A method for determining a well spacing for primary development of a conventional gas reservoir

Abstract

This invention relates to the field of oil and gas reserve assessment technology, and in particular to a method for determining the well spacing for primary development of conventional gas reservoirs. The method involves obtaining basic data files of sample wells; time-normalizing the stable daily production of the sample wells to establish the relationship between dynamic reserves and stable daily production; calculating the dynamic reserves of target wells based on this relationship; calculating the corresponding primary development well spacing using the dynamic reserves of the target wells; and finally, calculating the primary development well spacing of the target gas reservoir using the calculated primary development well spacing of the target wells. This method effectively solves the problem of inaccurate calculation of the primary development well spacing for assessing SEC reserves in the early stages of conventional gas reservoir development. It improves the reliability of assessment results and reduces exploration and development investment risks.

Description

Technical Field

[0001] This invention relates to the field of oil and gas reserve assessment technology, and in particular to a method for determining the well spacing in a single development of a conventional gas reservoir. Background Technology

[0002] Gas-bearing area is a key parameter for assessing SEC expansion and newly discovered reserves using the volumetric method, and determining the gas-bearing area hinges on determining the well spacing during primary development. Primary development well spacing refers to the average well spacing during the initial, uninfiltrated phase of a gas reservoir, directly reflecting the size of well-controlled reserves under specific development technology conditions. However, in the early stages of reservoir or block development, with limited well test data and scarce production dynamics data, it is often difficult to directly calculate and determine well-controlled reserves using existing technology. Therefore, it is impossible to accurately determine the primary development well spacing. SEC assessors typically use the neighboring area analogy method or the analogy gas reservoir comparison method to determine the primary development well spacing. This mainstream approach is highly dependent on the assessor's skill and experience, making it difficult to guarantee the reliability of the assessment results. This results in low reliability of SEC reserve assessments. SEC reserves, also known as listed reserves, specifically refer to reserve assets listed in the United States and subject to audit and regulation by the SEC. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a method for determining the well spacing in the first development of conventional gas reservoirs. This method effectively solves the problem of inaccurate calculation of the well spacing in the first development of conventional gas reservoirs when assessing SEC reserves. This method can improve the reliability of the assessment results and reduce the investment risk of exploration and development.

[0004] This invention is achieved by adopting the following technical solution:

[0005] A method for determining the well spacing in the primary development of a conventional gas reservoir, characterized by the following steps:

[0006] S1. Obtain the basic data file of the sample well, which includes the stable daily production, stable production time and dynamic reserves of the sample well;

[0007] S2. Time normalize the stable daily production of the sample wells to establish the relationship between dynamic reserves and stable daily production;

[0008] S3. Calculate the dynamic reserves G of the target well by analyzing the relationship between dynamic reserves and stable daily production. a ;

[0009] S4. Calculate the corresponding primary development well spacing D using the dynamic reserves of the target well. a :

[0010]

[0011] Among them, Ω a The abundance of reserves in the area where the target well is located;

[0012] S5. The initial development well spacing D calculated using the target single well. a Calculate the initial development well spacing of the target gas reservoir.

[0013] The time normalization of the stable daily production of the sample well in step S2 specifically includes:

[0014] S 21 Calculate the average stable production time t for all sample wells. wa ;

[0015] S 22 Based on the average stable production time t wa Calculate the normalized steady-state daily output q wi :

[0016]

[0017] Where, q wi Normalized stable daily production of sample wells; q w For the stable daily production of the sample well; t wa t represents the average stable production time of the sample wells. w This represents the stable production period of the sample well.

[0018] The relationship between dynamic reserves and stable daily production in step S2 is obtained by fitting using the least squares method, and the relationship is as follows:

[0019]

[0020] Among them, G s The dynamic reserves of the sample well are represented by C, and q is a coefficient. wi To normalize the stable daily production of the sample wells.

[0021] Step S3 specifically refers to: drawing a chart based on the relationship between dynamic reserves and stable daily production, and calculating the dynamic reserves G of the target single well based on the chart. a .

