Method and device for evaluating EUR of a sidetracked horizontal well in a tight sand gas reservoir

Abstract

The application discloses a method and device for evaluating EUR of a sidetracked horizontal well in a tight sandstone gas reservoir. The method comprises the following steps: obtaining the EUR of a plurality of sidetracked horizontal wells with a production time exceeding a set time and the maximum casing pressure after sidetracking determined according to gas testing data, and the original casing pressure of a straight well corresponding to the sidetracked horizontal well; determining the gas-bearing volume of an effective sand body in a horizontal section of the sidetracked horizontal well, determining a gas enrichment index according to the gas-bearing volume of the sidetracked horizontal well, the maximum casing pressure after sidetracking and the original casing pressure of the corresponding straight well, obtaining a plurality of data pairs containing the gas enrichment index and the EUR, and forming a first data pair set; and establishing a first relationship between the gas enrichment index and the EUR according to the set, and using the first relationship to predict the EUR of a to-be-evaluated sidetracked horizontal well after gas testing. The method can evaluate the EUR of the sidetracked horizontal well at the first time when the gas testing is completed, and can give a preliminary judgment on the development effect of the sidetracked horizontal well, so as to provide a basis for scientifically and reasonably distributing production of the production site at the first time and for subsequent tapping potential deployment of the gas field.

Description

Technical Field

[0001] This invention relates to the field of gas reservoir engineering technology in natural gas development, and in particular to a method and apparatus for evaluating the EUR (Earnings Estimation) of sidetracked horizontal wells in tight sandstone gas reservoirs. Background Technology

[0002] Sidetracked horizontal wells are an important means of tapping the production potential of low-yield and inefficient wells in tight sandstone gas reservoirs and improving gas field recovery. Rapidly and accurately predicting the estimated ultimate recovery (EUR) and EUR increment (the difference between the EUR of the sidetracked horizontal well and the pre-sidetracked vertical well) of sidetracked horizontal wells is crucial for evaluating the development effect and incremental benefits of sidetracked horizontal wells.

[0003] 1) Zhang Jinwu, Wang Guoyong, He Kai, et al. Practice and understanding of sidetracking and horizontal well development technology in old wells of Sulige Gas Field [J]. Petroleum Exploration and Development, 2019, 46(2):370-377

[0004] This paper elucidates the impact of factors such as the length of the horizontal section, the length of the sandstone section encountered, the position of the horizontal section trajectory in the reservoir, the thickness of the effective gas layer, gas saturation, controlled reserves, and fracturing stimulation on the production efficiency of old sidetracked horizontal wells in the Sulige Gas Field. Through numerical simulation, the relationship between the length of the horizontal section and the cumulative gas production (EUR) is obtained. Correlation analysis is conducted to determine the relationship between the initial daily gas production of sidetracked horizontal wells and the thickness of the effective gas layer, the length of the sandstone section encountered, and the controlled reserves.

[0005] 2) Wang Liqiong, Wang Zhiheng, Ma Yulong, et al. Development technology and application of sidetracking horizontal wells in old wells of Sulige Gas Field [J]. Xinjiang Petroleum Geology, 2022, 43(3):368-377

[0006] Taking the Sulige Gas Field as an example, this paper summarizes the key geological technologies for sidetracking horizontal wells in old wells from the perspectives of optimized deployment and geological guidance, based on the field's geological characteristics and current development status. The paper also studies the development effects of sidetracking horizontal wells in old wells from the aspects of drilling results, production indicators, and benefit evaluation, and comprehensively analyzes the impact of various factors on the implementation effect of sidetracking wells. Summary of the Invention

