Shallow heavy oil sampling probe selection method and system based on dynamic flow window

Abstract

The shallow heavy oil sampling probe selection method and system based on a dynamic mobility window selects data in the process of adjacent well sampling, fits a differential pressure-time function, and then calculates the upper limit and lower limit of the mobility window of each probe to form a probe sliding mobility window, compares each probe sliding mobility window with the best sampling mobility range of the sampling target layer one by one, and selects the optimal probe type. Meanwhile, when the sampling operation cannot meet the success standard, the measured formation pressure and pipeline pressure of the target well are fitted into a new differential pressure-time function to cover the original function, and dynamic adjustment is realized. The beneficial effects of the present application are: improving the sampling success rate, accurately matching the formation conditions and probe parameters through the dynamic mobility window. Shortening the operation time, optimizing the sampling probe type, and effectively improving the operation timeliness. Enhancing system automation, and adapting to changes in complex formations.

Description

Technical Field

[0001] This invention relates to the field of unconventional oil and gas geophysical logging technology, and more specifically to a method and system for selecting shallow heavy oil sampling probes based on a dynamic mobility window. Background Technology

[0002] In current technologies, the exploration and understanding of heavy oil and gas reservoirs often rely on expensive oil testing processes. To reduce exploration costs, wireline logging sampling is often used, provided that sufficient heavy oil samples are obtained for laboratory analysis. However, as the exploration depth of heavy oil decreases, gradually increasing from 1500m to less than 1000m, traditional wireline sampling technology faces the following challenges: (1) Low sampling success rate: shallow formations are loosely cemented, making them prone to sand production, failure to set the well, and even well wall collapse; (2) Poor sample purity: Heavy oil has high viscosity and poor fluidity, and is prone to degassing and emulsification under large pressure difference, which affects subsequent analysis; (3) Low efficiency of operation: unreasonable selection of sampling points and excessive pumping time result in low efficiency of operation. Summary of the Invention

[0003] This invention overcomes the shortcomings of the prior art and provides a method and system for selecting shallow heavy oil sampling probes based on a dynamic mobility window.

[0004] The method for selecting sampling probes for shallow heavy oil based on dynamic mobility windows includes the following steps: S1. Select a neighboring well based on the well spacing condition of the target well. Fit the relationship data of formation pressure and pipeline pressure difference with time during the sampling process of the selected neighboring well to obtain the pressure difference-time function. According to the maximum allowable sampling time and pressure difference-time function To obtain the maximum stable pressure difference The minimum pressure difference is obtained based on regional experience. ; S2. Obtain the volumetric flow rate of the target well. and the probe length of each probe Flow area The data was used to calculate the upper limit of the flow rate window for each probe. and lower limit of the flow window Through the upper limit of the probe flow window and lower limit of the flow window Forming the probe sliding flow window; S3. Compare the sliding mobility windows of each probe obtained in S2 with the optimal sampling mobility range of the target layer to select the optimal probe type. S4. Use the probes selected in S3 to perform sampling operations. If the sampling operation fails to meet the success criteria, replace the formation pressure and pipeline pressure difference measured in the target well with the formation pressure and pipeline pressure difference during the sampling process of the adjacent well to obtain a new pressure difference-time function. After overriding the previous function, execute steps S1 to S3 in sequence to re-select the probe type.

[0005] Pressure difference-time function Specifically: In the formula, The pressure difference between the formation pressure and the pipeline pressure is expressed in P (Pa). The coefficients of a quadratic polynomial in one variable. <0; t is the sampling time, in hours.

[0006] Lower limit of the flow window The formula is: In the formula, This is the lower limit of the mobility window, in meters. 2 / CP; The maximum stable pressure difference is expressed in Pa. The volumetric flow rate of the target well, in cubic meters. 3 / s; The probe length is in meters (m). The probe's flow area is expressed in m². 2 .

[0007] upper limit of flow window The formula is: In the formula, This is the upper limit of the flow rate window, in meters. 2 / CP; The maximum stable pressure difference is expressed in Pa. The volumetric flow rate of the target well, in cubic meters. 3 / s; The probe length is in meters (m). The probe's flow area is expressed in m². 2 .

