A high-efficiency and low-cost method for evaluating interwell interference of shale gas well groups

Abstract

The application discloses a kind of high-efficiency low-cost shale gas well group well interference evaluation method, including based on the change of well pressure and flow to identify well interference situation;After fracturing operation ends, inject tracer into the stratum after being reformed, until to be fully washed well after flowback, and according to the flowback of tracer and the metering result of entering monitoring well to evaluate the degree of hydraulic wave and crack well interference;After fracturing operation ends, inject tracer particles into the stratum after being reformed, until to be fully washed well after flowback, and according to the flowback of tracer particles and the metering result of entering monitoring well to evaluate the degree of hydraulic tension crack well interference;According to the flowback of tracer and tracer particles and the metering result of entering monitoring well, well interference of shale gas well group is evaluated.The method of the application can distinguish the interference degree of hydraulic wave and crack, and further help to judge the influence of well interference on adjacent well.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas resource development and its stimulation, in particular to a high-efficiency and low-cost shale gas well group interwell interference evaluation method. BACKGROUND

[0002] Interwell interference leads to the decline of the productivity of some adjacent wells and the failure of the fractured well to reach the designed productivity. The traditional interwell interference methods mainly include monitoring during fracturing (distributed optical fiber, bottom hole flowing pressure test, microseismic monitoring, tracer, acoustic monitoring) and monitoring during production (bottom hole flowing pressure test, tracer, DNA monitoring): ① In the fracturing process monitoring means: distributed optical fiber, microseismic monitoring, acoustic monitoring and other means are essentially to depict the fracture morphology, reconstruction range, etc., and there are still a lot of errors in interwell interference, and the cost is high; ② In the fracturing process, the bottom hole flowing pressure is disturbed by the pressure fluctuation factors caused by the formation fracture and fault; in the fracturing process, the tracer is added in the fracturing fluid of the fracturing well and is flowed back, but once the interwell interference is connected, a part of the tracer cannot be effectively flowed back to the fracturing well; and in the fracturing process, the high-pressure fluid is easy to squeeze the tracer into the formation, further affecting the flow back, and then affecting the judgment; in the production process monitoring means: the bottom hole flowing pressure can only judge whether there is interwell interference and the influence of the interference on the production, but cannot effectively quantify the degree of interwell interference; in the production process, the tracer and DNA monitoring are also affected by the formation, and the degree of interwell interference cannot be accurately quantified. SUMMARY

[0003] The present application aims at the problems existing in the prior art, and provides a high-efficiency and low-cost shale gas well group interwell interference evaluation method.

[0004] The technical scheme provided by the present application to solve the above technical problems is: a high-efficiency and low-cost shale gas well group interwell interference evaluation method, comprising the following steps:

[0005] Step S10, identifying the interwell interference condition based on the changes of the well pressure and flow rate;

[0006] Step S20, after the fracturing operation is completed, injecting a tracer into the reconstructed formation, flowing back after sufficient well washing, and evaluating the degree of hydraulic wave and fracture interwell interference according to the flow back of the tracer and the metering result of the tracer into the monitoring well;

[0007] Step S30, after the fracturing operation is completed, injecting a tracer particle into the reconstructed formation, flowing back after sufficient well washing, and evaluating the degree of hydraulic tensile fracture interwell interference according to the flow back of the tracer particle and the metering result of the tracer particle into the monitoring well;

[0008] Step S40, evaluating the inter-well interference of the shale gas well group according to the metering results of the tracer and the tracer particles flowing back and entering the monitoring well.

[0009] Further technical solutions are that the specific process of the step S10 is:

[0010] Step S11, obtaining the construction curve of the fracturing well in real time during the fracturing construction of the well, regarding the adjacent well as the monitoring well and obtaining the fracturing construction curve of the monitoring well as well;

[0011] Step S12, reading the pressure and flow changes on the construction curves of the fracturing well and the monitoring well;

[0012] When either of the pressure or flow values in the monitoring well or either of the pressure or flow values in the fracturing well fluctuates, it is determined that the inter-well interference occurs.

