Method for identifying oil reservoir high-permeability channel by using A-type water drive characteristic curve

Abstract

The invention relates to a method for identifying a high-permeability channel of an oil reservoir by using a type A water drive characteristic curve. The method comprises the following steps: constructing three groups of experimental cores according to a target reservoir; the middle layers of the three groups of experimental rock cores are high-permeability channels with different specifications, and the rest parts are homogeneous matrix rock cores; carrying out a water-oil displacement experiment aiming at the three groups of experiment cores; the result of the water-oil displacement experiment is converted into a mine field scale, so that an A-type water displacement characteristic curve of the target reservoir is obtained; dividing a high-permeability channel development degree division standard according to the slopes of the different A type water drive characteristic curves corresponding to the three groups of experimental cores in the stable straight line section, and dividing the high-permeability channel wells of the oil well in the target reservoir into a complete development type, a high development type, a medium development type and a low development type according to the high-permeability channel development degree division standard. The method solves the problems that high-permeability channel identification data are difficult to obtain and the high-permeability channel is difficult to quantitatively identify in the water injection development process of the low-permeability reservoir at present.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development, and in particular relates to a method for identifying a high-permeability channel in an oil reservoir by using a type A water drive characteristic curve. Background Art

[0002] At present, most of the domestic oil fields developed by water injection have entered the medium-high water content period. Due to the influence of natural heterogeneity of reservoirs and artificial fracturing, high permeability channels exist or are formed between some oil and water wells. In order to alleviate or reduce the water content of high water-cut wells, it is necessary to identify the type of high permeability channels between oil and water wells, and further adopt measures such as profile adjustment and water plugging, oil and water well replacement, and injection and production system adjustment. Practice has proved that accurate identification of high permeability channels is a prerequisite for improving the development effect of high water-cut reservoirs.

[0003] Application No. 201110240837.X discloses a method and device for identifying dominant channels in water-drive oil fields. The method uses unstable pressure recovery well test data to identify dominant channels formed during the development of water-drive oil fields. First, a typical characteristic curve template is set, the bottom hole pressure of the well test is obtained, and the well test curve is drawn to determine whether a dominant channel exists. Finally, the development level of the dominant channel is judged.

[0004] Application No. 201210449079.7 discloses a method for quantitatively identifying the dominant flow channels of oil reservoirs by using dimensionless comparison charts. First, the geological parameters and fluid parameters of the oil field are collected, and the cumulative frequency curve of parameter distribution is made to obtain the corresponding distribution interval and distribution characteristics. According to the distribution characteristics of the target reservoir parameters, the corresponding numerical conceptual model is combined to calculate the water drive development dynamics. The calculation results of the statistical conceptual model are used to find the water absorption and liquid production parameters of the small layer with the largest water absorption and liquid production, and perform dimensionless processing; draw a dimensionless parameter distribution chart, use the cluster analysis method to divide the dominant channel development space, and obtain a quantitative chart. Perform dimensionless parameter processing for a single well, and use the dimensionless comparison chart to judge the development status of the dominant flow channel.

[0005] Application No. 201811046388.3 discloses a method for identifying high water consumption channels in extremely high water-content oil reservoirs. The method mainly sets and calculates the ratio of cumulative water production to cumulative water injection through a permeability extreme difference distribution plane diagram and a plane distribution diagram of cumulative production and injection of oil and water wells, and combines the production liquid water absorption profile data to determine whether there is a high water consumption channel between the oil and water wells.

[0006] Application No. 202010916883.6 discloses a method for identifying and characterizing dominant seepage channels in ultra-low permeability reservoirs. The method first determines the source direction of the oil-producing layer, the orientation of the ancient river channel, the internal architectural structure of the sand body, and the rhythmic type of a single sand body; establishes a reservoir prediction model and a streamline evolution model at the current development stage, and comprehensively identifies the location and plane orientation of the dominant seepage channels between well groups through the injection-production correspondence rate.

[0007] At present, there are many methods for identifying hyperpermeable channels, which can be divided into production logging method, core well observation method, tracer monitoring method, well test method and production dynamic data analysis method. The existing superior channel identification technology is often costly and labor-intensive to apply in mines, and the interpretation time is long. In addition, the method is highly theoretical, and it is difficult to obtain relevant data, making it difficult to promote in mines. Most of the existing methods cannot quantitatively identify hyperpermeable channels, resulting in inaccurate identification of hyperpermeable channels. At present, there is a lack of real characterization and inversion of hyperpermeable channels based on physical experimental simulation, and research on the accurate identification of hyperpermeable channels is relatively insufficient. Summary of the invention

[0008] The present invention aims to solve the above problems and proposes a method for identifying high permeability channels in oil reservoirs by using type A water drive characteristic curves.