[0008] Maximum allowable sampling time Substitute into the pressure difference-time function In the middle, calculation The value.

[0009] The well spacing condition for selecting the target well and its adjacent wells is: the well spacing between the target well and its adjacent wells is less than 5 km.

[0010] In S4, if any of the following occurs: seal failure, operation timeout, or failure to meet sample purity requirements, the sampling operation is judged as failing to meet the success criteria.

[0011] A shallow heavy oil sampling probe selection system based on a dynamic mobility window includes: The data entry module is used to enter regional data and target well data; The computational processing module is used to calculate the upper limit of the probe flow rate window. and lower limit of the flow window Data; The mobility window slides to select the probe module, and selects the optimal probe type based on the calculation results of the calculation processing module and the optimal sampling mobility range of the sampling target layer.

[0012] The beneficial effects of this invention are as follows: (1) Improve sampling success rate: accurately match formation conditions and probe parameters through dynamic mobility window.

[0013] (2) Shorten operation time: Optimize the type of sampling probe, which can effectively improve the efficiency of operation.

[0014] (3) Enhanced system automation: It integrates data import, embedded calculation, and sliding window probe selection, and can adapt to complex and changing strata.

[0015] In summary, this application, based on solving the existing technical difficulties, further introduces a method for dynamically adjusting the mobility window range, which can be used in multiple different blocks, forming a more accurate and engineerable new shallow heavy oil sampling technology. Attached Figure Description

[0016] Figure 1 This is a flowchart of the process of the present invention; Figure 2 Given a well A, the fitting function of sampling pressure difference versus time at a certain depth is given. Figure 3 This is a logging curve from Example 2, applied to a shallow heavy oil target well B at a sampling depth of 1010.0m. Figure 4 This is a sampling curve diagram of a shallow heavy oil target well B in Example 2 at a sampling depth of 1010.0m; Figure 5 This is a logging curve from Example 2, applied to a shallow heavy oil target well B at a sampling depth of 867.0m. Figure 6 This is a sampling curve diagram of a shallow heavy oil target well B in Example 2, at a sampling depth of 867.0m. Detailed Implementation

[0017] Example 1 like Figure 1 As shown, the method for selecting shallow heavy oil sampling probes based on dynamic mobility windows includes the following specific steps: S1. Select a neighboring well based on the well spacing condition of the target well. Fit the relationship data of formation pressure and pipeline pressure difference with time during the sampling process of the selected neighboring well to obtain the pressure difference-time function. According to the maximum allowable sampling time and pressure difference-time function To obtain the maximum stable pressure difference The minimum pressure difference is obtained based on regional experience. ; Minimum pressure difference The acquisition of this data relies on regional experience, which is obtained by summarizing and constructing a database based on pumping experience data for that region. The minimum pressure differential is then determined by using the data corresponding to that region within the database. .

[0018] Sampling of a certain block is not allowed to exceed 5 hours. The reason is that if the time is exceeded, there is a risk of cables and equipment sticking together.

[0019] The other area is a temporary work zone; work in this area must be stopped if it exceeds 4 hours because the work time is not permitted.

[0020] As the examples above show, because different blocks have different upper limits for allowed operating time, the greater the pressure differential in a region, the faster the heavy oil extraction rate. Conversely, the smaller the pressure differential in a region, the slower the heavy oil extraction rate. When the pressure differential in a region decreases to a certain limit, it will exceed the upper limit of pumping time for that region; this limit is the minimum pressure differential. .

[0021] If the pumping time limit for a certain area is 5 hours, the pressure difference must be controlled above 21 psi; otherwise, the upper limit will be exceeded, leading to the failure of the entire operation.

[0022] S2. Obtain the volumetric flow rate of the target well. and the probe length of each probe Flow area The data was used to calculate the upper limit of the flow rate window for each probe. and lower limit of the flow window Through the upper limit of the probe flow window and lower limit of the flow window Forming the probe sliding flow window; S3. Compare the sliding mobility windows of each probe obtained in S2 with the optimal sampling mobility range of the target layer to select the optimal probe type. The probe type selection method is to choose the probe type with the largest flow window. In practical applications, other factors can also be considered when making the selection, such as the stability of the setting seal and operating costs. Further selection can be made based on specific working conditions and construction budget to obtain the optimal choice.

