiber or any other optical fiber.

[0061] The distance between the fiber optic monitoring well and the fracturing well should be kept within 600m as much as possible.

[0062] Furthermore, the surface node acquisition array includes a plurality of node detectors arranged directly above the fracturing well, and the plurality of node detectors are arranged around the fracturing section to form the surface node acquisition array. Preferably, the plurality of node detectors cover 100m before and after the fracturing section along the well direction, and cover above the adjacent well or 600m above the adjacent well perpendicular to the well section direction. Try not to exceed the adjacent well.

[0063] For example, in this embodiment, a 300m*1200m rectangular ground node acquisition array is arranged with the fracturing section as the center, with a single line along the well trajectory (300m), a line spacing of 20m, a total of 16 lines, and a line spacing of 50m perpendicular to the well trajectory, a total of 25 lines, requiring 16*25=400 lines of node acquisition equipment. The line spacing and line spacing can be denser or sparser based on the actual vertical well depth, horizontal well group spacing, surface geological conditions and other factors.

[0064] If a fiber optic monitoring well is set up on one side of the fracturing well and optical fiber is laid in the fiber optic monitoring well, the number of node detectors laid on the ground on the other side will increase, for example, the number of node detectors can be doubled.

[0065] When the fracturing section starts to move forward from the bottom of the well, the ground node monitors the length of the fracturing section each time it moves forward. For example, if each section is 100m, the entire arrangement moves forward 100m. A rolling arrangement or other methods may be used.

[0066] The monitoring method specifically comprises the following steps:

[0067] (1) using the optical fiber deployed in the optical fiber monitoring well to collect data in real time, and performing microseismic event identification and event determination using a preset algorithm, and if it is determined to be a valid event, sending a data return instruction to the ground node acquisition component;

[0068] The preset algorithm may be a conventional microseismic identification algorithm, which generally identifies the larger energy time point of each acquisition channel within a time window of a set length (e.g., 30 seconds). If the time difference between adjacent acquisition channels has a certain regularity (e.g., the absolute value of the time difference is a group of event axes less than a certain threshold), it is determined to be a valid event.

[0069] (2) The ground node array adopts a blind acquisition working mode (the blind acquisition working mode specifically refers to 7×24 hours of uninterrupted acquisition after the start of acquisition). The communication adopts 4G / 5G transmission, public network or self-organizing network mode. After the node receives the data return instruction, the optical fiber microseismic event is used as the time reference point, and the data of the first 1 second + the last 10 seconds are intercepted, packaged and returned;

[0070] (3) Fusion processing and analysis of optical fiber acquisition data and ground node data:

[0071] Intelligent event recognition is performed on the data transmitted back by the ground nodes. If microseismic events can be identified, they are combined with the fiber optic acquisition data for joint positioning. If the data transmitted back by the ground nodes cannot identify microseismic events, artificial intelligence recognition is used for the corresponding fiber optic acquisition data. The recognition method mainly combines the located strong energy events to determine the direction of fracture development and reduce multiple solutions, or combines the vertical well section fiber optic data for comprehensive analysis to perform positioning interpretation.

[0072] Event identification is performed on the optical fiber acquisition data and the ground node return data respectively. The GPS time corresponding to each event is used to determine whether the optical fiber and the ground node simultaneously receive the rupture signal at the same position. The first arrival time of normal ground data lags behind that of the optical fiber, and the earliest first arrival time difference between the two methods needs to be within the set range (such as within 100ms). The specific time difference allowable range is appropriately adjusted according to the formation velocity.

[0073] Determine the direction of crack development and conduct microseismic monitoring. For example, A and B are two located microseismic strong events. The two events are in the same direction and close to each other. A is earlier than B in GPS time. Then it is determined that the crack developed from A to B. The fiber optic positioning result C is a spherical multiple solution (the main reason is that the fiber optic acquisition data is a single component). The GPS time of C is exactly between A and B, and the spherical positioning of C passes through AB. Then the spherical multiple solution of C can be reduced to the intersection of the sphere and the line connecting AB.

[0074] (4) If single-sided fiber optic monitoring is used, due to distance issues, the other side of the fracturing well will not be able to detect or will detect very few microseismic signals (because there is no fiber optic cable on the other side. Currently, the effective distance for fiber optic sensing of microseisms is within a few hundred meters, and the other side cannot be effectively monitored due to the long-distance attenuation of weak signals). However, the ground node equipment can receive it. In this case, it is usually necessary to encrypt the monitoring points on the other side when designing the ground node array. In subsequent processing, the ground node equipment must recover all data and perform intelligent microseismic identification on the ground node data separately to increase the microseismic monitoring capability on the opposite side.

