Method for improving single well yield of oil well

Abstract

The invention belongs to the technical field of exploration and development, and discloses a method for improving the single well yield of an oil well, which increases the contact volume between a reservoir transformation artificial fracture and a reservoir by converting an original main body vertical well into a short horizontal well, increases the probability of finding a new oil reservoir, optimizes the stage number and the tripping-in position of a well cementation sliding sleeve, and improves the well cementation efficiency. And a displacement injection section and an oil extraction section are determined, so that same-well subsection oil extraction and short-distance high-pressure displacement can be realized, the displacement power of crude oil difficult to use is increased, effective use of the crude oil is realized, repeated displacement and different-medium displacement can be performed in the development process, the final recovery rate of the crude oil is further improved, the requirement of differentiated seam distribution between different sections can be met, and the development cost is reduced. High-pressure displacement and low-pressure oil extraction functions of different sections of cracks are achieved, the wettability of a target section is analyzed in real time by means of drilling cuttings, the method is used for guiding model selection of oil displacement liquid and fracturing liquid, and the pertinence of segmented pressure displacement extraction is improved.

Description

Technical Field

[0001] This invention belongs to the field of exploration and development technology, specifically a method for increasing the production of a single oil well. Background Technology

[0002] In the field of exploration and development, as exploration and development progresses, low-charge reservoirs inevitably become an important successor area for increasing reserves and production. The formation of low-charge reservoirs is mainly influenced by reservoir heterogeneity, which is strongly coupled with low hydrocarbon generation intensity. This manifests as large differences in reservoir properties (permeability 0.11–49.7 mD), low formation pressure coefficient (0.7–0.8), low oil saturation (less than 30%), complex rock wettability (coexistence of water and oil), and locally high crude oil viscosity. No patents or journal articles on reservoir stimulation technologies for increasing single-well production in low-charge reservoirs have been found domestically or internationally. Current production practices indicate that exploration and development in this new area still primarily relies on vertical wells, employing hydraulic fracturing to stimulate the reservoir.

[0003] To address the issues of significant differences in physical properties and low formation pressure coefficients, the main approach employed was pre-flush fluid replenishment combined with large-scale volumetric fracturing, aiming to increase formation energy and the degree of vertical reservoir stimulation. For locally high crude oil viscosity, pre-flush CO2 and N2 fracturing and chemical viscosity reduction techniques were tested, aiming to reduce crude oil viscosity and improve its fluidity. However, no new materials or processes have been tested to address the complex wettability of the rock. However, all of these approaches involve single-well unidirectional high-pressure injection and reverse low-pressure flowback, resulting in unsatisfactory overall practical effects. This is mainly evidenced by the presence of crude oil erosion traces in logging cuttings analysis, but during oil testing, most wells exhibited oil slicks or water production, with an overall oil testing success rate of only about 20%. Furthermore, during development and production, wells put into production generally showed low production (less than 1.5 tons of oil per day) and a large annual decline rate (greater than 30%). Summary of the Invention

[0004] This invention provides a method for increasing the production of a single oil well, solving the problem of low success rate of oil testing in low-charge reservoirs.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for increasing the production of a single oil well includes:

[0007] The target exploration well was optimized into a horizontal well, and the key parameters of the horizontal well were optimized.

[0008] Based on the optimized key parameters of the horizontal well, drill and record important parameters of cuttings throughout the horizontal section;

[0009] Based on the key cuttings parameters of the entire horizontal section, optimize the number of cementing sleeve stages and the insertion location, and determine the displacement injection section and the oil production section;

[0010] Based on the displacement injection section and the oil production section, design the fracture parameters, key construction parameters, fracture fluid system and proppant parameters for the oil production section and the displacement section;

[0011] The fracturing method is designed based on the fracture parameters of the oil production section and the displacement section, key construction parameters, fracturing fluid system and important proppant parameters;

[0012] The entire well is fractured based on the optimal fracturing method. After fracturing, the well is shut down and the fluid is pumped out to evaluate the reservoir productivity.

[0013] Preferably, the key parameters of a horizontal well include the length of the horizontal section, the drilling azimuth of the horizontal section, and the completion method.

[0014] Preferably, the key parameters of the cuttings in the entire horizontal section include the oil layer drilling rate, physical properties, brittleness, oil content, and wettability of the reservoir in different horizontal sections.

