Gas Well Chemical-Assisted Well Selection Method and System

Abstract

This invention discloses a method and system for selecting gas wells using chemical-assisted drainage. The method includes: acquiring key data of the gas well; calculating the surplus score of the gas well based on the key data; and determining a suitable chemical-assisted drainage process for the gas well based on the surplus score. Using this invention, the effectiveness of chemical-assisted drainage processes for gas wells can be improved.

Description

Technical Field

[0001] This invention relates to the field of gas field production enhancement, specifically to a gas well chemical-assisted well selection method and system. Background Technology

[0002] For older gas wells that have been in development for some time, in addition to conventional drainage and gas production processes, there is also a method to increase production by injecting chemicals into the reservoir to resolve reservoir problems. The chemical-assisted drainage process for older wells involves injecting a drainage agent into the reservoir, along with nitrogen injection to propel the agent to a predetermined location. By providing lower surface tension, this process treats the reservoir, thereby increasing reservoir production. However, the success rate of implementing chemical-assisted drainage in older wells is currently low. Therefore, selectively choosing shale gas wells with development potential is crucial to improving the effectiveness of the chemical-assisted drainage process for older wells. Summary of the Invention

[0003] This invention provides a method and system for selecting gas wells using chemical-assisted drainage, in order to improve the effectiveness of the chemical-assisted drainage process in gas wells.

[0004] Therefore, the present invention provides the following technical solution:

[0005] A method for selecting gas wells using chemical-assisted drainage, the method comprising:

[0006] Obtain key data from gas wells;

[0007] The surplus score of the gas well is calculated based on the key data of the gas well.

[0008] The appropriate chemical drainage process for the gas well is determined based on the well's surplus score.

[0009] Optionally, the key data of the gas well includes any one or more of the following: the number of production days D at the start of the artificial intervention period. R ,Yield pressure Cumulative production days D t The casing pressure at the well has recovered to its highest value in the past 30 days. Highest yield during rapid drainage period Peak pressure during rapid drainage period Current production Well type J, recovery rate R.

[0010] Optionally, calculating the surplus score of the gas well based on the key data of the gas well includes:

[0011] The gas well is evaluated for different characteristics based on the key data of the gas well, and an evaluation score is obtained for each characteristic.

[0012] The surplus score of the gas well is calculated based on the evaluation scores of each corresponding feature.

[0013] Optionally, the step of evaluating the gas well based on the key data of the gas well to obtain evaluation scores for each feature includes any one or more of the following:

[0014] Calculate the ratio S1 between the current number of production days of the gas well and the starting point of the artificial intervention period;

[0015] Calculate the ratio S2 between the current production output of the gas well and the starting point of the artificial intervention period;

[0016] Calculate the ratio of the shut-in pressure to the average pressure during the artificial intervention period for the gas well, S3;

[0017] Calculate the reservoir remaining gas S4 of the gas well;

[0018] Calculate the baseline score S of the gas well. b .

[0019] Optionally, calculating the surplus score of the gas well based on the evaluation scores corresponding to each feature includes:

[0020] The surplus score S of the gas well is calculated using the following formula:

[0021] S = (S1 + S2 + S3 + S4) - S b .

[0022] Optionally, determining the appropriate chemical discharge assistance process for the gas well based on its surplus score includes:

[0023] If the surplus score of the gas well is positive, then the appropriate chemical drainage process for the gas well is determined to be the chemical drainage process for old wells.

[0024] Otherwise, the appropriate chemical drainage process for the gas well is determined manually.

[0025] Optionally, the method further includes:

[0026] The production stage of the gas well is determined, which includes three stages: rapid drainage period, self-flowing production period, and manual intervention period.

[0027] If the gas well is in a production stage prior to artificial intervention, then the appropriate chemical drainage process for the gas well is determined to be the old well chemical drainage process.

[0028] Optionally, determining the production stage of the gas well includes:

[0029] The production stage of the gas well is determined based on its bottomhole pressure coefficient and flowback rate; or

[0030] The production stage of the gas well is determined based on the inflection points of the flowback fluid curve and the cumulative gas production curve.

[0031] Optionally, the characteristic parameter range of the rapid drainage period is before the inflection point of the backflow rate curve; the characteristic parameter range of the self-spraying production period is the front end of both the cumulative output inflection point and the set time before the start of production; the starting point of the manual intervention period is the self-spraying production period.

[0032] A gas well reagent-assisted well selection system, the system comprising:

[0033] The data acquisition module is used to acquire key data from gas wells;

[0034] The calculation module is used to calculate the surplus score of the gas well based on the key data of the gas well;

[0035] The judgment module is used to determine the appropriate chemical drainage process for the gas well based on the surplus score of the gas well.