[0007] The inventors have discovered that current research on sidetracked horizontal wells in tight sandstone gas reservoirs primarily focuses on the selection of geological targets and supporting technologies. In terms of development effect analysis, the main focus is on the impact of factors such as the length of multiple horizontal sections, the length of sandstone sections encountered, the thickness of the effective gas layer utilized, gas saturation, and fracturing stimulation. For the evaluation of the energy return (EUR) of sidetracked horizontal wells in tight sandstone gas reservoirs, conventional EUR calculation methods are used. This involves evaluating the well using traditional methods such as pressure drop and mass balance methods after a relatively long production period (more than one year). These traditional evaluation methods require a considerable period of production for the production pressure drop to reach the reservoir boundary and for the seepage to reach a quasi-steady-state flow before the evaluation results can be relatively accurate. This evaluation method is cumbersome for field application in gas fields and cannot provide a prediction of the development effect of the sidetracked horizontal well immediately after the gas testing is completed. It also fails to provide a scientific basis for field technicians to rationally allocate production and manage the well. In order to at least partially solve the technical problems existing in the prior art, the inventors made this invention, which provides a method and device for evaluating the EUR of sidetracked horizontal wells in tight sandstone gas reservoirs through specific embodiments, which can give a prediction of the development effect of the sidetracked horizontal well at the first time after the gas test is completed.

[0008] In a first aspect, embodiments of the present invention provide a method for evaluating the EUR (Earnings Equivalent) of sidetracked horizontal wells in tight sandstone gas reservoirs, comprising:

[0009] Obtain the EUR of multiple sidetracked horizontal wells whose production time exceeds the set time, the maximum casing pressure after sidetracking determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking;

[0010] Determine the effective gas-bearing volume of the sand body in the horizontal section of the side-drilled horizontal well. Based on the effective gas-bearing volume of the sand body in the side-drilled horizontal well, the maximum casing pressure after side-drilling, and the original casing pressure of the corresponding vertical well, determine the gas-rich index and obtain multiple data pairs containing the gas-rich index and EUR, which constitute the first data pair set.

[0011] Based on the first data, a first relationship is established between the gas abundance index and EUR for the set. This first relationship is used to predict the EUR of the sidetracked horizontal well to be evaluated after gas testing.

[0012] Secondly, embodiments of the present invention provide an EUR evaluation device for sidetracked horizontal wells in tight sandstone gas reservoirs, comprising:

[0013] The data acquisition module is used to acquire the EUR of multiple sidetracked horizontal wells whose production time exceeds a set time, the maximum casing pressure after sidetracking determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking.

[0014] The first data pair set establishment module is used to determine the effective gas-bearing volume of the sand body in the horizontal section of the side-drilled horizontal well. Based on the effective gas-bearing volume of the sand body in the side-drilled horizontal well, the maximum casing pressure after side-drilling, and the original casing pressure of the corresponding vertical well, the gas enrichment index is determined, and multiple data pairs containing the gas enrichment index and EUR are obtained, which constitute the first data pair set.

[0015] The module for establishing the first relationship between the gas abundance index and EUR is used to establish a first relationship between the gas abundance index and EUR based on the first data set. The first relationship is used to pre-test the EUR of the sidetracked horizontal well to be evaluated after gas testing.

[0016] Thirdly, embodiments of the present invention provide a computer storage medium storing computer-executable instructions, which, when executed by a processor, implement the aforementioned EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs.

[0017] Fourthly, this disclosure provides a server, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs.

[0018] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0019] The method for evaluating the gas enrichment index (EUR) of sidetracked horizontal wells in tight sandstone gas reservoirs provided in this invention establishes a primary relationship between the gas enrichment index and EUR by utilizing relevant dynamic and static parameters of multiple sidetracked horizontal wells that have exceeded a set production time and the vertical wells before sidetracking. This allows the EUR to be predicted based on this relationship after the sidetracked horizontal wells have achieved maximum casing pressure following gas testing. This enables immediate EUR evaluation and provides a preliminary assessment of the development effect of sidetracked horizontal wells, offering a basis for guiding the scientific and rational allocation of gas well production and subsequent potential tapping deployment in the gas field.

[0020] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a flowchart of the EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs in Embodiment 1 of the present invention;

[0024] Figure 2 This is a flowchart illustrating the process of determining the effective gas-bearing volume of the horizontal sand body in Embodiment 1 of the present invention.

