Shale oil well pressure recovery well test interpretation method and device and electronic equipment

Abstract

The invention provides a shale oil well pressure recovery well test interpretation method and device and electronic equipment.The method comprises the steps that effective well shut-in pressure test data and well entering time of a pressure gauge are obtained, the effective well shut-in pressure test data are well bottom pressure data after well shut-in and after the pressure gauge is lowered to the target test depth away from a well opening, and the well entering time is obtained; the well entering time is the time required for lowering the pressure gauge to a target test depth from a well mouth after the well is closed; obtaining well shut-in starting time and a pressure gradient in a well entering process of the pressure gauge; according to the pressure gradient, fluid pressure data at the well shut-in starting time and the target test depth from the well mouth are calculated to serve as supplementary pressure data; according to the effective shut-in pressure test data, the well entering time and the supplementary pressure data, a complete pressure recovery well test curve is determined; and on the basis of the complete pressure recovery well test curve, pressure recovery well test interpretation is carried out. According to the method, the problem of data missing in the early stage of well shut-in testing can be solved, the integrity of a pressure recovery well testing curve is guaranteed, and the accuracy of pressure recovery well testing interpretation is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of well test interpretation of shale oil wells, and particularly to a pressure build-up well test interpretation method, device and electronic equipment for shale oil wells. Background Technique

[0002] China is rich in shale oil reserves and has great potential for exploitation, making it an important front for increasing oil and gas reserves and production. Due to the dense pores, diverse occurrence modes, and complex migration mechanisms of shale oil reservoirs, there are currently problems such as unclear oil-water flow laws after artificial water injection fracturing and difficulty in predicting oil-water co-production. Pressure build-up well test analysis is one of the important means of reservoir dynamic monitoring, which can directly obtain reservoir dynamic parameters and describe the reservoir flow law, and is an indispensable dynamic monitoring technology in the exploration and development process of oil and gas wells. However, before shale oil wells are put into production, they have undergone large-scale volume fracturing, which greatly raises the reservoir pressure, resulting in a relatively high wellhead pressure in the initial production stage. It is impossible to lower a pressure gauge to the bottom of the well by wire under the open well condition, and lowering the pressure gauge under the closed well condition leads to the lack of early data in the pressure build-up test curve, seriously affecting the interpretation result and accuracy of the pressure build-up curve.

[0003] Currently existing pressure build-up well test interpretation methods, such as a well test analysis method for coalbed methane wells (CN111339481A), apply the production data of the entire section of coalbed methane and the analysis section reflecting the characteristics of formation pressure change to perform deconvolution to obtain the double logarithm curves of pressure and its derivative, select the corresponding reservoir and well models, and determine the interpretation result by comprehensively considering the adjacent wells and reservoir geological characteristics, which can be used to obtain parameters such as permeability and initial formation pressure. A well test interpretation method, device, storage medium and computer equipment (CN114086934A) constructs a well test interpretation model for a fractured vuggy composite formation based on reservoir parameters to obtain the real-space bottom hole pressure solution, draws the real-space well test theoretical curve, and fits it with the well test measured data. The obtained well test interpretation result is combined with geological understanding and is applicable to complex fracture-cavity patterns. In summary, the existing technologies all establish models for interpretation based on the pressure build-up data of different reservoirs, and there is no method for interpreting the situation of missing pressure build-up data. Summary of the Invention

[0004] The embodiments of the present disclosure provide a pressure build-up well test interpretation method, device and electronic equipment for shale oil wells, which can solve the problem of missing pressure build-up data in the closed well test of shale oil wells and provide a reliable basis for oil well dynamic analysis.

[0005] According to one aspect of the present disclosure, a pressure build-up well test interpretation method for shale oil wells is provided, including:

[0006] Obtain the effective shut-in pressure test data of the pressure gauge and the time of entering the well. The effective shut-in pressure test data is the bottom-hole pressure data after shut-in and when the pressure gauge is lowered to the target test depth from the wellhead. The time of entering the well is the time required for the pressure gauge to be lowered to the target test depth from the wellhead after shut-in;

[0007] Obtain the shut-in start time and the pressure gradient during the process of the pressure gauge entering the well;

[0008] According to the pressure gradient, calculate the fluid pressure data at the target test depth from the wellhead at the shut-in start time as supplementary pressure data;

[0009] Determine the complete pressure build-up test curve according to the effective shut-in pressure test data, the time of entering the well, and the supplementary pressure data;

[0010] Based on the complete pressure build-up test curve, conduct pressure build-up test interpretation.

[0011] In one embodiment, the pressure gradient includes the static pressure gradient.

[0012] In one embodiment, the obtaining the pressure gradient during the process of the pressure gauge entering the well includes:

[0013] Obtain the pressure gradient when the pressure gauge is lowered to a depth within a preset depth threshold range from the wellhead since the shut-in start time. The preset depth threshold is less than the target test depth; or,

[0014] Obtain the pressure gradient at the first temporary stop point after the pressure gauge enters the well since the shut-in start time. Among them, multiple temporary stop points are set during the process of the pressure gauge from the wellhead to the target test depth.

