Real-time abnormality determination method for shale gas hydraulic fracturing based on dynamic reference points

Abstract

This invention provides a real-time anomaly detection method for shale gas hydraulic fracturing based on dynamic reference points. Based on real-time data, combined with the static pressure of the proppant-carrying fluid in the wellbore, the flow friction of the fracturing fluid in the wellbore, and the flow friction of the fracturing fluid through the perforation orifice, the bottom-hole net pressure at each moment is calculated. The bottom-hole net pressure array is smoothed. From the smoothed bottom-hole net pressure array, several moments' bottom-hole net pressure data are selected, and the moment corresponding to the maximum relative error of the net pressure fitting is used as the dynamic reference point. The bottom-hole net pressure derivative and the maximum pressure are used as indicators, combined with the average net pressure exponent of the dynamic reference point, to perform a comprehensive anomaly detection. This invention enables more detailed and timely anomaly detection.

Description

Technical Field

[0001] This invention belongs to the field of shale gas development, specifically relating to a real-time anomaly determination method for hydraulic fracturing of shale gas based on dynamic reference points. Background Technology

[0002] Due to the complexity of geostress, the degree of development of natural fractures, and construction parameters, hydraulic fracturing of horizontal wells in shale gas is a complex engineering process. While technologies such as microseismic monitoring can monitor the formation of fracture networks, their high cost has limited their application to only a few typical wells. Furthermore, the complex geographical and reservoir conditions of shale gas blocks make it difficult to ensure the accuracy and timeliness of these assessments for timely guidance of on-site operations. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a real-time anomaly determination method for shale gas hydraulic fracturing based on dynamic reference points, which can improve the accuracy of the determination.

[0004] As a first aspect of the present invention, the technical solution adopted by the present invention to solve the above-mentioned technical problem is: a method for real-time anomaly determination of shale gas hydraulic fracturing based on dynamic reference points, comprising:

[0005] Read real-time data;

[0006] Based on real-time data, combined with the static pressure of the sand-carrying fluid in the wellbore, the flow friction of the fracturing fluid in the wellbore, and the flow friction of the fracturing fluid through the perforation orifice, the net pressure at the bottom of the well at each moment is calculated.

[0007] Based on the bottom hole net pressure at each moment, a bottom hole net pressure array ordered by time is obtained;

[0008] Smooth the net pressure array at the bottom of the well;

[0009] For the smoothed bottom hole net pressure array, select the bottom hole net pressure data at several times, and use the time corresponding to the maximum relative error of net pressure fitting as the dynamic reference point.

[0010] The bottom hole net pressure derivative and maximum pressure are used as indicators, and combined with the average net pressure index of the dynamic reference point, anomalies are comprehensively judged.

[0011] The above method is used to smooth the bottom hole net pressure array, specifically by using a time-weighted method for forward smoothing.

[0012] According to the above method, the selection of bottom hole net pressure data at several specific moments, and using the moment corresponding to the maximum relative error of the net pressure fitting as the dynamic reference point, specifically includes:

[0013] The net pressure fitting relative error is calculated by taking the time points that are a certain time ago from the current time up to the two time points before the current time as reference points.

[0014] The moment corresponding to the maximum relative error of the calculated net pressure fitting is used as the dynamic reference point.

[0015] According to the above method, the comprehensive anomaly determination specifically includes:

[0016] If the net pressure derivative at the current moment is greater than or equal to the first preset derivative, then the extension is determined to be blocked.

[0017] If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, the current bottom hole net pressure is less than or equal to the first preset bottom hole net pressure value, and the current net pressure derivative is greater than or equal to the second preset derivative, then the extension is determined to be blocked.

[0018] If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended.

[0019] If at the current moment, the net pressure derivative is less than or equal to the second preset derivative, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended.

[0020] If, at the current moment, the average net pressure index of the dynamic reference point is less than or equal to the second preset net pressure index, and the current bottom hole net pressure is less than or equal to the second preset bottom hole net pressure value, then rapid filtering is determined.

