Method for determining horizontal well plugging length of fractured water breakthrough oil well and plugging method

Abstract

The present application relates to a kind of fracture water breakthrough oil well horizontal well plugging length determination method, plugging method, belong to petroleum and natural gas exploration and development technical field.The determination method includes the following steps:1) determine the main water breakthrough section of oil well horizontal well;2) predict the comprehensive water cut and water drive volume sweep efficiency of reservoir injection-production well group under different plugging schemes;Various plugging schemes are centered on the main water breakthrough section, and the plugging length proportion of well section is different;The plugging section of each plugging scheme includes the main water breakthrough section;3) the comprehensive water cut and water drive volume sweep efficiency of each plugging scheme are weighted and averaged respectively, to obtain evaluation index parameter, and then determine the plugging length of fracture oil reservoir oil well horizontal well.The method can realize the purpose of reducing water and increasing oil, reducing the invalid displacement of injected water, guiding the water plugging measures of fracture reservoir injection-production well group, improving the swept volume of fracture reservoir and effectively supplementing formation energy, and ultimately achieving the purpose of improving the development effect of fracture reservoir.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for determining the plugging length of a horizontal well of a fractured water breakthrough oil well, and a plugging method, and belongs to the technical field of oil and gas exploration and development. BACKGROUND

[0002] Low-permeability fractured reservoirs have strong heterogeneity, and natural fractures and micro-fractures are developed. After multi-stage fracturing reconstruction of a horizontal well, artificial fractures are complex, and in the process of water injection development, it is more likely to form a communication between the artificial fractures and the natural fractures between the injection wells. Since the matrix permeability of the reservoir is much smaller than the fracture permeability, in the process of water injection development, injected water is extremely easy to flow directly into the wellbore along the high-permeability fractures, resulting in ineffective displacement of water injection, and ultimately causing water breakthrough in the fractured horizontal well, rapid water cut rise, and low recovery degree. In view of the above problems in water injection development, measures such as water control and water plugging need to be taken for the fractured horizontal well of the oil well to expand the swept volume of the injected water and improve the recovery of crude oil.

[0003] Existing technologies and documents focus on measures and processes for improving or improving the plugging of water breakthrough horizontal wells in fractured reservoirs. For example, the patent document with the application publication number CN108003854A discloses a channeling sealing agent for plugging difficult buried hill fractured reservoirs, which includes 34-60 parts of oil sludge, 0.2-0.5 parts of thickening agent, 0.5-1 parts of foaming agent, 1.5-2.5 parts of polypropylene phthalate, 0.05-0.15 parts of adjusting agent, 0.05-0.25 parts of crosslinking agent, and 1.0-3.0 parts of body expansion particles, and the balance is water. In 2003, how to sail in the water plugging research of deep fractured reservoirs, in-depth research was carried out around the water plugging technology such as pump injection equipment, pump injection parameters, pump injection process, and plugging radius and plugging agent dosage, and it was concluded that high-strength body expansion plugging agent and modified tannin plugging agent could meet the requirements of water plugging in deep fractured reservoirs.

[0004] But the above researches are all around the water plugging technology, and how to reasonably plug the water breakthrough well section of the horizontal well in the fractured reservoir to realize the effective utilization of injected water, tap the remaining oil and improve the recovery degree. At present, the main technical means is to determine the main water breakthrough section of the horizontal well of the oil well through the saturation logging data, water absorption of the injection well or the oil well, and liquid production profile test data, and to carry out single plugging in a targeted manner. However, in the water injection development, the plugging of the main water breakthrough section of the horizontal well cannot effectively control the rising speed of the water content of the oil well. With the increase of the injection pressure of the injection well, the horizontal well opens the remaining artificial fracture section and the natural fracture to communicate, causes the secondary breakthrough of the injected water, and makes the water content continue to increase, which finally affects the water plugging effect. Moreover, if the main water breakthrough section of the horizontal well of the oil well is simply and greatly plugged, the length of the effective production section of the horizontal well will be reduced, the drainage area of the horizontal well will be reduced, the oil loss will be caused, and finally the recovery degree of the reservoir will be affected. Therefore, it is very important to reasonably plug the length of the horizontal well of the oil well in combination with the geological characteristics in the fractured reservoir, which can guide the engineering construction and achieve the effect of achieving the goal with half the effort. SUMMARY

[0005] The purpose of the present application is to provide a method for determining the plugging length of the horizontal well of the fractured water breakthrough oil well, and the plugging of the water breakthrough section according to the determined plugging length can reduce the comprehensive water content and improve the recovery degree of the reservoir.