[0036] Optionally, the system further includes a prediction module for determining the production stage of the gas well, wherein the production stage of the gas well includes three stages: rapid drainage period, self-flowing production period, and artificial intervention period, and if the production stage of the gas well is before the artificial intervention period, the system determines that the appropriate chemical drainage process for the gas well is the chemical drainage process for old wells.

[0037] The present invention provides a method and system for selecting gas wells using chemical-assisted drainage, which acquires key data of the gas well, calculates the well's surplus score based on the key data, and determines the appropriate chemical-assisted drainage process for the gas well based on the surplus score. Using the solution of the present invention, the effectiveness of chemical-assisted drainage processes for gas wells can be improved.

[0038] Furthermore, the entire production cycle of shale gas wells is divided into different production stages. For gas wells in the pre-artificial intervention stage, the old well chemical drainage process can be directly used, thereby reducing unnecessary calculations and improving efficiency.

[0039] Using the solution of this invention, it is possible to quickly determine whether a gas well is suitable for chemical drainage process. This is a new method for judging the production potential of gas wells and also provides some ideas for handling other types of gas wells. Attached Figure Description

[0040] Figure 1 This is a flowchart of a gas well reagent-assisted well selection method provided by the present invention;

[0041] Figure 2 This is another flowchart of the gas well reagent-assisted well selection method provided by the present invention;

[0042] Figure 3 This is a schematic diagram of the flowback rate and cumulative gas production curve of a certain gas well;

[0043] Figure 4 This is a schematic diagram of a gas well reagent-assisted well selection system provided by the present invention;

[0044] Figure 5 This is another structural schematic diagram of the gas well reagent-assisted well selection system provided by the present invention;

[0045] Figure 6 The curves showing the flowback rate and cumulative gas production of well 2HX-3 in this invention example are shown. Detailed Implementation

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0048] In view of the low success rate of implementing chemical-assisted drainage technology in existing old wells, there is a need to selectively implement chemical-assisted drainage technology in shale gas wells with development potential. This invention provides a method and system for selecting gas wells for chemical-assisted drainage, which obtains key data of the gas well, calculates the surplus score of the gas well based on the key data, and determines the appropriate chemical-assisted drainage technology for the gas well based on the surplus score.

[0049] like Figure 1 The diagram shown is a flowchart of a gas well reagent-assisted well selection method provided by the present invention, which includes the following steps:

[0050] Step 101: Obtain key data from the gas well.

[0051] The key data for the gas well includes, but is not limited to, any one or more of the following: the number of production days at the start of the artificial intervention period (D). R ,Yield (For example, it could be the average yield over the 7 days following the start of the intervention period), pressure (For example, it could be the average pressure over the 7 days following the start of the intervention period). Cumulative production days D t The casing pressure at the well has recovered to its highest value in the past 30 days. Highest yield during rapid drainage period (For example, it could be the average yield over 7 days after the start of the artificial intervention period), or the highest pressure during the rapid drainage period. (For example, it could be the average pressure over 7 days after the start of the self-flowing drainage period), current production capacity. Well type J (e.g., 0.44 for upward-inclined wells, 0.56 for downward-inclined wells, and 1 for vertical wells), and production rate R.

[0052] Step 102: Calculate the surplus score of the gas well based on the key data of the gas well.

[0053] Specifically, the gas well can be evaluated for different characteristics based on the key data of the gas well to obtain the evaluation score for each characteristic; then the surplus score of the gas well can be calculated based on the evaluation score for each characteristic.

[0054] The evaluation of the gas well based on its key data, and the resulting evaluation scores for each feature, may include, but are not limited to, any one or more of the following:

[0055] (1) Calculate the ratio S1 between the current number of production days of the gas well and the starting point of the artificial intervention period, i.e. The closer to the start of the artificial intervention period, the higher the S1 score. This is because the closer to the start of the artificial intervention period, the better the gas well is in a high-production stage, the greater the gas reservoir energy, and the greater the likelihood of successful implementation of chemical-assisted drainage measures.

[0056] (2) Calculate the ratio S2 between the current production output of the gas well and the production output at the start of the artificial intervention period, i.e. The closer the two production levels are, the better the gas well is in a high-production stage, the greater the gas reservoir energy, and the greater the likelihood of successful chemical-assisted drainage measures.

[0057] (3) Calculate the ratio S3 of the shut-in pressure to the average pressure during the artificial intervention period of the gas well, i.e. The higher the S3 value, the more it indicates that the reservoir still has high gas layer energy, which helps to increase production after the agent-assisted drainage.