[0025] Figure 3 This is a flowchart illustrating the specific implementation of the EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs in Embodiment 2 of the present invention.

[0026] Figure 4 This is a schematic diagram of a sand body layer encountered during the horizontal section of a side-drilled horizontal well in Embodiment 2 of the present invention.

[0027] Figure 5 This is the curve showing the relationship between the gas abundance index Vg and the EUR of a sidetracked horizontal well in Embodiment 2 of the present invention.

[0028] Figure 6 This is the curve showing the relationship between the gas abundance index Vg and the incremental EUR in Embodiment 2 of the present invention;

[0029] Figure 7 This is a diagram showing the intersection of formation coefficient KH and EUR of a side-drilled horizontal well in Embodiment 2 of the present invention.

[0030] Figure 8 This is a diagram showing the intersection of the storage capacity coefficient φSg and the EUR of a side-drilled horizontal well in Embodiment 2 of the present invention.

[0031] Figure 9 This is a schematic diagram of the EUR evaluation device for side-drilled horizontal wells in tight sandstone gas reservoirs in an embodiment of the present invention. Detailed Implementation

[0032] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] To address the issue in existing technologies where sidetracked horizontal wells require a certain period of production before relatively accurate prediction of the Emergency Estimation (EUR), this invention provides a method and apparatus for evaluating the EUR of sidetracked horizontal wells in tight sandstone gas reservoirs. This method can evaluate the EUR immediately after the sidetracked horizontal well completes its gas testing and provide a prediction of the development effect of the sidetracked horizontal well.

[0036] Example 1

[0037] Embodiment 1 of this invention provides a method for evaluating the EUR (Earnings Equivalent) of sidetracked horizontal wells in tight sandstone gas reservoirs, the process of which is as follows: Figure 1 As shown, it includes the following steps:

[0038] Step S11: Obtain the EUR of multiple sidetracked horizontal wells whose production time exceeds the set time, the maximum casing pressure after sidetracking determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking.

[0039] Typically, sidetracked horizontal wells that have been in production for more than one year and their corresponding pre-sidetracked vertical wells are selected as research subjects. This is because only sidetracked horizontal wells with a production time of more than one year can ensure that the EUR determined by existing methods (traditional methods such as pressure drop method and material balance method) is relatively accurate.

[0040] Step S12: Determine the effective gas-bearing volume of the horizontal section of the side-drilled horizontal well. Based on the effective gas-bearing volume of the horizontal section of the side-drilled horizontal well, the maximum casing pressure after side-drilling, and the original casing pressure of the corresponding vertical well, determine the gas enrichment index and obtain multiple data pairs containing the gas enrichment index and EUR, forming the first data pair set.

[0041] Determine the ratio of the maximum casing pressure after sidetracking of the horizontal well to the original casing pressure of the corresponding vertical well, and multiply this ratio by the effective gas-bearing volume of the sand body to determine the gas-rich index of the sidetracked horizontal well.

[0042] Furthermore, for determining the effective gas-bearing volume of the sand body in the horizontal section of a sidetracked horizontal well, see [reference needed]. Figure 2 As shown, the following steps may be included:

[0043] Step S21: Determine the thickness and width of the effective sand body in the horizontal section of the side-drilled horizontal well based on the effective sand body thickness at the corresponding vertical well side-drilling point.

[0044] A horizontal well is obtained by sidetracking along the horizontal extension of the effective sand body at the sidetracking point, based on a vertical well. Assuming that the thickness of the sand body remains constant along the sidetracking trajectory, the thickness of the effective sand body at the corresponding vertical well sidetracking point can be determined as the thickness of the effective sand body in the horizontal section of the horizontal well.

[0045] Then, based on the thickness of the effective sand body in the horizontal section of the side-drilled horizontal well and the predetermined correspondence between thickness and width, the width of the effective sand body in the horizontal section of the side-drilled horizontal well is determined.

[0046] The relationship between thickness and width can be predetermined based on geological knowledge. Typically, the relationship between the thickness and width of a sand body is that the width is 100 times the thickness.

