Shale gas well bottom hole flowing pressure calculation method based on production dynamic data, medium and device

Abstract

The invention provides a shale gas well bottom hole flowing pressure calculation method based on production dynamic data, a medium and a device. The method comprises the following steps: calculating wellbore pressure gradients P of different gas wells; calculating a production water-gas ratio WGR corresponding to the gas well pressure test; the ratio a of the wellbore pressure gradient P to the production water-gas ratio WGR is calculated; establishing a double logarithmic relation curve of'ratio a-production water-gas ratio WGR '; actual measurement data of the gas well in the production stable stage are selected, and a double logarithmic relation curve is further established; and through the established double logarithmic relation curve, the wellhead pressure, yield and depth of the gas well are combined, and the bottom hole flowing pressure is obtained through calculation. According to the method, the flowing bottomhole pressure in the production process can be rapidly calculated only by using the wellhead pressure, the yield and the gas well depth, and the reliability is high; the method can effectively overcome the defects of high test cost, more required parameters, complex calculation, large error and the like in a traditional method, and ensures the accuracy of gas well dynamic analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas well bottom hole flow pressure calculation technology, and in particular to a shale gas well bottom hole flow pressure calculation method, medium and device based on production dynamic data. Background Art

[0002] Bottom hole flowing pressure is an important parameter for gas well dynamic analysis. Accurate calculation of gas well bottom hole flowing pressure is the basis for productivity evaluation, dynamic analysis, EUR prediction and reasonable system optimization.

[0003] Bottomhole pressure is primarily measured domestically and internationally through downhole pressure gauge measurements or empirical formulas. However, with over a thousand shale gas wells currently in production, obtaining the measured bottomhole pressure using downhole pressure gauges in each well is unrealistic. Furthermore, scholars at home and abroad have developed a variety of calculation models and methods based on theoretical derivation and experimental simulation, including the average deviation coefficient method, the Cullender & Smith method, the pseudo-single-phase method, the Beggs & Brill model, the Gray model, and the Hagedorn-Brown model. These methods vary in applicable conditions, the calculation process is generally complex, and they handle too many parameters, resulting in significant discrepancies in the results of gas-liquid two-phase calculations in shale gas wells. For example, the average deviation coefficient method and the Cullender & Smith method assume a simple model and do not consider the impact of water production, resulting in low calculation results. The pseudo-single-phase flow method assumes no slip between the gas and water phases and is not suitable for gas wells with large liquid production. The Beggs & Brill model is based on the conservation equation of homogeneous flow energy and is suitable for inclined pipe two-phase flow. Its accuracy fluctuates with the production conditions of the gas well. The Hagedorn-Brown model requires the calculation of liquid holdup, and its results are high and the error is large. Therefore, the present invention provides a method for quickly calculating the bottomhole flowing pressure of shale gas wells based on production dynamic data. By analyzing big data, the relationship between the bottomhole flowing pressure and wellhead pressure, production data, and gas well depth is established, achieving a continuous description of the bottomhole flowing pressure. Summary of the Invention

[0004] The present invention aims to provide a method, medium and device for calculating the bottomhole flowing pressure of shale gas wells based on production dynamic data, so as to solve the problem that the bottomhole flowing pressure of shale gas wells is difficult to calculate accurately, make up for the shortcomings of existing calculation methods such as many parameters required, complex calculation process and large differences in results, better understand the changing characteristics of the bottomhole flowing pressure during the production process of gas wells, and thus better support the dynamic analysis of gas wells.