[0013] Further technical solutions are that the specific process of the step S20 is:

[0014] Step S21, selecting a colored tracer that does not have physical and chemical reactions with the formation as the solvent, selecting the gel liquid used in the field fracturing as the solution, and mixing the two to form the tracer solution;

[0015] Step S22, continuously pumping the tracer solution into the formation at a pump pressure lower than the formation breakdown pressure, wherein the total liquid volume of the tracer solution is greater than the total liquid volume of the fracturing construction, so as to ensure that the tracer solution can fully saturate the reservoir after the reconstruction, and the tracer solution appearing at the wellhead of the monitoring well is collected;

[0016] Step S23, after the well flushing is completed, setting a displacement pump with a displacement not less than the pumping pump at the wellhead of the fracturing well, pumping the tracer solution injected into the well of the fracturing well to the wellhead and collecting the tracer solution;

[0017] Step S24, metering the amount of tracer J0 returned to the fracturing well and the amount of tracer J1 entering the adjacent monitoring well, respectively;

[0018] Step S25, evaluating the degree of inter-well interference of the hydraulic wave and the fracture according to the amount of tracer J0 returned to the fracturing well and the amount of tracer J1 entering the adjacent monitoring well.

[0019] Further technical solutions are that the colored tracer is red ink.

[0020] Further technical solutions are that the tracer solution in the monitoring well and the fracturing well is left to room temperature before metering in the step S24.

[0021] Further technical solutions are that in step S25, the degree of interference between hydraulic fracture wells is evaluated according to the tracer amount J0 returned to the fracturing well and the tracer amount J1 entering the adjacent monitoring well; and an evaluation index J=J1 / J0 of the degree of interference between hydraulic fracture wells is calculated; and the degree of interference between hydraulic fracture wells is evaluated.

[0022] When J=0, there is no interference between hydraulic fracture wells.

[0023] When 0

[0024] When 0.1≤J<0.25, it is determined that the degree of interference between hydraulic fracture wells is moderate.

[0025] When J≥0.25, it is determined that the degree of interference between hydraulic fracture wells is severe.

[0026] Further technical solutions are that the specific process of step S30 is as follows:

[0027] Step S31, selecting a gel solution for field fracturing as a solution, and mixing the non-soluble inert tracer particles with the solution to form a tracer particle two-phase liquid;

[0028] Step S32, continuously pumping the tracer particle two-phase liquid into the formation at a pump pressure lower than the formation breakdown pressure, wherein the total liquid amount of the tracer particle two-phase liquid is greater than the total liquid amount of the fracturing operation, so as to ensure that the tracer particle two-phase liquid can fully saturate the reservoir after reconstruction, and the tracer particle two-phase liquid appearing at the wellhead of the monitoring well is collected;

[0029] Step S33, after well flushing, setting a displacement pump with a displacement not less than the pumping pump at the wellhead of the fracturing well, pumping the tracer particle two-phase liquid injected into the well of the fracturing well back to the wellhead and collecting;

[0030] Step S34, respectively measuring the weight K0 of the tracer particles returned to the fracturing well and the weight K1 of the tracer particles entering the adjacent monitoring well;

[0031] Step S35, evaluating the degree of interference between hydraulic tension fracture wells according to the weight K0 of the tracer particles returned to the fracturing well and the weight K1 of the tracer particles entering the adjacent monitoring well.

[0032] Further technical solutions are that before the measurement in step S34, the tracer particle two-phase liquid in the monitoring well and the fracturing well is left to room temperature.

[0033] Further technical solutions are that in step S35, an evaluation index K=K1 / K0 of the degree of interference between hydraulic tension fracture wells is calculated according to the weight K0 of the tracer particles returned to the fracturing well and the weight K1 of the tracer particles entering the adjacent monitoring well, and the degree of interference between hydraulic tension fracture wells is evaluated.