[0058] (4) The remaining gas in the reservoir of the gas well, S4, can be calculated using the following formula: S4 = 10(1-R) ​​× J; the greater the recovery rate, the smaller the score of this item.

[0059] (5) Calculate the baseline score S of the gas well. b .

[0060] Benchmark S b The calculation is as follows:

[0061] S b =S1'+S2'+S3'+S4';

[0062] The calculation formulas for S1', S2', S3', and S4' are the same as those for S1, S2, S3, and S4 mentioned above. For example, based on experience, 1-R = 0.5 can be set.

[0063]

[0064] The baseline scores for different types of wells can then be calculated: 5.5 for upsloping wells, 7.2 for downsloping wells, and 12.5 for vertical wells.

[0065] Accordingly, the surplus score S of the gas well can be calculated using the following formula:

[0066] S = (S1 + S2 + S3 + S4) - S b .

[0067] It should be noted that the above method for calculating the surplus score of gas wells is only an illustrative example. In practical applications, other methods can be adopted according to application needs, and this embodiment of the invention does not limit the scope of the invention.

[0068] Step 103: Determine the appropriate chemical discharge process for the gas well based on the surplus score of the gas well.

[0069] The surplus score of the gas well calculated in step 102 above represents the production potential of the gas well when implementing the old well chemical drainage process; the higher the score, the greater the potential.

[0070] Therefore, the appropriate chemical drainage process for the gas well can be determined as follows: if the surplus score of the gas well is positive, then the appropriate chemical drainage process for the gas well is determined to be the chemical drainage process for old wells; otherwise, the appropriate chemical drainage process for the gas well can be determined by manual judgment.

[0071] The gas well chemical-assisted drainage method of this invention calculates the well's surplus score using key gas well data, and determines the appropriate chemical-assisted drainage process based on the calculated surplus score. Using this invention, it is possible to quickly determine whether a gas well is suitable for chemical-assisted drainage, thereby improving gas well operation efficiency.

[0072] Furthermore, considering that gas wells at different production stages have different characteristics, it is possible to directly determine whether some gas wells can use the old well chemical-assisted drainage process based on their production stage. This will be discussed in the following section. Figure 2 Provide a detailed explanation.

[0073] like Figure 2 The diagram shown is another flowchart of the gas well reagent-assisted well selection method provided by the present invention, which includes the following steps:

[0074] Step 201: Select the gas well to be determined.

[0075] Step 202: Determine the production stage of the gas well. If the gas well is in a production stage prior to artificial intervention, proceed to step 203; otherwise, proceed to step 204.

[0076] In a non-limiting embodiment, the bottom hole pressure coefficient B can be used. wf and return rate R R Using these as characteristic parameters, the entire production cycle of shale gas wells is divided into three stages: rapid fluid discharge period, self-flowing production period, and artificial intervention period. Among them:

[0077] The characteristic parameters of the rapid drainage period are within the range before the inflection point of the backflow rate curve.

[0078] The characteristic parameters of the self-spraying production period are the first of two: the cumulative output inflection point and the time set before the start of production (e.g., 24 hours).

[0079] The period of manual intervention begins during the self-spraying production period.

[0080] like Figure 3 As shown, curves represent the flowback rate and cumulative gas production of a gas well. Curve 31 is the flowback fluid curve, and curve 32 is the cumulative gas production curve.

[0081] Based on the bottomhole pressure coefficient and flowback rate, for example, the characteristic parameter range for the rapid fluid discharge period can be set as 1≤B. wf And R R <0.3, the characteristic parameter range during the self-spraying production period is 0.5≤B wf <1 and 0.3≤R R <1, The characteristic parameter range of the artificial production period is B wf <0.5 and R R >1.

[0082] Considering that a single numerical definition method cannot encompass and accurately describe the production status of all gas wells, in another non-limiting embodiment, the rapid drainage period can be determined by using the curve inflection point method, and the self-flowing production period can be determined by using the judgment method where the cumulative production inflection point and the continuous production inflection point are relatively earlier.

[0083] Combination Figure 3 As shown, the rapid discharge period of the gas well is determined by using inflection point A of curve 31 as the dividing point, and the earlier inflection point B between curve 32 and curve 31 (inflection point B) is used as the dividing point to determine the self-flowing production period of the gas well. That is:

[0084] Before inflection point A, there is a rapid drainage period. During this period, the self-spraying output is high and the water carrying capacity is extremely strong. The production capacity is minimally affected by the accumulation of liquid. During this period, there is no human intervention involved in the chemical-assisted drainage construction.

