Method, system and equipment for identifying free gas well in deep coal reservoir and medium
By calculating the comparison of the gas mining index change curve and typical characteristic curve, the accurate identification of free gas wells in the deep coal reservoir has solved the problem of inefficient identification of existing technology and promoted the efficient development of deep coalbed methane.
Patent Information
- Application Number
- CN202411399836.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-01-10
AI Technical Summary
The existing technology cannot accurately identify the deep coal reservoirs containing free gas wells, resulting in inefficient coalbed methane development.
By comparing the gas production index change curve of a single well to be measured with the pre-established typical gas production index characteristic curve, we can judge whether it is a free gas well. The gas production volume under the unit production pressure difference is calculated based on the material equilibrium equation The average formation pressure of deep coal reservoirs is then determined.
Accurately identifying free gas wells containing deep coal reservoirs breaks the limitations of traditional "gas can be seen when you open a well", promotes efficient exploration and development of deep coalbed methane, and improves the characterization and prediction technology of free gas.
Smart Images
Figure CN119293374A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of coalbed methane development, and in particular to a method, system, equipment and medium for identifying free gas wells in deep coal reservoirs. Background Art
[0002] Deep coalbed methane has the characteristics of "high pressure, high temperature, high gas content, high saturation, and high freedom". High free gas content is a major "sweet spot" for achieving economical and efficient development of coalbed methane, which has become an industry consensus.
[0003] However, the understanding of free gas is still unclear, and the conventional identification method of the production characteristics of "gas is seen as soon as the well is opened" is generally used. With the exploration and development practice of deep coalbed methane, most production wells show the production characteristics of "slow production", and even the two-gas co-production wells do not show the production characteristics of "gas is seen as soon as the well is opened". It can be seen that this method has certain limitations and cannot accurately identify deep coal reservoirs containing free gas wells. Summary of the invention
[0004] In view of the above problems, the purpose of the present invention is to provide a method, system, equipment and medium for identifying free gas wells in deep coal reservoirs, which can accurately identify free gas wells in deep coal reservoirs.
[0005] To achieve the above objectives, the present invention adopts the following technical solutions: In a first aspect, a method for identifying a well containing free gas in a deep coal reservoir is provided, comprising: Calculate the gas production index change curve of the single well to be tested; According to the gas production index change curve of the single well to be tested and the typical gas production index characteristic curve established in advance, it is judged whether the single well to be tested meets the typical gas production index characteristics of a well containing free gas, and it is determined whether the single well to be tested is a well containing free gas.
[0006] Furthermore, the process of establishing the typical gas production index characteristic curve includes: Determine the gas production index as a characteristic parameter for identifying wells containing free gas; Based on the material balance equation, the average formation pressure of the deep coal reservoir is calculated, and then the gas production index of the deep coal reservoir is calculated, and a typical gas production index characteristic curve is established.
[0007] Furthermore, the gas production index is the gas production under unit production pressure difference, and the expression is:
[0008] In the formula, is the gas production index; is the gas production of the coalbed methane well; is the average formation pressure; is the bottom hole flowing pressure.
[0009] Furthermore, the average formation pressure of the deep coal reservoir is calculated based on the material balance equation, and then the gas production index of the deep coal reservoir is calculated, and a typical gas production index characteristic curve is established, including: Calculate water saturation in deep coal reservoirs; Calculate the gas deviation coefficient of deep coal reservoirs according to the water saturation of deep coal reservoirs; Calculate the average formation pressure of deep coal reservoirs based on the gas deviation coefficient of deep coal reservoirs; According to the average formation pressure of deep coal reservoirs, the gas production index is obtained, and a typical gas production index characteristic curve is established.