[0034] wherein when K=0, then there is no hydraulic tensile fracture well interference;

[0035] when 0

[0036] when 0.1

[0037] when K is greater than or equal to 0.25, then it is determined as severe hydraulic tensile fracture well interference.

[0038] Further technical solutions are that the specific evaluation process in the step S40 is:

[0039] when J>0 and K=0, it is I-grade well interference, and the pressure and flow changes of the two wells need to be paid attention to during subsequent fracturing;

[0040] when 0

[0041] when 0.1

[0042] when 0.1

[0043] when J>0.25, it is V-grade well interference, the current fracturing should be stopped immediately, and the adjacent production well needs to be shut down for at least 12 months to recover the pressure or increase the well spacing by 200m during subsequent fracturing.

[0044] The present application has the following beneficial effects:

[0045] (1) Compared with other monitoring methods, no additional monitoring means (such as microseismic, electromagnetic, DTS, DAS, etc. The monitoring means is essentially to depict the fracture morphology, reconstruction range, etc. There is still a large error in well interference, and the cost is high), the present application has low cost and high efficiency;

[0046] (2) Compared with the traditional tracer flowback method, the tracer is optimized and the tracer particle washing well flowback process is added, so that the result is more accurate;

[0047] (3) The method can distinguish the interference degree of hydraulic wave and fracture, and further help to determine the influence of interwell interference on adjacent wells. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Flow chart of the present application;

[0049] Figure 2 Identification of pressure and flow in fracturing operation curve to interwell interference;

[0050] Figure 3 Tracer washing and flowback schematic diagram;

[0051] Figure 4 Tracer evaluation of interwell interference schematic diagram;

[0052] Figure 5 Tracer particle washing and flowback schematic diagram;

[0053] Figure 6 Tracer particle interwell interference schematic diagram. DETAILED DESCRIPTION

[0054] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0055] The present application provides a high-efficiency and low-cost interwell interference evaluation method for shale gas well groups, specifically comprising the following steps:

[0056] Step S10, identifying interwell interference conditions based on changes in well pressure and flow rate;

[0057] Step S11, during the fracturing operation of the fracturing well, the operation curve of the fracturing well is obtained in real time, the adjacent well is regarded as a monitoring well, and the fracturing operation curve of the monitoring well is also obtained;

[0058] Step S12, reading the pressure and flow rate changes on the operation curves of the fracturing well and the monitoring well;

[0059] When either of the pressure or flow rate in the monitoring well fluctuates (rises sharply within a short time (ten minutes)), or either of the pressure or flow rate in the fracturing well fluctuates (drops sharply (more than 10 MPa) momentarily), it is determined that interwell interference occurs, as shown in Figure 2

[0060] ​Step S20, after the fracturing operation is completed, tracer is injected into the reformed formation, and after sufficient well flushing, the tracer is flowed back, and the degree of interference between hydraulic fracture wells is evaluated according to the flow back of the tracer and the metering result of the tracer entering the monitoring well;

[0061] Step S21, a colored tracer (such as red ink) which does not have a physical and chemical reaction with the formation is selected as a solvent, and a gel solution used in the field fracturing is selected as a solution, and the two are mixed to form a tracer solution, as shown in Figure 3 ;

[0062] Step S22, the tracer solution is continuously pumped into the formation at a pump pressure lower than the formation breakdown pressure, and the total liquid volume of the tracer solution is greater than the total liquid volume of the fracturing operation, so as to ensure that the tracer solution can fully saturate the reformed reservoir, and the tracer solution appearing at the wellhead of the monitoring well is collected, as shown in Figure 4 ;

[0063] Step S23, after the well flushing is completed, a pump with a displacement not less than the pumping pump of the fracturing pump is arranged at the wellhead of the fracturing well, the tracer solution injected into the well of the fracturing well is pumped and flowed back to the wellhead, and the tracer solution is collected;