[0015] Preferably, the cementing sleeve has 5, 7, or 9 stages to achieve 2-stage drive and 3-stage production, 3-stage drive and 4-stage production, or 4-stage drive and 5-stage production, so that even-numbered stages in the horizontal section are displacement stages and odd-numbered stages are oil production stages.

[0016] Preferably, the distance between the oil production section and the displacement section is 30m-50m.

[0017] Preferably, the fracture parameters of the oil-producing section include fracture length, fracture width, and conductivity, wherein the fracture length is 200–240 m, the fracture width is 10–18 m, and the conductivity is greater than or equal to 25 μm. 2 ·cm.

[0018] Preferably, the fracturing method is to first fracture the oil-producing section and then fracture the oil-displacing section. The fracturing process is as follows:

[0019] The deepest section of the sliding sleeve is opened using a switchable cementing sleeve tool, and the other sections are closed. After fracturing, the deepest section of the sliding sleeve is closed. The oil production sliding sleeves from the bottom of the well to the wellhead are opened and closed one by one, and continuous fracturing is used. The deepest oil displacement section of the sliding sleeve is opened using a switchable cementing sleeve tool, and the cementing sliding sleeves are closed one by one. The fracturing time for each stage within a section does not exceed 2 hours, and the interval between each section is less than 8 hours.

[0020] Preferably, the proppant in the oil production section is 20-40 mesh quartz sand or ceramsite, and the proppant in the displacement section is 40-70 mesh quartz sand.

[0021] Preferably, the specific steps for well shut-in after fracturing are as follows:

[0022] After the well has been closed for 7 to 10 days, all odd-numbered oil production sections are opened using a switchable cementing sleeve tool, and continuous fluid drainage is employed to increase production.

[0023] An application of the above method in the evaluation of single-well productivity in oil wells.

[0024] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method to improve the production of a single oil well. By changing the original main vertical well to a short horizontal well, the contact volume between the artificial fracture and the reservoir is increased, the probability of discovering new oil reservoirs is increased, the number of cementing sleeve stages and the insertion position are optimized, and the displacement injection section and the oil production section are determined. This can realize segmented oil production and short-distance high-pressure displacement in the same well, increase the displacement power of difficult-to-move crude oil, and realize the effective utilization of crude oil. During the development process, repeated displacement and displacement with different media can be carried out to further improve the final recovery rate of crude oil. It can meet the differentiated fracture layout requirements between different sections and realize the functions of high-pressure displacement and low-pressure oil production in different fracture sections.

[0025] Furthermore, by using real-time analysis of the wettability of the target section using drilling cuttings, the selection of oil displacement fluids and fracturing fluids can be guided, thereby improving the targeting of staged hydraulic fracturing. Attached Figure Description

[0026] Figure 1 This is a flowchart of a method for increasing the production of a single oil well according to the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] Example 1

[0035] like Figure 1 As shown, this embodiment of the invention provides a method for increasing the production of a single oil well, comprising:

[0036] S101 optimizes the target exploration well into a horizontal well and optimizes the key parameters of the horizontal well;

[0037] S102 drills and records important parameters of cuttings throughout the horizontal section based on the optimized key parameters of the horizontal well.

[0038] Based on the important cuttings parameters of the entire horizontal section, S103 optimizes the number of cementing sleeve stages and the insertion position, and determines the displacement injection section and the oil production section.

[0039] S104 is based on the displacement injection section and the oil production section, and designs the fracture parameters, key construction parameters, fracture fluid system and proppant parameters for the oil production section and the displacement section.

[0040] S105 designs fracturing methods based on fracture parameters, key construction parameters, fracturing fluid system, and important proppant parameters of the oil production section and displacement section.

[0041] S106 performs full-well fracturing based on the optimal fracturing method. After fracturing, the well is shut down and fluid is pumped out to evaluate reservoir productivity.

[0042] Specifically, the following steps are included:

[0043] S1, optimize the target exploration well from the original main vertical or directional well to a horizontal well, and optimize the key parameters of the horizontal well;

[0044] S2, based on the optimized horizontal well parameters in S1, proceed with normal drilling. After drilling to the horizontal section, record the important parameters of the cuttings throughout the horizontal section.

