CN109184654B - Crack propagation mode identification method and device - Google Patents
Crack propagation mode identification method and device Download PDFInfo
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- CN109184654B CN109184654B CN201811202748.4A CN201811202748A CN109184654B CN 109184654 B CN109184654 B CN 109184654B CN 201811202748 A CN201811202748 A CN 201811202748A CN 109184654 B CN109184654 B CN 109184654B
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- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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Abstract
本发明提供的一种裂缝扩展模式识别方法和装置，方法包括：向压裂管柱内注入压裂液，以使所述压裂液能通过射孔孔眼进入地层使地层发生破裂，并形成人工裂缝，其中，所述射孔孔眼设置于所述压裂管柱上，且所述射孔孔眼处设置有压力传感器；持续向所述压裂管柱内注入所述压裂液，以使所述人工裂缝能向前扩展；并通过所述压力传感器获取所述压裂液的第一当前压力曲线；根据所述第一当前压力曲线获取所述人工裂缝在破碎带周围的扩展路径。本申请实施方式提供了一种裂缝扩展模式识别方法和装置，其能够识别人工裂缝在经过破碎带周围时的扩展模式。
The invention provides a fracture propagation pattern recognition method and device. The method includes: injecting fracturing fluid into a fracturing pipe string, so that the fracturing fluid can enter the formation through perforation holes to fracture the formation and form artificial fractures, wherein the perforation holes are arranged on the fracturing string, and a pressure sensor is arranged at the perforation holes; the fracturing fluid is continuously injected into the fracturing string, so that all the The artificial fracture can expand forward; and the first current pressure curve of the fracturing fluid is obtained through the pressure sensor; the propagation path of the artificial fracture around the fracture zone is obtained according to the first current pressure curve. The embodiments of the present application provide a fracture propagation pattern recognition method and apparatus, which can recognize the propagation pattern of artificial fractures when passing around the fractured zone.
Description
Technical Field
The invention relates to the technical field of petrochemical industry, in particular to a crack propagation pattern recognition method and device.
Background
Artificial fractures are horizontal or vertical fractures that the fracturing fluid will fracture the formation.
When a fracture zone exists in the stratum, the artificial fracture can be expanded forwards in the following three types of expansion modes: firstly, the artificial crack can continue to linearly expand along the predicted expansion direction when passing around the fractured zone; secondly, bending and expanding the artificial crack in a direction deviating from the predicted expansion direction when the artificial crack passes around the broken zone; third, the artificial fracture moves closer to and through the fractured zone away from the predicted direction of propagation as it passes around the fractured zone. There is no prior art method that can identify the propagation pattern of an artificial fracture as it passes around the fracture zone. The diversity of these expansion patterns therefore increases the uncertainty of the effectiveness of the fracturing reservoir modifications.
Disclosure of Invention
In view of the above, the present application provides a fracture propagation pattern recognition method and apparatus, which can recognize a propagation pattern of an artificial fracture when passing around a fracture zone.
The above object of the present invention can be achieved by the following technical solutions: a fracture propagation pattern recognition method, comprising: injecting fracturing fluid into a fracturing string so that the fracturing fluid can enter a stratum through perforation holes to fracture the stratum and form artificial fractures, wherein the perforation holes are formed in the fracturing string, and pressure sensors are arranged at the perforation holes; continuously injecting the fracturing fluid into the fracturing string to enable the artificial fracture to expand forwards; acquiring a first current pressure curve of the fracturing fluid in the forward expansion process of the artificial fracture through the pressure sensor; acquiring an expansion path of the artificial fracture around a fracture zone according to the first current pressure curve; if the first current pressure curve is a substantially flat straight line, the artificial fracture propagates forward around the fracture zone along a first direction, wherein the first direction is an extending direction of the artificial fracture when the formation fractures.
As a preferred embodiment, if the first current pressure curve includes a first extension section that is substantially flat, a first arc section that changes in an arc shape, and a second extension section that is substantially flat, wherein one end of the first arc section is connected to the first extension section, and the other end of the first arc section is connected to one end of the second extension section, the artificial fracture propagates forward around the fractured zone away from a first direction, wherein the first direction is a direction in which the artificial fracture propagates when the formation fractures.
As a preferred embodiment, if the first current pressure curve further includes a second arc segment changing in an arc shape and a third extension segment being substantially flat, wherein one end of the second arc segment is connected to the other end of the second extension segment, the other end of the second arc segment is connected to the third extension segment, and the third extension segment is collinear with the first extension segment, the artificial fracture bypasses the fracture zone during the forward propagation deviating from the first direction and continues to propagate forward in the first direction after bypassing the fracture zone.