[0064] Step S24, considering the influence of the formation pressure and temperature, the two tracers are placed at room temperature, and then the amount of the tracer J0 returned to the fracturing well and the amount of the tracer J1 entering the adjacent monitoring well are metered respectively;

[0065] Step S25, the interference degree evaluation index J = J1 / J0 of the hydraulic fracture well interference is calculated according to the amount of the tracer J0 returned to the fracturing well and the amount of the tracer J1 entering the adjacent monitoring well, and the interference degree of the hydraulic fracture well interference is evaluated;

[0066] When J = 0, there is no hydraulic fracture well interference;

[0067] When 0 < J < 0.1, it is determined that the hydraulic fracture well interference is slight;

[0068] When 0.1 ≤ J < 0.25, it is determined that the hydraulic fracture well interference is moderate;

[0069] When J ≥ 0.25, it is determined that the hydraulic fracture well interference is severe;

[0070] Step S30, after the fracturing operation is completed, tracer particles are injected into the reformed formation, and after sufficient well flushing, the tracer particles are flowed back, and the degree of interference between hydraulic tension fracture wells is evaluated according to the flow back of the tracer particles and the metering result of the tracer particles entering the monitoring well;

[0071] Step S31, select the gel solution for field fracturing as the solution, and mix the insoluble inert tracer particles with the solution to form the tracer particle two-phase liquid;

[0072] Step S32, continuously pump the tracer particle two-phase liquid into the formation at a pressure lower than the formation fracture pressure, wherein the total liquid volume of the tracer particle two-phase liquid is greater than the total liquid volume of the fracturing operation, so as to ensure that the tracer particle two-phase liquid can fully saturate the reservoir after reconstruction, and the tracer particle two-phase liquid appearing in the monitoring well is collected, as shown in Figure 5 ;

[0073] Step S33, after the well flushing is completed, set a displacement pump with a displacement not less than the pumping capacity of the fracturing pump at the wellhead of the fracturing well, and pump the tracer particle two-phase liquid injected into the well of the fracturing well back to the wellhead and collect, as shown in Figure 6 ;

[0074] Step S34, considering the influence of formation pressure and temperature, place the two tracer particle two-phase liquids to room temperature, and then measure the weight K0 of the tracer particles returned to the fracturing well and the weight K1 of the tracer particles entering the adjacent monitoring well, respectively;

[0075] Step S35, calculate the hydraulic tensile fracture interwell interference degree evaluation index K = K1 / K0 according to the weight K0 of the tracer particles returned to the fracturing well and the weight K1 of the tracer particles entering the adjacent monitoring well, and evaluate the hydraulic tensile fracture interwell interference degree;

[0076] When K = 0, there is no hydraulic tensile fracture interwell interference;

[0077] When 0 < K < 0.1, it is determined as mild hydraulic tensile fracture interwell interference;

[0078] When 0.1 ≤ K < 0.25, it is determined as moderate hydraulic tensile fracture interwell interference;

[0079] When K ≥ 0.25, it is determined as severe hydraulic tensile fracture interwell interference;

[0080] Step S40, evaluate the interwell interference of the shale gas well group according to the measurement results of the tracer and the tracer particles returned and entering the monitoring well;

[0081] When J > 0 and K = 0, it is I-class interwell interference, and the pressure and flow changes of the two wells need to be paid attention to during subsequent fracturing;

[0082] When 0 < J < 0.1 and 0 < K < 0.1, it is II-class interwell interference, the current fracturing should be stopped immediately, and the liquid injection intensity should be reduced during subsequent fracturing;

[0083] When 0.1≤J<0.25 and 0<K<0.1, it is a third grade interwell interference, the current fracturing should be stopped immediately, and the adjacent production well needs to be shut in for at least one month to restore the pressure or increase the well spacing by 50m during the subsequent fracturing;

[0084] When 0.1≤J<0.25 and 0.1≤K<0.25, it is a fourth grade interwell interference, the current fracturing should be stopped immediately, and the adjacent production well needs to be shut in for at least six months to restore the pressure or increase the well spacing by 100m during the subsequent fracturing;

[0085] When J>0.25, it is a fifth grade interwell interference, the current fracturing should be stopped immediately, and the adjacent production well needs to be shut in for at least 12 months to restore the pressure or increase the well spacing by 200m during the subsequent fracturing.