[0022] The dynamic reserves G of the target well a The specific method for obtaining it is as follows:

[0023]

[0024] Where, q wia The goal is to normalize and stabilize the daily production of a single well.

[0025] The target single-well normalized stable daily production is obtained by time normalization of the stable daily production designed according to the development plan or pilot production plan, that is:

[0026]

[0027] Where, q wa The target stable daily production per well as predicted based on the development plan or pilot production plan; t wp For the target stable production period of a single well predicted in the development plan or pilot production plan, t wa This represents the average stable production time.

[0028] Step S5 specifically refers to using the average value of the primary development well spacing calculated for the target single well as the primary development well spacing for the target gas reservoir.

[0029] The term "first-stage development well spacing" specifically refers to the average development well spacing of a gas reservoir before it is fully developed and densified.

[0030] A device for determining the well spacing in a conventional gas reservoir development, characterized in that it comprises:

[0031] The acquisition module is used to acquire and store the stable daily production, stable production time and dynamic reserves of sample wells, as well as to acquire the stable daily production, stable production period and stable production time of target single wells;

[0032] The normalization module is used to perform time normalization on the stable daily production of the sample wells to obtain the normalized stable daily production of the sample wells.

[0033] The first data processing module is used to fit the relationship between dynamic reserves and stable daily production based on the normalized stable daily production and dynamic reserves of the sample wells using the least squares method.

[0034] The second data processing module is used to calculate the dynamic reserves of the target single well based on the relationship between dynamic reserves and stable daily production.

[0035] The first determining module is used to determine the corresponding primary development well spacing using the dynamic reserves of the target single well;

[0036] The second determining module is used to determine the primary development well spacing of the target gas reservoir based on the primary development well spacing determined by the target single well.

[0037] It also includes a chart generation module, which generates a corresponding chart based on the relationship between dynamic reserves and stable daily production; the second data processing module is used to calculate the dynamic reserves of the target single well based on the chart.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. This invention solves the problem of low reliability in conventional gas reservoir reserve assessments due to the inaccurate calculation of the first-stage development well spacing. It improves the reliability of assessment results and reduces exploration and development investment risks. Comparing this method with the analogy method, the first-stage development well spacing determined by this method matches the results verified by international SEC reserve assessment agencies. However, using the analogy method to determine the gas-bearing area results in a gas-bearing area that is 2.25 times the actual area, leading to an inflated reserve assessment. This results in a significant reduction in reserves after development, posing a huge risk to exploration and development investment and reducing the competitiveness of oil and gas production and operation companies in the international capital market. Attached Figure Description

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein:

[0041] Figure 1 This is a schematic diagram of the process of the present invention;

[0042] Figure 2 This is a schematic diagram drawn in this invention. Detailed Implementation

[0043] Example 1

[0044] As a basic embodiment of the present invention, the present invention includes a method for determining the well spacing in the primary development of a conventional gas reservoir, comprising the following steps:

[0045] S1. Obtain basic data files for the sample wells, including the stable daily production, stable production time, and dynamic reserves of the sample wells.

[0046] S2. Time normalize the stable daily production of the sample wells to establish the relationship between dynamic reserves and stable daily production.

[0047] S3. Calculate the dynamic reserves G of the target well by analyzing the relationship between dynamic reserves and stable daily production. a .

[0048] S4. Calculate the corresponding primary development well spacing D using the dynamic reserves of the target well. a :

[0049]

[0050] Among them, Ω a The reserve abundance in the area where the target well is located is used. The single-development well spacing specifically refers to the average development well spacing of the gas reservoir before it is fully developed and densified.

[0051] S5. The initial development well spacing D calculated using the target single well. a Calculate the initial development well spacing of the target gas reservoir.

[0052] Example 2

[0053] In a preferred embodiment of the present invention, the present invention includes a method for determining the well spacing in the primary development of a conventional gas reservoir, comprising the following steps:

[0054] S1. Obtain basic data files for the sample wells, including the stable daily production, stable production time, and dynamic reserves of the sample wells.