[0023] S4. Use the probes selected in S3 to perform sampling operations. If the sampling operation fails to meet the success criteria, replace the formation pressure and pipeline pressure difference measured in the target well with the formation pressure and pipeline pressure difference during the sampling process of the adjacent well to obtain a new pressure difference-time function. After overriding the previous function, execute steps S1 to S3 in sequence to re-select the probe type.

[0024] Furthermore, section S4 presents adjustment schemes when simulation results significantly deviate from actual construction conditions. Since actual production involves one or more sampling operations, when multiple samplings occur, the data from the previous sampling is used to fit and obtain a new pressure-time function. By covering existing functions before performing the filtering process, the prediction accuracy can be effectively improved.

[0025] Pressure difference-time function Specifically: In the formula, The pressure difference between the formation pressure and the pipeline pressure is expressed in P (Pa). The coefficients of a quadratic polynomial in one variable. <0; t is the sampling time, in hours.

[0026] Lower limit of the flow window The formula is: In the formula, This is the lower limit of the mobility window, in meters. 2 / CP; The maximum stable pressure difference is expressed in Pa. The volumetric flow rate of the target well, in cubic meters. 3 / s; The probe length is in meters (m). The probe's flow area is expressed in m². 2 .

[0027] upper limit of flow window The formula is: In the formula, This is the upper limit of the flow rate window, in meters. 2 / CP; The maximum stable pressure difference is expressed in Pa. The volumetric flow rate of the target well, in cubic meters. 3 / s; The probe length is in meters (m). The probe's flow area is expressed in m². 2 .

[0028] Maximum allowable sampling time Substitute into the pressure difference-time function In the middle, calculation The value.

[0029] The well spacing condition for selecting the target well and its adjacent wells is: the well spacing between the target well and its adjacent wells is less than 5 km.

[0030] In S4, if any of the following occurs: seal failure, operation timeout, or failure to meet sample purity requirements, the sampling operation is judged as failing to meet the success criteria.

[0031] During cable formation testing, specifically sampling, the sampling probe's rubber sheath adheres tightly to the wellbore wall as it contacts the formation. The probe pierces the mud cake in the center of the rubber sheath; this process is known as "seating." Throughout the process, the rubber sheath isolates the probe from external fluids, ensuring no communication occurs between the probe's internal tubing and the external fluids. If communication does occur, it signifies pressure leakage, meaning the "seating" has failed.

[0032] A shallow heavy oil sampling probe selection system based on a dynamic mobility window includes: The data entry module is used to enter regional data and target well data; The computational processing module is used to calculate the upper limit of the probe flow rate window. and lower limit of the flow window Data; The mobility window slides to select the probe module, and selects the optimal probe type based on the calculation results of the calculation processing module and the optimal sampling mobility range of the sampling target layer.

[0033] Preferably, the shallow heavy oil sampling probe selection system based on the dynamic mobility window can be used as a module attached to the GDI (Geological Data Interpretation) software.

[0034] Example 2 Taking cable sampling operations conducted on well A in a certain block as an example.

[0035] We collected well logging data, geological reports, and engineering data, including pressure difference-time curves, flow velocity-time curves, fluid conductivity-time curves, fluid density-time curves, and fluid fluorescence-time curves at five sampling points at different depths in Well A.

[0036] The plan is to drill a well B at a distance of 2.5 km from the wells, and a sampling plan has been designed for two depths (inclination depths: 1010.0 m and 867.0 m).

[0037] The sampling probe types are shown in Table 1: Table 1: Seven different probe sizes selected for Well B Based on the above data, a specific example of probe selection is described.

[0038] S1 and Well A meet the requirements of being adjacent wells to Well B (well spacing less than 5km). Pressure difference-time curve data at 5 sampling depths during the sampling process were entered into the data input module of the shallow heavy oil sampling probe selection system based on a dynamic mobility window. The average pressure difference-time fitting function was obtained through the calculation and processing module. .

[0039] Based on the fitting results, the coefficients are: According to calculations, its maximum stable pressure difference The scatter plot and fitted function graphs are shown in the attached figure. Figure 2 As shown.