[0015] In one embodiment, the calculating the fluid pressure data at the target test depth from the wellhead at the shut-in start time according to the pressure gradient includes:

[0016] According to the pressure gradient, the well depth corresponding to the pressure gradient, the measured reference pressure at the well depth corresponding to the pressure gradient, and the target test depth, calculate the fluid pressure data at the target test depth from the wellhead at the shut-in start time.

[0017] In one embodiment, the following calculation formula is used to calculate the fluid pressure data:

[0018] P wf =(H o -H1)*P 梯 / 100+P 压 ; where, H o is the target test depth, P 梯is the pressure gradient, H1 is the well depth corresponding to the pressure gradient, and P 压 is the measured reference pressure at the well depth corresponding to the pressure gradient.

[0019] In one embodiment, determining the complete pressure build-up test curve according to the effective shut-in pressure test data, the time of entering the well, and the supplementary pressure data includes:

[0020] Taking the supplementary pressure data as the starting point pressure data for the shut-in test, and the effective shut-in pressure test data as the pressure data after a time equal to the time of entering the well since the start time of the shut-in test, and fitting to obtain the complete pressure build-up test curve.

[0021] According to another aspect of the present disclosure, there is provided a device for interpreting the pressure build-up test of a shale oil well, including:

[0022] A data acquisition module, configured to acquire the effective shut-in pressure test data of the pressure gauge and the time of entering the well. The effective shut-in pressure test data is the bottom hole pressure data after shut-in and when the pressure gauge is lowered to the target test depth from the wellhead. The time of entering the well is the time required for the pressure gauge to be lowered to the target test depth from the wellhead after shut-in; acquire the start time of the shut-in, and the pressure gradient during the process of the pressure gauge entering the well;

[0023] A data supplement module, configured to calculate the fluid pressure data at the target test depth from the wellhead at the start time of the shut-in according to the pressure gradient as the supplementary pressure data;

[0024] A curve fitting module, configured to determine the complete pressure build-up test curve according to the effective shut-in pressure test data, the time of entering the well, and the supplementary pressure data;

[0025] An interpretation module, configured to perform pressure build-up test interpretation based on the complete pressure build-up test curve.

[0026] In one embodiment, the data acquisition module is configured to acquire the pressure gradient at a depth within a preset depth threshold range from the wellhead starting from the start time of the shut-in, where the preset depth threshold is less than the target test depth; or acquire the pressure gradient at the first temporary stop point after the pressure gauge enters the well starting from the start time of the shut-in, where multiple temporary stop points are set during the process of the pressure gauge from the wellhead to the target test depth.

[0027] In one embodiment, the data supplement module is configured to calculate the fluid pressure data at the target test depth from the wellhead at the start time of the shut-in according to the pressure gradient, the well depth corresponding to the pressure gradient, the measured reference pressure at the well depth corresponding to the pressure gradient, and the target test depth.

[0028] In one embodiment, the curve fitting module is configured to use the supplementary pressure data as the starting point pressure data for the shut-in test, and the effective shut-in pressure test data as the pressure data after a time equal to the well logging time has elapsed since the start time of the shut-in test, and fit to obtain a complete pressure build-up well test curve.

[0029] According to another aspect of the present disclosure, there is provided an electronic device, including:

[0030] At least one processor; and

[0031] At least one memory storing a computer program,

[0032] The processor calls the computer program to cause the processor to execute the shale oil well pressure build-up well test interpretation method according to one aspect of the present disclosure as described above.

[0033] According to another aspect of the present disclosure, there is provided a non-transitory computer-readable storage medium storing a computer program, the computer program being configured to cause a computer to execute the shale oil well pressure build-up well test interpretation method according to one aspect of the present disclosure as described above.

[0034] The above technical features can be combined in various suitable ways or replaced by equivalent technical features as long as the object of the present invention can be achieved.

[0035] In one or more technical solutions provided in the embodiments of the present disclosure, after obtaining the pressure gradient during the process of the pressure gauge entering the well after shut-in, and then approximating and calculating the fluid pressure data at the target test depth of the wellhead from the start time of shut-in according to the pressure gradient as supplementary pressure data, the problem of data loss caused by the inability to measure the pressure data at the target test depth at the start time of shut-in due to the pressure gauge not being lowered to the target test depth after shut-in is solved. Combining the converted fluid pressure data with the effective shut-in pressure test data of the pressure gauge can fit a complete pressure build-up well test curve, thereby improving the accuracy of the pressure build-up well test interpretation and providing a reliable basis for the dynamic analysis of oil wells. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the following description of exemplary embodiments with reference to the accompanying drawings, more details, features, and advantages of the present disclosure are disclosed. In the drawings:

[0037] Figure 1 A flowchart showing a method for interpreting a shale oil well pressure build-up well test according to an exemplary embodiment of the present disclosure is shown;

[0038] Figure 2 A schematic diagram of a pressure curve and a pressure derivative curve when the production time before shut-in is 15 h is shown;

[0039] Figure 3Shows a schematic diagram of the pressure curve and the pressure derivative curve when the production time before well shut-in is 200 h;