As a preferred embodiment, if the first current pressure curve further comprises a linear extension of the sudden pressure drop, wherein one end of the linear extension is connected to the other end of the second extension, the artificial fracture communicates with the fracture zone after propagating forward away from the first direction.
As a preferred embodiment, if the first current pressure curve further comprises at least one set of pressure fluctuation sections consisting of a rising pressure section and a falling pressure section, wherein one end of the pressure fluctuation section is connected to the other end of the linear extension section, the artificial fracture passes through the fracture zone after being communicated with the fracture zone.
As a preferred embodiment, if the first current pressure curve further comprises a fourth extension which is substantially flat, wherein the fourth extension is connected to the other end of the pressure fluctuation section, and the fourth extension is collinear with the first extension, the artificial fracture propagates forward in the first direction after passing through the fracture zone.
In a preferred embodiment, the perforations are located on one side of the fracturing string.
In a preferred embodiment, the injection rate of the fracturing fluid is greater than the absorption rate of the fracturing fluid into the formation.
A fracture propagation pattern recognition device, comprising: a fracturing module; the fracturing module is used for injecting fracturing fluid into a fracturing string so that the fracturing fluid can enter a stratum through perforation holes to fracture the stratum and form artificial fractures, wherein the perforation holes are formed in the fracturing string, and pressure sensors are arranged at the perforation holes; the continuous injection module is used for continuously injecting the fracturing fluid into the fracturing string so as to enable the artificial fracture to be expanded forwards; the first acquisition module is used for acquiring a first current pressure curve of the fracturing fluid in the forward expansion process of the artificial fracture through the pressure sensor; the second acquisition module is used for acquiring the expansion path of the artificial fracture around the fracture zone according to the first current pressure curve; if the first current pressure curve is a substantially flat straight line, the artificial fracture propagates forward around the fracture zone along a first direction, wherein the first direction is an extending direction of the artificial fracture when the formation fractures.
The crack propagation mode identification method and device provided by the application have the beneficial effects that: according to the crack propagation mode identification method and device, the propagation path of the artificial crack around the fracture zone is obtained through the first current pressure curve of the fracturing fluid. The fractured zone has certain influence on the ground stress field of the formation around the fractured zone, and when the ground stress of the formation changes, the direction of the ground stress of the formation changes correspondingly. Therefore, when the artificial fracture extends to the periphery of the broken zone, the extension pressure of the artificial fracture is changed, the pressure of the fracturing fluid is correspondingly changed, and the change of the expansion direction of the artificial fracture can be judged according to the pressure change of the fracturing fluid. And further acquiring the propagation path of the artificial fracture around the fracture zone. Therefore, the embodiment of the application provides a crack propagation pattern recognition method and device, which can recognize the propagation pattern of an artificial crack when the artificial crack passes around a fracture zone.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic illustration of a fracture propagation pattern provided by one embodiment of the present invention;
FIG. 2 is a schematic diagram of a pressure curve for a first expansion path provided by one embodiment of the present invention;
FIG. 3 is a pressure curve diagram of a second expansion path provided in accordance with an embodiment of the present invention;
FIG. 4 is a schematic pressure curve of a third expansion path provided by an embodiment of the present invention;
FIG. 5 is a flow chart of a fracture propagation pattern recognition method provided by one embodiment of the present invention;
fig. 6 is a schematic diagram of a crack propagation pattern recognition apparatus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Please refer to fig. 1 and 5. The crack propagation pattern recognition method provided by an embodiment of the present application may include: step S11: injecting fracturing fluid into a fracturing string 12 so that the fracturing fluid can enter a stratum through a perforation hole to fracture the stratum and form an artificial fracture 13, wherein the perforation hole is arranged on the fracturing string 12, and a pressure sensor is arranged at the perforation hole; step S13: continuously injecting the fracturing fluid into the fracturing string 12 to enable the artificial fracture to be expanded forwards; acquiring a first current pressure curve of the fracturing fluid through the pressure sensor; step S15: and acquiring the expansion path of the artificial fracture 13 around the fracture zone 15 according to the first current pressure curve.