[0086] Therefore, the efficient and low-cost interwell interference evaluation method for shale gas well groups can qualitatively and quantitatively evaluate the interwell interference of fracturing wells, avoid the problems of wellbore failure and capacity drop caused by interwell interference of fracturing, and greatly ensure the safety of wellbore and the capacity of single well; the combination of the construction curve in the fracturing process and the washing process before the post-fracturing production measurement realizes the combination of qualitative evaluation and quantitative evaluation of interwell interference, solves the defects of large error of traditional monitoring methods (which cannot effectively distinguish different types of interference cracks) and high cost of introducing additional construction equipment, and overcomes the high requirement of the tracer monitoring method in the traditional fracturing process for tracer materials (such as special acoustic emission particles).

[0087] The present application can not only distinguish different interwell interference forms by distinguishing hydraulic spread (small channels that liquid can enter) and hydraulic tension (large channels that solid particles can enter), but also give an interwell interference early warning grading scheme, support the effective prevention and control of interwell interference in the shale gas fracturing design and construction process, and improve the shale gas development potential.

[0088] The above description is not intended to limit the present application in any form, although the present application has been disclosed by the above examples, however, it is not intended to limit the present application, any skilled person in the art can make some changes or modifications for equivalent examples with the disclosed technical content without departing from the scope of the technical scheme of the present application, any simple modification, equivalent change and modification made to the above examples according to the technical essence of the present application, all still belong to the scope of the technical scheme of the present application.

Claims

1. A high-efficiency and low-cost method for evaluating interwell interference of shale gas well groups, characterized in that, The method comprises the following steps: Step S10, identifying the interwell interference based on the changes of the well pressure and flow rate; Step S20, injecting the tracer into the reformed formation after the fracturing operation is completed, and the tracer is flowed back after sufficient well flushing, and the degree of the hydraulic fracture interwell interference is evaluated according to the flow back of the tracer and the metering result of the tracer into the monitoring well; Step S30, injecting the tracer particles into the reformed formation after the fracturing operation is completed, and the tracer particles are flowed back after sufficient well flushing, and the degree of the hydraulic tensile fracture interwell interference is evaluated according to the flow back of the tracer particles and the metering result of the tracer particles into the monitoring well; Step S31, selecting the gel liquid used in the field fracturing as the solution, mixing the insoluble inert tracer particles with the solution to form the tracer particle two-phase liquid; Step S32, continuously pumping the tracer particle two-phase liquid into the formation at a pump pressure lower than the formation breakdown pressure, wherein the total liquid volume of the tracer particle two-phase liquid is greater than the total liquid volume of the fracturing operation, so as to ensure that the tracer particle two-phase liquid can fully saturate the reformed reservoir, and the tracer particle two-phase liquid appearing at the wellhead of the monitoring well is collected; Step S33, after well flushing is completed, setting a pump with a displacement not less than the pumping capacity of the fracturing pump at the wellhead of the fracturing well, pumping the tracer particle two-phase liquid injected into the well of the fracturing well to the wellhead and collecting; Step S34, metering the weight K0 of the tracer particles returned to the fracturing well and the weight K1 of the tracer particles into the adjacent monitoring well, respectively; Step S35, evaluating the degree of the hydraulic tensile fracture interwell interference according to the weight K0 of the tracer particles returned to the fracturing well and the weight K1 of the tracer particles into the adjacent monitoring well; Step S40, evaluating the interwell interference of the shale gas well group according to the flow back of the tracer and the tracer particles and the metering result of the tracer and the tracer particles into the monitoring well; When J>0 and K=0, it is I-level interwell interference, and the pressure and flow rate of the two wells need to be paid attention to during subsequent fracturing; When 0J<0.1 and 0<K<0.1, it is II-level interwell interference, the current fracturing should be stopped immediately, and the liquid injection intensity should be reduced during subsequent fracturing; When 0.1J<0.25 and 0<K<0.1, it is III-level interwell interference, the current fracturing should be stopped immediately, and the adjacent production well needs to be shut in for at least one month to restore the pressure or increase the well spacing by 50m during subsequent fracturing; When 0.1J<0.25 and 0.1<K<0.25, it is IV-level interwell interference, the current fracturing should be stopped immediately, and the adjacent production well needs to be shut in for at least six months to restore the pressure or increase the well spacing by 100m during subsequent fracturing; When J>0.25, it is V-level interwell interference, the current fracturing should be stopped immediately, and the adjacent production well needs to be shut in for at least 12 months to restore the pressure or increase the well spacing by 200m during subsequent fracturing.