[0055] S2. Time normalize the stable daily production of the sample wells to establish the relationship between dynamic reserves and stable daily production, specifically:

[0056] S 21 Calculate the average stable production time t for all sample wells. wa .

[0057] S 22 Based on the average stable production time t wa Calculate the normalized steady-state daily output q wi :

[0058]

[0059] Where, q wi Normalized stable daily production of sample wells; q w For the stable daily production of the sample well; t wa t represents the average stable production time of the sample wells. w The sample well's stable production period is determined by reading the actual production data of the gas well from the start of stable production to the decline period.

[0060] S 23 The relationship between dynamic reserves and stable daily production was obtained by fitting using the least squares method. This relationship is as follows:

[0061]

[0062] Among them, G s The dynamic reserves of the sample well are represented by C, and q is a coefficient. wi To normalize the stable daily production of the sample wells.

[0063] S3. Calculate the dynamic reserves G of the target well by analyzing the relationship between dynamic reserves and stable daily production. a .

[0064] S4. Calculate the corresponding primary development well spacing D using the dynamic reserves of the target well. a :

[0065]

[0066] Among them, Ω aThe reserve abundance in the area where the target well is located is used. The single-development well spacing specifically refers to the average development well spacing of the gas reservoir before it is fully developed and densified.

[0067] S5. The initial development well spacing D calculated using the target single well. a Calculate the initial development well spacing of the target gas reservoir.

[0068] Example 3

[0069] In another preferred embodiment of the present invention, the present invention includes a method for determining the well spacing in the primary development of a conventional gas reservoir, comprising the following steps:

[0070] S1. Obtain the basic data file of the sample well; the basic data file includes the stable daily production, stable production time and dynamic reserves of the sample well.

[0071] S2. Time normalize the stable daily production of the sample wells and establish the relationship between dynamic reserves and stable daily production by fitting the data using the least squares method.

[0072] S3. By analyzing the relationship between dynamic reserves and stable daily production, draw a chart, and calculate the dynamic reserves G of the target single well based on the chart. a .

[0073] S4. Calculate the corresponding primary development well spacing D using the dynamic reserves of the target well. a :

[0074]

[0075] Among them, Ω a The abundance of reserves in the area where the target well is located.

[0076] S5. The initial development well spacing D calculated using the target single well. a The average value is used to calculate the primary development well spacing of the target gas reservoir. Specifically, the primary development well spacing refers to the average development well spacing of the gas reservoir before infill drilling is completed.

[0077] Example 4

[0078] As the preferred embodiment of the present invention, please refer to the appendix to the specification. Figure 1 This invention includes a method for determining the well spacing in the primary development of a conventional gas reservoir, comprising the following steps:

[0079] S1. Obtain the basic data file of the sample well, which includes the stable daily production, stable production time and dynamic reserves of the sample well, and the sample well includes the sample gas reservoir or gas field well.

[0080] S2. Time normalize the stable daily production of the sample wells to establish the relationship between dynamic reserves and stable daily production. Specifically, this includes:

[0081] S 21 Calculate the average stable production time t for all sample wells. wa .

[0082] S 22 Based on the average stable production time t wa Calculate the normalized steady-state daily output q wi :

[0083]

[0084] Where, q wi To normalize the stable daily production of the sample wells, 10 4 m 3 / d;q w To ensure stable daily production of the sample wells, 10 4 m 3 / d;t wa t represents the average stable production time of the sample wells. w Let a be the stable production period of the sample well. The stable production period of the sample well is determined based on the actual production data of the gas well, from the start of stable production to the decline period.

[0085] S 23 The relationship between dynamic reserves and stable daily production was obtained by fitting using the least squares method, and a graph was plotted.

[0086] The relationship between dynamic reserves and stable daily production is as follows:

[0087]

[0088] Among them, G s For the dynamic reserves of the sample well, 10 8 m 3 C is the coefficient, q wi To normalize the stable daily production of the sample wells.