[0075] The present invention uses optical fiber to enter the horizontal section to obtain more microseismic events, and then uses a small number of ground node detectors to assist the optical fiber in achieving precise positioning, which can increase the number of effective microseismic events and solve the problem that optical fiber microseismic monitoring cannot accurately locate.

[0076] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] In the description of the present invention, unless otherwise specified, the directions or positional relationships indicated by terms such as "up", "down", "left", "right", "inside" and "outside" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0078] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A microseismic monitoring device combining optical fiber in a well and ground node, characterized in that: include: An optical fiber monitoring well is arranged on at least one side of the fracturing well, wherein an optical fiber is arranged in the optical fiber monitoring well; The ground node acquisition component is set directly above the fracturing well.

2. The well optical fiber and ground node combined microseismic monitoring device according to claim 1, characterized in that: The optical fiber monitoring wells are located on both sides or one side of the fracturing well, and the optical fiber in the optical fiber monitoring well is laid out in a continuous oil pipe with optical fiber or an optoelectronic composite cable inside the casing, a permanent laying outside the casing, and other optical fiber laying methods.

3. The well optical fiber and ground node combined microseismic monitoring device according to claim 2, characterized in that: The distance between the optical fiber monitoring well and the fracturing well is maintained within 600m.

4. The well optical fiber and ground node combined microseismic monitoring device according to claim 1, characterized in that: The ground node acquisition array includes a plurality of node detectors arranged directly above the fracturing well.

5. The well optical fiber and ground node combined microseismic monitoring device according to claim 4, characterized in that: A plurality of node detectors are arranged around the fracturing section to form the surface node acquisition array.

6. The well optical fiber and ground node combined microseismic monitoring device according to claim 5, characterized in that: Directly above the fracturing well, a 300m×1200m rectangular ground node acquisition array is arranged with the fracturing section as the center. The single line is 300m along the well trajectory, with a line spacing of 20m, a total of 16 lines, and the line spacing perpendicular to the well trajectory is 50m, a total of 25 lines, requiring 16×25=400 node detectors.

7. The well optical fiber and ground node combined microseismic monitoring device according to claim 6, characterized in that: If an optical fiber monitoring well is set on one side of the fracturing well, the number of node detectors arranged on the ground on the other side will increase, preferably, the number of node detectors will be doubled.

8. A microseismic monitoring method combining optical fiber in a well with ground nodes, characterized in that: Microseismic monitoring is performed using the well optical fiber and ground node combined microseismic monitoring device as described in any one of claims 1 to 7, specifically comprising the following steps: Step 1, using the optical fiber deployed in the optical fiber monitoring well to collect data in real time, and performing microseismic event identification and event determination through a preset algorithm, and if it is determined to be a valid event, sending a data return instruction to the ground node acquisition component; Step 2: The ground node array adopts a blind sampling working mode. After receiving the data return instruction, the ground node uses the optical fiber microseismic event as the time reference point, intercepts and packages the data of the first 1 second + the last 10 seconds for return; Step 3: Fusion processing and analysis of optical fiber data and ground node data.

9. The microseismic monitoring method of well optical fiber and ground node combined according to claim 8, characterized in that: In step 3, the optical fiber data and the ground node data are integrated, processed and analyzed, specifically: Intelligent event recognition is performed on the data sent back by the ground nodes, and microseismic events can be identified and combined with the optical fiber acquisition data for joint positioning; If the data transmitted back by the ground node fails to identify microseismic events, the corresponding fiber optic acquisition data will be identified using artificial intelligence. The identification method combines the located strong energy events to determine the direction of fracture development and reduce multiple solutions, or combines the vertical well section fiber optic data for comprehensive analysis to perform positioning interpretation.

10. The method for microseismic monitoring using optical fiber in a well and ground nodes according to claim 8, characterized in that: The monitoring method further comprises: If single-sided fiber optic monitoring is used, due to distance issues, no or very few microseismic signals may be detected by the fiber optic on the other side of the fracturing well, but the ground node array can receive them. In this case, the monitoring points on the other side should be encrypted when designing the ground node array. In subsequent processing, the ground node array should be fully recovered, and the ground node data should be intelligently identified for microseisms to increase the microseismic monitoring capabilities on the opposite side.

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