[0010] Furthermore, the water saturation is:
[0011] In the formula, is the initial water saturation; is the water phase compressibility coefficient; is the original formation pressure; is the current formation pressure; is the cumulative water production; is the volume coefficient of water phase; is the gas-bearing area; is the thickness; is the original porosity; is the comprehensive compression coefficient of coal rock; The gas deviation coefficient is:
[0012] In the formula, is the original porosity; is the standard pressure; is temperature; is the Langmuir volume; is the adsorption equilibrium constant; is the compression factor under standard conditions; is the standard condition temperature; The average formation pressure of the deep coal reservoir is:
[0013] In the formula, is the original gas deviation coefficient; is the cumulative gas production; is the original gas reserves.
[0014] Furthermore, the typical gas production index characteristic curve includes a typical gas production index characteristic curve of a well without free gas and a typical gas production index characteristic curve of a well with free gas, wherein: The characteristics of the typical gas production index characteristic curve of the well without free gas are: basically stable, the ratio of the initial gas production index to the mid-to-late gas production index is less than 3; The characteristics of the typical gas production index characteristic curve of free gas wells are: large difference, and the ratio of the initial gas production index to the mid-to-late gas production index is greater than 3.
[0015] In a second aspect, a system for identifying free gas wells in deep coal reservoirs is provided, comprising: A calculation module, used to calculate the gas production index change curve of the single well to be tested; The judgment module is used to judge whether the single well to be tested meets the typical gas production index characteristics of a well containing free gas based on the gas production index change curve of the single well to be tested and the pre-established typical gas production index characteristic curve, and determine whether the single well to be tested is a well containing free gas.
[0016] Furthermore, a curve establishment module is included, which is used to establish a typical gas production index characteristic curve, including: Determine the gas production index as a characteristic parameter for identifying wells containing free gas; Based on the material balance equation, the average formation pressure of the deep coal reservoir is calculated, and then the gas production index of the deep coal reservoir is calculated, and a typical gas production index characteristic curve is established.
[0017] In a third aspect, a processing device is provided, comprising computer program instructions, wherein the computer program instructions, when executed by the processing device, are used to implement the steps corresponding to the above-mentioned method for identifying wells containing free gas in deep coal reservoirs.
[0018] In a fourth aspect, a computer-readable storage medium is provided, on which computer program instructions are stored, wherein the computer program instructions, when executed by a processor, are used to implement the steps corresponding to the above-mentioned method for identifying free gas wells in deep coal reservoirs.
[0019] The present invention adopts the above technical solution, which has the following advantages: 1. The present invention breaks the previous method of identifying the production characteristics of free gas wells in deep coal reservoirs, which is "gas is seen as soon as the well is opened". It points out that the production characteristics are affected by the drainage system, and the change in production pressure difference is the main reason for the difference in production characteristics. It can accurately identify free gas wells in deep coal reservoirs.
[0020] 2. The present invention innovatively proposes a method for identifying free gas wells in deep coal reservoirs based on gas production index, which can be extended to practical application on site.
[0021] 3. The present invention has strongly promoted the development of characterization and prediction technology of "free gas sweet spots" in deep coal reservoirs, which is of great significance to the efficient exploration and development of deep coalbed methane.
[0022] In summary, the present invention can be widely used in the field of coalbed methane development. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings: Figure 1 It is a schematic diagram of a method flow provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of typical gas production index curves of a well without free gas and a well with free gas provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of gas production index of wells A and B in Shenfu block provided by one embodiment of the present invention. DETAILED DESCRIPTION
[0024] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.
[0025] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.
[0026] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.
[0027] Since the understanding of free gas is still unclear, the conventional identification method of the production characteristic of "gas is seen as soon as the well is opened" is generally used. With the exploration and development practice of deep coalbed methane, most production wells show the production characteristic of "slow production", and even the two-gas co-production wells do not show the production characteristic of "gas is seen as soon as the well is opened". It can be seen that this method has certain limitations and cannot accurately identify deep coal reservoirs containing free gas wells. An embodiment of the present invention provides a method for identifying deep coal reservoirs containing free gas wells, including: calculating a gas production index change curve of a single well to be tested; judging whether the single well to be tested meets the typical gas production index characteristics of a well containing free gas based on the gas production index change curve of the single well to be tested and a pre-established typical gas production index characteristic curve, and determining whether the single well to be tested is a well containing free gas. The present invention breaks the previous method of identifying the production characteristics of free gas wells in deep coal reservoirs, which is "gas is seen as soon as the well is opened". It points out that the production characteristics are affected by the drainage and production system, and the change in production pressure difference is the main reason for the difference in production characteristics. It innovatively proposes a method for identifying free gas wells in deep coal reservoirs based on gas production index, and promotes it to practical application on site, which has strongly promoted the development of characterization and prediction technology of "free gas sweet spots" in deep coal reservoirs, and is of great significance to the efficient exploration and development of deep coalbed methane.