[0040] Figure 4 Shows the test curve of the pressure gauge during the lowering process after well shut-in according to an exemplary embodiment of the present disclosure;

[0041] Figure 5 Shows a schematic diagram of the measured data curve corresponding to the pressure build-up test data after adding supplementary pressure data according to an exemplary embodiment of the present disclosure;

[0042] Figure 6 Shows a schematic diagram of the measured data curve corresponding to the pressure build-up test data without adding supplementary pressure data;

[0043] Figure 7 Shows the double logarithmic curve obtained without adding supplementary pressure data;

[0044] Figure 8 Shows the double logarithmic curve obtained when adding supplementary pressure data according to an exemplary embodiment of the present disclosure;

[0045] Figure 9 Shows a schematic block diagram of an interpretation device for pressure build-up well testing of a shale oil well according to an exemplary embodiment of the present disclosure. Detailed implementation manners

[0046] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although some embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are only for exemplary purposes and are not used to limit the protection scope of the present disclosure.

[0047] It should be understood that the steps recited in the method embodiments of the present disclosure can be executed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present disclosure is not limited in this regard.

[0048] As used herein, the term "including" and its variations are open-ended, that is, "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Relevant definitions of other terms will be given in the following description. It should be noted that the concepts such as "first", "second", etc. mentioned in this disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0049] It should be noted that the modifications of "one" and "a plurality" mentioned in this disclosure are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise clearly specified in the context, it should be understood as "one or more".

[0050] The names of the messages or information exchanged between multiple devices in the embodiments of this disclosure are only for illustrative purposes and are not used to limit the scope of these messages or information.

[0051] The solutions of the embodiments of this disclosure will be described below with reference to the accompanying drawings.

[0052] The embodiments of this disclosure provide a method for interpreting pressure buildup test of shale oil wells, as Figure 1 shown, Figure 1 FIG. shows a schematic flow chart of a method for interpreting pressure buildup test of shale oil wells according to an exemplary embodiment of this disclosure. The method includes:

[0053] S101, obtaining the effective shut-in pressure test data of the pressure gauge and the time of entering the well. The effective shut-in pressure test data is the bottom-hole pressure data after shut-in and when the pressure gauge is lowered to the target test depth from the wellhead. The time of entering the well is the time required for the pressure gauge to be lowered to the target test depth from the wellhead after shut-in.

[0054] S102, obtaining the start time of shut-in and the pressure gradient during the process of the pressure gauge entering the well.

[0055] Pressure buildup test, that is, pressure recovery test, is to transfer the well from a stable production state to a shut-in state and measure the change of the bottom-hole pressure with time after shut-in.

[0056] The shut-in pressure test data, namely the shut-in pressure build-up test data, is abbreviated as the pressure build-up test data. Here, the effective shut-in pressure test data of the pressure gauge refers to the bottom-hole pressure data after shut-in and when the pressure gauge is lowered to the target test depth from the wellhead. During the actual construction process, after shut-in, the pressure gauge can be lowered from the wellhead to the target measurement depth by wire to measure the pressure change at the target test depth of the bottom hole. During the process of lowering the pressure gauge into the well, the pressure data obtained starts from the shut-in start time, and the pressure data measured before the pressure gauge is lowered to the target test depth is not required. Therefore, the pressure data during this period needs to be deleted to obtain the effective shut-in pressure test data.

[0057] The time of entry into the well, that is, the time required for the pressure gauge to be lowered to the target test depth from the wellhead after shut-in, is here a time length. The shut-in start time, that is, the moment when the shut-in operation is executed. For example, if the well is shut in at 10:00 am, the shut-in start time is 10:00. If the time or moment when the pressure gauge is lowered to the target test depth is 14:00, then the time of entry into the well is 4 hours. The shut-in start time and the moment when the pressure gauge is lowered to the target test depth will be recorded during the actual construction process.

[0058] The pressure gradient, such as the flowing pressure gradient, refers to the pressure generated by each meter (or every 100 m) of liquid column when the oil well is in normal production, and is generally measured under the open-well condition. During the calculation of the flowing pressure gradient, the ratio of the pressure difference measured at two different points to the distance is the flowing pressure gradient. Another example is the static pressure gradient, which refers to the pressure generated by each meter (or every 100 meters) of liquid column when the bottom-hole pressure of the oil well returns to stability after shut-in. When calculating the static pressure gradient, similarly, the static pressure gradient can be obtained by choosing the ratio of the pressures at any two different points to the distance, such as where P1 and P2 are the pressures at any two points, and H1 and H2 are the distances from the corresponding position points to the wellhead or the well depths. Therefore, the pressure gradient during the process of the pressure gauge entering the well can be calculated based on the depth to which the pressure gauge is lowered and the pressure at the corresponding depth.

[0059] S103, according to the pressure gradient, calculate the fluid pressure data at the target test depth from the wellhead at the shut-in start time as supplementary pressure data.