[0006] The present application also provides a plugging method for the horizontal well of the fractured water breakthrough oil well.

[0007] In order to achieve the above purpose, the technical scheme adopted by the method for determining the plugging length of the horizontal well of the fractured water breakthrough oil well is as follows:

[0008] A method for determining the plugging length of the horizontal well of the fractured water breakthrough oil well, comprising the following steps:

[0009] 1) determining the main water breakthrough section of the horizontal well of the oil well in the fractured reservoir;

[0010] 2) designing different plugging schemes through a numerical simulation software, carrying out numerical simulation, predicting the comprehensive water content and the water drive volume sweep efficiency of the injection-production well group of the reservoir under different plugging schemes; the various plugging schemes are all centered on the main water breakthrough section, and the plugging length proportions of the well sections are different;

[0011] 3) weighting and averaging the comprehensive water content and the water drive volume sweep efficiency of each plugging scheme respectively to obtain an evaluation index parameter, and then comparing the evaluation index parameters of different plugging schemes, taking the plugging length corresponding to the plugging scheme with the maximum evaluation index parameter as the plugging length of the horizontal well of the oil well in the fractured reservoir.

[0012] The method for determining the plugging length of a fractured water breakthrough oil well horizontal well of the application considers the water content distribution of the fractured water breakthrough oil well horizontal well, quantitatively calculates the comprehensive water cut and water drive swept volume coefficient under different plugging schemes, determines the optimal horizontal well plugging well length, can realize the purposes of reducing water and increasing oil, reducing the invalid displacement of injected water, guiding the water plugging measures of the injection-production well group of the fractured reservoir, improving the water injection swept volume of the fractured reservoir and effectively supplementing the formation energy, and finally improving the development effect of the fractured reservoir. The determining method of the application is simple, easy to operate, economical and practical, avoids the problem of repeated operations due to the failure and incompleteness of water plugging in the field, and has great popularization significance.

[0013] Preferably, the method for determining the plugging length of a fractured water breakthrough oil well horizontal well further comprises the following steps: determining the number of artificial fracturing sections of the oil well horizontal well in the fractured reservoir, denoted as n.

[0014] In step 2), the design method of the plugging scheme is: taking the main water breakthrough section as the center, the total length of the horizontal section is 1 / n unit step, and an edge plugging section is added from near to far on the side of the main water breakthrough section to form a plugging scheme; and n is the number of artificial fracturing sections of the oil well horizontal well in the fractured reservoir.

[0015] Preferably, in step 1), the main water breakthrough section of the oil well horizontal well in the fractured reservoir is determined by the method comprising the following steps:

[0016] i) a dual medium three-dimensional numerical model representing the characteristics of the fractured reservoir is established, and history matching is performed;

[0017] ii) the monitoring data and production dynamic data of the oil and water wells are used, and the history matching results are combined to select a well section meeting the following conditions as the main water breakthrough section: the corresponding comprehensive water cut of the well section is higher than the water cut of the remaining most perforated well sections of the oil well horizontal well; or the water absorption percentage on the water injection layer of the water well corresponding to the well section in the annual water absorption profile data of the water well is greater than or equal to 45%, and the remaining oil saturation of the well section is lower than the remaining oil saturation of the remaining most perforated well sections of the oil well horizontal well. The most perforated well section refers to a well section accounting for more than 75% of the total number of perforated well sections of the oil well horizontal well.

[0018] The method for determining the main water breakthrough section of the oil well horizontal well considers the influence degree of natural fractures in the water injection development of the fractured reservoir, and the established dual medium three-dimensional numerical model conforms to the geological characteristics and field development dynamic characteristics of the fractured reservoir.