[0089] S3. Use the chart to determine the dynamic reserves G of the target well. a :

[0090]

[0091] Among them, G a For the target single-well dynamic reserves, 10 8 m 3 q wia To achieve a normalized and stable daily production rate for a single well, 10 4 m 3 / d. Where q wia The target single-well normalized stable daily production rate, obtained by time normalization of the stable daily production rate designed according to the development plan or pilot production plan, is as follows:

[0092]

[0093] Where, q wa To achieve the target stable daily production per well as predicted by the development or pilot production plan, 10 4 m 3 / d;t wp a, t are the target stable production period for a single well predicted for the development or pilot production plan. wa This represents the average stable production time.

[0094] S4. Calculate the corresponding primary development well spacing D using the dynamic reserves of the target well. a :

[0095]

[0096] Among them, Ω a For the reserve abundance of the area where the target well is located, 10 8 m 3 / km 2 D a The first-stage development well spacing is calculated for a target single well, in km. Reserve abundance can be found in oil and gas company reserve reports; or it can be estimated or found from existing, officially recognized volumetric reserve calculations: Geological reserve abundance = Geological reserves / Gas-bearing area. Specifically, the first-stage development well spacing refers to the average development well spacing of the gas reservoir before infill drilling is completed.

[0097] S5. The average well spacing for primary development of the target gas reservoir is taken as the average well spacing for primary development of the target gas reservoir.

[0098] Taking gas field C as an example, the Carboniferous system in block A of this gas field is in the late stage of development, with a total of 122 producing wells, all of which are in a declining phase. Eleven of these wells are used as sample wells, and ten as verification wells. The relationship between dynamic reserves and stable daily production is established as follows:

[0099] G s =0.776q wi 1.006 ,

[0100] The created diagram is shown in the instruction manual. Figure 2 As shown.

[0101] The dynamic reserves and well spacing for primary development of the gas reservoirs of the 10 verification wells calculated using the above method are shown in the table below:

[0102]

[0103] The international SEC reserves assessment agency, when evaluating the annual expansion and new discoveries of the block, used a well spacing of 1.2 km for primary development, which is consistent with the actual gas reservoir development plan. However, the well spacing determined by analogy is 1.8 km. If 1.8 km is used as the primary development well spacing to delineate the gas-bearing area, the resulting gas-bearing area will be 2.25 times the actual area, leading to an inflated reserves assessment. This would result in a significant reduction in reserves after development, posing a huge risk to exploration and development investment and reducing the competitiveness of oil and gas production and operation companies in the international capital market.

[0104] Example 5

[0105] In another preferred embodiment of the present invention, the present invention includes a device for determining the well spacing in a conventional gas reservoir primary development, comprising:

[0106] The acquisition module is used to acquire and store the stable daily production, stable production time and dynamic reserves of sample wells, as well as to acquire the stable daily production, stable production period and stable production time of target single wells.

[0107] The normalization module is used to perform time normalization on the stable daily production of the sample wells to obtain the normalized stable daily production of the sample wells.

[0108] The first data processing module is used to fit the relationship between dynamic reserves and stable daily production based on the normalized stable daily production and dynamic reserves of the sample wells using the least squares method.

[0109] The chart generation module is used to generate corresponding charts based on the relationship between dynamic reserves and stable daily production.

[0110] The second data processing module is used to calculate the dynamic reserves of the target single well based on the chart.

[0111] The first determining module is used to determine the corresponding primary development well spacing using the dynamic reserves of the target single well.

[0112] The second determining module is used to determine the primary development well spacing of the target gas reservoir based on the primary development well spacing determined by the target single well.

[0113] In summary, any other corresponding modifications made by those skilled in the art after reading this invention document, without requiring creative mental effort, based on the technical solutions and concepts of this invention, are all within the scope of protection of this invention.