[0009] The technical solution of the present invention is: A method for identifying high permeability channels in oil reservoirs using type A water drive characteristic curves is as follows: Three groups of experimental cores were constructed according to the target reservoir; the middle layers of the three groups of experimental cores were high permeability channels of different specifications, and the rest were homogeneous matrix cores; the parameters of high permeability channels of different specifications were as follows: Water-flooding experiments were carried out on three groups of experimental cores; and the results of the water-flooding experiments were converted to field scale to obtain the type A water-flooding characteristic curve of the target reservoir; The high permeability channel development degree classification standard is divided according to the slopes of different type A water drive characteristic curves corresponding to the three groups of experimental cores in the stable straight line segment, and the high permeability channel wells in the target reservoir are divided into fully developed type, highly developed type, medium developed type and low developed type according to the high permeability channel development degree classification standard.

[0010] The specific classification criteria for the development degree of the hyperosmotic channel are: Criteria for the classification of the degree of development of hyperosmotic channels The slope of the type A water drive characteristic curve in the stable straight line segment Fully developed ＞b1 High development type b2~b1 Medium Development b3~b2 Low development ＜b3 ; Among them, b1 is the slope of the type A water drive characteristic curve corresponding to the first group of experimental cores in the stable straight line segment, b2 is the slope of the type A water drive characteristic curve corresponding to the second group of experimental cores in the stable straight line segment, and b3 is the slope of the type A water drive characteristic curve corresponding to the third group of experimental cores in the stable straight line segment.

[0011] The isovolumetric flow rate conversion method is used to convert the results of the water flooding experiment to the mine scale, and the conversion formula is as follows: o-core / V core =Q o / αLHD q w-core / V core =Qw / αLHD Where: q o-core is the oil production rate of the experimental core, 10 4 t / d;q w-core is the experimental core fluid production rate, 10 4 t / d; Q o is the oil production rate of the simulated reservoir unit after equivalent conversion, 10 4 t / d; Q w is the liquid production rate of the simulated reservoir unit after equivalent conversion, 10 4 t / d; V core is the experimental core volume, m 3 ; α is the simulated reservoir unit sweep coefficient after equivalent conversion, dimensionless; L is the distance between oil and water wells in the simulated reservoir unit after equivalent conversion, m; H is the reservoir thickness of the simulated reservoir unit after equivalent conversion, m; D is the reservoir water injection sweep width of the simulated reservoir unit after equivalent conversion, m.

[0012] The characteristic equation of the type A water drive characteristic curve is: ㏑W p =a+bN p ; in,

[0013] Where: W p is the cumulative water production of the simulated reservoir unit, 10 4 t;N p To simulate the cumulative oil production of the reservoir unit, 10 4 m 3 ; a is the intercept of the type A water drive characteristic curve, dimensionless; b is the slope of the type A water flooding characteristic curve, dimensionless; t 1～ t n are n time recording points during the water-to-oil drive experiment.

[0014] It also includes that if the number of experimental cores in each of the three groups of experimental cores is 2 or more, the slope of each group of type A water drive characteristic curves in the stable straight line segment is the average value of the sum of the slopes of the type A water drive characteristic curves of all experimental cores in the group in the stable straight line segment.

[0015] The specific process of the water flooding experiment is as follows: Preparation of experimental cores: By adjusting the quartz sand particle size distribution and epoxy resin adhesive content, the quartz sand particle size distribution ratio, adhesive content, compaction pressure and compaction time parameters of the matrix core and the high permeability channel were obtained, and finally three groups of experimental cores were formed; after the experimental cores were pressed, they were placed in a constant temperature box for curing, and then cut into 4.5cm×4.5cm×30cm experimental cores; water-displacement oil experiment was carried out: the experimental cores were evacuated for more than 12 hours, simulated formation water was pumped into them, and they were placed in a core holder. The oil-displacement water method was used to establish the bound water saturation. After the experimental oil was used to displace 10 times the pore volume, the bound water saturation of the experimental cores was calculated, and they were aged for more than 24 hours; The displacement pump is turned on to inject water to drive the oil until the water content of the outlet section of the water drive oil experiment reaches more than 90%.