[0085] The period between inflection points A and B is the self-flowing production period. During this time, the self-flowing output can fully meet the fluid carrying requirements of the gas well, and there will be no problems such as reservoir fluid accumulation in the early stages. However, as the reservoir pressure decreases, the gas volume of the gas well also decreases, and the water carrying capacity of the gas well declines. Fluid accumulation often occurs in the later stages of this period, which can lead to a series of other problems. Therefore, artificial intervention with chemical drainage measures is often required at the end of this stage.

[0086] Accordingly, when determining the production stage of a gas well, the bottom hole pressure coefficient and flowback rate can be used as characteristic parameters. Specifically, the stage can be determined based on the range of the aforementioned characteristic parameters or the inflection point of the corresponding flowback fluid curve and cumulative gas production curve; however, this embodiment of the invention does not limit this determination.

[0087] For gas wells that are still in the pre-artificial intervention phase, the old well chemical-assisted drainage process can be directly adopted. For gas wells in the artificial intervention phase, the surplus score of the gas well needs to be calculated to determine whether the old well chemical-assisted drainage process is recommended, i.e., to proceed with the subsequent steps.

[0088] Continue to refer to Figure 2 In step 203, it is determined that the suitable chemical drainage process for the gas well is the old well chemical drainage process. Otherwise, proceed to step 204.

[0089] Step 204: Obtain key data from the gas well.

[0090] Step 205: Calculate the surplus score of the gas well based on the key data of the gas well.

[0091] Step 206: Determine the appropriate chemical drainage process for the gas well based on the surplus score of the gas well.

[0092] Steps 203 to 205 above and Figure 1 Steps 101 to 103 shown are the same and will not be repeated here.

[0093] The gas well chemical-assisted drainage well selection method provided in this embodiment of the invention divides the entire production cycle of shale gas wells into different production stages. For gas wells in the pre-artificial intervention stage, the old well chemical-assisted drainage process can be directly used, thereby reducing unnecessary calculations and improving efficiency.

[0094] The following example, using the Weiyuan 2HX-3 well in Sichuan, further illustrates the process of determining whether the old well chemical drainage process can be used in gas wells using the method of the present invention.

[0095] like Figure 6 The figure shows the flowback rate and cumulative gas production curves of well 2HX-3.

[0096] according to Figure 6 The flowback rate and cumulative gas production curves of well 2HX-3 show that the rapid drainage period is 127 days after production, the self-flowing production period is 333 days after production, followed by the artificial intervention period. Well 2HX-3 is currently in the artificial intervention period. Therefore, it is necessary to calculate the surplus score of well 2HX-3 to determine whether the old well chemical-assisted drainage process can be used.

[0097] First, the key data obtained from well 2HX-3 are as follows:

[0098] Production days D at the start of the artificial intervention period R It lasted 333 days;

[0099] Production at the start of the artificial intervention period It is 57,300 cubic meters per day;

[0100] Pressure at the beginning of the artificial intervention period It is 5.28 MPa;

[0101] Cumulative production days D t It lasted 1593 days;

[0102] The casing pressure at the well shut-in point has recovered to its highest value in the past 30 days. It is 2.15 MPa;

[0103] Highest yield during rapid drainage period It is 151,800 cubic meters per day;

[0104] Peak pressure during rapid drainage period It is 12.86 MPa;

[0105] Current production It is 0.35 million cubic meters per day;

[0106] The well type is a downsloping well, and the corresponding parameter J is 0.56;

[0107] The extraction rate R = 0.35.

[0108] Based on the key data above, calculate the gas well surplus score:

[0109]

[0110] If the calculated well surplus score is greater than 0, it is recommended to implement the old well chemical drainage process for this well.

[0111] By implementing a chemical-assisted drainage process on the well, the average daily production increased by 7,400 cubic meters per day, with the measure effective for 52 days, resulting in a cumulative increase in gas production of 203,400 cubic meters.

[0112] Accordingly, the present invention also provides a gas well reagent-assisted well selection system, such as... Figure 4 The diagram shown is a structural schematic of the system.

[0113] The gas well chemical-assisted well selection system 400 includes the following modules:

[0114] Data acquisition module 401 is used to acquire key data from gas wells;

[0115] The calculation module 402 is used to calculate the surplus score of the gas well based on the key data of the gas well;

[0116] The judgment module 403 is used to determine the appropriate chemical drainage process for the gas well based on the surplus score of the gas well.

[0117] like Figure 5 The diagram shown is another structural schematic of the gas well reagent-assisted well selection system of the present invention.