[0045] S3, based on the cuttings parameters in S2, optimize the number of cementing sleeve stages and the insertion location, and determine the displacement injection section and the oil production section;

[0046] S4. Based on the displacement injection section and oil production section determined in S3, design the fracture parameters, key construction parameters, fracturing fluid system, and important proppant parameters for the oil production section.

[0047] S5, based on the displacement injection section and oil production section determined in S3, design the fracture parameters, key construction parameters, fracturing fluid system, and important proppant parameters of the displacement section;

[0048] S6, taking into account the overall design purpose of pressure-driven production, to ensure that the fractures in the oil displacement section and the fracturing section reach the design shape, and to determine the optimal fracturing method;

[0049] S7. After the entire well is fractured, design the well shut-in method and the pumping and drainage method, and evaluate the reservoir productivity.

[0050] Furthermore, the target exploration wells mentioned in step S1 are often vertical or directional wells. However, due to the low oil saturation of low-charge reservoirs, the volume of reservoir stimulation fractures in conventional vertical or directional wells is limited, and the oil test often shows oil slicks or low production (less than 4 tons of oil per day during the test). However, by conducting a two-month trial production of wells that showed oil slicks, three wells reached the economically viable production level in the area (more than 1 ton of oil per day), thus discovering a production reservoir. Therefore, the original main vertical or directional wells are optimized into horizontal wells to obtain higher production by increasing the stimulation volume.

[0051] The optimization of key parameters for horizontal wells mentioned in step S1 refers to the length of the horizontal section, the drilling azimuth of the horizontal section, and the completion method of the horizontal well.

[0052] A horizontal section length of 300m is reasonable, as it provides the slotting locations needed to increase the volume of the modification, and avoids excessive increases in drilling footage.

[0053] The drilling orientation of the horizontal section is more reasonable when it is perpendicular to the maximum horizontal principal stress in the target area, which facilitates the control of fracturing fractures. In particular, when it is designed as a single fracture, the fracture extension orientation is unique and clear.

[0054] For horizontal well completion trials, a 5.5-inch or 4.5-inch N80 grade casing with a switchable cementing sleeve of the same size and grade can be used for completion. This approach satisfies several criteria: first, it meets the differentiated segmentation design requirements in step S4; second, it meets the design requirements for construction parameters to create different fracture morphologies; and third, it does not incur excessive additional costs.

[0055] The important parameters of cuttings recorded in step S2 mainly refer to the oil layer drilling rate, physical properties, brittleness, oil content and wettability of reservoirs in different horizontal sections.

[0056] Oil layer encounter rate, reservoir properties, oil content, and wettability are commonly measured items in well logging, while brittleness can be determined by calculation based on the rock and mineral composition of the well logging.

[0057] Oil layer drilling rate, reservoir properties, and oil content are important bases for determining the number and location of the switchable cementing sleeve in step S3, as well as the displacement injection section and the production section; brittleness is an important base for determining the fracturing fracture morphology in step S4; wettability is an important base for determining the selection of injection fluid for different pump sections in step S5.

[0058] The number of stages of the cementing sliding sleeve mentioned in step S3 is designed according to the logging parameters obtained from different single wells in step S2, with 5, 7, and 9 stages, to achieve 2-stage drive and 3-stage production, 3-stage drive and 4-stage production, and 4-stage drive and 5-stage, that is, the design is that the even-numbered stages in the horizontal section are the displacement stages and the odd-numbered stages are the oil production stages.

[0059] The production section is used to produce oil and obtain crude oil from the reservoir after the whole well is fractured; the displacement section is used to displace the crude oil between the horizontal sections after the whole well is fractured, so as to improve the utilization of crude oil with low charging.

[0060] In step S3, the location of the cementing sliding sleeve is determined first in the oil production section and then in the oil displacement section. The distance between the oil production section and the oil displacement section is designed to be 30-50m.

[0061] The location of the cementing sleeve in the oil production section is determined according to the priority principle of good oil content, high brittleness index, good physical properties, and water wettability.

[0062] The relative position of the oil displacement section is determined by designing a distance of 30-50m between the production section and the oil displacement section. In order to ensure uniform and efficient displacement, the position with good homogeneity (i.e., continuous sandstone section) and low brittleness index is selected as the oil displacement section. At the same time, the wettability of the rock in the oil displacement section is determined.