[0028] Example 1 like Figure 1 As shown, this embodiment provides a method for identifying a deep coal reservoir containing free gas well, comprising the following steps: 1) Based on the coalbed gas flow mechanism and reservoir numerical simulation method, the characteristic parameters for identifying wells containing free gas were explored. It was found that the change of production pressure difference was the main reason for the difference in production characteristics. Therefore, the gas production index was determined as the characteristic parameter for identifying wells containing free gas.
[0029] Specifically, the gas production index is the gas production under unit production pressure difference, and the expression is: (1) In the formula, is the gas production index; is the gas production of coalbed methane well, in m3 / d; is the average formation pressure, in MPa; It is the bottom hole flowing pressure, in MPa.
[0030] 2) Based on the material balance equation, the average formation pressure of the deep coal reservoir is calculated, and then the gas production index of the deep coal reservoir is calculated, and a typical gas production index characteristic curve is established, which is as follows: 2.1) Calculation of water saturation in deep coal reservoirs .
[0031] Specifically, water saturation The calculation formula is: (2) In the formula, is the initial water saturation, in %; is the water phase compressibility coefficient, in MPa -1 ; is the original formation pressure, in MPa; is the current formation pressure, in MPa; is the cumulative water production, the unit is 10 4 m 3 ; is the volume coefficient of water phase; is the gas-bearing area, in m 2 ; is the thickness, in m; is the original porosity, in %; is the comprehensive compression coefficient of coal rock, in MPa -1 .
[0032] 2.2) Based on the water saturation of deep coal reservoirs , calculate the gas deviation coefficient of deep coal reservoirs .
[0033] Specifically, the gas deviation coefficient The calculation formula is: (3) In the formula, is the original porosity; is the standard pressure, in MPa; is the temperature in °C; is the Langmuir volume, in m 3 / t; is the adsorption equilibrium constant; is the compression factor under standard conditions; is the standard temperature, in °C.
[0034] 2.3) Based on the gas deviation coefficient of deep coal reservoirs , calculate the average formation pressure in deep coal reservoirs .
[0035] Specifically, calculate the average formation pressure in deep coal reservoirs The calculation formula is: (4) In the formula, is the original gas deviation coefficient; is the cumulative gas production, the unit is 10 4 m 3 ; is the original gas reserves, in units of 10 4 m 3 .
[0036] 2.4) The average formation pressure of deep coal reservoirs Substitute it into the above formula (1) to obtain the gas production index, and establish a typical gas production index characteristic curve.
[0037] Specifically, the typical gas production index characteristic curve includes a typical gas production index characteristic curve of a well without free gas and a typical gas production index characteristic curve of a well with free gas, wherein the typical gas production index characteristic curve of a well without free gas is characterized by being basically stable, and the ratio of the initial gas production index to the mid-to-late gas production index is less than 3; the typical gas production index characteristic curve of a well with free gas is characterized by being relatively different, and the ratio of the initial gas production index to the mid-to-late gas production index is greater than 3. Figure 2 The figure shows a schematic diagram of typical gas production index characteristic curves for wells without free gas and wells with free gas.
[0038] 3) Calculate the gas production index change curve of the single well to be tested.
[0039] 4) According to the gas production index change curve of the single well to be tested and the typical gas production index characteristic curve established in advance, it is judged whether the single well to be tested meets the typical gas production index characteristics of a well containing free gas, and whether the single well to be tested is a well containing free gas.