2. The method according to claim 1, wherein, The specific process of the step S10 is as follows: Step S11, during the fracturing operation of the fracturing well, the operation curve of the fracturing well is obtained in real time, the adjacent well is regarded as a monitoring well, and the fracturing operation curve of the monitoring well is also obtained; Step S12, reading the pressure and flow rate changes on the operation curves of the fracturing well and the monitoring well; When any one of the pressure or flow rate in the monitoring well or the pressure or flow rate in the fractured well fluctuates, it is determined that the interwell interference occurs.

3. The method according to claim 1, wherein, The step S20 has the following specific process: In step S21, a colored tracer which does not have physical and chemical reaction with the formation is selected as the solvent, and a gel solution used in the field fracturing is selected as the solution, and the two are mixed to form the tracer solution; In step S22, the tracer solution is continuously pumped into the formation at a pressure lower than the formation breakdown pressure, and the total liquid volume of the tracer solution is greater than the total liquid volume of the fracturing operation, so as to ensure that the tracer solution can fully saturate the reservoir after the reconstruction, and the tracer solution appearing at the wellhead of the monitoring well is collected; In step S23, after the well flushing is completed, a pump with a displacement not less than the pumping pump of the fracturing pump is arranged at the wellhead of the fractured well, the tracer solution injected into the well of the fractured well is pumped back to the wellhead, and the tracer solution is collected; In step S24, the amount of the tracer J0 returned to the fractured well and the amount of the tracer J1 entering the adjacent monitoring well are measured respectively; In step S25, the degree of the hydraulic wave and fracture interwell interference is evaluated according to the amount of the tracer J0 returned to the fractured well and the amount of the tracer J1 entering the adjacent monitoring well.

4. The method according to claim 3, wherein, The colored tracer is red ink.

5. The method of claim 3, wherein, In step S24, the tracer solution in the monitoring well and the fractured well is allowed to stand to room temperature before the measurement.

6. The method of claim 3, wherein, In step S25, the degree of the hydraulic wave and fracture interwell interference is evaluated according to the amount of the tracer J0 returned to the fractured well and the amount of the tracer J1 entering the adjacent monitoring well. When J=0, there is no hydraulic wave and fracture interwell interference. When 0 When 0.1≤J<0.25, it is determined that the hydraulic wave and fracture interwell interference is moderate. When J≥0.25, it is determined that the hydraulic wave and fracture interwell interference is severe.

7. The method of claim 1, wherein, In step S34, the two-phase liquid of the tracer particles in the monitoring well and the fractured well is allowed to stand to room temperature before the measurement.

8. The method of claim 1, wherein, In step S35, the degree of the hydraulic tensile fracture interwell interference is evaluated according to the weight K0 of the tracer particles returned to the fractured well and the weight K1 of the tracer particles entering the adjacent monitoring well. When K=0, there is no hydraulic tensile fracture interwell interference. When 0 When 0.1≤K<0.25, it is determined that the hydraulic tensile fracture interwell interference is moderate. When K≥0.25, it is determined that the hydraulic tensile fracture interwell interference is severe.

Images