[0019] Preferably, the dual-media three-dimensional numerical model is established by using a dual-media three-dimensional geological model representing the characteristics of the fractured reservoir, in combination with the physical characteristics of the oil, gas and water fluids in the fractured reservoir in the target region and the production performance data of the oil and water wells. The physical characteristics of the oil, gas and water fluids in the fractured reservoir include PVT data, relative permeability curves and rock data. The production performance data of the oil and water wells include well history and production data. The target region is the region where the horizontal well of the fractured water breakthrough well is located.

[0020] Preferably, the method for establishing the dual-media three-dimensional geological model representing the fractured reservoir comprises the following steps: determining a sublayer division scheme by using the electric logging data and core data of all the single wells in the region where the oil well is located, in combination with regional sedimentary markers and the development conditions of stable mudstone interbeds and physical property interbeds; and establishing the dual-media three-dimensional geological model of the fractured reservoir by using the sublayer division scheme, in combination with seismic data and breakpoint, fault, sedimentary facies and physical property interpretation data.

[0021] Preferably, the monitoring data include production profile, water injection profile and temperature logging data. Further, in determining the main water breakthrough section, in addition to the monitoring data, the development characteristics of the fractures in the fractured reservoir and the distribution characteristics of the water injection well pattern are also used.

[0022] In step 2), by using the principle that the length proportion of the plugging section in different plugging schemes causes the change of the angle between the injection flow line and the natural fractures and the artificial fractures, the production and development indexes of the injection and production well groups in the reservoir under different plugging schemes are simulated and predicted under the same production conditions within the same production time. The development indexes mainly include cumulative oil production, comprehensive water cut and recovery degree. When the cumulative oil production, comprehensive water cut and recovery degree are used to calculate the size of the water drive swept volume, preferably, the calculation method of the water drive volume swept coefficient is as follows:

[0023]

[0024] In the formula, E v is the water drive volume swept coefficient; B oi is the oil volume coefficient under the initial state of the reservoir; B o is the oil volume coefficient under the current condition; f w is the comprehensive water cut of the reservoir, %;

[0025] a and b are determined according to the water drive characteristic curve formula W p is the cumulative water production of the reservoir, m 3 ; N p is the cumulative oil production of the reservoir, ×10 4 t. The above water drive characteristic curve formula is proposed by Zhang Jinqing in the document "A Simple and Practical Water Drive Characteristic Curve".

[0026] Considering the production indexes and water drive swept volume coefficients of different plugging schemes, the comprehensive water cut and water drive swept volume coefficient are selected as the comprehensive evaluation indexes.

[0027] The technical scheme of the plugging method for the fractured water breakthrough oil well horizontal well of the application is as follows:

[0028] The plugging method for the fractured water breakthrough oil well horizontal well comprises the following steps:

[0029] 1) determining the main water breakthrough section of the oil well horizontal well in the fractured reservoir;

[0030] 2) designing different plugging schemes by using a numerical simulation software, performing numerical simulation, and predicting the comprehensive water cut and water drive swept volume coefficient of the injection-production well group in the reservoir under different plugging schemes; each plugging scheme is centered on the main water breakthrough section, and the plugging length proportions of the well sections are different;

[0031] 3) weighting and averaging the comprehensive water cut and water drive swept volume coefficient of each plugging scheme to obtain the evaluation index parameters, and then comparing the evaluation index parameters of different plugging schemes, wherein the plugging length corresponding to the plugging scheme with the maximum evaluation index parameter is taken as the plugging length of the oil well horizontal well in the fractured reservoir;

[0032] 4) plugging the oil well horizontal well according to the plugging length determined in step 3).

[0033] The plugging method for the fractured water breakthrough oil well horizontal well of the application considers the water cut distribution of the fractured water breakthrough oil well horizontal well, quantitatively calculates the comprehensive water cut and water drive swept volume coefficient under different plugging schemes, determines the optimal horizontal well plugging section length, and guides the water plugging measures of the injection-production well group in the fractured reservoir according to the determined plugging length, so as to realize the purposes of reducing water breakthrough, reducing the invalid displacement of injected water, improving the water injection swept volume of the fractured reservoir, and effectively supplementing the formation energy, and finally improving the development effect of the fractured reservoir.