[0060] Due to the relatively high wellhead pressure in the early stage of shale oil wells, it is difficult for the wireline to carry the pressure gauge into the well, making it impossible to lower the pressure gauge under the open well production condition, and the shale oil well cannot conduct a normal pressure build-up test. At this time, for some oil wells, the method of lowering the pressure gauge after shutting in the well can be adopted. At the starting time of shutting in the well, that is, at the moment of shutting in the well, the pressure gauge is just about to be lowered from the wellhead at the wellhead. Therefore, at the starting time of shutting in the well, the pressure data at the target test depth cannot be obtained, resulting in the pressure data at the target test depth being missing during the period from the starting time of shutting in the well to the pressure gauge being lowered to the target test depth. In the embodiments of the present disclosure, according to the pressure gradient during the process of the pressure gauge entering the well, the fluid pressure data at the target test depth at the starting time of shutting in the well is converted as supplementary pressure data, which can supplement the pressure data at the target test depth at the starting time of shutting in the well and prepare for fitting a complete pressure build-up curve subsequently.

[0061] S104. Determine a complete pressure build-up well test curve according to the effective shut-in pressure test data, the time of entering the well, and the supplementary pressure data.

[0062] S105. Conduct pressure build-up well test interpretation based on the complete pressure build-up well test curve.

[0063] According to the principle of pressure drop superposition, the premise of pressure build-up well test interpretation is that the production time before shutting in the well (i.e., the production duration) should be much greater than the shut-in time (i.e., the shut-in duration). The embodiments of the present disclosure are applicable to the situation where the production time before shutting in the well is much greater than the shut-in time.

[0064] Insufficient production time will affect the shape of the pressure build-up curve, causing situations such as the curve crossing and rising upwards in the later stage. This phenomenon is particularly obvious when the formation permeability is relatively low. As Figure 2 shown, c1 is the pressure curve and c2 is the pressure derivative curve. When the production time before shutting in the well is 15 h, the pressure curve and the pressure derivative curve will cross in the later stage. At this time, there are relatively large errors in the interpretation results of the double logarithmic curve, and the curve results cannot be applied. When the shut-in time is extended to 200 h, as Figure 3 shown, the shape of the double logarithmic curve completely changes, and the pressure curve and the pressure derivative curve will not cross in the later stage. It can be seen that whether the production time is long enough will affect the change of the curve in the later stage.

[0065] The pressure build-up formula is derived from the superposition principle. Assume that an oil well A produces at a constant production rate q for t p time and then shuts in the well (at this time, the production time is t p ), then the calculation formula for the pressure change during the shut-in pressure build-up stage can be obtained. After formula derivation, the bottom-hole shut-in pressure p ws of the oil well is the following calculation formula (1).

[0066] Calculation formula (1):

[0067]

[0068] where p ws (Δt) is the bottom-hole pressure during the shut-in period of Δt, with the unit of MPa;

[0069] p wf (t p ) is the bottom-hole pressure during the production period of t p , with the unit of MPa;

[0070] t p is the production time before shut-in, with the unit of h; Δt is the shut-in time, which is a time length; q is the stable surface production rate of the well, with the unit of m 3 / d; u is the fluid viscosity, with the unit of mPa·S; B is the fluid volume factor, dimensionless; K is the reservoir permeability, with the unit of μm 2 ; h is the effective thickness of the reservoir, with the unit of m; φ is the porosity of the reservoir or formation, dimensionless; C t is the comprehensive compressibility of the formation and the fluid therein, with the unit of MPa -1 ; r w is the wellbore radius, with the unit of m; S is the skin factor, dimensionless.

[0071] When the production time t p before shut-in is much longer than the shut-in time Δt, i.e., t p >>Δt, then the above calculation formula (1) can be simplified to calculation formula (2) at this time.

[0072] Calculation formula (2):

[0073]

[0074] In the later stage of pressure build-up well test interpretation, the simplified calculation formula (2) is used to calculate formation parameters or reservoir parameters. Regarding the relationship between the production time before shut-in and the shut-in time, generally Δt < 0.1t p , and in unconventional tight reservoirs, at least ensure that t p > Δt.

[0075] In the embodiments of the present disclosure, by obtaining the pressure gradient during the process of the pressure gauge entering the well after shut-in, and then approximating the calculation of the fluid pressure data at the target test depth from the wellhead at the start time of shut-in based on the pressure gradient as supplementary pressure data, the problem of data loss caused by the inability to measure the pressure data at the target test depth at the start time of shut-in due to the pressure gauge not being lowered to the target test depth after shut-in is solved. Combining the converted fluid pressure data with the effective shut-in pressure test data of the pressure gauge can fit a complete pressure build-up well test curve, thereby improving the accuracy of pressure build-up well test interpretation and providing a reliable basis for oil well dynamic analysis.

[0076] In step S101, when obtaining the effective shut-in pressure test data of the pressure gauge, the accurate time when the pressure gauge is lowered to the target test depth is also important. Generally, during the construction process, the time and pressure data when lowered to the target test depth are recorded and can be used directly. However, to improve the accuracy, after shutting in the well, the data of the pressure gauge from the wellhead to the target test depth and after reaching the target test depth can be characterized by a test curve, and then combined with the test curve during the lowering process of the pressure gauge and the construction record, the time when the pressure gauge is lowered to the target test depth can be determined.