[0016] The technical effects of the present invention are: The present invention builds a physical model of a hyperpermeability channel, uses a water injection displacement test to simulate the water injection development characteristics of an oil reservoir under different hyperpermeability channel conditions, defines key parameter standards for the hyperpermeability channel, and fits the development characteristics and key parameters of the hyperpermeability channel during the water injection development of a mine through a water drive characteristic curve. The main purpose is to solve the current problems of difficulty in obtaining high permeability channel identification data and difficulty in quantitatively identifying high permeability channels during the water injection development of a low permeability oil reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the experimental core.

[0018] Figure 2 Schematic diagram of the simulated reservoir unit.

[0019] Figure 3 These are the type A water drive characteristic curves of three groups of experimental cores.

[0020] Figure 4 This is the water drive characteristic curve of type A oil well with fully developed high permeability channel.

[0021] Figure 5 This is the water drive characteristic curve of type A oil well with high development and high permeability channel.

[0022] Figure 6 This is the water drive characteristic curve of type A oil well with medium-development high permeability channel.

[0023] Figure 7 This is the characteristic curve of type A water drive in low-development high-permeability channel oil well. DETAILED DESCRIPTION

[0024] Example 1 A method for identifying high permeability channels in oil reservoirs using type A water drive characteristic curves is as follows: Three groups of experimental cores were constructed according to the target reservoir; the middle layers of the three groups of experimental cores were high permeability channels of different specifications, and the rest were homogeneous matrix cores; the parameters of high permeability channels of different specifications were as follows: Water-flooding experiments were carried out on three groups of experimental cores; and the results of the water-flooding experiments were converted to field scale to obtain the type A water-flooding characteristic curve of the target reservoir; The high permeability channel development degree classification standard is divided according to the slopes of different type A water drive characteristic curves corresponding to the three groups of experimental cores in the stable straight line segment, and the high permeability channel wells in the target reservoir are divided into fully developed type, highly developed type, medium developed type and low developed type according to the high permeability channel development degree classification standard.

[0025] Example 2 Based on Example 1, the criterion for the classification of the degree of development of the hyperosmotic channel is specifically as follows: Criteria for the classification of the degree of development of hyperosmotic channels The slope of the type A water drive characteristic curve in the stable straight line segment Fully developed ＞b1 High development type b2~b1 Medium Development b3~b2 Low development ＜b3 ; Wherein, b1 is the slope of the type A water drive characteristic curve corresponding to the first group of experimental cores in the stable straight line segment, b2 is the slope of the type A water drive characteristic curve corresponding to the second group of experimental cores in the stable straight line segment, and b3 is the slope of the type A water drive characteristic curve corresponding to the third group of experimental cores in the stable straight line segment; If the slope of the Type A water drive characteristic curve of the oil well in the target reservoir in the stable straight line segment is greater than b1, the level of the corresponding high permeability channel well is fully developed; if the slope of the Type A water drive characteristic curve of the oil well in the target reservoir in the stable straight line segment satisfies (b2, b1], the level of the corresponding high permeability channel well is highly developed; if the slope of the Type A water drive characteristic curve of the oil well in the target reservoir in the stable straight line segment satisfies [b3, b2], the level of the corresponding high permeability channel well is medium developed; if the slope of the Type A water drive characteristic curve of the oil well in the target reservoir in the stable straight line segment is less than b3, the level of the corresponding high permeability channel well is low developed.

[0026] Example 3 On the basis of Example 1, the conversion of the results of the water-to-oil experiment to the mine field scale is carried out using the equal volume flow rate conversion method, and the conversion formula is as follows: q o-core / V core =Q o / α LHD q w-core / V core =Q w / α LHD The characteristic equation of the type A water drive characteristic curve is: l W p =a+bN p ; in,

[0027] Example 4 On the basis of Example 1, it also includes that if the number of experimental cores in each of the three groups of experimental cores is 2 or more, the slope of each group of type A water drive characteristic curves in the stable straight line segment is the average value of the sum of the slopes of the type A water drive characteristic curves of all experimental cores in the group in the stable straight line segment.

[0028] Example 5 Based on Example 1, the specific process of the water-to-oil experiment is as follows: Preparation of experimental cores: By adjusting the quartz sand particle size distribution and epoxy resin adhesive content, the quartz sand particle size distribution ratio, adhesive content, compaction pressure and compaction time parameters of the matrix core and the high permeability channel were obtained, and finally three groups of experimental cores were formed; after the experimental cores were pressed, they were placed in a constant temperature box for curing, and then cut into 4.5cm×4.5cm×30cm experimental cores; water-displacement oil experiment was carried out: the experimental cores were evacuated for more than 12 hours, simulated formation water was pumped into them, and they were placed in a core holder. The oil-displacement water method was used to establish the bound water saturation. After the experimental oil was used to displace 10 times the pore volume, the bound water saturation of the experimental cores was calculated, and they were aged for more than 24 hours; The displacement pump is turned on to inject water to drive the oil until the water content of the outlet section of the water drive oil experiment reaches more than 90%.