[0005] The present invention provides a method for calculating the bottom hole flowing pressure of a shale gas well based on production dynamic data, comprising the following steps:

[0006] Step 1: Calculate the wellbore pressure gradient ΔP of different gas wells based on the actual flow pressure test data carried out in the target block;

[0007] Step 2: According to the gas well pressure test time, the corresponding daily gas production and daily liquid production are obtained, and the production water-gas ratio WGR corresponding to the gas well pressure test is calculated;

[0008] Step 3, calculating the ratio a of the wellbore pressure gradient ΔP and the produced water-gas ratio WGR;

[0009] Step 4, establishing a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR";

[0010] Step 5: Select the measured data of the gas wells in the stable production stage and further establish a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR";

[0011] Step 6: Calculate the bottomhole flowing pressure by combining the double logarithmic relationship curve established in step 5 with the wellhead pressure, production rate, and depth of the gas well.

[0012] Furthermore, in step 1, the wellbore pressure gradient ΔP of different gas wells is calculated as:

[0013]

[0014] in:

[0015] △P is the wellbore pressure gradient;

[0016] P 测点 Indicates the measured pressure deep below the gas well pressure gauge;

[0017] P 井口 represents the wellhead pressure of the gas well during the corresponding period;

[0018] h 测点 Indicates the measured gas well pressure gauge insertion depth.

[0019] Furthermore, in step 2, the production water-gas ratio WGR corresponding to the gas well pressure test is calculated as:

[0020]

[0021] Among them, q g Indicates daily gas production, q w Indicates daily fluid production.

[0022] Furthermore, in step 3, the ratio of the wellbore pressure gradient ΔP to the produced water-gas ratio WGR is calculated as:

[0023]

[0024] Where a represents the ratio of the wellbore pressure gradient ΔP to the produced water-gas ratio WGR.

[0025] Furthermore, in step 4, the double logarithmic relationship curve of "ratio a-production water-gas ratio WGR" is expressed as log(a)=-0.69628*log(WGR)-0.94762.

[0026] Furthermore, the double logarithmic relationship curve of "ratio a-production water-gas ratio WGR" established in step 5 is expressed as

[0027] Furthermore, the selection of measured data of gas wells in the stable production stage in step 5 refers to selecting wells with bottom hole pressure greater than the set pressure as sample points.

[0028] Furthermore, in step 6, the bottom hole flowing pressure is calculated as:

[0029]

[0030] Among them, Pv 测点 Represents the calculated bottom hole flowing pressure.

[0031] The present invention also provides a computer terminal storage medium storing computer terminal executable instructions, wherein the computer terminal executable instructions are used to execute the above-mentioned shale gas well bottom hole flowing pressure calculation method based on production dynamic data.

[0032] The present invention further provides a computing device, comprising:

[0033] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the above-mentioned method for calculating the bottom hole flow pressure of a shale gas well based on production dynamic data.

[0034] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0035] 1. The present invention establishes a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR", which is also a relationship curve between wellbore pressure gradient and production water-gas ratio. By using the easily accessible wellhead pressure, production water-gas ratio, and gas well depth (vertical depth at point A), the bottomhole flowing pressure of the gas well can be quickly predicted during the production process. There is no need to carry out pressure testing, the operating cost is low, and it has good economic efficiency.

[0036] 2. The present invention fully combines measured flow pressure data, production dynamic data, and wellbore depth, and selects data from the stable production stage for analysis, effectively improving the accuracy of flow pressure during the production process and ensuring the accuracy of production capacity evaluation and EUR prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 Flow chart of a method for calculating bottom hole flowing pressure of a shale gas well based on production dynamic data in an embodiment of the present invention.

[0039] Figure 2 This is a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR" established in step 4 in an embodiment of the present invention.

[0040] Figure 3 This is a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR" established in step 5 in the embodiment of the present invention.

[0041] Figure 4 This is a comparison chart of the bottom hole flow pressure and the measured flow pressure since the well was put into production as an example in the embodiment of the present invention. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0044] Example

[0045] Design Concept: The bottomhole flowing pressure of a gas well is primarily composed of three components: wellhead pressure, pure gas column pressure in the wellbore, and mixed gas column pressure in the wellbore. Wellhead pressure, wellbore fluid properties, and well depth significantly influence bottomhole flowing pressure. Therefore, this paper analyzes the relationship between measured wellbore pressure, depth, and production output using big data methods by stabilizing the measured flowing pressure of production wells and corresponding period production data. This method proposes a method for calculating bottomhole flowing pressure in shale gas wells based on production dynamics data.