[0040] By using sampling data from adjacent wells, a scatter plot of pressure difference versus time can be obtained.

[0041] However, the points in this scatter plot may not represent the actual maximum pressure difference. The scatter plot may show instances where the desired fluid has been pumped and the operation has ended before the maximum pressure difference has been reached.

[0042] This application obtains the maximum stable pressure difference by first fitting a functional relationship between pressure difference and time, and then finding the maximum value of this function. .

[0043] In S2, the stable volumetric flow rate of the target well is accurately obtained through geological daily reports, well logging data, and engineering data. m 3 / s .

[0044] Substituting the probe flow area and length data from Table 1, the lower limit of the flow window for different probes can be obtained. : According to project requirements, sampling at Well B should be completed within 4 hours, based on regional experience (due to actual operational difficulties). Due to marginal effects, when the time exceeds 4 hours, a fitting function is not used; instead, regional experience is employed. (Minimum pressure difference) Substituting into the following formula, we can obtain the upper limit of the mobility window for different probes. : The mobility windows for different probes were obtained through the calculation process of S2, as shown in Table 2: Table 2: Upper and lower limits of flow rate for 7 different probe sizes selected for well B Based on the daily geological report, well logging data, and engineering information for Well A, the density of heavy oil in this area is approximately 0.98 g / cm³. 3 The viscosity is between 500-5000 cP, and the optimal sampling flow rate range is 2~20 D / cP. Based on the sliding sampling window of the probe (Table 2), it was determined that both probe No. 3 and probe No. 4 could meet the operational requirements, but probe No. 3 has a larger flow rate window range. Therefore, probe No. 3 was selected in the actual sampling process.

[0045] Dimensional conversion: Viscosity unit: 1 cP = 1 × 10⁻¹⁰ -3 Pa·s; Permeability unit: 1D = 1×10 -12 m 2 ; Mobility unit: 1D / cP = 1×10 -9 m 2 / (Pa·s).

[0046] like Figure 3 and Figure 4 As shown.

[0047] Figure 3 This includes: SPDH (Natural Point Path Curve); Natural Gamma Curve; Wellbore Curve; Shallow and Deep Resistivity Curve; Microsphere Focused Resistivity Curve; Compensated Neutron Curve; Neutron and Density Crossover Filling Curve; Acoustic Transit Time Curve.

[0048] Figure 4 The sampling curves are from 0 seconds to 12000 seconds, and include: pressure curve; density curve; conductivity curve; pump speed curve.

[0049] Using probe #3 at 1010.0 m, the actual measured flow rate was 19.32 D / cP. Pumping for 180 min (3 h) resulted in a cumulative pump output of 37.6 L of liquid. The maximum pressure differential during pumping was 322 psi. The minimum pressure differential is 124 psi. The average pressure differential is 282 psi. ).

[0050] A 680ml injection tank was used, from which 613ml of oil and 37ml of formation water and mud filtrate were collected. The actual measured mobility was within the predicted mobility window, the sampling was successful, and the oil content reached 94.3%.

[0051] like Figure 5 and Figure 6 As shown.

[0052] Figure 5 This includes: SPDH (Natural Point Path Curve); Natural Gamma Curve; Wellbore Curve; Shallow and Deep Resistivity Curve; Microsphere Focused Resistivity Curve; Compensated Neutron Curve; Neutron and Density Crossover Filling Curve; Acoustic Transit Time Curve.

[0053] Figure 6 The sampling curves are from 0 seconds to 20,000 seconds. The figure includes: pressure curve; density curve; conductivity curve; pump speed curve.

[0054] Using probe #3 at 867.0 m, the actual measured flow rate was 54.01 D / cP. Pumping for 300 min (5 h) resulted in a cumulative pump output of 47.5 L of liquid. The maximum pressure differential during pumping was 490 psi. The minimum pressure differential is 32 psi. The average pressure differential is 222 psi. ).