[0021] According to the above method, the first preset derivative is 5, and the second preset derivative is -5.

[0022] According to the above method, the first preset net pressure index is 0.3, and the second preset net pressure index is -0.6.

[0023] According to the above method, the first preset bottom hole net pressure value is 0.7 times the maximum bottom hole net pressure; the second preset bottom hole net pressure value is 0.5 times the maximum bottom hole net pressure.

[0024] Following the above method, this method also includes:

[0025] Plot and display the bottom hole net pressure curve and abnormal data in real time.

[0026] As a second aspect of the present invention, the present invention also provides a real-time anomaly determination system for shale gas hydraulic fracturing based on dynamic reference points, comprising:

[0027] The data acquisition unit is used to read real-time data;

[0028] The bottom hole net pressure calculation unit is used to calculate the bottom hole net pressure at each moment based on real-time data, combined with the static pressure of the sand-carrying fluid in the wellbore, the flow friction of the fracturing fluid in the wellbore, and the flow friction of the fracturing fluid through the perforation orifice. Based on the bottom hole net pressure at each moment, a bottom hole net pressure array in time order is obtained.

[0029] The smoothing unit is used to smooth the bottom hole net pressure array;

[0030] The dynamic reference point acquisition unit is used to select the bottom hole net pressure data at several times from the smoothed bottom hole net pressure array, and take the time corresponding to the maximum value of the relative error of net pressure fitting as the dynamic reference point.

[0031] The anomaly comprehensive judgment unit is used to make anomaly comprehensive judgment by using the bottom hole net pressure derivative and maximum pressure as indicators, combined with the average net pressure index of the dynamic reference point.

[0032] As a third aspect of the invention, the invention also provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method.

[0033] The beneficial effects of this invention are as follows: by smoothing real-time data and calculating dynamic reference points, the bottom hole net pressure index is obtained. Combined with the net pressure derivative, real-time anomaly determination is achieved according to the established rules, which enables more detailed and timely capture of anomalies. Attached Figure Description

[0034] Figure 1 This is a flowchart of a method according to an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of control points according to an embodiment of the present invention.

[0036] Figure 3 This is a rendering of an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] This invention provides a method for real-time anomaly determination in shale gas hydraulic fracturing based on dynamic reference points, such as... Figure 1 As shown, this method includes the following steps:

[0039] S1. Read real-time data.

[0040] In this embodiment, the data is first prepared: minimum horizontal principal stress. Well length L, well diameter D, well depth Z, number of blast holes blast hole diameter fracturing fluid density proppant density .

[0041] Then read real-time data, including wellhead pressure. Displacement q and sand ratio .

[0042] S2. Based on real-time data, combined with the static pressure of the sand-carrying fluid in the wellbore, the flow friction of the fracturing fluid in the wellbore, and the flow friction of the fracturing fluid through the perforation orifice, calculate the bottom hole net pressure at each moment; based on the bottom hole net pressure at each moment, obtain the bottom hole net pressure array in time order.

[0043] Static pressure of sand-carrying fluid inside the wellbore :

[0044]

[0045] In the formula The unit is Pa; This indicates the proportion of proppant, i.e., the sand ratio; This indicates the density of the fracturing fluid. . Indicates the density of the proppant. g represents gravitational acceleration. Z represents the vertical depth of the wellbore, in meters (m).

[0046] Fracturing fluid wellbore flow friction :

[0047]

[0048] In the formula The unit is MPa; q is the wellbore diameter (m); q is the displacement. L is the length of the well shaft, in meters.

[0049] Flow friction of fracturing fluid through perforation orifice :

[0050]

[0051] In the formula The unit is MPa; Number of gun holes; q represents the borehole diameter in mm; q represents the displacement. .

[0052] Then calculate the net pressure at the bottom of the well using the following formula.