[0040] Specifically, if the gas production index change curve of the single well to be tested conforms to the characteristics of the typical gas production index characteristic curve of the well not containing free gas, that is, it is basically stable, and the ratio of the initial gas production index to the mid-to-late gas production index is less than 3, then the single well to be tested is judged to be a well not containing free gas; if the gas production index change curve of the single well to be tested conforms to the characteristics of the typical gas production index characteristic curve of the well containing free gas, that is, the difference is large, and the ratio of the initial gas production index to the mid-to-late gas production index is greater than 3, then the single well to be tested is judged to be a well containing free gas.
[0041] like Figure 3As shown in the figure, it is a schematic diagram of the gas production index curve of two wells A and B in the Shenfu block of China. The ratio of the initial gas production index to the mid-to-late gas production index of well A is about 1.5, which is less than 3. Therefore, well A is judged to be a well without free gas; the ratio of the initial gas production index to the mid-to-late gas production index of well B is about 9, which is greater than 3. Therefore, well B is judged to be a well with free gas.
[0042] Example 2 This embodiment provides a deep coal reservoir free gas well identification system, comprising: The calculation module is used to calculate the gas production index change curve of the single well to be tested.
[0043] The judgment module is used to judge whether the single well to be tested meets the typical gas production index characteristics of a well containing free gas based on the gas production index change curve of the single well to be tested and the pre-established typical gas production index characteristic curve, and determine whether the single well to be tested is a well containing free gas.
[0044] In a preferred embodiment, a curve establishment module is further included, which is used to establish a typical gas production index characteristic curve, including: The gas production index is determined as a characteristic parameter for identifying wells containing free gas.
[0045] Based on the material balance equation, the average formation pressure of the deep coal reservoir is calculated, and then the gas production index of the deep coal reservoir is calculated, and a typical gas production index characteristic curve is established.
[0046] The system provided in this embodiment is used to execute the above-mentioned method embodiments. Please refer to the above-mentioned embodiments for specific processes and detailed contents, which will not be repeated here.
[0047] Example 3 This embodiment provides a processing device corresponding to the method for identifying free gas wells in deep coal reservoirs provided in Example 1. The processing device can be suitable for client processing devices, such as mobile phones, laptops, tablet computers, desktop computers, etc., to execute the method of Example 1.
[0048] The processing device includes a processor, a memory, a communication interface and a bus, and the processor, the memory and the communication interface are connected through the bus to complete mutual communication. The memory stores a computer program that can be run on the processing device, and the processing device executes the method for identifying free gas wells in deep coal reservoirs provided in Example 1 when running the computer program.
[0049] In some implementations, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk storage.
[0050] In some other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors of various types, which are not limited herein.
[0051] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on such an understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.
[0052] Those skilled in the art will understand that the structure of the above-mentioned computing device is only a partial structure related to the solution of the present invention, and does not constitute a limitation on the computing device to which the solution of the present invention is applied. The specific computing device may include more or fewer components, or combine certain components, or have a different arrangement of components.
[0053] Example 4 This embodiment provides a computer program product corresponding to the method for identifying deep coal reservoirs containing free gas wells provided in Example 1. The computer program product may include a computer-readable storage medium on which computer-readable program instructions for executing the method for identifying deep coal reservoirs containing free gas wells described in Example 1 are loaded.
[0054] Computer readable storage media can be tangible devices that hold and store instructions used by instruction execution devices. Computer readable storage media can be, for example, but not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any combination thereof.
[0055] The above embodiment provides a computer-readable storage medium, whose implementation principle and technical effect are similar to those of the above method embodiment, and will not be repeated here.
[0056] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.
[0057] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0058] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.
[0059] The above embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component may be changed. Any equivalent transformations and improvements based on the technical solution of the present invention should not be excluded from the protection scope of the present invention.
Claims
1. A method for identifying free gas wells in deep coal reservoirs, characterized in that: include: Calculate the gas production index change curve of the single well to be tested; According to the gas production index change curve of the single well to be tested and the typical gas production index characteristic curve established in advance, it is judged whether the single well to be tested meets the typical gas production index characteristics of a well containing free gas, and it is determined whether the single well to be tested is a well containing free gas.
