A method for evaluating uniformity of vertical well pattern in oilfield

Abstract

The present invention relates to the field of oil reservoir development, and belongs to a method for evaluating the uniformity of a vertical well network in an oil field. The evaluation method comprises the following steps: step (1), obtaining the geodetic coordinates, well type, perforation layer, and perforation time of all oil and water wells in a target work area; step (2), dividing the oil and water wells in the work area into different well groups with the water well as the center according to the oil and water well type; step (3), calculating the injection and production well spacing and the average well spacing of each oil well connected to the water well in each well group according to the perforation conditions of the oil and water wells; step (4), calculating various area parameters and angle parameters; step (5), calculating the well spacing uniformity coefficient L V and well pattern distribution coefficient N V ; Step (6), calculate the well spacing uniformity coefficient L of all well groups according to the above method V and well pattern distribution coefficient N V ; Step (7), comprehensively determine the uniformity of the well pattern. The present invention can evaluate the uniformity of the vertical well pattern of the oil field, has a guiding role in the preparation of the oil field development plan, can improve the rationality of the well layout plan, maintain the efficient development of the oil field, and has great application value.

Description

Technical Field

[0001] The invention relates to the field of oil reservoir development, and in particular to a method for evaluating the uniformity of a vertical well pattern in an oil field in well pattern adaptability research. Background Art

[0002] The quality of the development well network directly determines the effect of oil field development to a large extent, and the uniformity of the well network has always been an important indicator for the evaluation of well network adaptability, but there is a lack of evaluation methods. Vertical wells are the most common well type in oil field development. At present, most of my country's oil fields have entered a high water cut period or even a very high water cut period, and the well network is relatively complex, and the uneven well network phenomenon is relatively serious. The uneven well network is mainly reflected in two aspects. One is the uneven well spacing, that is, the injection and production well spacing of each oil well connected to the water well is not equal. Field practice shows that in the case of uneven well spacing, the injected water is easy to advance in the direction of the small well spacing with smaller seepage resistance, resulting in inefficient and ineffective circulation, affecting the development effect. The second is the uneven distribution of the well network, that is, the oil wells are concentrated in a certain direction around the water well. Even if the injection and production well spacing are equal, the well network will not be uniform.

[0003] If the oil and water wells are unevenly distributed on the plane, it will lead to uneven displacement, smaller swept volume, and affect the recovery rate. Some literature has studied the impact of uneven well spacing on development effects, mostly macroscopically studying the water injection effect of a single well group in dynamic analysis, but has not studied the situation of uneven well network distribution, and there is no accurate, systematic, and comprehensive method to evaluate the uniformity of the well network. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for evaluating the uniformity of the vertical well network of an oil field; the uniformity of the vertical well network of an oil field can be evaluated, and the degree of plane interference caused by the uneven well network can be determined, which has a guiding role in the formulation of oil field development plans, can improve the rationality of the well layout plan, and maintain the efficient development of the oil field.

[0005] The present invention achieves the above-mentioned purpose by the following technical solutions:

[0006] A method for evaluating the uniformity of a vertical well pattern in an oil field comprises the following steps:

[0007] Step (1), obtaining the geodetic coordinates, well type, perforation layer, and perforation time of all oil and water wells in the target work area;

[0008] Step (2), dividing the oil and water wells in the work area into different well groups with the water wells as the center according to the oil and water wells;

[0009] Step (3), calculating the injection and production well spacing and the average well spacing of each oil well connected to the water wells in each well group according to the perforation conditions of the oil and water wells;

[0010] Step (4), calculating various area parameters and angle parameters;

[0011] Step (5), calculate the well spacing uniformity coefficient L V and well pattern distribution coefficient N V ;

[0012] Step (6): Calculate the uniform coefficient L of the well spacing of all well groups according to the above method. V and well pattern distribution coefficient N V , first L V and N V Normalize, and then determine the uniformity coefficient L of each well group based on the actual situation of the work area V and well pattern distribution coefficient N V Weight, calculate the uniformity of each well group;

[0013] Step (7), calculating the average well network uniformity of each well group in each oil layer to obtain the well network uniformity of different oil layers; comprehensively analyzing the well network uniformity of each oil layer to determine the well network uniformity of the work area.