[0055] A 680ml injection sample container was used, yielding 222ml of oil and 428ml of formation water and mud filtrate. The actual measured mobility exceeded the predicted mobility window. Although sampling was successful, the oil content was only 32.2%, and the sampling timeout was significantly exceeded. Therefore, the sampling operation was deemed unsuccessful. For operations involving multiple sampling depths and requiring multiple instrument deployments, the pressure difference-time function from the previous sampling process needs to be processed before the next deployment. The probe is loaded, refitted, and a new mobility window is obtained, which is then used to further optimize the next well probe insertion. Since this well is designed to complete the operation in one run with only two sampling depths, there is no need to reload the difference-time function. Since the process is the same as the example above, it will not be repeated here.

[0056] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for selecting sampling probes for shallow heavy oil based on a dynamic mobility window, characterized in that, The specific steps include: S1. Select a neighboring well based on the well spacing condition of the target well. Fit the relationship data of formation pressure and pipeline pressure difference with time during the sampling process of the selected neighboring well to obtain the pressure difference-time function. According to the maximum allowable sampling time and pressure difference-time function To obtain the maximum stable pressure difference The minimum pressure difference is obtained based on regional experience. ; S2. Obtain the volumetric flow rate of the target well. and the probe length of each probe Flow area The data was used to calculate the upper limit of the flow rate window for each probe. and lower limit of the flow window Through the upper limit of the probe flow window and lower limit of the flow window Forming the probe sliding flow window; S3. Compare the sliding mobility windows of each probe obtained in S2 with the optimal sampling mobility range of the target layer to select the optimal probe type. S4. Use the probes selected in S3 to perform sampling operations. If the sampling operation fails to meet the success criteria, replace the formation pressure and pipeline pressure difference measured in the target well with the formation pressure and pipeline pressure difference during the sampling process of the adjacent well to obtain a new pressure difference-time function. After overriding the previous function, execute steps S1 to S3 in sequence to re-select the probe type.

2. The method for selecting shallow heavy oil sampling probes based on a dynamic mobility window according to claim 1, characterized in that, Pressure difference-time function Specifically: In the formula, The pressure difference between the formation pressure and the pipeline pressure is expressed in P (Pa). The coefficients of a quadratic polynomial in one variable. <0; t is the sampling time, in hours.

3. The method for selecting shallow heavy oil sampling probes based on a dynamic mobility window according to claim 2, characterized in that, Lower limit of the flow window The formula is: In the formula, This is the lower limit of the mobility window, in meters. 2 / CP; The maximum stable pressure difference is expressed in Pa. The volumetric flow rate of the target well, in cubic meters. 3 / s; The probe length is in meters (m). The probe's flow area is expressed in m². 2 .

4. The method for selecting shallow heavy oil sampling probes based on a dynamic mobility window according to claim 2, characterized in that, upper limit of flow window The formula is: In the formula, This is the upper limit of the flow rate window, in meters. 2 / CP; The maximum stable pressure difference is expressed in Pa. The volumetric flow rate of the target well, in cubic meters. 3 / s; The probe length is in meters (m). The probe's flow area is expressed in m². 2 .

5. The method for selecting shallow heavy oil sampling probes based on a dynamic mobility window according to claim 1, characterized in that: Maximum allowable sampling time Substitute into the pressure difference-time function In the middle, calculation The value.

6. The method for selecting shallow heavy oil sampling probes based on a dynamic mobility window according to claim 1, characterized in that, The well spacing condition for selecting the target well and its adjacent wells is: the well spacing between the target well and its adjacent wells is less than 5 km.

7. The method for selecting shallow heavy oil sampling probes based on a dynamic mobility window according to claim 1, characterized in that: In S4, if any of the following occurs: seal failure, operation timeout, or failure to meet sample purity requirements, the sampling operation is judged as failing to meet the success criteria.

8. A shallow heavy oil sampling probe selection system based on a dynamic mobility window, used to execute the shallow heavy oil sampling probe selection method based on a dynamic mobility window as described in any one of claims 1-7, characterized in that, include: The data entry module is used to enter regional data and target well data; The computational processing module is used to calculate the upper limit of the probe flow rate window. and lower limit of the flow window Data; The mobility window slides to select the probe module, and selects the optimal probe type based on the calculation results of the calculation processing module and the optimal sampling mobility range of the sampling target layer.

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