[0047] Step S22: Determine the gas-bearing volume of the effective sand body in the horizontal section of the side-drilled horizontal well based on the length, porosity, gas saturation, thickness, and width of each effective sand body encountered in the horizontal section of the side-drilled horizontal well.

[0048] Determine the length and sum of the effective sand bodies encountered in each section of the horizontal section of the side-drilled horizontal well; determine the effective gas-bearing volume of the horizontal sand body in the horizontal section of the side-drilled horizontal well by multiplying the porosity, gas saturation, length, thickness and width of the horizontal section.

[0049] Step S13: Establish the first relationship between the wealth index and EUR based on the first data set.

[0050] Based on the first set of data, a first relationship between the gas abundance index and EUR is established through fitting, which is used to predict the EUR of the sidetracked horizontal well to be evaluated after gas testing.

[0051] The sidetracked horizontal wells to be evaluated, along with the multiple sidetracked horizontal wells selected in the previous steps whose production time exceeded the set time, are all located within the same gas field.

[0052] The EUR (Earning Potential) evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs provided in Embodiment 1 of this invention establishes a primary relationship between the gas enrichment index and EUR by utilizing relevant dynamic and static parameters of multiple sidetracked horizontal wells that have exceeded a set production time and the vertical wells before sidetracking. This allows the EUR to be predicted based on this relationship after the sidetracked horizontal wells have achieved maximum casing pressure following gas testing. This enables immediate EUR evaluation and provides a preliminary assessment of the development effect of sidetracked horizontal wells, offering a basis for guiding the scientific and rational allocation of gas well production and subsequent potential tapping deployment in the gas field.

[0053] In some embodiments, the EUR increment of the sidetracked horizontal well relative to the corresponding vertical well can be determined based on the EUR of the sidetracked horizontal well and the EUR of the corresponding vertical well, resulting in multiple data pairs containing the gas enrichment index and the EUR increment, forming a second data pair set; a second relationship between the gas enrichment index and the EUR increment can be established based on the second data pair set, which is used to predict the EUR increment of the sidetracked horizontal well to be evaluated after gas testing.

[0054] Example 2

[0055] Embodiment 2 of this invention provides a specific implementation process for the EUR evaluation method of sidetracked horizontal wells in tight sandstone gas reservoirs. See [link to documentation]. Figure 3 As shown, it includes the following steps:

[0056] Step S301: Screen multiple sidetracked horizontal wells and corresponding pre-sidetracked vertical wells that have been in production for more than one year.

[0057] Step S302: Based on the vertical well before side-drilling, determine the original casing pressure Pcinit, effective sand body thickness H, width W, porosity φ, and gas saturation Sg.

[0058] Step S303: Based on the gamma ray and gas logging of the horizontal section of the sidetracked horizontal well, determine the lengths La(i) of each effective sand body encountered in the horizontal section, and determine the maximum casing pressure Pcmax after sidetracking based on the gas testing results of the sidetracked horizontal well.

[0059] See Figure 4 The diagram shows a schematic of an effective sand body layer encountered in the horizontal section of a sidetracked horizontal well. The effective sand body is a gas-bearing sand body. Ls is the total length of the horizontal section, and La1 and La2 are the lengths of the two effective sand bodies encountered (this is just an example of two sections).

[0060] Step S304: Determine the gas enrichment index Vg based on the determined original casing pressure Pcinit of the vertical well, the maximum casing pressure Pcmax after sidetracking of the horizontal well, the effective sand body thickness H, width W, porosity φ, gas saturation Sg, and the lengths La(i) of each effective sand body encountered in the horizontal section.

[0061]

[0062] Where Vg is the abundance index, m 3 The units for the initial casing pressure Pcinit in vertical wells and the maximum casing pressure Pcmax after sidetracking in horizontal wells are MPa; the units for the effective sand body thickness H, width W, and length La(i) of each effective sand body encountered in the horizontal section are m. i represents the sequence number of the effective sand body encountered in the horizontal section, and n represents the total number of effective sand body sections encountered in the horizontal section; the units for porosity φ and gas saturation Sg are %.