The technical scheme shows that: the fracture propagation pattern recognition method of the embodiment of the application obtains the propagation path of the artificial fracture 13 around the fractured zone 15 through the first current pressure curve of the fracturing fluid. The fractured zone 15 has certain influence on the ground stress field of the formation around the fractured zone, and when the magnitude of the ground stress of the formation changes, the direction of the ground stress of the formation changes correspondingly. Therefore, when the artificial fracture 13 extends to the periphery of the fracture zone 15, the extension pressure of the artificial fracture 13 will change, and the pressure of the fracturing fluid will also change correspondingly, so that the change of the expansion direction of the artificial fracture 13 can be judged according to the pressure change of the fracturing fluid. Thereby acquiring the propagation path of the artificial fracture 13 around the fractured zone 15.
As shown in fig. 1, in the present embodiment, step S11: and injecting fracturing fluid into the fracturing string 12 so that the fracturing fluid can enter the stratum through perforation holes to fracture the stratum and form artificial fractures 13, wherein the perforation holes are formed in the fracturing string 12, and pressure sensors are arranged at the perforation holes. Specifically, a single side of the fracturing string 12 within the wellbore 11 is first perforated. Because the artificial fractures 13 formed in the deep stratum of hydraulic fracturing are generally vertical artificial fractures 13, perforation is carried out on one side of the fracturing string 12 in the shaft 11, and only the stratum on one side of the shaft 11 can be fractured, so that the problem that the fracturing fluid construction curve is complex due to the fact that two sides or multiple stratums around the shaft 11 are fractured simultaneously in the conventional hydraulic fracturing process is avoided, and accurate measurement of the first current pressure curve of the single artificial fractures 13 can be achieved. I.e., perforations, are located on one side of the fracturing string 12. Then, the fracturing fluid is filled into the fracturing string 12, the fracturing fluid is injected at a fixed displacement, and the fracturing fluid is suppressed at high pressure at the bottom of the well, so that the adjacent stratum of the shaft 11 is firstly fractured through the perforation holes, and the artificial fracture 13 is formed. Further, in order to avoid the absorption of the fracturing fluid by the formation, the injection rate of the fracturing fluid is greater than the absorption rate of the fracturing fluid by the formation. And the rate of the fracturing fluid cannot be too high, so that the influence on the accurate measurement of the extension pressure of the artificial fracture 13 around the fractured zone 15 in the stratum caused by the fact that the artificial fracture 13 extends too fast due to the fact that the injection rate of the fracturing fluid is too high is avoided. Further, as shown in fig. 2, 3 and 4, a second current pressure curve of the fracturing fluid may be obtained by a pressure sensor during the process of injecting the fracturing fluid into the fracturing string 12 so that the fracturing fluid can enter the formation through the perforation holes to fracture the formation and form the artificial fracture 13. Specifically, when the fracturing fluid is filled into the fracturing string 12 and injected at a fixed displacement, the pressure of the fracturing fluid is always in a rising state in the process of building a high pressure at the bottom of the well, when the pressure of the fracturing fluid is higher than the fracture pressure of the stratum, the stratum is fractured, the fracturing fluid instantly flows into the artificial fracture 13 in a large amount, so that the pressure of the fracturing fluid is suddenly reduced, and a second current pressure curve is, for example, the OA section in FIG. 2; OD segment in FIG. 3; the OQ segment in fig. 2.
Step S13: continuously injecting fracturing fluid into the fracturing string 12 to enable the artificial fracture 13 to expand forwards; and acquiring a first current pressure curve of the fracturing fluid through the pressure sensor. Specifically, the fracturing fluid is injected continuously at a fixed displacement so that the artificial fracture 13 can extend forwards, and when the artificial fracture 13 extends to the periphery of the fractured zone 15, the magnitude and direction of the ground stress of the formation around the fractured zone 15 may change, and the extension pressure of the artificial fracture 13 correspondingly changes, so that the pressure of the fracturing fluid changes during the process of extending the artificial fracture 13 forwards. Further, the pressure change of the fracturing fluid during the forward propagation of the artificial fracture 13 is known through the first current pressure curve.
Step S15: and acquiring the expansion path of the artificial fracture 13 around the fractured zone 15 according to the first current pressure curve.