[0046] like Figure 1As shown, the method for calculating the bottom hole flowing pressure of a shale gas well based on production dynamic data includes the following steps:

[0047] Step 1: Calculate the wellbore pressure gradient ΔP of different gas wells based on the actual flow pressure test data carried out in the target block:

[0048]

[0049] in:

[0050] △P is the wellbore pressure gradient, MPa / 100 m;

[0051] P 测点 Indicates the measured pressure deep below the gas well pressure gauge, MPa;

[0052] P 井口 represents the wellhead pressure of the gas well during the corresponding period, MPa;

[0053] h 测点 Indicates the measured gas well pressure gauge insertion depth, meters;

[0054] Step 2: Obtain the corresponding daily gas production q according to the gas well pressure measurement time g (Wanfang), Nissan Liquid Q w (cubic meters), calculate the production water-gas ratio WGR (cubic meters / 10,000 cubic meters) corresponding to the gas well pressure test:

[0055]

[0056] Step 3: Calculate the ratio a of the wellbore pressure gradient △P and the produced water-gas ratio WGR:

[0057]

[0058] Step 4: Establish a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR", such as Figure 2 As shown, there is an obvious downward trend, which can be expressed as:

[0059] log(a)=-0.69628*log(WGR)-0.94762

[0060] This relationship curve represents all measured pressure gas wells in the target block, including the early stage with sufficient capacity and stable production, as well as the mid-to-late stage with unstable gas and liquid and prone to liquid accumulation. The correlation of the relationship is relatively low, less than 80%.

[0061] Step 5: Since tens of thousands of tons of fracturing fluid are often injected during the transformation of shale gas wells, in the early stage of gas well production, the energy is sufficient, the output is high, the flow in the wellbore is stable, and there is almost no liquid accumulation. However, as production progresses, the formation pressure decreases, the output decreases, the gas well is prone to liquid accumulation, and the wellbore pressure changes are complex. In order to ensure the accuracy of the bottomhole flow pressure calculation, the measured data of gas wells in the stable production stage, that is, wells with bottomhole pressure greater than the set pressure (generally 10 MPa) are selected as sample points, and a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR" is established, as shown in the following figure: Figure 3 As shown, the downward trend is more obvious and the correlation is high, greater than 90%, which can be expressed as:

[0062] log(a)=-0.84455*log(WGR)-0.75501

[0063] Right now:

[0064]

[0065] In step 6, the bottomhole flowing pressure is calculated by combining the double logarithmic relationship curve established in step 5 with the wellhead pressure, production rate, and depth of the gas well. This enables a rapid and reliable prediction of the bottomhole flowing pressure, providing support for gas well productivity evaluation and EUR prediction.

[0066]

[0067] Among them, P′ 测点 Represents the calculated bottom hole flowing pressure.

[0068] Example:

[0069] The shale gas well has a vertical depth of 3,123 meters. It was put into production in 2021, and two bottom hole pressure monitorings were carried out in 2022.

[0070] According to the actual daily wellhead pressure, daily gas production and daily water production of the well since it was put into production, the calculation method established in the present invention can realize continuous calculation of bottom hole flowing pressure. The results are shown in Table 1 and Figure 4 shown.

[0071] Table 1, example comparison table of measured and converted pressure:

[0072]

[0073] From Table 1, Figure 4Clearly, the bottomhole flowing pressure calculated using the present method closely matches the measured pressure data, with an error of less than 3%. This method also enables continuous calculation of bottomhole pressure during gas well production. Therefore, the present method, utilizing only wellhead pressure, production rate, and well depth, can rapidly and reliably calculate bottomhole flowing pressure during production. This method effectively overcomes the shortcomings of traditional methods, such as high testing costs, multiple parameters, complex calculations, and large errors. It provides a more accurate data foundation for gas well productivity evaluation and EUR forecasting, ensuring the accuracy of gas well dynamic analysis.