[0063] Step S305: Based on the production dynamic data of the selected sidetracked horizontal well and the pre-sidetracked vertical well, the EUR of the original vertical well and the post-sidetracked horizontal well are calculated using the material balance method.

[0064] Step S306: Based on the rectangular coordinate system, plot the relationship curves between the gas abundance index Vg and the EUR of the sidetracked horizontal well, and between the gas abundance index Vg and the increment of EUR.

[0065] Figure 5 The curve showing the relationship between the gas abundance index Vg and the EUR of a sidetracked horizontal well reflects the positive correlation between the gas abundance index and the EUR of a sidetracked horizontal well in a rectangular coordinate system, indicating that the larger the gas abundance index, the higher the EUR of the sidetracked horizontal well. Figure 6 The curve showing the relationship between the abundance index Vg and the increment of EUR reflects the positive correlation between the abundance index and the increment of EUR in a rectangular coordinate system, indicating that the larger the abundance index, the higher the increment of EUR.

[0066] Step S307: Obtain the maximum casing pressure after sidetracking of the horizontal well to be evaluated, determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking.

[0067] Step S308: Determine the effective gas-bearing volume of the horizontal section of the side-drilled horizontal well to be evaluated. Based on the effective gas-bearing volume of the horizontal section of the side-drilled horizontal well to be evaluated, the maximum casing pressure after side-drilling, and the original casing pressure of the corresponding vertical well, determine the gas enrichment index.

[0068] Step S309: Based on the relationship curve between the gas enrichment index of the sidetracked horizontal well to be evaluated and the gas enrichment index Vg and the EUR of the sidetracked horizontal well, predict the EUR of the sidetracked horizontal well to be evaluated.

[0069] Step S310: Based on the relationship curve between the gas enrichment index of the sidetracked horizontal well to be evaluated and the gas enrichment index Vg and the EUR increment of the sidetracked horizontal well, predict the EUR increment of the sidetracked horizontal well to be evaluated.

[0070] This invention defines the concept of a "gas-rich index" for sidetracked horizontal wells, mathematically expressed as: Gas-rich index = Ratio of maximum casing pressure after sidetracking to original casing pressure × Gas-bearing volume of effective sandstone in the horizontal section of the sidetracked horizontal well. From a combined dynamic and static perspective, the gas-rich index is established by comprehensively considering various static parameters and dynamic depressurization conditions of the effective sandstone encountered in the horizontal section of the sidetracked horizontal well. The static parameters of the encountered effective sandstone include: effective sandstone thickness, width, length, porosity, and gas saturation; the dynamic parameters include the original casing pressure and the maximum casing pressure during the sidetracked horizontal well test. Furthermore, a relationship curve between the gas-rich index and the EUR (Earnings Regulator) of a production sidetracked horizontal well is established. This curve represents a typical curve for rapid evaluation of the EUR of a sidetracked horizontal well representing a target tight sandstone gas reservoir. Using this curve, the EUR of a new sidetracked horizontal well can be quickly analyzed and predicted, providing a reference for determining a reasonable production system and development management for gas wells.

[0071] Table 1 shows a comparison of the intersection results of EUR with formation coefficient, reservoir coefficient and gas richness index for sidetracked horizontal wells. Figure 7 This reflects the intersection of formation coefficient and EUR in a sidetracked horizontal well in a rectangular coordinate system, showing that the intersection is chaotic and there is no good correlation between the two. Figure 8 This reflects the intersection of the reservoir capacity coefficient and the EUR of the sidetracked horizontal well in the rectangular coordinate system, showing that the intersection of the two is chaotic and there is no good correlation.

[0072] Table 1 compares the cross-sectional results of EUR with formation coefficient, reservoir coefficient, and gas abundance index.