Specifically, there are 3 propagation paths for the artificial fracture 13 around the fractured zone 15: as shown in fig. 2, in the first expansion path 29, the first current pressure curve is a substantially flat straight line. The artificial fracture 13 propagates forward around the fractured zone 15 in a first direction, wherein the first direction is the direction in which the artificial fracture 13 extends when the formation fractures. As shown in fig. 2, the AB segment is the first current pressure curve of the fracturing fluid during the forward propagation of the artificial fracture 13. Since the pressure of the fracturing fluid is in a steady state until the artificial fracture 13 propagates forward but does not meet the fractured zone, the first current pressure curve of the fracturing fluid is a substantially flat straight line. The artificial fracture 13 develops in the direction of propagation when the formation fractures. Therefore, when the first current pressure curve artificial fracture 13 is propagated forward in the whole process, that is, the artificial fracture 13 is still in a substantially flat state after encountering the fractured zone, it indicates that the extension pressure of the artificial fracture 13 is substantially unchanged around the fractured zone 15, further indicates that the formation ground stress field around the fractured zone 15 is substantially unchanged, and the fractured zone 15 has substantially no influence on the propagation of the artificial fracture 13, so that the artificial fracture 13 is propagated forward around the fractured zone 15 in the first direction.
As shown in fig. 3, in the second propagation path 31, the first current pressure curve includes a first extension 17 that is substantially flat, a first arc 21 that changes in an arc, and a second extension 19 that is substantially flat, wherein one end of the first arc 21 is connected to the first extension 17, the other end of the first arc 21 is connected to one end of the second extension 19, and the artificial fracture 13 propagates around the fractured zone 15 forward away from the first direction, wherein the first direction is the extending direction of the artificial fracture 13 when the formation fractures. As shown in fig. 3, the VE section is the first current pressure curve of the fracturing fluid during the forward propagation of the artificial fracture 13. When the pressure of the fracturing fluid is in the first extension 17, it is indicated that the extension pressure has not changed; the artificial fracture 13 progresses in a first direction. When the pressure of the fracturing fluid is in the first arc-shaped section 21, it is described that the extension pressure changes around the fractured zone 15, and further, it is described that the formation ground stress field around the fractured zone 15 changes, and the fractured zone 15 has a certain influence on the expansion of the artificial fracture 13, so that the expansion direction of the artificial fracture 13 changes, that is, the artificial fracture develops forward deviating from the first direction.
As shown in fig. 3, further, in the second propagation path 31, the first current pressure curve further includes a second arc segment 23 changing in an arc shape and a third extension segment 25 being substantially flat, wherein one end of the second arc segment 23 is connected to the other end of the second extension segment 19, the other end of the second arc segment 23 is connected to the third extension segment 25, and the third extension segment 25 is collinear with the first extension segment 17, and the artificial fracture 13 bypasses the fracture zone 15 during the propagation forward from the first direction and continues to propagate forward in the first direction after bypassing the fracture zone 15. When the pressure of the fracturing fluid is in the second extension 19, it is indicated that there is substantially no change in extension pressure, i.e., that there is no change in formation pressure, and therefore, no fracture zone 15 is passed during the progression of the artificial fracture 13 away from the first direction. When the pressure of the fracturing fluid reaches the third extension section 25 from the second extension section 19 through the second arc-shaped section 23, the extension pressure is changed around the fractured zone 15, and further, the formation ground stress field around the fractured zone 15 is changed, the fractured zone 15 has a certain influence on the expansion of the artificial fracture 13, so that the artificial fracture 13 returns to the first extension direction after being developed forwards from the first direction. Thus, it is shown that in such a path, the fractured zone 15 has a certain degree of disturbance to the ground stress field of the formation, the artificial fracture 13 is diverted when passing around the fractured zone 15 and does not pass through the fractured zone 15, and the first current pressure curve may change temporarily when passing around the fractured zone 15 and return to normal after passing through the disturbance zone.
As shown in fig. 4, in the third propagation path 33, the first current pressure curve includes a first extension 17 which is substantially flat, a first arc-shaped segment 21 which changes in an arc shape, and a linear extension 29 of sudden pressure drop, wherein one end of the first arc-shaped segment 21 is connected with the first extension 17, the other end of the first arc-shaped segment 21 is connected with one end of the linear extension 29, so that the artificial fracture 13 propagates forwards around the fractured zone 15 deviating from the first direction, and the artificial fracture 13 communicates with the fractured zone 15 deviating from the first direction, wherein the first direction is the extension direction of the artificial fracture 13 when the formation fractures. As shown in FIG. 4, the QN segment is the first current pressure curve of the fracturing fluid during the forward propagation of the artificial fracture 13. The pressure drop indicates that the fracturing fluid flows into the natural artificial fractures 13 in the area of the fractured zone 15, and therefore, the artificial fractures 13 are communicated with the fractured zone 15.