[0014] Furthermore, the steps of calculating various area parameters and angle parameters in step 4 are as follows:

[0015] Step ①, connect the oil wells O1, O2, O3, O4, etc. in the well group in sequence to form a polygon S1, and calculate its area as A1;

[0016] Step ②, connect a line from the water well to each oil well, and mark the virtual wells A, B, C, D, ... at the average well spacing on the connecting line or the extended line; connect the virtual wells A, B, C, D, ... in sequence to form a polygon S2, and calculate its area as A2;

[0017] Step ③, calculate the sum of the areas within S1 and outside S2, A3

[0018] Step ④, calculate the sum of the areas A4 outside S1 and inside S2;

[0019] Step ⑤, calculate the angles ∠1, ∠2, ∠3, ∠4, etc. between the lines connecting the water well and the oil well.

[0020] Furthermore, the step 5 calculates the well spacing uniformity coefficient L V and well pattern distribution coefficient N V for:

[0021] L V =(A3+A4) / A1

[0022] N V =∠max / ∠min

[0023] Where A1 is the area defined by the connecting line of oil well points O1, O2, O3, O4, etc.;

[0024] A2 is the area of ​​polygon S2 defined by connecting lines of virtual wells A, B, C, D, etc. determined by the average well spacing;

[0025] A3 is the sum of the areas within S1 and outside S2;

[0026] A4 is the sum of the areas outside S1 and inside S2;

[0027] ∠max is the maximum value among ∠1, ∠2, ∠3, ∠4, etc.;

[0028] ∠min is the minimum value among ∠1, ∠2, ∠3, ∠4, etc.

[0029] Furthermore, the larger the well spacing uniformity coefficient is, the more uneven the well spacing is, and the well spacing uniformity coefficient of a uniform well pattern is 0.

[0030] Furthermore, the larger the well pattern distribution coefficient is, the more uneven the well pattern distribution is, and the well pattern distribution coefficient of a uniform well pattern is 1.

[0031] Furthermore, what is calculated is the uniformity of the well pattern at a single time node; the calculation method of the uniformity of the well pattern at different time points is the same.

[0032] The beneficial effects of the present invention are:

[0033] The vertical well network uniformity evaluation method can calculate the well spacing uniformity and well network distribution of the vertical well network system in the oil field, evaluate the plane non-uniformity of the well network, and thus determine the plane interference degree caused by the uneven well network. It has great application value in the preparation of development adjustment plans and the evaluation of well network adaptability, and can improve the development effect of the oil field. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the vertical well pattern uniformity evaluation process of the present invention;

[0035] Figure 2 Schematic diagram of well pattern distribution coefficient according to an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of calculating the uniformity of a well pattern according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of evaluating the uniformity of a well pattern by layer and time period according to an embodiment of the present invention;

[0038] Figure 5 It is a schematic diagram of the evaluation results of the uniformity of the well pattern in a certain work area according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The present invention provides a method for evaluating the uniformity of a vertical well pattern in an oil field, the method comprising the following steps:

[0041] Step (1), obtaining the geodetic coordinates, well type, perforation layer, and perforation time of all oil and water wells in the target work area;

[0042] Step (2), dividing the oil and water wells in the work area into different well groups with the water wells as the center according to the oil and water wells;

[0043] Step (3), calculating the injection and production well spacing and the average well spacing of each oil well connected to the water wells in each well group according to the perforation conditions of the oil and water wells;

[0044] Step (4), calculating various area parameters and angle parameters;

[0045] Step (5), calculate the well spacing uniformity coefficient L V and well pattern distribution coefficient N V ;

[0046] Step (6): Calculate the uniform coefficient L of the well spacing of all well groups according to the above method. V and well pattern distribution coefficient N V , first L V and N V Normalize, and then determine the uniformity coefficient L of each well group based on the actual situation of the work area V and well pattern distribution coefficient N V Weight, calculate the uniformity of each well group;

[0047] Step (7), calculating the average well network uniformity of each well group in each oil layer to obtain the well network uniformity of different oil layers; comprehensively analyzing the well network uniformity of each oil layer to determine the well network uniformity of the work area.