[0073] Formation coefficient KH ~ EUR for sidetracked horizontal wells No obvious pattern none Storage capacity coefficient φSg ~ EUR for sidetracked horizontal wells No obvious pattern none Gas richness index Vg ~ EUR for sidetracked horizontal wells Linear positive correlation <![CDATA[Y=0.0219X+1672.5,R 2 =0.68]]>

[0074] The comparison results show that the static cross-parameters of formation coefficient and reservoir coefficient, which are commonly used in gas well productivity evaluation studies, do not have a significant correlation with the EUR of sidetracked wells. However, the gas enrichment index, which is established by combining various static parameters and dynamic pressure indicators of effective sand bodies encountered in sidetracked horizontal wells, has a significant linear positive correlation with the EUR of sidetracked horizontal wells, and the fit is good. It can be used to quickly predict the EUR of sidetracked horizontal wells after drilling and gas testing, and to evaluate their development effect.

[0075] Based on the inventive concept of this invention, embodiments of this invention also provide an EUR evaluation device for sidetracked horizontal wells in tight sandstone gas reservoirs, the structure of which is as follows: Figure 9 As shown, it includes:

[0076] The data acquisition module 91 is used to acquire the EUR of multiple side-drilled horizontal wells whose production time exceeds the set time, the maximum casing pressure after side-drilling determined based on the gas test data, and the original casing pressure of the corresponding vertical well before side-drilling.

[0077] The data pair set establishment module 92 is used to determine the effective gas-bearing volume of the sand body in the horizontal section of the side-drilled horizontal well. Based on the effective gas-bearing volume of the sand body in the side-drilled horizontal well, the maximum casing pressure after side-drilling, and the original casing pressure of the corresponding vertical well, the gas enrichment index is determined, and multiple data pairs containing the gas enrichment index and EUR are obtained, forming the first data pair set.

[0078] The gas abundance index ~ EUR first relationship establishment module 93 is used to establish a first relationship between the gas abundance index and EUR based on the first data set. The first relationship is used to pre-test the EUR of the sidetracked horizontal well to be evaluated after gas testing.

[0079] In some embodiments, the EUR prediction module 95 is further included for:

[0080] Obtain the maximum casing pressure after sidetracking of the horizontal well to be evaluated, as determined by the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking; determine the effective gas-bearing volume of the horizontal sand body in the horizontal section of the horizontal well to be evaluated; determine the gas enrichment index based on the effective gas-bearing volume of the horizontal well to be evaluated, the maximum casing pressure after sidetracking, and the original casing pressure of the corresponding vertical well; predict the EUR of the well based on the gas enrichment index of the horizontal well to be evaluated and the first relationship.

[0081] In some embodiments, the data pair set creation module 92 is specifically used for:

[0082] The ratio of the maximum casing pressure after sidetracking of a horizontal well to the original casing pressure of the corresponding vertical well is determined, and the product of the ratio and the effective gas-bearing volume of the sand body is determined as the gas-rich index of the sidetracked horizontal well.

[0083] In some embodiments, the data pair set creation module 92 is specifically used for:

[0084] Based on the effective sand body thickness at the corresponding vertical well side-drilling point, determine the thickness and width of the effective sand body in the horizontal section of the side-drilled horizontal well; based on the length, porosity, and gas saturation of each effective sand body encountered in the horizontal section of the side-drilled horizontal well, as well as the aforementioned thickness and width, determine the gas-bearing volume of the effective sand body in the horizontal section of the side-drilled horizontal well.

[0085] In some embodiments, the data pair set creation module 92 is specifically used for:

[0086] The effective sand body thickness at the corresponding vertical well side-drilling point is determined as the effective sand body thickness of the horizontal section of the side-drilled horizontal well; the width of the effective sand body of the horizontal section of the side-drilled horizontal well is determined based on the effective sand body thickness of the horizontal section of the side-drilled horizontal well and the pre-determined correspondence between thickness and width.

[0087] In some embodiments, the data pair set creation module 92 is specifically used for:

[0088] Determine the length and sum of the effective sand bodies encountered in each section of the horizontal segment of the side-drilled horizontal well; determine the effective gas-bearing volume of the horizontal sand body in the horizontal segment of the side-drilled horizontal well by multiplying the porosity, gas saturation, the aforementioned length and sum, and the aforementioned thickness and width.