As shown in fig. 4, further, in the third propagation path 33, the first current pressure curve further includes at least one set of pressure fluctuation sections 31 composed of a rising pressure section 33 and a falling pressure section 35, wherein one end of the pressure fluctuation section 31 is connected to the other end of the linear extension section 29, so that the artificial fracture 13 passes through the crushing zone 15 after communicating with the crushing zone 15. Since the first current pressure curve suddenly drops due to a large flow of the fracturing fluid such as a natural fracture in the fractured zone 15 when the artificial fracture 13 passes through the fractured zone 15, it can be determined whether the artificial fracture 13 passes through the fractured zone 15. Specifically, when the pressure of the fracturing fluid is above the pressure surge section 31, the fracturing fluid is illustrated as flowing into the natural fractures within the area of the fractured zone 15, and thus the artificial fractures 13 are in continuous communication with the natural fractures, illustrating the passage of the artificial fractures 13 through the fractured zone 15 after communicating with the fractured zone 15.
Further, as shown in fig. 4, in the third propagation path 33, the first current pressure curve further includes a fourth extension 27 which is substantially even, wherein the fourth extension 27 is connected with the other end of the pressure fluctuation section 31, and the fourth extension 27 is collinear with the first extension 17, so that the artificial fracture 13 propagates forward in the first direction after passing through the fractured zone 15. When the pressure of the fracturing fluid reaches the fourth extension section 27 from the pressure fluctuation section 31, the artificial fracture 13 is restored to normal after passing through the fractured zone 15.
As shown in fig. 1 and 6, in the present embodiment, a crack propagation pattern recognition apparatus according to an embodiment of the present invention may include: a fracturing module 50; the fracturing module 50 is used for injecting fracturing fluid into the fracturing string 12 so that the fracturing fluid can enter the stratum through perforations arranged on the fracturing string 12 to fracture the stratum and form artificial fractures, wherein pressure sensors are arranged at the perforations; a first obtaining module 52, wherein the first obtaining module 52 is used for continuously injecting the fracturing fluid into the fracturing string 12 so as to enable the artificial fracture to be expanded forwards; acquiring a first current pressure curve of the fracturing fluid through the pressure sensor; a second obtaining module 54, wherein the second obtaining module 54 is configured to obtain a propagation path of the artificial fracture around the fracture zone according to the first current pressure curve.
The technical scheme shows that: the fracture propagation pattern recognition device of the embodiment of the application acquires the propagation path of the artificial fracture 13 around the fractured zone 15 through the first current pressure curve of the fracturing fluid. The fractured zone 15 has certain influence on the ground stress field of the formation around the fractured zone, and when the magnitude of the ground stress of the formation changes, the direction of the ground stress of the formation changes correspondingly. Therefore, when the artificial fracture 13 extends to the periphery of the fracture zone 15, the extension pressure of the artificial fracture 13 will change, and the pressure of the fracturing fluid will also change correspondingly, so that the change of the expansion direction of the artificial fracture 13 can be judged according to the pressure change of the fracturing fluid. Thereby acquiring the propagation path of the artificial fracture 13 around the fractured zone 15.
As shown in fig. 1, in the present embodiment, the fracturing module 50 is used for injecting fracturing fluid into the fracturing string 12, so that the fracturing fluid can enter the formation through the perforation holes arranged on the fracturing string 12 to fracture the formation and form the artificial fractures 13, wherein the pressure sensors are arranged at the perforation holes. Specifically, a single side of the fracturing string 12 within the wellbore 11 is first perforated. Because the artificial fractures 13 formed in the deep stratum of hydraulic fracturing are generally vertical artificial fractures 13, perforation is carried out on one side of the fracturing string 12 in the shaft 11, and only the stratum on one side of the shaft 11 can be fractured, so that the problem that the fracturing fluid construction curve is complex due to the fact that two sides or multiple stratums around the shaft 11 are fractured simultaneously in the conventional hydraulic fracturing process is avoided, and accurate measurement of the first current pressure curve of the single artificial fractures 13 can be achieved. I.e., perforations, are located on one side of the fracturing string 12. Then, the fracturing fluid is filled into the fracturing string 12, the fracturing fluid is injected at a fixed displacement, and the fracturing fluid is suppressed at high pressure at the bottom of the well, so that the adjacent stratum of the shaft 11 is firstly fractured through the perforation holes, and the artificial fracture 13 is formed. Further, in order to avoid the absorption of the fracturing fluid by the formation, the injection rate of the fracturing fluid is greater than the absorption rate of the fracturing fluid by the formation. And the rate of the fracturing fluid cannot be too high, so that the influence on the accurate measurement of the extension pressure of the artificial fracture 13 around the fractured zone 15 in the stratum caused by the fact that the artificial fracture 13 extends too fast due to the fact that the injection rate of the fracturing fluid is too high is avoided. Further, as shown in fig. 2, 3 and 4, a second current pressure curve of the fracturing fluid may be obtained by a pressure sensor during the process of injecting the fracturing fluid into the fracturing string 12 so that the fracturing fluid can enter the formation through the perforation holes to fracture the formation and form the artificial fracture 13. Specifically, when the fracturing fluid is filled into the fracturing string 12 and injected at a fixed displacement, the pressure of the fracturing fluid is always in a rising state in the process of building a high pressure at the bottom of the well, when the pressure of the fracturing fluid is higher than the fracture pressure of the stratum, the stratum is fractured, the fracturing fluid instantly flows into the artificial fracture 13 in a large amount, so that the pressure of the fracturing fluid is suddenly reduced, and a second current pressure curve is, for example, the OA section in FIG. 2; OD segment in FIG. 3; the OQ segment in fig. 2.