[0063] The fracture design of the oil production section in step S4 is a single-segment, single-family fracture. Furthermore, based on the fact that the orientation of the horizontal segment in step S1 is perpendicular to the orientation of the maximum principal stress, it is beneficial to form a single fracture and achieve precise control of the fracture in the oil production section.

[0064] The fracture parameters of the oil production section defined in this invention refer to the length, width, and conductivity of the hydraulic fracture (also known as artificial fracture).

[0065] The fracture parameters for the oil-producing section are designed as follows: moderate fracture length (experience has shown that 200–240 m is optimal), moderate fracture width (1 / 3 of the distance between the oil-producing and displacement sections, i.e., 10–18 m), and high conductivity (designed to be ≥25 μm). 2 ·cm).

[0066] The key construction parameters of the oil production section mentioned in step S4, as well as the important parameters of the fracturing fluid system and proppant, refer to the construction parameters required for precise control of fracture parameters and the matching fracturing fluid and proppant. Priority is given to designing the construction flow rate and fracturing fluid viscosity, which affect fracture bandwidth parameters; then, the total fluid injection volume, which affects fracture length parameters, is designed; finally, the pumping method, sand depth, and proppant type, which affect conductivity, are designed.

[0067] The matching relationship between fracture width, fracturing fluid displacement, and fracturing fluid viscosity needs to be studied using laboratory physical models or based on field fracture parameter tests. The general principle is to create relatively independent, single fractures, and a fracturing fluid displacement parameter of less than 3.0 m is recommended. 3 / min, the viscosity of the fracturing fluid base fluid is medium viscosity (12-18 mPa·s) + high viscosity (≥33 mPa·s). Among them, the pre-flush fluid and the low sand ratio (≤15%) use medium viscosity base fluid or weak cross-linked fluid, that is, a fracture bandwidth of 10-18 m is formed under low filtration loss. In the high sand ratio stage (>15%), high viscosity cross-linked fluid is used, and the fracture bandwidth is slightly increased.

[0068] In the early stages of fracturing, medium-viscosity base fluids or weakly cross-linked fluids are used for fracture creation, which is also suitable for low sand ratio stages. After fracture creation, the base fluid concentration of the fracturing fluid is adjusted to a higher level and cross-linked during the fracturing process, significantly increasing the viscosity and consequently increasing the fracture width. High sand ratios require high-concentration cross-linked fluids; otherwise, it will be difficult to carry sand. Furthermore, there is a certain correlation between base fluid viscosity and concentration.

[0069] Based on the reservoir properties of different oil production sections determined in step S2, and considering the filtration coefficient of the fracturing fluid, the total amount of fluid injected into the formation for a designed fracture zone length of 200–240 m is determined using the material balance equation. (When using the material balance equation, the fracture height is assumed to be equal.)

[0070] Based on the fracture conductivity requirement (≥25μm) 2Based on long-term proppant conductivity tests, design the average sand ratio (or sand concentration) and proppant size. A recommended average sand ratio of 25–30% and proppant of 20–40 mesh quartz sand or ceramsite are suggested.

[0071] To meet the different fracturing viscosity and proppant carrying capacity requirements at different stages of fracturing, it is recommended to use a fracturing fluid system that optimizes the design viscosity by varying the concentration of the solution. This invention preferentially uses guar gum with a concentration of 0.15% to 0.35%.

[0072] The displacement fracture design described in step S5 is based on the large differences in reservoir properties (permeability of 0.11–49.7 mD) and low formation pressure coefficient (0.7–0.8). The aim is to achieve uniform displacement and replenish energy, and the displacement section is designed as a linear high-pressure displacement mode. Therefore, the displacement section is designed as a single, long, narrow fracture with low conductivity (the horizontal section designed in step S1 is perpendicular to the orientation of the maximum horizontal principal stress, which is beneficial for forming a single fracture).

[0073] The fracture parameters for the displacement section mentioned in step S5 refer to fracture bandwidth, fracture length, and conductivity. The fracture bandwidth is designed to be 1 / 5 (6–10 m) of the distance between the production section and the displacement section; the fracture length is 1.2 times the length of the production section (240–290 m) to achieve full coverage of crude oil displacement in both the production and displacement sections; the fracture conductivity is 3 μm. 2 ·cm.