2. A method for identifying free gas wells in deep coal reservoirs according to claim 1, characterized in that: The process of establishing the typical gas production index characteristic curve includes: Determine the gas production index as a characteristic parameter for identifying wells containing free gas; Based on the material balance equation, the average formation pressure of the deep coal reservoir is calculated, and then the gas production index of the deep coal reservoir is calculated, and a typical gas production index characteristic curve is established.
3. A method for identifying free gas wells in deep coal reservoirs according to claim 2, characterized in that: The gas production index is the gas production under unit production pressure difference, and the expression is: In the formula, is the gas production index; is the gas production of the coalbed methane well; is the average formation pressure; is the bottom hole flowing pressure.
4. A method for identifying free gas wells in deep coal reservoirs according to claim 2, characterized in that: The method of calculating the average formation pressure of the deep coal reservoir based on the material balance equation, and then calculating the gas production index of the deep coal reservoir, and establishing a typical gas production index characteristic curve includes: Calculate water saturation in deep coal reservoirs; Calculate the gas deviation coefficient of deep coal reservoirs according to the water saturation of deep coal reservoirs; Calculate the average formation pressure of deep coal reservoirs based on the gas deviation coefficient of deep coal reservoirs; According to the average formation pressure of deep coal reservoirs, the gas production index is obtained, and a typical gas production index characteristic curve is established.
5. A method for identifying free gas wells in deep coal reservoirs according to claim 4, characterized in that: The water saturation is: In the formula, is the initial water saturation; is the compressibility coefficient of water phase; is the original formation pressure; is the current formation pressure; is the cumulative water production; is the volume coefficient of water phase; is the gas-bearing area; is the thickness; is the original porosity; is the comprehensive compression coefficient of coal rock; The gas deviation coefficient is: In the formula, is the original porosity; is the standard pressure; is temperature; is the Langmuir volume; is the adsorption equilibrium constant; is the compression factor under standard conditions; is the standard condition temperature; The average formation pressure of the deep coal reservoir is: In the formula, is the original gas deviation coefficient; is the cumulative gas production; is the original gas reserves.
6. A method for identifying free gas wells in deep coal reservoirs according to claim 4, characterized in that: The typical gas production index characteristic curve includes a typical gas production index characteristic curve of a well without free gas and a typical gas production index characteristic curve of a well with free gas, wherein: The characteristics of the typical gas production index characteristic curve of the well without free gas are: basically stable, the ratio of the initial gas production index to the mid-to-late gas production index is less than 3; The characteristics of the typical gas production index characteristic curve of free gas wells are: large difference, and the ratio of the initial gas production index to the mid-to-late gas production index is greater than 3.
7. A deep coal reservoir free gas well identification system, characterized in that: include: A calculation module, used to calculate the gas production index change curve of the single well to be tested; The judgment module is used to judge whether the single well to be tested meets the typical gas production index characteristics of a well containing free gas based on the gas production index change curve of the single well to be tested and the pre-established typical gas production index characteristic curve, and determine whether the single well to be tested is a well containing free gas.
8. A deep coal reservoir free gas well identification system as claimed in claim 7, characterized in that: It also includes a curve building module for building a typical gas production index characteristic curve, including: Determine the gas production index as a characteristic parameter for identifying wells containing free gas; Based on the material balance equation, the average formation pressure of the deep coal reservoir is calculated, and then the gas production index of the deep coal reservoir is calculated, and a typical gas production index characteristic curve is established.
9. A processing device, characterized in that: It includes computer program instructions, wherein the computer program instructions, when executed by a processing device, are used to implement the steps corresponding to the method for identifying free gas wells in deep coal reservoirs as described in any one of claims 1-6.
10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions, wherein the computer program instructions, when executed by a processor, are used to implement the steps corresponding to the method for identifying free gas wells in deep coal reservoirs according to any one of claims 1 to 6.