[0034] Preferably, the design method of the plugging scheme is as follows: taking the main water breakthrough section as the center, the total length of the horizontal section is 1 / n unit step, and an edge plugging section is added every unit step from near to far on the side of the main water breakthrough section to form a plugging scheme; the n is the number of artificial fracturing sections of the oil well horizontal well in the fractured reservoir.

[0035] Preferably, in step 1), the main water breakthrough section of the oil well horizontal well in the fractured reservoir is determined by using the method comprising the following steps:

[0036] i) establishing a dual medium three-dimensional numerical model characterizing the features of the fractured reservoir, and performing history matching;

[0037] ii) using the monitoring data and production performance data of the oil and water wells, and combining the history matching results, selecting a well section that meets the following conditions as the main water production section: the corresponding comprehensive water cut of the well section is higher than the water cut of the rest of the most open sections of the horizontal well of the oil well; or the water absorption percentage of the water injection layer of the water well corresponding to the well section in the annual water absorption profile data of the water well is greater than or equal to 45%, and the remaining oil saturation of the well section is lower than the remaining oil saturation of the rest of the most open sections of the horizontal well of the oil well. Preferably, the most open sections refer to the sections that account for more than 75% of the total open sections of the horizontal well of the oil well.

[0038] Preferably, the dual medium three-dimensional numerical model is established by using a dual medium three-dimensional geological model characterizing the features of the fractured reservoir, and combining the oil, gas and water fluid physical features of the fractured reservoir in the target area and the production performance data of the oil and water wells. The oil, gas and water fluid physical features of the fractured reservoir include the PVT data, relative permeability curves and rock data of the fluids. The production performance data of the oil and water wells include the well history and production data of the oil and water wells.

[0039] Preferably, the method for establishing a dual medium three-dimensional geological model characterizing the fractured reservoir comprises the following steps: determining a small layer division scheme by using the electric logging data and core data of all single wells in the area where the oil well is located, and combining regional sedimentary markers and the development conditions of stable mudstone interlayers and physical property interlayers; and establishing a dual medium three-dimensional geological model of the fractured reservoir by using the small layer division scheme, and combining seismic data and breakpoint, fault, sedimentary facies and physical property interpretation data.

[0040] Preferably, the monitoring data include production profile, water injection profile and temperature logging data. Further, in determining the main water production section, the development features of the fractures in the fractured reservoir and the distribution features of the water injection well pattern are also used.

[0041] In step 2), the production and development indexes of the injection-production well group under different plugging schemes are simulated and predicted in the same production time under the same production conditions by using the principle that the change of the length proportion of the plugging section in different plugging schemes causes the change of the angle between the water injection flow line and the natural fractures and artificial fractures. The development indexes mainly include cumulative oil production, comprehensive water cut and recovery degree. When the cumulative oil production, comprehensive water cut and recovery degree are used to calculate the size of the water drive swept volume, preferably, the calculation method of the water drive swept volume coefficient is as follows:

[0042]

[0043] In the formula, E v is the water drive swept volume coefficient; Boi is the oil volume coefficient under the initial state of the reservoir; B o is the oil volume coefficient under the current condition; f w is the comprehensive water cut of the reservoir, %;

[0044] a, b are determined according to the water drive characteristic curve formula is determined, W p is the cumulative water production of the reservoir, m 3 ; N p is the cumulative oil production of the reservoir, × 10 4 t. The above water drive characteristic curve formula is proposed by Zhang Jinqing in the document “A Simple and Practical Water Drive Characteristic Curve”.

[0045] The production index and the water drive swept volume coefficient of different plugging schemes are comprehensively considered, and the comprehensive water cut and the water drive swept volume coefficient are selected as the comprehensive evaluation indexes. When the parameters of the comprehensive evaluation indexes are determined, the weights of the comprehensive water cut and the water drive swept volume coefficient are both 0.5. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a flowchart of the method for determining the plugging length of the horizontal well of the fractured water breakthrough oil well in the embodiment;

[0047] Figure 2 is a longitudinal remaining oil distribution map of the A1 well group in the embodiment;

[0048] Figure 3 is a planar remaining oil distribution map of the A1 well group in the embodiment;

[0049] Figure 4 is an injection-production flow line diagram after the plugging of the water breakthrough well section of the horizontal well of the fractured reservoir in the embodiment;