[0089] In some embodiments, a second relationship establishment module 94 for the abundance index ~ EUR increment is also included;

[0090] The data pair set establishment module 92 is also used to determine the EUR increment of the side-drilled horizontal well relative to the corresponding vertical well based on the EUR of the side-drilled horizontal well and the EUR of the corresponding vertical well, and to obtain multiple data pairs containing the gas rich index and the EUR increment, forming a second data pair set;

[0091] The second relationship establishment module 94 between the gas abundance index and the EUR increment is used to establish a second relationship between the gas abundance index and the EUR increment based on the second data set. The second relationship is used to predict the EUR increment of the sidetracked horizontal well to be evaluated after gas testing.

[0092] In some embodiments, the EUR prediction module 95 is further configured to:

[0093] Obtain the maximum casing pressure after sidetracking of the horizontal well to be evaluated, as determined by the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking; determine the effective gas-bearing volume of the horizontal sand body in the horizontal section of the horizontal well to be evaluated; determine the gas enrichment index based on the effective gas-bearing volume of the horizontal well to be evaluated, the maximum casing pressure after sidetracking, and the original casing pressure of the corresponding vertical well; predict the EUR increment of the well based on the gas enrichment index of the horizontal well to be evaluated and the second relationship.

[0094] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0095] Based on the inventive concept of the present invention, the embodiments of the present invention also provide a computer storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-mentioned EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs.

[0096] Based on the inventive concept of this invention, this embodiment of the invention also provides a server, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-mentioned EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs.

[0097] Unless otherwise specifically stated, terms such as processing, calculation, operation, determination, display, etc., may refer to the actions and / or processes of one or more processing or computing systems or similar devices that represent the manipulation and conversion of data representing physical (e.g., electronic) quantities within the registers or memory of the processing system into other data similarly representing physical quantities within the memory, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0098] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0099] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

[0100] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments herein can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of this disclosure.

[0101] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0102] For software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or outside the processor; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

[0103] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term “comprising” as used in the specification or claims is interpreted in a manner similar to the term “including,” as it is understood when used as a conjunction in the claims. Additionally, the use of any term “or” in the specification of the claims is intended to mean “non-exclusive or.” The terms “first” and “second” are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

Claims

1. A method for evaluating the EUR (Earnings Equivalent) of sidetracked horizontal wells in tight sandstone gas reservoirs, characterized in that, include: Obtain the EUR of multiple sidetracked horizontal wells whose production time exceeds the set time, the maximum casing pressure after sidetracking determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking; Based on the effective sand body thickness at the corresponding vertical well sidetracking point, determine the thickness and width of the effective sand body in the horizontal section of the sidetracked horizontal well; based on the length, porosity, and gas saturation of each effective sand body encountered in the horizontal section of the sidetracked horizontal well, as well as the aforementioned thickness and width, determine the gas-bearing volume of the effective sand body in the horizontal section of the sidetracked horizontal well; determine the ratio of the maximum casing pressure after sidetracking of the sidetracked horizontal well to the original casing pressure of the corresponding vertical well, and multiply the ratio by the gas-bearing volume of the effective sand body in the sidetracked horizontal well to determine the gas-rich index of the sidetracked horizontal well; obtain multiple data pairs containing the gas-rich index and EUR, forming the first data pair set; Based on the first data, a first relationship is established between the gas abundance index and EUR for the set. The first relationship is used to predict the EUR of the sidetracked horizontal well to be evaluated after gas testing. Based on the gas abundance index of the sidetracked horizontal well to be evaluated and the first relationship, the EUR of the well is predicted.

2. The method as described in claim 1, characterized in that, Also includes: Obtain the maximum casing pressure after sidetracking of the horizontal well to be evaluated, determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking. Determine the effective gas-bearing volume of the horizontal section of the sidetracked horizontal well to be evaluated. Based on the effective gas-bearing volume of the horizontal section of the sidetracked horizontal well to be evaluated, the maximum casing pressure after sidetracking, and the original casing pressure of the corresponding vertical well, determine the gas enrichment index.