[0053]

[0054] In the formula, p represents the net pressure at the bottom of the well, in Pa; Indicates wellhead pressure, in Pa; This represents the static pressure of the sand-carrying fluid inside the wellbore, in Pa. This represents the frictional resistance of fracturing fluid flow in the wellbore, expressed in Pa. The frictional resistance of fracturing fluid flowing through the perforation orifice, expressed in Pa; This represents the minimum horizontal principal stress, expressed in Pa.

[0055] Based on the net pressure at the bottom of the well at each moment, a time-ordered array of net pressure at the bottom of the well is obtained: that is, the net pressure at the bottom of the well varies with time. The time series of changing bottom hole net pressure is as follows .

[0056] S3. Smooth the net pressure array at the bottom of the well. Due to the randomness of real-time data, it is necessary to smooth the real-time data to a certain extent. In this embodiment, a time-weighted method is used for forward smoothing.

[0057]

[0058] In the formula, This represents the current net pressure at the bottom of the well. For the current moment, For the previous moment, It refers to the two moments before the previous moment (i.e., the moment before the previous moment). for Net pressure at the bottom of the well at all times; for Net pressure at the bottom of the well at all times.

[0059] S4. For the smoothed bottom hole net pressure array, select bottom hole net pressure data at several times, and use the time corresponding to the maximum value of the net pressure fitting relative error as the dynamic reference point. Specifically, this includes: taking the time points a certain time before the current time up to the two time points before the current time as reference points, calculating the net pressure fitting relative error; and using the time corresponding to the maximum value of the calculated net pressure fitting relative error as the dynamic reference point.

[0060] In this embodiment, let the current real-time point be i, and the point a certain time interval prior (2 minutes in this embodiment) be k. Using i-2 to k as reference points, the average net pressure index is calculated. and relative error of net pressure fitting Find the maximum relative error of the net pressure fitting. .

[0061] Fitted value of the net pressure index at point i at the bottom of the well for:

[0062]

[0063] Where j is the reference point, the corresponding wellbore net pressure index fitting value can be calculated by substituting i-2 to k respectively.

[0064] Average net pressure index for:

[0065]

[0066]

[0067] Pick If the reference point n is a dynamic reference point, then: .

[0068] S5. Using the bottom hole net pressure derivative and maximum pressure as indicators, and combining them with the average net pressure index of the dynamic reference points, a comprehensive anomaly determination is made, specifically including:

[0069] If the net pressure derivative at the current moment is greater than or equal to the first preset derivative, then the extension is determined to be blocked.

[0070] If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, the current bottom hole net pressure is less than or equal to the first preset bottom hole net pressure value, and the current net pressure derivative is greater than or equal to the second preset derivative, then the extension is determined to be blocked.

[0071] If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended.

[0072] If at the current moment, the net pressure derivative is less than or equal to the second preset derivative, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended.

[0073] If, at the current moment, the average net pressure index of the dynamic reference point is less than or equal to the second preset net pressure index, and the current bottom hole net pressure is less than or equal to the second preset bottom hole net pressure value, then rapid filtering is determined.

[0074] In this embodiment, the first preset derivative is 5, the second preset derivative is -5; the first preset net pressure index is 0.3, the second preset net pressure index is -0.6; the first preset bottom hole net pressure value is 0.7 times the maximum bottom hole net pressure; and the second preset bottom hole net pressure value is 0.5 times the maximum bottom hole net pressure.

[0075] Among them, net pressure derivative :

[0076]

[0077] As the fracturing process progresses, the maximum net pressure at the bottom of the well is calculated in real time. It is used for rapid filter loss determination.

[0078] The determination rule is expressed by the following formula:

[0079]

[0080] S5. Plot and display the bottom hole net pressure curve and abnormal data in real time. For example... Figure 2 and Figure 3 As shown, a lot of smoothing is required to obtain a reasonable control point. The method of this invention uses dynamic reference points to capture anomalies more meticulously.

[0081] As a second aspect of the present invention, the present invention also provides a real-time anomaly determination system for shale gas hydraulic fracturing based on dynamic reference points, comprising:

[0082] The data acquisition unit is used to read real-time data. The specific reading process has been described in detail in the above method, so it will not be repeated here.