[0077] Suppose in the construction record, the tool string is assembled from 10:00 to 11:00, the blowout preventer and the blowout preventer pipe are installed, and the pressure gauge is lowered to the target test depth of 3500 m in the time period from 11:00 to 14:00. During the lowering process, multiple temporary stop points are set for pressure measurement, and the depths of the temporary stop points are respectively: 500 m, 1000 m, 1500 m, 2000 m, 2500 m, 3000 m, 3500 m. From 14:00 to 15:00, the tools are put away, the site is cleaned up, and after placing safety signs, the site is evacuated. From 14:00 to 24:00, shut-in pressure measurement is carried out on the target test depth. According to this construction record, the shut-in start time can be determined as 10:00, the target test depth for lowering the pressure gauge is 3500 m, the time for the pressure gauge to enter the well is 4 h. When obtaining the effective shut-in pressure test data, the pressure data before the pressure gauge is lowered to the target test depth can be directly deleted according to the record, and the data recorded by the pressure gauge after the pressure gauge is lowered to the target test depth is used as the effective shut-in pressure test data. To improve the accuracy, the construction record can also be combined to obtain the test curve. See Figure 4 , Figure 4 is the test curve of the pressure gauge during the lowering process after shutting in the well. At each different temporary stop point, its pressure value will change suddenly, which is shown as a sudden step in the figure. According to this test curve, it can be known that the last step (the area circled in the upper right corner of the figure) is the pressure data when the pressure gauge starts to test after being lowered to the target test depth. The pressure and time data of the first point R of this step can be read as the starting data of the effective shut-in pressure test data, and the data before this point is deleted. The starting data is combined with the data after this point to obtain the effective shut-in pressure test data, that is, all the measured bottom-hole pressure data after shutting in the well and after the pressure gauge is lowered to the target test depth.

[0078] After obtaining effective shut-in pressure test data, in the prior art, generally based on the effective shut-in pressure test data, a pressure buildup test curve is determined, and then pressure buildup test interpretation is carried out. However, during the period from when the pressure gauge is lowered from the wellhead to the target test depth, the pressure data at the target test depth cannot be measured, resulting in missing data in the early stage, and the pressure buildup test data is not complete. In particular, the fluid pressure data at the target test depth at the start time of shut-in is missing, which affects the shape of the pressure buildup double logarithmic curve and the result of pressure buildup interpretation. Therefore, in order to supplement the missing data, improve the accuracy of the pressure buildup test curve, and further improve the accuracy of pressure buildup test interpretation, the embodiments of the present disclosure will obtain the pressure gradient during the process of the pressure gauge being lowered into the well.

[0079] The pressure gradient, as described above, can be the flowing pressure gradient or the static pressure gradient. In the case where the pressure gauge can be lowered a short distance under the open well state in some wells, the fluid pressure data at the target test depth at the start time of shut-in can be converted by obtaining the flowing pressure gradient. In some embodiments of the present disclosure, based on a more common scenario, the pressure gradient is the static pressure gradient, and the fluid pressure data at the target test depth at the start time of shut-in is converted by obtaining the static pressure gradient.

[0080] In some embodiments of the present disclosure, obtaining the pressure gradient during the process of the pressure gauge being lowered into the well may be obtaining the pressure gradient at a depth within a preset depth threshold range from the wellhead since the start time of shut-in, and the preset depth threshold is less than the target test depth. For example, if the target test depth is 3500 m, the preset depth threshold may be 500 m. During specific implementation, the pressure gradient at a depth of 500 m from the wellhead may be obtained, or the pressure gradient at a depth of 400 m from the wellhead may be obtained, etc.

[0081] In some embodiments of the present disclosure, obtaining the pressure gradient during the process of lowering the pressure gauge into the well may also be: obtaining the pressure gradient at the first stop point after the pressure gauge is lowered into the well since the start time of well shut-in, where multiple stop points are set during the process of the pressure gauge from the wellhead to the target test depth. For example, if the target test depth is 3500 m, a stop point is set every 500 m, that is, the depths corresponding to the stop points are: 500 m, 1000 m, 1500 m, 2000 m, 2500 m, 3000 m, 3500 m. At this time, the pressure gradient at the first stop point after the pressure gauge is lowered into the well, that is, at a depth of 500 m, can be obtained. Of course, the depth interval of the stop points can also be smaller, such as 200 m, which is not limited in the embodiments of the present disclosure. In some feasible ways, it may also be to obtain the pressure gradient at the second stop point or the third stop point after the pressure gauge is lowered into the well, etc., which is not limited in the embodiments of the present disclosure. For example, if the pressure gradient data at a certain stop point is significantly incorrect, the pressure gradient at another stop point can be used for conversion. By obtaining the pressure gradient at the first stop point after the pressure gauge is lowered into the well to convert the fluid pressure data at the target test depth at the start time of well shut-in in the exemplary embodiments of the present disclosure, the accuracy can be improved because after well shut-in, the first stop point is closest to the start time of well shut-in and is closer to the fluid state.