[0118] and Figure 4 The difference between the illustrated embodiment and the gas well chemical-assisted well selection system 400 in this embodiment further includes:

[0119] The prediction module 501 is used to determine the production stage of the gas well, which includes three stages: rapid drainage period, self-flowing production period, and manual intervention period. If the gas well is in a production stage prior to the manual intervention period, the module determines that the suitable chemical drainage process for the gas well is the old well chemical drainage process. If the gas well is in a production stage of manual intervention, the data acquisition module 401 is triggered to acquire key data of the gas well, and then performs corresponding calculations based on the key data to determine the suitable chemical drainage process for the gas well.

[0120] For further descriptions of the modules and units in the gas well reagent-assisted well selection system of the present invention, please refer to the corresponding descriptions in the previous embodiments of the method of the present invention, which will not be repeated here.

[0121] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0122] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. Furthermore, the system embodiments described above are merely illustrative. The modules and units described as separate components may or may not be physically separate; that is, they may be located on a single network unit or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0123] The embodiments of the present invention have been described in detail above. Specific implementation methods have been used to illustrate the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and systems of the present invention, and are merely some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention, and the content of this specification should not be construed as a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for selecting gas wells using chemical-assisted drainage, characterized in that, The method includes: Obtain key data from gas wells; The surplus score of the gas well is calculated based on the key data of the gas well. The appropriate chemical drainage process for the gas well is determined based on the well's surplus score. The key data for the gas well includes any one or more of the following: the number of production days at the start of the artificial intervention period. ,Yield ,pressure Cumulative production days The casing pressure at the well has recovered to its highest value in the past 30 days. Highest yield during rapid drainage period Peak pressure during rapid drainage period Current production Well type Extraction degree R; The calculation of the gas well's surplus score based on the key data of the gas well includes: The gas well is evaluated for different characteristics based on the key data of the gas well, and an evaluation score is obtained for each characteristic. The surplus score of the gas well is calculated based on the evaluation scores of each corresponding feature; The evaluation of the gas well based on its key data, yielding evaluation scores for each feature, includes any one or more of the following: Calculate the ratio between the current number of production days of the gas well and the number of production days at the start of the artificial intervention period. ; Calculate the ratio between the current production output of the gas well and the production output at the start of the artificial intervention period. ; Calculate the ratio of the shut-in pressure to the average pressure during the artificial intervention period for the gas well. ; Calculate the reservoir remaining gas of the gas well. Calculate using the following formula: ； Calculate the benchmark score of the gas well. ; Benchmark score The calculation is as follows: ; in, The calculation formula is the same as the above. The calculation formula is the same; calculation The parameter values ​​involved are set based on experience; The calculation of the gas well's surplus score based on the evaluation scores corresponding to each feature includes: The surplus score of the gas well is calculated using the following formula. : ； The step of determining the appropriate chemical discharge assistance process for the gas well based on its surplus score includes: If the surplus score of the gas well is positive, then the appropriate chemical drainage process for the gas well is determined to be the chemical drainage process for old wells. Otherwise, the appropriate chemical drainage process for the gas well is determined manually.

2. The gas well chemical-assisted well selection method according to claim 1, characterized in that, The method further includes: The production stage of the gas well is determined, which includes three stages: rapid drainage period, self-flowing production period, and manual intervention period. If the gas well is in a production stage prior to artificial intervention, then the appropriate chemical drainage process for the gas well is determined to be the old well chemical drainage process.

3. The gas well chemical-assisted well selection method according to claim 2, characterized in that, Determining the production stage of a gas well includes: The production stage of the gas well is determined based on its bottomhole pressure coefficient and flowback rate; or The production stage of the gas well is determined based on the inflection points of the flowback fluid curve and the cumulative gas production curve.

4. The gas well chemical-assisted well selection method according to claim 3, characterized in that, The characteristic parameters of the rapid drainage period are within the range before the inflection point of the backflow rate curve. The characteristic parameter range of the self-spraying production period is the front end of both the cumulative output inflection point and the set time before the start of production. The starting point of the manual intervention period is the self-spraying production period.

5. A gas well chemical-assisted well selection system according to claim 1, characterized in that, The system includes: The data acquisition module is used to acquire key data from gas wells; The calculation module is used to calculate the surplus score of the gas well based on the key data of the gas well; The judgment module is used to determine the appropriate chemical drainage process for the gas well based on the surplus score of the gas well.

6. The gas well chemical-assisted well selection system according to claim 5, characterized in that, The system also includes: The prediction module is used to determine the production stage of the gas well, which includes three production stages: rapid drainage period, self-flowing production period, and artificial intervention period. If the gas well is in a production stage before the artificial intervention period, the module determines that the appropriate chemical drainage process for the gas well is the chemical drainage process for old wells.

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