[0083] The bottom hole net pressure calculation unit is used to calculate the bottom hole net pressure at each moment based on real-time data, combined with the static pressure of the proppant-carrying fluid in the wellbore, the flow friction of the fracturing fluid in the wellbore, and the flow friction of the fracturing fluid through the perforation orifice. Based on the bottom hole net pressure at each moment, a bottom hole net pressure array ordered by time is obtained. The specific calculation process has been detailed in the above method and will not be repeated here.

[0084] The smoothing unit is used to smooth the bottom hole net pressure array; the specific processing procedure has been described in detail in the above method, so it will not be repeated here.

[0085] The dynamic reference point acquisition unit is used to select the bottom hole net pressure data at several times from the smoothed bottom hole net pressure array, and take the time corresponding to the maximum value of the relative error of net pressure fitting as the dynamic reference point; the specific acquisition process has been described in detail in the above method, so it will not be repeated here.

[0086] The anomaly comprehensive judgment unit is used to perform anomaly comprehensive judgment by using the bottom hole net pressure derivative and maximum pressure as indicators, combined with the average net pressure index of the dynamic reference point. The specific judgment process has been detailed in the above method, so it will not be repeated here.

[0087] As a third aspect of the present invention, the present invention also provides a computer device, such as a smartphone, tablet computer, laptop computer, desktop computer, rack server, blade server, tower server, or cabinet server (including a standalone server or a server cluster composed of multiple servers) capable of executing programs. The computer device of this embodiment includes, but is not limited to, at least: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method.

[0088] This invention focuses on the real-time anomaly detection requirements of fracturing. Based on the bottom hole net pressure index and the net pressure fitting relative error model, and on the basis of establishing a real-time data smoothing method, a reference point is dynamically calculated for specific real-time data points to obtain the bottom hole net pressure index. Combined with the net pressure derivative, real-time anomaly detection is achieved according to the established rules. The real-time anomaly detection method for shale gas horizontal wells based on dynamic reference points captures anomalies more meticulously and promptly.

[0089] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for real-time anomaly determination in shale gas hydraulic fracturing based on dynamic reference points, characterized in that: include: Read real-time data; Based on real-time data, combined with the static pressure of the sand-carrying fluid in the wellbore, the flow friction of the fracturing fluid in the wellbore, and the flow friction of the fracturing fluid through the perforation holes, the net pressure at the bottom of the well at each moment is calculated. Based on the net pressure at the bottom of the well at each moment, a net pressure array at the bottom of the well in time order is obtained; Smooth the net pressure array at the bottom of the well; For the smoothed bottom hole net pressure array, select the bottom hole net pressure data at several times, and use the time corresponding to the maximum value of the relative error of net pressure fitting as the dynamic reference point. The bottom hole net pressure derivative and maximum pressure are used as indicators, and combined with the average net pressure index of the dynamic reference point, anomalies are comprehensively judged. The aforementioned comprehensive anomaly determination specifically includes: If the net pressure derivative at the current moment is greater than or equal to the first preset derivative, then the extension is determined to be blocked. If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, the current bottom hole net pressure is less than or equal to the first preset bottom hole net pressure value, and the current net pressure derivative is greater than or equal to the second preset derivative, then the extension is determined to be blocked. If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended. If at the current moment, the net pressure derivative is less than or equal to the second preset derivative, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended. If, at the current moment, the average net pressure index of the dynamic reference point is less than or equal to the second preset net pressure index, and the current bottom hole net pressure is less than or equal to the second preset bottom hole net pressure value, then rapid filtering is determined. The average net pressure index is obtained using the following formula: Let the current real-time point be i, and let k be the point k a certain time ago. Let the fitted value of the bottom hole net pressure index at point i be... for: In the formula, j is the reference point; This represents the current net pressure at the bottom of the well. for Net pressure at the bottom of the well at all times; For the current moment, The previous moment; Using i-2 to k as reference points respectively, we calculate the corresponding wellbore net pressure index fitting values; Average net pressure index for: 。 2. The real-time anomaly determination method for shale gas hydraulic fracturing based on dynamic reference points according to claim 1, characterized in that: The smoothing of the bottom hole net pressure array is specifically performed using a time-weighted method for forward smoothing.