[0082] In some embodiments of the present disclosure, calculating the fluid pressure data at the target test depth from the wellhead at the start time of well shut-in according to the pressure gradient includes: calculating the fluid pressure data at the target test depth from the wellhead at the start time of well shut-in according to the pressure gradient, the well depth corresponding to the pressure gradient, the measured reference pressure at the well depth corresponding to the pressure gradient, and the target test depth.

[0083] Exemplarily, the following calculation formula (3) is used to calculate the fluid pressure data:

[0084] Calculation formula (3): P wf =(H o -H1)*P 梯 / 100+P 压 ; where H o is the target test depth, P 梯 is the pressure gradient, H1 is the well depth corresponding to the pressure gradient, and P 压 is the measured reference pressure at the well depth corresponding to the pressure gradient.

[0085] After obtaining the fluid pressure data at the target test depth at the shut-in start time, it can be used as supplementary pressure data, and then combined with the well entry time and the effective shut-in pressure test data of the pressure gauge, so as to fit a complete pressure build-up well test curve. In a feasible way, according to the effective shut-in pressure test data, the well entry time, and the supplementary pressure data, a complete pressure build-up well test curve is determined, including: using the supplementary pressure data as the starting point pressure data of the shut-in test, and the effective shut-in pressure test data as the pressure data after a long time equal to the well entry time since the shut-in start time of the shut-in test, and fitting to obtain a complete pressure build-up well test curve.

[0086] For example, the well entry time t1, which is the time required from the shut-in start time t0 to the pressure gauge being lowered to the target test depth, is obtained. As Figure 5 shown, Figure 5 is the measured data curve corresponding to the pressure build-up test data after adding supplementary pressure data. In the figure, the upper part area is the curve of pressure changing with time, and the lower part area is the curve of production changing with time. Taking the shut-in start time t0 as the starting point, and using the calculated fluid pressure data at the target test depth at the shut-in start time as the pressure value at the starting point, and supplementing it into the pressure build-up test data, as point A in the figure, as the starting point pressure data of the shut-in test. At this time, according to the well entry time t1, it can be known that the starting time point of the obtained effective shut-in pressure test data should be t0 + t1, that is, the data after t0 + t1 is the measured pressure data after the pressure gauge is lowered to the target test depth. To facilitate the understanding of this solution, the measured data curve corresponding to the pressure build-up test data without adding supplementary pressure data is given. Figure 6 shown, Figure 6 is the measured data curve corresponding to the pressure build-up test data without adding supplementary pressure data. It can be seen from this figure that without supplementing the missing data, taking the shut-in start time t0 as the starting point, the data corresponding to the shut-in start time t0 will directly adopt the first data in the effective shut-in pressure test data.

[0087] According to the pressure build-up test data, a complete pressure build-up well test curve can be fitted. After obtaining the pressure build-up well test curve, by applying the pressure build-up well test software and selecting a suitable well test model, pressure build-up well test interpretation can be carried out, and a double logarithmic curve can be drawn for fitting interpretation to obtain reservoir parameters such as flow coefficient, formation coefficient, effective permeability, skin factor, etc.

[0088] For the case without supplementing the missing data, the result after well test interpretation and drawing a double logarithmic curve for fitting interpretation is as Figure 7 shown, Figure 7The double logarithmic curve obtained without adding supplementary pressure data is shown. In the figure, the discrete points are the measured data before fitting. The discrete points in the shape of circles represent the pressure derivative, and the discrete points in the shape of crosses represent the pressure value. The solid line represents the curve after fitting. c3 is the fitting curve of the pressure value, and c4 is the fitting curve of the pressure derivative. Through the embodiments of the present application, after obtaining the complete pressure buildup well test curve according to the supplementary pressure data, further pressure buildup well test interpretation is carried out, and the double logarithmic curve is plotted for fitting interpretation. The obtained double logarithmic curve is as shown in Figure 8 In the figure, c5 is the fitting curve of the pressure value, and c6 is the fitting curve of the pressure derivative. Corresponding to their respective fitting curves are the discrete numerical values before fitting. It can be seen from the comparison between the two that the lack of pressure data at the target test depth during the period from the start time of shut-in to the time when the pressure gauge is lowered to the target test depth will seriously affect the interpretation result of the pressure buildup curve.

[0089] Through the exemplary embodiments of the present disclosure, by obtaining the pressure gradient during the process of the pressure gauge entering the well after shut-in, and then approximately calculating the fluid pressure data at the target test depth from the wellhead at the start time of shut-in according to the pressure gradient as the supplementary pressure data, the problem of data loss caused by the inability to measure the pressure data at the target test depth at the start time of shut-in due to the pressure gauge not being lowered to the target test depth after shut-in is solved. Combining the converted fluid pressure data with the effective shut-in pressure test data of the pressure gauge can fit the complete pressure buildup well test curve, thereby improving the accuracy of pressure buildup well test interpretation and providing a reliable basis for the dynamic analysis of oil wells.

[0090] The following takes a specific example to illustrate the embodiments of the present disclosure schematically.