The first acquisition module 52 is used for continuously injecting fracturing fluid into the fracturing string 12 so as to enable the artificial fracture 13 to expand forwards; and acquiring a first current pressure curve of the fracturing fluid through the pressure sensor. Specifically, the fracturing fluid is injected continuously at a fixed displacement so that the artificial fracture 13 can extend forwards, and when the artificial fracture 13 extends to the periphery of the fractured zone 15, the magnitude and direction of the ground stress of the formation around the fractured zone 15 may change, and the extension pressure of the artificial fracture 13 correspondingly changes, so that the pressure of the fracturing fluid changes during the process of extending the artificial fracture 13 forwards. Further, the pressure change of the fracturing fluid during the forward propagation of the artificial fracture 13 is known through the first current pressure curve.
The second obtaining module 54 is used for obtaining the expansion path of the artificial fracture 13 around the fractured zone 15 according to the first current pressure curve.
Specifically, there are 3 propagation paths for the artificial fracture 13 around the fractured zone 15: as shown in fig. 2, in the first expansion path 29, the first current pressure curve is a substantially flat straight line. The artificial fracture 13 propagates forward around the fractured zone 15 in a first direction, wherein the first direction is the direction in which the artificial fracture 13 extends when the formation fractures. As shown in fig. 2, the AB segment 66 is the first current pressure curve of the fracturing fluid during the forward propagation of the artificial fracture 13. Since the pressure of the fracturing fluid is in a steady state until the artificial fracture 13 propagates forward but does not meet the fractured zone, the first current pressure curve of the fracturing fluid is a substantially flat straight line. The artificial fracture 13 develops in the direction of propagation when the formation fractures. Therefore, when the first current pressure curve artificial fracture 13 is propagated forward in the whole process, that is, the artificial fracture 13 is still in a substantially flat state after encountering the fractured zone, it indicates that the extension pressure of the artificial fracture 13 is substantially unchanged around the fractured zone 15, further indicates that the formation ground stress field around the fractured zone 15 is substantially unchanged, and the fractured zone 15 has substantially no influence on the propagation of the artificial fracture 13, so that the artificial fracture 13 is propagated forward around the fractured zone 15 in the first direction.
As shown in fig. 3, in the second propagation path 31, the first current pressure curve includes a first extension 17 that is substantially flat, a first arc 21 that changes in an arc, and a second extension 19 that is substantially flat, wherein one end of the first arc 21 is connected to the first extension 17, the other end of the first arc 21 is connected to one end of the second extension 19, and the artificial fracture 13 propagates around the fractured zone 15 forward away from the first direction, wherein the first direction is the extending direction of the artificial fracture 13 when the formation fractures. As shown in fig. 3, the VE section is the first current pressure curve of the fracturing fluid during the forward propagation of the artificial fracture 13. When the pressure of the fracturing fluid is in the first extension 17, it is indicated that the extension pressure has not changed; the artificial fracture 13 progresses in a first direction. When the pressure of the fracturing fluid is in the first arc-shaped section 21, it is described that the extension pressure changes around the fractured zone 15, and further, it is described that the formation ground stress field around the fractured zone 15 changes, and the fractured zone 15 has a certain influence on the expansion of the artificial fracture 13, so that the expansion direction of the artificial fracture 13 changes, that is, the artificial fracture develops forward deviating from the first direction.