3. The real-time anomaly determination method for shale gas hydraulic fracturing based on dynamic reference points according to claim 1, characterized in that: The selection of bottom hole net pressure data at several specific moments, with the moment corresponding to the maximum relative error of the net pressure fitting as the dynamic reference point, specifically includes: The net pressure fitting relative error is calculated by taking the time points that are a certain time ago from the current time up to the two time points before the current time as reference points. The moment corresponding to the maximum relative error of the calculated net pressure fitting is used as the dynamic reference point.

4. The real-time anomaly determination method for shale gas hydraulic fracturing based on dynamic reference points according to claim 1, characterized in that: The first preset derivative is 5, and the second preset derivative is -5.

5. The real-time anomaly determination method for shale gas hydraulic fracturing based on dynamic reference points according to claim 1, characterized in that: The first preset net pressure index is 0.3, and the second preset net pressure index is -0.

6.

6. The real-time anomaly determination method for shale gas hydraulic fracturing based on dynamic reference points according to claim 1, characterized in that: The first preset bottom hole net pressure value is 0.7 times the maximum bottom hole net pressure; the second preset bottom hole net pressure value is 0.5 times the maximum bottom hole net pressure.

7. The method for real-time anomaly determination of shale gas hydraulic fracturing based on dynamic reference points according to claim 1, characterized in that: This method also includes: Plot and display the bottom hole net pressure curve and abnormal data in real time.

8. A real-time anomaly detection system for shale gas hydraulic fracturing based on dynamic reference points, characterized in that: include: The data acquisition unit is used to read real-time data; The bottom hole net pressure calculation unit is used to calculate the bottom hole net pressure at each moment based on real-time data, combined with the static pressure of the sand-carrying fluid in the wellbore, the flow friction of the fracturing fluid in the wellbore, and the flow friction of the fracturing fluid through the perforation orifice. Based on the bottom hole net pressure at each moment, a bottom hole net pressure array in time order is obtained. The smoothing unit is used to smooth the bottom hole net pressure array; The dynamic reference point acquisition unit is used to select the bottom hole net pressure data at several times from the smoothed bottom hole net pressure array, and take the time corresponding to the maximum value of the relative error of net pressure fitting as the dynamic reference point. The anomaly comprehensive judgment unit is used to make anomaly comprehensive judgment by using the bottom hole net pressure derivative and maximum pressure as indicators, combined with the average net pressure index of the dynamic reference point; The aforementioned comprehensive anomaly determination specifically includes: If the net pressure derivative at the current moment is greater than or equal to the first preset derivative, then the extension is determined to be blocked. If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, the current bottom hole net pressure is less than or equal to the first preset bottom hole net pressure value, and the current net pressure derivative is greater than or equal to the second preset derivative, then the extension is determined to be blocked. If, at the current moment, the average net pressure index of the dynamic reference point is greater than or equal to the first preset net pressure index, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended. If at the current moment, the net pressure derivative is less than or equal to the second preset derivative, and the current bottom hole net pressure is greater than the first preset bottom hole net pressure value, then the fracture network is determined to be extended. If, at the current moment, the average net pressure index of the dynamic reference point is less than or equal to the second preset net pressure index, and the current bottom hole net pressure is less than or equal to the second preset bottom hole net pressure value, then rapid filtering is determined. The average net pressure index is obtained using the following formula: Let the current real-time point be i, and let k be the point k a certain time ago. Let the fitted value of the bottom hole net pressure index at point i be... for: In the formula, j is the reference point; This represents the current net pressure at the bottom of the well. for Net pressure at the bottom of the well at all times; For the current moment, The previous moment; Using i-2 to k as reference points respectively, we calculate the corresponding wellbore net pressure index fitting values; Average net pressure index for: 。 9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

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