[0050] Figure 5 is a remaining oil saturation distribution map after the development of the A1 well group for 15 years without plugging in the embodiment;

[0051] Figure 6 is a remaining oil saturation distribution map after the development of the A1 well group for 15 years with the plugging of the horizontal well section at a ratio of 5 / 9 in the embodiment;

[0052] Figure 7 is an injection-production flow line diagram after the development of the A1 well group for 15 years with the plugging of the horizontal well section at a ratio of 3 / 9 in the embodiment;

[0053] Figure 8 is a cumulative oil production change curve under different plugging schemes of the A1 well group in the embodiment;

[0054] Figure 9 is a comprehensive water cut change curve under different plugging schemes of the A1 well group in the embodiment;

[0055] Figure 10 The comprehensive evaluation index R change curve for different plugging schemes of the A1 well group. DETAILED DESCRIPTION

[0056] The technical solutions of the present application are further described below in combination with specific embodiments.

[0057] Embodiment 1

[0058] This embodiment takes the A1 well group of the H oilfield fractured reservoir development direct injection flat mining as an example, and quantitatively optimizes the horizontal well plugging length of the fractured water breakthrough oil well according to the method of the present application.

[0059] The method for determining the horizontal well plugging length of the fractured water breakthrough oil well in this embodiment, as shown in Figure 1 , includes the following steps:

[0060] 1) Establish a dual medium three-dimensional numerical model representing the characteristics of the fractured reservoir:

[0061] ① Use the electric logging data and core data of all single wells in the target area (i.e. the area where the A1 well group is located), combined with regional sedimentary markers and stable mudstone interbeds, and the development of physical property interbeds to determine the sublayer division scheme; use the sublayer division scheme, combined with seismic data and breakpoints, faults, sedimentary facies and physical property interpretation data to establish a dual medium three-dimensional geological model of the fractured reservoir;

[0062] ② Based on the three-dimensional geological model established in the above step, combined with the oil, gas and water fluid physical properties and oil and water well production dynamic data of the fractured reservoir in the target area, a dual medium three-dimensional numerical model representing the characteristics of the fractured reservoir is established and history matching is performed, and the matching results are shown in Figures 2-3 ( Figure 2 INJ1, INJ2, INJ3, INJ4 are injection wells, and PRO-P1, PRO-P2 are oil well horizontal wells); the oil, gas and water fluid physical properties of the fractured reservoir here include PVT data, relative permeability curves, rock data; the oil and water well production dynamic data here include oil and water well history and production data;

[0063] 2) According to the oil and water well logging monitoring data and oil and water well production dynamic data collected from the mine site, such as production profile, water injection profile and temperature, combined with the history matching results of the dual medium three-dimensional numerical model established in step 1), the main water breakthrough section (A4-A5) of the oil well horizontal well fracturing is determined, as shown in Figure 4 .

[0064] The main water outlet section is a section that meets the following characteristics: the corresponding comprehensive water cut of the section is higher than the water cut of the rest of the most open sections of the horizontal well of the oil well; or the water absorption percentage of the water injection layer corresponding to the section in the water absorption profile data of the water well over the years is greater than or equal to 45%, and the remaining oil saturation of the section is lower than the remaining oil saturation of the rest of the most open sections of the horizontal well of the oil well (the number of most open sections refers to more than 75% of the total number of open sections of the horizontal well of the oil well).

[0065] 3) According to the fracture monitoring data collected on the mine site and the fracturing operation summary data, the artificial fracture position and the number of artificial fracture sections of the horizontal well of the oil well after fracturing in the fractured reservoir are determined, and the number of artificial fracture sections is denoted as n;

[0066] 4) On the basis of step 3), a scheme of different plugging lengths of the horizontal well section of the oil well is designed: the scheme includes a plugging scheme of only plugging the main water outlet section, and a plugging scheme of plugging the section centered on the main water outlet section A4-A5 of the horizontal well of the oil well (the length is 1 / n of the total length of the horizontal section, n is the number of artificial fracture sections of the horizontal well of the oil well), and a plugging scheme formed by plugging the edge section on both sides of the main water outlet section by a unit step of 1 / n of the total length of the horizontal section (i.e. the distance between adjacent artificial fracture sections, n is the number of artificial fracture sections of the horizontal well of the oil well) from near to far, a total of 8 plugging schemes, as shown in Table 1.