[0074] Furthermore, in some embodiments, a computer terminal storage medium is provided, storing computer terminal executable instructions for executing the method for calculating bottomhole flowing pressure of a shale gas well based on production dynamics data, as described in the preceding embodiments. Examples of computer storage media include magnetic storage media (e.g., floppy disks, hard disks, etc.), optical recording media (e.g., CD-ROMs, DVDs, etc.), or memory devices such as memory cards, ROMs, or RAM. Computer storage media can also be distributed across networked computer systems, such as in an application store.

[0075] Furthermore, in some embodiments, a computing device is provided, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method for calculating bottomhole flowing pressure of a shale gas well based on production performance data as described in the above embodiments. Examples of computing devices include a PC, a tablet computer, a smartphone, or a PDA.

[0076] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data, characterized in that: The steps include: Step 1: Calculate the wellbore pressure gradient ΔP of different gas wells based on the actual flow pressure test data carried out in the target block; Step 2: According to the gas well pressure test time, the corresponding daily gas production and daily liquid production are obtained, and the production water-gas ratio WGR corresponding to the gas well pressure test is calculated; Step 3, calculating the ratio a of the wellbore pressure gradient ΔP and the produced water-gas ratio WGR; Step 4: Establish a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR"; Step 5: Select measured data of gas wells in the stable production stage and further establish a double logarithmic relationship curve of "ratio a-production water-gas ratio WGR"; Step 6: Calculate the bottomhole flowing pressure by combining the double logarithmic relationship curve established in step 5 with the wellhead pressure, production rate, and depth of the gas well.

2. The method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data according to claim 1, characterized in that: In step 1, the wellbore pressure gradient ΔP of different gas wells is calculated as: in: △P is the wellbore pressure gradient; P 测点 Indicates the measured pressure deep below the gas well pressure gauge; P 井口 represents the wellhead pressure of the gas well during the corresponding period; h 测点 Indicates the measured gas well pressure gauge insertion depth.

3. The method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data according to claim 2, characterized in that: In step 2, the production water-gas ratio WGR corresponding to the gas well pressure test is calculated as: Among them, q g Indicates daily gas production, q w Indicates daily fluid production.

4. The method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data according to claim 3, characterized in that: In step 3, the ratio of the wellbore pressure gradient ΔP to the produced water-gas ratio WGR is calculated as: Where a represents the ratio of the wellbore pressure gradient ΔP to the produced water-gas ratio WGR.

5. The method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data according to claim 4, characterized in that: In step 4, the double logarithmic relationship curve of "ratio a-production water-gas ratio WGR" is expressed as log(a)=-0.69628*log(WGR)-0.94762.

6. The method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data according to claim 5, characterized in that: The double logarithmic relationship curve of "ratio a-production water-gas ratio WGR" established in step 5 is expressed as 7. The method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data according to claim 6, characterized in that: The selection of measured data of gas wells in the stable production stage in step 5 refers to selecting wells with bottom hole pressure greater than the set pressure as sample points.

8. The method for calculating bottom hole flowing pressure of shale gas wells based on production dynamic data according to claim 6, characterized in that: In step 6, the bottom hole flowing pressure is calculated as: Among them, P′ 测点 Represents the calculated bottom hole flowing pressure.

9. A computer terminal storage medium storing computer terminal executable instructions, characterized in that: The computer terminal executable instructions are used to execute the shale gas well bottom hole flowing pressure calculation method based on production dynamic data as described in any one of claims 1 to 8.

10. A computing device, characterized in that: include: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method for calculating bottom hole flow pressure of a shale gas well based on production dynamic data as described in any one of claims 1 to 8.

Images