[0048] Furthermore, the steps of calculating various area parameters and angle parameters in step 4 are as follows:

[0049] Step ①, connect the oil wells O1, O2, O3, O4, etc. in the well group in sequence to form a polygon S1, and calculate its area as A1;

[0050] Step ②, connect a line from the water well to each oil well, and mark the virtual wells A, B, C, D, ... at the average well spacing on the connecting line or the extended line; connect the virtual wells A, B, C, D, ... in sequence to form a polygon S2, and calculate its area as A2;

[0051] Step ③, calculate the sum of the areas within S1 and outside S2, A3

[0052] Step ④, calculate the sum of the areas A4 outside S1 and inside S2;

[0053] Step ⑤, calculate the angles ∠1, ∠2, ∠3, ∠4, etc. between the lines connecting the water well and the oil well.

[0054] Furthermore, the step 5 calculates the well spacing uniformity coefficient L V and well pattern distribution coefficient N V for:

[0055] L V =(A3+A4) / A1

[0056] N V =∠max / ∠min

[0057] Where A1 is the area defined by the connecting line of oil well points O1, O2, O3, O4, etc.;

[0058] A2 is the area of ​​polygon S2 defined by connecting lines of virtual wells A, B, C, D, etc. determined by the average well spacing;

[0059] A3 is the sum of the areas within S1 and outside S2;

[0060] A4 is the sum of the areas outside S1 and inside S2;

[0061] ∠max is the maximum value among ∠1, ∠2, ∠3, ∠4, etc.;

[0062] ∠min is the minimum value among ∠1, ∠2, ∠3, ∠4, etc.

[0063] Furthermore, the larger the well spacing uniformity coefficient is, the more uneven the well spacing is, and the well spacing uniformity coefficient of a uniform well pattern is 0.

[0064] Furthermore, the larger the well pattern distribution coefficient is, the more uneven the well pattern distribution is, and the well pattern distribution coefficient of a uniform well pattern is 1.

[0065] Furthermore, what is calculated is the uniformity of the well pattern at a single time node; the calculation method of the uniformity of the well pattern at different time points is the same.

[0066] The specific application of the vertical well pattern uniformity evaluation process of the present invention is described in detail below with reference to the accompanying drawings through specific embodiments. The specific process is as follows:

[0067] Figure 1 It is a flow chart for evaluating the uniformity of vertical well patterns. Based on the geodetic coordinates of oil and water wells, oil and water well types, perforation layers, and perforation time, the plane positions of oil and water wells are determined, and the wells are divided into different well groups with the water wells as the center. The well spacing uniformity coefficient and well pattern distribution coefficient of different oil layers, different time nodes, and different well groups are calculated. After normalization, the uniformity of well patterns of different oil layers and different time nodes is comprehensively evaluated.

[0068] Figure 2 This is a schematic diagram of the well network distribution coefficient. The figure lists a special case where the water well is located in the center and the oil wells are located on circles with the water well as the center. The distance between the injection and production wells is the same. Since the oil wells are unevenly distributed in all directions on the plane, even if the distance between the injection and production wells is the same, the well network distribution is uneven. The size of ∠1, ∠2, ∠3, and ∠4 reflects whether the distribution of the oil wells around the water wells is uniform; Figure 2 Among them, ∠1, ∠2, ∠3, and ∠4 are 137°, 26°, 40°, and 157°, respectively. It can be calculated that the well pattern distribution coefficient is 6.04, which is relatively large and the well pattern distribution is uneven.

[0069] Figure 3 This is a schematic diagram for calculating the uniformity of the well network. The area of ​​the polygon S1 defined by the lines connecting the oil wells O1, O2, O3, and O4 is A1; the area of ​​the polygon S2 defined by the lines connecting the virtual wells A, B, C, and D determined by the average well spacing is A2; the sum of the areas within S1 and outside S2 is A3; the sum of the areas outside S1 and within S2 is A4; the well spacing uniformity coefficient is calculated based on A1, A2, A3, and A4; Figure 3 It can be calculated that A1 is 352 m2, A3 is 32 m2, and A4 is 126 m2, so the well spacing uniformity coefficient is 0.45, and the well spacing is relatively uneven;

[0070] There are angles ∠1, ∠2, ∠3, and ∠4 between the lines connecting the water wells to the oil wells. The well pattern distribution coefficient is determined based on the ratio of the maximum angle to the minimum angle.