[0067] Table 1 Design table of different plugging proportion schemes of horizontal well sections

[0068]

[0069] Using the principle that the change of the length proportion of the different plugging sections causes the change of the angle between the water injection flow line and the natural fracture and the artificial fracture, the production and development indexes of the injection and production well groups in the reservoir under different plugging schemes are simulated and predicted under the same production conditions within the same production time. The development indexes mainly include cumulative oil production, water cut and recovery degree, etc. When calculating the production indexes of different plugging schemes, the production dynamic data of the well group before plugging is kept unchanged, i.e. daily water injection of 20m 3 , daily liquid production of 20t, and injection-production ratio of 1. On this basis, the development and production index changes of each scheme after 15 years of production of the horizontal well under the 8 plugging schemes are simulated and predicted, and the simulation results are shown in Table 2.

[0070] Table 2 Production index results table of different plugging proportion schemes of horizontal well sections

[0071] Number Cumulative oil production (xlO 4 t) Water content (%) Recovery (%) Scheme 1 0.7487 96.3 6.9 Scheme 2 1.3504 94.1 10.2 Scheme 3 1.4817 93.6 13.3 Scheme 4 1.7992 92.9 14.4 Scheme 5 2.0145 91.9 15.2 Scheme 6 2.0718 91.5 17 Scheme 7 1.7676 92.1 16.3 Scheme 8 1.6779 92.6 15.1

[0072] The results of the numerical simulation software show that the relationship between the recovery percent of the well group after 15 years of production and the length proportion of the plugged well section is an "n" type curve: when the length proportion of the plugged water-bearing well section is in the range of 0-5 / 9, the recovery percent increases with the increase of the length proportion of the plugged section, but the increase amplitude gradually decreases; when the length proportion of the plugged water-bearing well section is in the range of 4 / 9-5 / 9, the recovery percent decreases with the increase of the length proportion of the plugged section. With the increase of the length proportion of the plugged section, the water cut of the well group is effectively controlled. According to the injection-production flow line diagram of the corresponding direct injection flat production well group, it is analyzed that when the injection-production flow line along the high permeability strip is at an angle of 30-45° with the horizontal reservoir production well section, the water drive swept range after water injection is large, the utilization rate of the injected water is improved, and the potential of the remaining oil enrichment area is effectively developed, as shown in Figs. Figure 5 、 6 、7.

[0073] 5) According to the production indexes of each scheme obtained in step 4), the water drive volume sweep efficiency under different plugging schemes is calculated, and the water drive volume sweep efficiency is calculated by using the following formula. According to the new water drive characteristic curve formula , the a and b under each scheme are determined;

[0074] The calculation formula of the water drive volume sweep efficiency Ev is:

[0075]

[0076] In the formula, E v is the water drive volume sweep efficiency; B oi is the oil volume coefficient under the initial state of the reservoir; B o is the oil volume coefficient under the current condition; f w is the comprehensive water cut of the reservoir, %; the results are shown in Tables 3, Figure 8 and Figure 9 .

[0077] Table 3 Statistics table of the water drive characteristic curve a, b values and Ev calculation results of different plugging horizontal well section proportion schemes

[0078] Number a b f w (%)]] E v (%)]] Scheme 1 7.74 1324.1 96.3 13.88 Scheme 2 6.85 1105 94.1 20.38 Scheme 3 5.51 1010.3 93.6 26.5 Scheme 4 5.05 902.2 92.9 28.9 Scheme 5 4.46 870.3 91.9 30.39 Scheme 6 4.06 845.2 91.5 34.55 Scheme 7 3.55 800.5 92.1 33.12 Scheme 8 3.51 798.1 92.6 30.44

[0079] 6) The production indexes and the water drive volume sweep efficiency of different plugging schemes in step 4) are comprehensively considered, the comprehensive water cut and the water drive volume sweep efficiency are selected as the comprehensive evaluation indexes, the weights are each 0.5, and the final evaluation index R is calculated, wherein the results are shown in Table 4, and the evaluation index R change curve is shown in Figure 10 .