[0091] The pressure buildup test process and test records of Well B are shown in Table 1 below. During the test process, first, the shut-in operation is carried out, and then the pressure gauge is lowered. When the pressure gauge is lowered, the static pressure gradient during the lowering of the pressure gauge is measured, as shown in Table 2.

[0092] Table 1

[0093]

[0094] It can be seen from Table 1 that the start time of shut-in is 10:00 am, the target test depth is 3460 m, the time when the pressure gauge is lowered to a depth of 3460 m is approximately 14:00 on July 23, and the time required for the pressure gauge to be lowered to the target test depth, that is, the entry time into the well, is 4 h.

[0095] Table 2

[0096]

[0097] The pressure and pressure gradient values at each temporary stopping point can be obtained from Table 2. The fluid pressure value at the target test depth from the wellhead at the starting time of well shut-in can be calculated based on the pressure and pressure gradient, and this value is used as supplementary pressure data. Here, the pressure gradient at a depth of 500 m is used to calculate the supplementary pressure data. That is, P 补充 =(3460 - 500)*0.926 / 100 + 10.46 = 37.38 MPa.

[0098] The calculated supplementary pressure data P 补充 is used as the starting point data of the pressure build-up curve (i.e., the 0-point data). Then, combined with the measured pressure data of the pressure gauge 4 hours after the starting time of well shut-in as the data 4 hours after the pressure build-up curve, a complete pressure build-up test curve is obtained. Then, well test interpretation software such as Saphir software is used to perform pressure build-up well test interpretation to obtain a double logarithmic fitting curve.

[0099] The embodiment of the present disclosure also provides a pressure build-up well test interpretation device for a shale oil well, as Figure 9 shown. Figure 9 The schematic block diagram of a pressure build-up well test interpretation device for a shale oil well according to an exemplary embodiment of the present disclosure is shown. The device includes:

[0100] A data acquisition module 901, configured to acquire the effective well shut-in pressure test data of the pressure gauge and the downhole time. The effective well shut-in pressure test data is the bottom hole pressure data after well shut-in and when the pressure gauge is lowered to the target test depth from the wellhead. The downhole time is the time required for the pressure gauge to be lowered to the target test depth from the wellhead after well shut-in; acquire the starting time of well shut-in, and the pressure gradient during the downhole process of the pressure gauge;

[0101] A data supplement module 902, configured to calculate the fluid pressure data at the target test depth from the wellhead at the starting time of well shut-in according to the pressure gradient, as supplementary pressure data;

[0102] A curve fitting module 903, configured to determine a complete pressure build-up well test curve according to the effective well shut-in pressure test data, the downhole time, and the supplementary pressure data;

[0103] An interpretation module 904, configured to perform pressure build-up well test interpretation based on the complete pressure build-up well test curve.

[0104] In some embodiments of the present disclosure, the data acquisition module 901 is configured to acquire the pressure gradient at a depth within a preset depth threshold range from the wellhead after the starting time of well shut-in, and the preset depth threshold is less than the target test depth.

[0105] In some embodiments of the present disclosure, the data acquisition module 901 acquires the pressure gradient at the first temporary stop point after the pressure gauge enters the well since the start time of well shut-in, where multiple temporary stop points are set during the process of the pressure gauge from the wellhead to the target test depth.

[0106] In some embodiments of the present disclosure, the data supplement module 902 is configured to calculate the fluid pressure data at the target test depth from the wellhead at the start time of well shut-in according to the pressure gradient, the well depth corresponding to the pressure gradient, the measured reference pressure at the well depth corresponding to the pressure gradient, and the target test depth.

[0107] In some embodiments of the present disclosure, the data supplement module 902 calculates the fluid pressure data by using the following calculation formula:

[0108] P wf =(H o -H1)*P 梯 / 100+P 压 ; where H o is the target test depth, P 梯 is the pressure gradient, H1 is the well depth corresponding to the pressure gradient, and P 压 is the measured reference pressure at the well depth corresponding to the pressure gradient.

[0109] In some embodiments of the present disclosure, the curve fitting module 903 is configured to use the supplementary pressure data as the starting point pressure data of the well shut-in test, and the effective well shut-in pressure test data as the pressure data after the same long time as the well entry time since the start time of well shut-in of the well shut-in test, and fit to obtain a complete pressure build-up test curve.

[0110] The related content of the pressure build-up test interpretation device for shale oil wells provided by the embodiments of the present disclosure corresponds to the above-mentioned pressure build-up test interpretation method for shale oil wells. For the matters not covered in detail, reference may be specifically made to the relevant descriptions of the foregoing pressure build-up test interpretation method for shale oil wells, and details are not described herein again.

[0111] An exemplary embodiment of the present disclosure further provides an electronic device, including: at least one processor; and a memory communicatively connected to the at least one processor. The memory stores a computer program that can be executed by the at least one processor, and when the computer program is executed by the at least one processor, it is configured to cause the electronic device to execute the method according to the embodiments of the present disclosure.

[0112] An exemplary embodiment of the present disclosure further provides a non-transitory computer-readable storage medium storing a computer program, where when the computer program is executed by a processor of a computer, it is configured to cause the computer to execute the method according to the embodiments of the present disclosure.