[0074] In step S5, the key parameters for the displacement section construction, as well as the important parameters for the fracturing fluid system and proppant, are designed first to meet the requirements of linear high-pressure displacement. Then, the construction parameters are optimized, and finally, the proppant parameters are designed.

[0075] To improve the displacement of crude oil from macropores, micropores, and pores in the reservoir matrix, the fracturing fluid in the displacement stage is designed to be a low-viscosity fluid with a viscosity ≤ 8 mPa·s. Furthermore, based on the wettability of the oil displacement stage specified in step S2, a fluid type with permeation and displacement functions is selected. If the reservoir wettability is water-wet, 0.08% guar gum + surfactant (such as CF-5C used in Changqing Oilfield) can be selected; if the reservoir wettability is oil-wet, 0.08% guar gum + wetting reversal agent (such as the wetting reversal agent in patent CN107384358B) can be selected.

[0076] The fracturing fluid displacement should be matched to a fracture width of 6–10 m based on the viscosity and filtration loss coefficient of the selected fracturing fluid. A displacement of 1.4–1.8 m³ / s is recommended. 3 / min. Sand ratio (or sand concentration) to meet 3μm 2The required conductivity (cm) is designed to be 3-5%. The injected fluid volume must meet the fracture zone length requirement while ensuring the fracture zone pressure coefficient is 0.2-0.5 times higher than the reservoir pressure coefficient. A single-stage injection volume of 1200-1500 m³ is recommended. 3 Two to three consecutive injections (designed with low flow rate and multi-stage water injection to control fracture length, increase pressure in the displacement section, and form high-pressure displacement), with a pre-fluid ratio of 50%, and the pre-fluid uses surfactants or wetting reversal agents according to wettability.

[0077] The proppant is designed to be 40-70 mesh quartz sand, which is convenient for uniform spreading at low sand concentrations and allows for long proppant transport distances due to its small particle size.

[0078] The optimal fracturing method described in step S6 is to first fracture the oil production section and then fracture the oil displacement section.

[0079] The deepest section of the sliding sleeve is opened and the other sections are closed using a switchable cementing sliding sleeve tool (it is normally closed during normal drilling and sliding sleeve installation). After fracturing, this section of the sliding sleeve is closed. The odd-numbered sections of the sliding sleeve from the bottom of the well to the wellhead are opened and closed one by one for fracturing, and continuous fracturing is preferred.

[0080] A switchable cementing sleeve tool is used to open the deepest even-numbered sections of the sleeve, fracturing them one by one and then closing the sleeves. Continuous fracturing is required, with each fracturing stage within a section lasting no more than 2 hours and the interval between stages less than 8 hours. The aim is to maintain a relatively balanced high-pressure oil displacement state in each displacement stage.

[0081] After 7-10 days of well closure, all odd-numbered production sections are opened using a switchable cementing sleeve tool, and high-intensity continuous fluid drainage is employed to increase production. The reservoir's development potential is determined based on the test results.

[0082] Example 2:

[0083] Based on Example 1:

[0084] The completion test design for horizontal wells can be completed with 5.5-inch N80 steel grade casing + a switchable cementing sleeve of the same size and steel grade.

[0085] The number of stages of the cementing sliding sleeve mentioned in step S3 is designed according to the logging parameters obtained from different single wells in step S2, with 5, 7, and 9 stages, to achieve 2-stage drive and 3-stage production, 3-stage drive and 4-stage production, and 4-stage drive and 5-stage, that is, the design is that the even-numbered stages in the horizontal section are the displacement stages and the odd-numbered stages are the oil production stages.

[0086] The production section is used to produce oil and obtain crude oil from the reservoir after the whole well is fractured; the displacement section is used to displace the crude oil between the horizontal sections after the whole well is fractured, so as to improve the utilization of crude oil with low charging.

[0087] In step S3, the location of the cementing sliding sleeve is determined first in the oil production section and then in the oil displacement section. The distance between the oil production section and the oil displacement section is designed to be 30m.

[0088] The relative positions of the oil displacement section are determined by designing a distance of 30m between the production section and the oil displacement section. In order to ensure uniform and efficient displacement, the sections with good homogeneity (i.e., continuous sandstone sections) and low brittleness index are selected as the oil displacement sections. At the same time, the wettability of the rocks in the oil displacement sections is determined.