[0080] Table 4 Statistics table of the comprehensive evaluation index calculation results of different plugging horizontal well section proportion schemes

[0081] Number F w (%)]] [WC fw ]]> E v (%)]] [WC Ev ]]> R Scheme 1 96.3 0.5 13.88 0.5 0.275 Scheme 2 94.1 0.5 20.38 0.5 0.286 Scheme 3 93.6 0.5 26.5 0.5 0.300 Scheme 4 92.9 0.5 28.9 0.5 0.305 Scheme 5 91.9 0.5 30.39 0.5 0.306 Scheme 6 91.5 0.5 34.55 0.5 0.315 Scheme 7 92.1 0.5 33.12 0.5 0.313 Scheme 8 92.6 0.5 30.44 0.5 0.308

[0082] According to the results in Table 4, the scheme 6 is determined, i.e. the reasonable length of the water plugging section of the horizontal well of the oil well in the fractured reservoir is 5 / 9 of the total length of the horizontal well. When the injection-production flow line along the high-permeability strip of the fracture is at an angle of 45° with the well section of the horizontal reservoir, the development effect of the well group and the control of the water cut rising speed are optimal.

[0083] Example 2

[0084] The method for determining the length of the water plugging section of the horizontal well of the fractured water breakthrough oil well in this example is implemented according to the following order of the steps of Example 1: Step 3), Step 1), Step 2), Step 4), Step 5), Step 6).

[0085] Example 3

[0086] The method for determining the length of the water plugging section of the horizontal well of the fractured water breakthrough oil well in this example is different from that of Example 1 only in that the size of the water drive volume sweep efficiency is calculated by using the cumulative oil production, the comprehensive water cut and the crude oil viscosity, and the calculation method of the water drive volume sweep efficiency is as follows:

[0087]

[0088] In the formula, E v is the water drive volume sweep efficiency; B oi is the crude oil volume coefficient under the initial state of the reservoir; B o is the crude oil volume coefficient under the current condition; f w is the comprehensive water cut of the reservoir, %; N p is the cumulative oil production, 10 4 t; N is the geological reserves of crude oil, 10 4 t; μ w is the viscosity of the formation water, mPa·s; μ o is the viscosity of the crude oil, mPa·s; S wi is the irreducible water saturation, %; S or is the final residual oil saturation, %.

[0089] a and b are determined according to the water drive characteristic curve formula K ro is the relative permeability of the crude oil, mD; K rw is the relative permeability of the crude oil, mD.

[0090] Example 4

[0091] The method for plugging the horizontal well of the fractured water breakthrough oil well in this example comprises the following steps:

[0092] 1) the length of plugging determined according to the method for determining the length of plugging of the fractured water breakthrough oil well horizontal well in Embodiment 1;

[0093] 2) plugging the water breakthrough oil well horizontal well according to the determined length of plugging.

[0094] Embodiment 5

[0095] The method for plugging the fractured water breakthrough oil well horizontal well in this embodiment comprises the following steps:

[0096] 1) the length of plugging determined according to the method for determining the length of plugging of the fractured water breakthrough oil well horizontal well in Embodiment 2;

[0097] 2) plugging the water breakthrough oil well horizontal well according to the determined length of plugging.

[0098] Embodiment 6

[0099] The method for plugging the fractured water breakthrough oil well horizontal well in this embodiment comprises the following steps:

[0100] 1) the length of plugging determined according to the method for determining the length of plugging of the fractured water breakthrough oil well horizontal well in Embodiment 3;

[0101] 2) plugging the water breakthrough oil well horizontal well according to the determined length of plugging.