[0029] Specific experimental case - Chang 622 reservoir in HZP area of ​​Xingzichuan Oilfield Step 1: Take the HZP district chief of Xingzichuan Oilfield as 62 2 The reservoir is the target reservoir, which is in the middle and high water content stage of water injection development, with 71 oil wells and 24 water injection wells, and the injection-production correspondence ratio and water drive degree are high. The statistical table of its reservoir data is shown in Table 3; Table 3 Reservoir data statistics

[0030] Step 2: Prepare experimental oil, simulated formation water and injection water according to the fluid properties of the target reservoir.

[0031] Step 3: Prepare three groups of experimental cores, each group of experimental cores consists of 2 cores; the experimental cores are all 4.5cm×4.5cm×30cm square cores with a high permeability channel in the middle. The physical properties of the experimental cores are shown in Table 4 and Figure 3 ; Table 4 Physical parameters of experimental core

[0032] Step 4: Evacuate the experimental core and displace 10 times the pore volume with the experimental oil to establish the irreducible water saturation; calculate the irreducible water saturation of the experimental core and age it in a constant temperature box at 42°C for more than 24 hours.

[0033] Step 5: Under the conditions of simulated formation temperature, carry out water drive oil experiment at a speed of 1m / d, and stop when the water content of the outlet section of the water drive oil experiment is higher than 90%; record the t 1～ t n The experimental core oil production rate q corresponding to the time o-core and the experimental core fluid production rate q w-core。

[0034] Step 6: Calculate the parameters of the experimental core and the parameters of the simulated reservoir unit, see Table 5; Table 5 Parameters of simulated reservoir units Since the experimental core is a cuboid, the volume V of the experimental core can be calculated using the volume formula core , combined with the data in Table 5, using the conversion formula of volume flow rate conversion method, the t 1～ t n The experimental core oil production rate q obtained at each time point o-core Converted to the oil production rate Q of the simulated reservoir unit after equivalent transformation o , experimental core fluid production rate q w-core Converted into the equivalent converted simulated reservoir unit liquid production rate Q w and through and The cumulative water production W of the simulated reservoir unit is obtained p and the cumulative oil production N of the simulated reservoir unit p。

[0035] Step 7: Based on the cumulative water production W of the simulated reservoir unit p and the cumulative oil production N of the simulated reservoir unit p , using the type A water drive characteristic curve formula: l W p =a+bN p ; Draw the type A water drive characteristic curve, and draw a total of 6 type A water drive characteristic curves from 3 groups of experimental cores in one figure ( Figure 3 ), and a stable straight line segment is fitted according to the shape of the type A water drive characteristic curve.

[0036] Step 8. Read the slope of the stable straight line segment (Table 6). Take the average of two values ​​of the same set of experimental cores and record them as b1, b2, and b3 respectively; Table 6 Classification criteria for hypertonic channels category The slope of the experimental core A The slope of experimental core B average value Group 1 206.17 235.05 b1＝220.61 Group 2 11.70 10.61 b2＝11.16 Group 3 1.60 2.10 b3＝1.85 .

[0037] Step 9. Determine the high permeability channel development degree classification standard of the target reservoir: when the slope of the type A water drive characteristic curve in the stable straight line segment is greater than 220.61, it is a fully developed type; when the slope of the type A water drive characteristic curve in the stable straight line segment is between 11.16 and 220.61, it is a highly developed type; when the slope of the type A water drive characteristic curve in the stable straight line segment is between 1.85 and 11.16, it is a medium developed type; when the slope of the type A water drive characteristic curve in the stable straight line segment is less than 1.85, it is a low developed type; Step 10: Count the HZP area head of Xingzichuan Oilfield 62 2 The cumulative water production and cumulative oil production of 71 oil wells in the reservoir are plotted, and their type A water drive characteristic curves are plotted in four figures ( Figures 4 to 7 ); Step 11: Fit the slopes of 71 type A water drive characteristic curves in the stable straight line segment, and classify the high permeability channel wells of the 71 oil wells according to the high permeability channel development degree classification standard in step 9 (see Table 7); Table 7 Results of high permeability channel division of oil wells in the study area

[0038] Among them, there are 17 fully developed high-permeability channel wells, 12 highly developed high-permeability channel wells, 21 moderately developed high-permeability channel wells, and 21 low-developed high-permeability channel wells.