Claims

1. A method for determining the well spacing in a single development of a conventional gas reservoir, characterized in that: Includes the following steps: S1. Obtain the basic data file of the sample well, which includes the stable daily production, stable production time and dynamic reserves of the sample well; S2. Time normalize the stable daily production of the sample wells to establish the relationship between dynamic reserves and stable daily production; S3. Calculate the dynamic reserves G of the target well by analyzing the relationship between dynamic reserves and stable daily production. a Specifically, this refers to: drawing a chart based on the relationship between dynamic reserves and stable daily production, and then calculating the dynamic reserves G of the target single well based on the chart. a : ， where q wia is the target normalized stabilized daily production for a single well; S4. Calculate the corresponding primary well spacing D using the dynamic reserves of the target single well a : ， Among them, Ω a The abundance of reserves in the area where the target well is located; S5. Using the calculated primary development well spacing D for the target single well a Calculate the primary development well spacing for the target gas reservoir; The time normalization of the stable daily production of the sample well in step S2 specifically includes: S 21 . Calculate the average stabilized production time t for all sample wells wa ; S 22 . According to the average stable production time t wa The normalized stable daily production q wi : ， Where, q wi Normalized stable daily production of sample wells; q w For the stable daily production of the sample well; t wa t represents the average stable production time of the sample wells. w This is the stable production period for gas wells; The relationship between dynamic reserves and stable daily production in step S2 is obtained by fitting using the least squares method, and the relationship is as follows: ， Among them, G s The dynamic reserves of the sample well are represented by C, and q is a coefficient. wi To normalize the stable daily production of the sample wells.

2. The method for determining the well spacing in a conventional gas reservoir during primary development according to claim 1, characterized in that: The target single-well normalized stable daily production is obtained by time normalization of the stable daily production designed according to the development plan or pilot production plan, that is: ， Where, q wa The target stable daily production per well as predicted based on the development plan or pilot production plan; t wp For the target stable production period of a single well predicted in the development plan or pilot production plan, t wa This represents the average stable production time.

3. The method for determining the well spacing in a conventional gas reservoir during primary development according to claim 1, characterized in that: Step S5 specifically refers to using the average value of the primary development well spacing calculated for the target single well as the primary development well spacing for the target gas reservoir.

4. The device for determining the well spacing in a conventional gas reservoir during primary development according to claim 1, characterized in that: The term "first-stage development well spacing" specifically refers to the average development well spacing of a gas reservoir before it is fully developed and densified.

5. A device for determining the well spacing in a conventional gas reservoir during primary development, characterized in that: include: The acquisition module is used to acquire and store the stable daily production, stable production time and dynamic reserves of sample wells, as well as to acquire the stable daily production, stable production period and stable production time of target single wells; The normalization module is used to perform time normalization on the stable daily production of the sample wells, obtaining the normalized stable daily production of the sample wells; specifically... include: S 21 Calculate the average stable production time t for all sample wells. wa ; S 22 Based on the average stable production time t wa Calculate the normalized steady-state daily output q wi : ， Where, q wi Normalized stable daily production of sample wells; q w For the stable daily production of the sample well; t wa t represents the average stable production time of the sample wells. w This is the stable production period for gas wells; The first data processing module is used to fit the relationship between dynamic reserves and stable daily production based on the normalized stable daily production and dynamic reserves of the sample wells using the least squares method; the relationship is as follows: ， Among them, G s The dynamic reserves of the sample well are represented by C, and q is a coefficient. wi To normalize the stable daily production of the sample wells; The second data processing module is used to calculate the dynamic reserves of the target well based on the relationship between dynamic reserves and stable daily production. Specifically, it involves plotting a graph based on the relationship between dynamic reserves and stable daily production, and then calculating the dynamic reserves G of the target well based on the graph. a : ， Where, q wia To achieve a normalized and stable daily production rate for a single well; The first determining module is used to determine the corresponding primary development well spacing using the dynamic reserves of the target single well; The second determining module is used to determine the primary development well spacing of the target gas reservoir based on the primary development well spacing determined by the target single well.

6. The device for determining the well spacing in a conventional gas reservoir during primary development according to claim 5, characterized in that: It also includes a chart generation module, which generates a corresponding chart based on the relationship between dynamic reserves and stable daily production; the second data processing module is used to calculate the dynamic reserves of the target single well based on the chart.

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