Claims

1. A method for determining the horizontal well plugging length of a fractured watered-out oil well, characterized in that: The method comprises the following steps: 1) determining a main water outlet section of a horizontal well in a fractured reservoir; 2) designing different plugging schemes by using a numerical simulation software, performing numerical simulation, and predicting a comprehensive water cut and a water drive volume sweep efficiency of an injection-production well group in the reservoir under different plugging schemes; the design method of the plugging scheme is that a center plugging section is the main water outlet section, and a unit step length is 1 / n of the total length of the horizontal section, and an edge plugging section is added every time by 1 unit step length from near to far beside the main water outlet section to form a plugging scheme; n is the number of artificial fracturing sections of the horizontal well in the fractured reservoir; 3) performing weighted average on the comprehensive water cut and the water drive volume sweep efficiency of each plugging scheme respectively to obtain an evaluation index parameter, then comparing the evaluation index parameters of different plugging schemes, and taking a plugging length corresponding to a plugging scheme with the maximum evaluation index parameter as the plugging length of the horizontal well in the fractured reservoir; 2. The method of claim 1, wherein: In step 1), the main water outlet section of the horizontal well in the fractured reservoir is determined by using a method comprising the following steps: i) establishing a dual medium three-dimensional numerical model representing the characteristics of the fractured reservoir, and performing history matching; ii) selecting a well section meeting the following conditions as the main water outlet section by using monitoring data and production dynamic data of oil and water wells and combining the history matching result: the comprehensive water cut corresponding to the well section is higher than the water cut of the remaining most perforated well sections of the horizontal well of the oil well; or the water absorption percentage of the water injection layer corresponding to the well section in the year-by-year water absorption profile data of the water well is greater than or equal to 45%, and the remaining oil saturation of the well section is lower than the remaining oil saturation of the remaining most perforated well sections of the horizontal well of the oil well.

3. The method of claim 2, wherein: The monitoring data comprises production profile, water absorption profile and temperature logging data.

4. The method of claim 1, wherein: The calculation method of the water drive volume sweep efficiency is: wherein E v is the volumetric sweep efficiency of water flooding; B oi is the volumetric coefficient of crude oil in the initial state of the reservoir; B o is the volumetric coefficient of crude oil under current conditions; f w is the overall water cut of the reservoir, %; a, b from water drive characteristic curve equation determined, W p cumulative water production for the reservoir, m 3 ; N p Cumulative oil production, x 10 4 t.

5. The method of claim 1, wherein: The weights of the comprehensive water cut and the water drive volume sweep efficiency are both 0.

5.

6. A method of plugging a horizontal well of a watered-out fractured oil well, characterized in that: The method comprises the following steps: 1) determining a main water outlet section of a horizontal well in a fractured reservoir; 2) designing different plugging schemes by using a numerical simulation software, performing numerical simulation, and predicting a comprehensive water cut and a water drive volume sweep efficiency of an injection-production well group in the reservoir under different plugging schemes; the design method of the plugging scheme is that a center plugging section is the main water outlet section, and a unit step length is 1 / n of the total length of the horizontal section, and an edge plugging section is added every time by 1 unit step length from near to far beside the main water outlet section to form a plugging scheme; n is the number of artificial fracturing sections of the horizontal well in the fractured reservoir; 3) performing weighted average on the comprehensive water cut and the water drive volume sweep efficiency of each plugging scheme respectively to obtain an evaluation index parameter, then comparing the evaluation index parameters of different plugging schemes, and taking a plugging length corresponding to a plugging scheme with the maximum evaluation index parameter as the plugging length of the horizontal well in the fractured reservoir; 4) plugging the horizontal well according to the plugging length of the horizontal well determined in step 3).

7. The method of plugging a fractured water-encroaching oil well horizontal well according to claim 6, characterized in that: In step 1), the main water outlet section of the horizontal well in the fractured reservoir is determined by using a method comprising the following steps: i) establishing a dual medium three-dimensional numerical model representing the characteristics of the fractured reservoir, and performing history matching; ii) using the monitoring data and production dynamic data of the oil and water wells, and combining with the history matching result, selecting a well section satisfying the following conditions as the main water production section: the corresponding comprehensive water cut of the well section is higher than the water cut of the rest of the most shot open well sections of the horizontal well of the oil well; or the water absorption percentage on the water injection layer of the water well corresponding to the well section in the year-by-year water absorption profile data of the water well is greater than or equal to 45%, and the remaining oil saturation of the well section is lower than the remaining oil saturation of the rest of the most shot open well sections of the horizontal well of the oil well.

8. The method of plugging a fractured watered-out oil well horizontal well according to claim 7, characterized in that: The monitoring data includes production profile, water injection profile and temperature logging data.

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