As shown in fig. 3, further, in the second propagation path 31, the first current pressure curve further includes a second arc segment 23 changing in an arc shape and a third extension segment 25 being substantially flat, wherein one end of the second arc segment 23 is connected to the other end of the second extension segment 19, the other end of the second arc segment 23 is connected to the third extension segment 25, and the third extension segment 25 is collinear with the first extension segment 17, and the artificial fracture 13 bypasses the fracture zone 15 during the propagation forward from the first direction and continues to propagate forward in the first direction after bypassing the fracture zone 15. When the pressure of the fracturing fluid is in the second extension 19, it is indicated that there is substantially no change in extension pressure, i.e., that there is no change in formation pressure, and therefore, no fracture zone 15 is passed during the progression of the artificial fracture 13 away from the first direction. When the pressure of the fracturing fluid reaches the third extension section 25 from the second extension section 19 through the second arc-shaped section 23, the extension pressure is changed around the fractured zone 15, and further, the formation ground stress field around the fractured zone 15 is changed, the fractured zone 15 has a certain influence on the expansion of the artificial fracture 13, so that the artificial fracture 13 returns to the first extension direction after being developed forwards from the first direction. Thus, it is shown that in such a path, the fractured zone 15 has a certain degree of disturbance to the ground stress field of the formation, the artificial fracture 13 is diverted when passing around the fractured zone 15 and does not pass through the fractured zone 15, and the first current pressure curve may change temporarily when passing around the fractured zone 15 and return to normal after passing through the disturbance zone.
As shown in fig. 4, in the third propagation path 33, the first current pressure curve includes a first extension 17 which is substantially flat, a first arc-shaped segment 21 which changes in an arc shape, and a linear extension 29 of sudden pressure drop, wherein one end of the first arc-shaped segment 21 is connected with the first extension 17, the other end of the first arc-shaped segment 21 is connected with one end of the linear extension 29, so that the artificial fracture 13 propagates forwards around the fractured zone 15 deviating from the first direction, and the artificial fracture 13 communicates with the fractured zone 15 deviating from the first direction, wherein the first direction is the extension direction of the artificial fracture 13 when the formation fractures. As shown in FIG. 4, the QN segment is the first current pressure curve of the fracturing fluid during the forward propagation of the artificial fracture 13. The pressure drop indicates that the fracturing fluid flows into the natural artificial fractures 13 in the area of the fractured zone 15, and therefore, the artificial fractures 13 are communicated with the fractured zone 15.
As shown in fig. 4, further, in the third propagation path 33, the first current pressure curve further includes at least one set of pressure fluctuation sections 31 composed of a rising pressure section 33 and a falling pressure section 35, wherein one end of the pressure fluctuation section 31 is connected to the other end of the linear extension section 29, so that the artificial fracture 13 passes through the crushing zone 15 after communicating with the crushing zone 15. Since the first current pressure curve suddenly drops due to a large flow of the fracturing fluid such as a natural fracture in the fractured zone 15 when the artificial fracture 13 passes through the fractured zone 15, it can be determined whether the artificial fracture 13 passes through the fractured zone 15. Specifically, when the pressure of the fracturing fluid is above the pressure surge section 31, the fracturing fluid is illustrated as flowing into the natural fractures within the area of the fractured zone 15, and thus the artificial fractures 13 are in continuous communication with the natural fractures, illustrating the passage of the artificial fractures 13 through the fractured zone 15 after communicating with the fractured zone 15.
Further, as shown in fig. 4, in the third propagation path 33, the first current pressure curve further includes a fourth extension 27 which is substantially even, wherein the fourth extension 27 is connected with the other end of the pressure fluctuation section 31, and the fourth extension 27 is collinear with the first extension 17, so that the artificial fracture 13 propagates forward in the first direction after passing through the fractured zone 15. When the pressure of the fracturing fluid reaches the fourth extension section 27 from the pressure fluctuation section 31, the artificial fracture 13 is restored to normal after passing through the fractured zone 15.
The above are only a few embodiments of the present invention, and those skilled in the art can make various changes or modifications to the embodiments of the present invention according to the disclosure of the application document without departing from the spirit and scope of the present invention.
Claims (9)
1. A fracture propagation pattern recognition method is characterized by comprising the following steps:
injecting fracturing fluid into a fracturing string so that the fracturing fluid can enter a stratum through perforation holes to fracture the stratum and form artificial fractures, wherein the perforation holes are formed in the fracturing string, and pressure sensors are arranged at the perforation holes;
continuously injecting the fracturing fluid into the fracturing string to enable the artificial fracture to expand forwards; acquiring a first current pressure curve of the fracturing fluid through the pressure sensor;
acquiring an expansion path of the artificial fracture around a fracture zone according to the first current pressure curve;
if the first current pressure curve is a substantially flat straight line, the artificial fracture propagates forward around the fracture zone along a first direction, wherein the first direction is an extending direction of the artificial fracture when the formation fractures.