Claims

1. A method for identifying high permeability channels in oil reservoirs using a type A water flooding characteristic curve, characterized in that: The method is as follows: 3 groups of experimental cores are constructed according to the target reservoir; the middle layers of the 3 groups of experimental cores are high permeability channels of different specifications, and the rest are homogeneous matrix cores; the parameters of high permeability channels of different specifications are as follows: Water-flooding experiments were carried out on three groups of experimental cores; and the results of the water-flooding experiments were converted to field scale to obtain the type A water-flooding characteristic curve of the target reservoir; The high permeability channel development degree classification standard is divided according to the slopes of different type A water drive characteristic curves corresponding to the three groups of experimental cores in the stable straight line segment, and the high permeability channel wells in the target reservoir are divided into fully developed type, highly developed type, medium developed type and low developed type according to the high permeability channel development degree classification standard.

2. The method for identifying high permeability channels in oil reservoirs using type A water flooding characteristic curve according to claim 1, characterized in that: The specific classification criteria for the development degree of the hyperosmotic channel are: ； Among them, b1 is the slope of the type A water drive characteristic curve corresponding to the first group of experimental cores in the stable straight line segment, b2 is the slope of the type A water drive characteristic curve corresponding to the second group of experimental cores in the stable straight line segment, and b3 is the slope of the type A water drive characteristic curve corresponding to the third group of experimental cores in the stable straight line segment.

3. The method for identifying high permeability channels in oil reservoirs using type A water flooding characteristic curve according to claim 1, characterized in that: The isovolumetric flow rate conversion method is used to convert the results of the water flooding experiment to the mine scale, and the conversion formula is as follows: q o-core / V core =Q o / αLHD q w-core / V core =Q w / αLHD Where: q o-core is the oil production rate of the experimental core, 10 4 t / d;q w-core is the experimental core fluid production rate, 10 4 t / d; Q o is the oil production rate of the simulated reservoir unit after equivalent conversion, 10 4 t / d; Q w is the liquid production rate of the simulated reservoir unit after equivalent conversion, 10 4 t / d; V core is the experimental core volume, m 3 ; α is the simulated reservoir unit sweep coefficient after equivalent conversion, dimensionless; L is the distance between oil and water wells in the simulated reservoir unit after equivalent conversion, m; H is the reservoir thickness of the simulated reservoir unit after equivalent conversion, m; D is the reservoir water injection sweep width of the simulated reservoir unit after equivalent conversion, m.

4. The method for identifying high permeability channels in oil reservoirs using type A water flooding characteristic curve according to claim 3, characterized in that: The characteristic equation of the type A water drive characteristic curve is: ㏑W p =a+bN p ; in, Where: W p is the cumulative water production of the simulated reservoir unit, 10 4 t;N p To simulate the cumulative oil production of the reservoir unit, 10 4 m 3 ; a is the intercept of the type A water drive characteristic curve, dimensionless; b is the slope of the type A water drive characteristic curve, dimensionless; t 1～ t n are n time recording points during the water-to-oil drive experiment.

5. The method for identifying high permeability channels in oil reservoirs using type A water flooding characteristic curve according to claim 1, characterized in that: It also includes that if the number of experimental cores in each of the three groups of experimental cores is 2 or more, the slope of each group of type A water drive characteristic curves in the stable straight line segment is the average value of the sum of the slopes of the type A water drive characteristic curves of all experimental cores in the group in the stable straight line segment.

6. The method for identifying high permeability channels in oil reservoirs using type A water flooding characteristic curve according to claim 1, characterized in that: The specific process of the water flooding experiment is as follows: Preparation of experimental cores: By adjusting the quartz sand particle size distribution and epoxy resin adhesive content, the quartz sand particle size distribution ratio, adhesive content, compaction pressure and compaction time parameters of the matrix core and the high permeability channel were obtained, and finally three groups of experimental cores were formed; after the experimental cores were pressed, they were placed in a constant temperature box for curing, and then cut into 4.5cm×4.5cm×30cm experimental cores; water-displacement oil experiment was carried out: the experimental cores were evacuated for more than 12 hours, simulated formation water was pumped into them, and they were placed in a core holder. The oil-displacement water method was used to establish the bound water saturation. After the experimental oil was used to displace 10 times the pore volume, the bound water saturation of the experimental cores was calculated, and they were aged for more than 24 hours; The displacement pump is turned on to inject water to drive the oil until the water content of the outlet section of the water drive oil experiment reaches more than 90%.

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