3. The method as described in claim 1, characterized in that, The determination of the effective sand body thickness and width of the horizontal section of the side-drilled horizontal well based on the effective sand body thickness at the corresponding vertical well side-drilling point specifically includes: The effective sand body thickness at the corresponding vertical well side-drilling point is determined as the effective sand body thickness of the horizontal section of the side-drilled horizontal well. The width of the effective sand body in the horizontal section of the side-drilled horizontal well is determined based on the thickness of the effective sand body in the horizontal section and the predetermined correspondence between thickness and width.

4. The method as described in claim 3, characterized in that, The relationship between the thickness and the width is as follows: the width is 100 times the thickness.

5. The method as described in claim 1, characterized in that, The determination of the gas-bearing volume of the effective sand body in the horizontal section of the side-drilled horizontal well, based on the length, porosity, gas saturation, thickness, and width of each effective sand body encountered in the horizontal section of the side-drilled horizontal well, specifically includes: Determine the length of each effective sand body encountered in the horizontal section of the side-drilled horizontal well; The effective gas-bearing volume of the sand body in the horizontal section of the side-drilled horizontal well is determined by multiplying the porosity, gas saturation, length, thickness, and width of the horizontal section.

6. The method as described in claim 1, characterized in that, The process of obtaining multiple data pairs containing the abundance index and EUR, forming a first data pair set, also includes: Based on the EUR of the sidetracked horizontal well and the corresponding vertical well, the EUR increment of the sidetracked horizontal well relative to the corresponding vertical well is determined, resulting in multiple data pairs containing the gas rich index and the EUR increment, which constitute the second data pair set. Based on the second data, a second relationship is established between the gas abundance index and the EUR increment for the set. This second relationship is used to predict the EUR increment of the sidetracked horizontal well to be evaluated after gas testing.

7. The method as described in claim 6, characterized in that, Also includes: Obtain the maximum casing pressure after sidetracking of the horizontal well to be evaluated, determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking. Determine the effective gas-bearing volume of the horizontal section of the side-drilled horizontal well to be evaluated. Based on the effective gas-bearing volume of the horizontal section of the side-drilled horizontal well to be evaluated, the maximum casing pressure after side-drilling, and the original casing pressure of the corresponding vertical well, determine the gas enrichment index. Based on the gas abundance index of the sidetracked horizontal well to be evaluated and the second relationship, the EUR increment of the well is predicted.

8. A EUR evaluation device for sidetracked horizontal wells in tight sandstone gas reservoirs, characterized in that, The apparatus is used to perform the EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs as described in claim 1, and the apparatus comprises: The data acquisition module is used to acquire the EUR of multiple sidetracked horizontal wells whose production time exceeds a set time, the maximum casing pressure after sidetracking determined based on the gas test data, and the original casing pressure of the corresponding vertical well before sidetracking. The first data pair set establishment module is used to determine the effective gas-bearing volume of the sand body in the horizontal section of the side-drilled horizontal well. Based on the effective gas-bearing volume of the sand body in the side-drilled horizontal well, the maximum casing pressure after side-drilling, and the original casing pressure of the corresponding vertical well, the gas enrichment index is determined, and multiple data pairs containing the gas enrichment index and EUR are obtained, which constitute the first data pair set. The module for establishing the first relationship between the gas abundance index and EUR is used to establish a first relationship between the gas abundance index and EUR based on the first data set. The first relationship is used to pre-test the EUR of the sidetracked horizontal well to be evaluated after gas testing.

9. A computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions, which, when executed by a processor, implement the EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs as described in any one of claims 1 to 7.

10. A server, characterized in that, include: A memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor, when executing the program, implements the EUR evaluation method for sidetracked horizontal wells in tight sandstone gas reservoirs as described in any one of claims 1 to 7.

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