[0071] Figure 4 It is a schematic diagram for evaluating the uniformity of the well pattern at different layers and time points. Based on the calculation method of the well spacing uniformity coefficient and the well pattern distribution coefficient, the well spacing uniformity coefficient and the well pattern distribution coefficient of different oil layers, different time points and different well groups can be calculated;

[0072] Figure 5 It is a schematic diagram of the evaluation results of the uniformity of the well network in a certain work area. From the evaluation results of the uniformity of the well network of each oil layer in a certain work area, it can be seen that the well network of each oil layer is relatively uneven, and the uniformity of the well network between each oil layer varies greatly.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present application is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present application, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions, all other embodiments obtained without creative work, are within the scope of protection of the present invention.

Claims

1. A method for evaluating the uniformity of vertical well patterns in oil fields, characterized by: The method is to input the well location coordinates of the target work area, the single well layer data, and the perforation data, and evaluate the well pattern uniformity by calculating the layered and time-divided well spacing uniformity coefficient and the well pattern distribution coefficient; the method includes the following steps: Step (1), obtaining the geodetic coordinates, well type, perforation layer, and perforation time of all oil and water wells in the target work area; Step (2), dividing the oil and water wells in the work area into different well groups with the water wells as the center according to the oil and water wells; Step (3), calculating the injection and production well spacing and the average well spacing of each oil well connected to the water wells in each well group according to the perforation conditions of the oil and water wells; Step (4), calculate various area parameters and angle parameters according to the following method; ①, connect the oil wells O1, O2, O3, O4, etc. in the well group in sequence to form a polygon S1, and calculate its area as A1; ②, connect a line from the water well to each oil well, and mark the virtual wells A, B, C, D, etc. at the average well spacing on the connecting line or the extension of the connecting line; connect the virtual wells A, B, C, D, etc. in sequence to form a polygon S2, and calculate its area as A2; ③, calculate the sum of the areas within S1 and outside S2, A3; ④, calculate the sum of the areas outside S1 and inside S2, A4; ⑤, calculate the angles ∠1, ∠2, ∠3, ∠4, etc. between the water well and the oil well; Step (5), calculating the well spacing uniformity coefficient LV and the well pattern distribution coefficient NV; LV=(A3+A4) / A1 NV=∠max / ∠min Where A1 is the area defined by the connecting line of oil well points O1, O2, O3, O4, etc.; A2 is the area of ​​polygon S2 defined by connecting lines of virtual wells A, B, C, D, etc. determined by the average well spacing; A3 is the sum of the areas within S1 and outside S2; A4 is the sum of the areas outside S1 and inside S2; ∠max is the maximum value among ∠1, ∠2, ∠3, ∠4, etc.; ∠min is the minimum value among ∠1, ∠2, ∠3, ∠4, etc.; Step (6), calculate the well spacing uniformity coefficient LV and well pattern distribution coefficient NV of all well groups, first L V and N V Normalize, and then determine the uniformity coefficient L of each well group based on the actual situation of the work area V and well pattern distribution coefficient N V Weight, calculate the uniformity of each well group; Step (7), calculating the average well network uniformity of each well group in each oil layer to obtain the well network uniformity of different oil layers; comprehensively analyzing the well network uniformity of each oil layer to determine the well network uniformity of the work area.

2. A method for evaluating the uniformity of a vertical well pattern in an oil field as claimed in claim 1, characterized in that: The larger the well spacing uniformity coefficient is, the more uneven the well spacing is. The well spacing uniformity coefficient of a uniform well network is 0.

3. The method for evaluating the uniformity of a vertical well pattern in an oil field as claimed in claim 1, characterized in that: The larger the well pattern distribution coefficient is, the more uneven the well pattern distribution is. The well pattern distribution coefficient of a uniform well pattern is 1.

4. The method for evaluating the uniformity of a vertical well pattern in an oil field as claimed in claim 1, characterized in that: The well pattern uniformity refers to the well pattern uniformity at a single time node; the calculation method of the well pattern uniformity at different time points is the same.

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