2. The fracture propagation pattern recognition method according to claim 1, characterized in that: if the first current pressure curve comprises a first extension section which is basically flat, a first arc-shaped section which changes in an arc shape and a second extension section which is basically flat, wherein one end of the first arc-shaped section is connected with the first extension section, and the other end of the first arc-shaped section is connected with one end of the second extension section, the artificial fracture is expanded forwards around the fractured zone in a way of deviating from a first direction, wherein the first direction is the extension direction of the artificial fracture when the stratum is fractured.
3. The fracture propagation pattern recognition method according to claim 2, characterized in that: if the first current pressure curve further comprises a second arc-shaped section which changes in an arc shape and a third extension section which is substantially flat, wherein one end of the second arc-shaped section is connected with the other end of the second extension section, the other end of the second arc-shaped section is connected with the third extension section, and the third extension section is collinear with the first extension section, the artificial fracture bypasses the fracture zone in the process of expanding forwards in the deviation direction, and continues to expand forwards in the first direction after bypassing the fracture zone.
4. The fracture propagation pattern recognition method according to claim 1, characterized in that: if the first current pressure curve comprises a first extension section which is basically flat, a first arc-shaped section which changes in an arc shape and a linear extension section with suddenly reduced pressure, wherein one end of the first arc-shaped section is connected with the first extension section, the other end of the first arc-shaped section is connected with one end of the linear extension section, the artificial fracture is expanded forwards around the fracture zone in a deviation manner from a first direction, the artificial fracture is communicated with the fracture zone in a deviation manner from the first direction, and the first direction is the extension direction of the artificial fracture when the stratum is fractured.
5. The crack propagation pattern recognition method according to claim 4, characterized in that: if the first current pressure curve further comprises at least one group of pressure fluctuation sections consisting of a rising pressure section and a falling pressure section, wherein one end of each pressure fluctuation section is connected with the other end of each linear extension section, the artificial cracks pass through the crushing zone after being communicated with the crushing zone.
6. The fracture propagation pattern recognition method according to claim 5, characterized in that: if the first current pressure profile further comprises a fourth extension that is substantially flat, wherein the fourth extension is connected to the other end of the pressure fluctuation section and the fourth extension is collinear with the first extension, the artificial fracture propagates forward in the first direction after passing through the fracture zone.
7. The fracture propagation pattern recognition method according to claim 1, characterized in that: the perforation hole is positioned on one side of the fracturing string.
8. The fracture propagation pattern recognition method according to claim 1, characterized in that: the injection rate of the fracturing fluid is greater than the absorption rate of the fracturing fluid by the formation.
9. A fracture propagation pattern recognition apparatus, comprising:
a fracturing module; the fracturing module is used for injecting fracturing fluid into a fracturing string so that the fracturing fluid can enter a stratum through perforation holes to fracture the stratum and form artificial fractures, wherein the perforation holes are formed in the fracturing string, and pressure sensors are arranged at the perforation holes;
the first acquisition module is used for continuously injecting the fracturing fluid into the fracturing string so as to enable the artificial fracture to expand forwards; acquiring a first current pressure curve of the fracturing fluid through the pressure sensor;
the second acquisition module is used for acquiring the expansion path of the artificial fracture around the fracture zone according to the first current pressure curve; if the first current pressure curve is a substantially flat straight line, the artificial fracture propagates forward around the fracture zone along a first direction, wherein the first direction is an extending direction of the artificial fracture when the formation fractures.
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| US4432078A (en) * | 1979-01-17 | 1984-02-14 | Daniel Silverman | Method and apparatus for fracturing a deep borehole and determining the fracture azimuth |
| BR0214600A (en) * | 2001-12-03 | 2004-09-14 | Shell Int Research | Methods for controlling pressures during subsea well drilling operations in an earth formation, and for maintaining well pressure control during drilling operations in an subsea drilling environment |
| GB2539056A (en) * | 2015-06-03 | 2016-12-07 | Geomec Eng Ltd | Improvements in or relating to injection wells |
| CN108468538B (en) * | 2018-03-23 | 2020-04-21 | 西南石油大学 | A Prediction Method of Hydraulic Fracture Propagation in Shale |
| CN109372498B (en) * | 2018-09-29 | 2021-09-21 | 中国石油大学(北京) | Method and device for determining fracture zone in rock stratum |
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