[0113] While the present invention has been described herein with reference to particular embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Accordingly, it should be understood that numerous modifications may be made to the exemplary embodiments, and other arrangements may be devised, without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the different dependent claims and the features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with separate embodiments may be used in other described embodiments.

Claims

1. A method for interpreting pressure build-up test of shale oil wells, characterized in that, Including: Obtaining the effective shut-in pressure test data of the pressure gauge and the downhole time, where the effective shut-in pressure test data is the bottom hole pressure data after shut-in and when the pressure gauge is lowered to the target test depth from the wellhead, and the downhole time is the time required for the pressure gauge to be lowered to the target test depth from the wellhead after shut-in; Obtaining the shut-in start time and the pressure gradient during the downhole process of the pressure gauge; Calculating the fluid pressure data at the target test depth from the wellhead at the shut-in start time according to the pressure gradient as supplementary pressure data; Determining a complete pressure build-up test curve according to the effective shut-in pressure test data, the downhole time, and the supplementary pressure data; Performing pressure build-up test interpretation based on the complete pressure build-up test curve.

2. The method according to claim 1, characterized in that The pressure gradient includes a static pressure gradient.

3. The method according to claim 1, characterized in that, The obtaining of the pressure gradient during the downhole process of the pressure gauge includes: Obtaining the pressure gradient when the pressure gauge is lowered to a depth within a preset depth threshold range from the wellhead since the shut-in start time, where the preset depth threshold is less than the target test depth; or, Obtaining the pressure gradient at the first temporary stop point after the pressure gauge is lowered into the well since the shut-in start time, where multiple temporary stop points are set during the process of the pressure gauge from the wellhead to the target test depth.

4. The method according to claim 1, wherein The calculating of the fluid pressure data at the target test depth from the wellhead at the shut-in start time according to the pressure gradient includes: Calculating the fluid pressure data at the target test depth from the wellhead at the shut-in start time according to the pressure gradient, the well depth corresponding to the pressure gradient, the reference pressure measured at the well depth corresponding to the pressure gradient, and the target test depth.

5. The method according to claim 4, wherein Calculating the fluid pressure data using the following calculation formula: P wf = (H o - H1) * P 梯 / 100 + P 压 ; where, H o is the target test depth, P 梯 is the pressure gradient, H1 is the well depth corresponding to the pressure gradient, and P 压 is the measured reference pressure at the well depth corresponding to the pressure gradient.

6. The method according to claim 1, characterized in that The determining of a complete pressure build-up test curve according to the effective shut-in pressure test data, the downhole time, and the supplementary pressure data includes: Taking the supplementary pressure data as the starting point pressure data for the shut-in test, and the effective shut-in pressure test data as the pressure data after the same time as the downhole time has elapsed since the shut-in start time for the shut-in test, and fitting to obtain a complete pressure build-up test curve.

7. A pressure build-up test interpretation device for shale oil wells, characterized in that, Including: A data acquisition module for obtaining the effective shut-in pressure test data of the pressure gauge and the downhole time, where the effective shut-in pressure test data is the bottom hole pressure data after shut-in and when the pressure gauge is lowered to the target test depth from the wellhead, and the downhole time is the time required for the pressure gauge to be lowered to the target test depth from the wellhead after shut-in; Obtaining the shut-in start time and the pressure gradient during the downhole process of the pressure gauge; A data supplement module for calculating the fluid pressure data at the target test depth from the wellhead at the shut-in start time according to the pressure gradient as supplementary pressure data; A curve fitting module for determining a complete pressure build-up test curve according to the effective shut-in pressure test data, the downhole time, and the supplementary pressure data; An interpretation module for performing pressure build-up test interpretation based on the complete pressure build-up test curve.

8. The device according to claim 7, characterized in that, The data acquisition module is configured to obtain the pressure gradient at a depth within a preset depth threshold range from the wellhead since the start time of well shut-in, where the preset depth threshold is less than the target test depth; or, obtain the pressure gradient at the first stop point after the pressure gauge enters the well since the start time of well shut-in, wherein a plurality of stop points are set during the process of the pressure gauge from the wellhead to the target test depth.

9. The device according to claim 7, characterized in that, The data supplement module is configured to calculate the fluid pressure data at the target test depth from the wellhead at the start time of well shut-in according to the pressure gradient, the well depth corresponding to the pressure gradient, the reference pressure measured at the well depth corresponding to the pressure gradient, and the target test depth.

10. The device according to claim 7, characterized in that, The curve fitting module is configured to use the supplemented pressure data as the starting point pressure data for the well shut-in test, and the effective well shut-in pressure test data as the pressure data after the same length of time as the well entry time since the start time of well shut-in for the well shut-in test, and fit to obtain a complete pressure build-up test curve.

11. An electronic device, characterized in that, Comprising: At least one processor; And At least one memory storing a computer program, The processor calls the computer program to cause the processor to execute the method according to any one of claims 1-6.

12. A non-transitory computer-readable storage medium storing a computer program, characterized in that, The computer program is used to cause the computer to execute the method according to any one of claims 1-6.

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