[0089] The fracture parameters for the oil-producing section are designed as follows: fracture zone length of 200m, fracture zone width of 10m, and fracture diameter of 25μm. 2 • cm flow capacity.

[0090] The matching relationship between fracture width, fracturing fluid displacement, and fracturing fluid viscosity needs to be studied using laboratory physical models or based on field fracture parameter tests. The general principle is to create relatively independent, single fractures, with a recommended displacement of 3.0 m³ / s. 3 / min, the fracturing fluid viscosity is medium viscosity (12mPa·s) + high viscosity (33mPa·s). The pre-flush fluid and the low sand ratio (14%) use medium viscosity fluid, which forms a fracture bandwidth of 10m with low filtration loss. The high sand ratio stage (16%) uses high viscosity fluid, and the fracture bandwidth is slightly increased.

[0091] Based on the reservoir properties of different oil production sections determined in step S2, and considering the filtration coefficient of the fracturing fluid, the total amount of fluid injected into the formation required for a designed fracture zone length of 200m is determined using the material balance equation. (When using the material balance equation, the fracture height is assumed to be equal.)

[0092] Based on the fracture conductivity requirement (25μm) 2 Based on the long-term flow test of the proppant, the average sand ratio (or sand concentration) and proppant size are designed.

[0093] The displacement fracture design described in step S5 is based on the large differences in reservoir properties (permeability of 0.11 mD) and the formation pressure coefficient of 0.8. The aim is to form uniform displacement and replenish energy, so the displacement section is designed as a linear high-pressure displacement mode. Therefore, the displacement section is designed as a single long, narrow fracture with low conductivity (the horizontal section designed in step S1 is perpendicular to the orientation of the maximum horizontal principal stress, which is conducive to the formation of a single fracture).

[0094] The fracture parameters for the displacement section mentioned in step S5 refer to fracture bandwidth, fracture length, and conductivity. The fracture bandwidth is designed to be 1 / 5 (6m) of the distance between the production section and the displacement section; the fracture length is 1.2 times the length of the production section (240m) to achieve full coverage of crude oil displacement in both the production and displacement sections; the fracture conductivity is 3μm. 2 ·cm.

[0095] To improve the displacement of crude oil from macropores, micropores, and pores in the reservoir matrix, the fracturing fluid in the displacement stage is designed to be a low-viscosity fluid with a viscosity of 8 mPa·s. Furthermore, based on the wettability of the oil displacement stage specified in step S2, a fluid type with percolation and displacement functions is selected. If the reservoir wettability is water-wet, 0.08% guar gum + surfactant (such as CF-5C used in Changqing Oilfield) can be selected; if the reservoir wettability is oil-wet, 0.08% guar gum + wetting reversal agent (such as the wetting reversal agent in patent CN107384358B) is selected.

[0096] The construction displacement is designed based on the viscosity and filtration loss coefficient of the selected fracturing fluid, matching a fracture width of 6m. A displacement of 1.4m is used. 3 / min. Sand ratio (or sand concentration) to meet 3μm 2 The required conductivity is 3% (cm). The injected fluid volume must meet the fracture zone length requirement while ensuring the fracture zone pressure coefficient is 0.2 times higher than the reservoir pressure coefficient. A single-stage injection volume of 1200 m³ is recommended. 3 Two to three consecutive injections (designed with low flow rate and multi-stage water injection to control fracture length, increase pressure in the displacement section, and form high-pressure displacement), with a pre-fluid ratio of 50%, and the pre-fluid uses surfactants or wetting reversal agents according to wettability.

[0097] The optimal fracturing method described in step S6 is to first fracture the oil production section and then fracture the oil displacement section.

[0098] The deepest section of the sliding sleeve is opened and the other sections are closed using a switchable cementing sliding sleeve tool (it is normally closed during normal drilling and sliding sleeve installation). After fracturing, this section of the sliding sleeve is closed. The odd-numbered sections of the sliding sleeve from the bottom of the well to the wellhead are opened and closed one by one for fracturing, and continuous fracturing is preferred.

[0099] A switchable cementing sleeve tool is used to open the deepest even-numbered sections of the sleeve, fracturing them one by one and then closing the sleeves. Continuous fracturing is required, with each fracturing stage within a section lasting no more than 2 hours and the interval between stages less than 8 hours. The aim is to maintain a relatively balanced high-pressure oil displacement state in each displacement stage.

[0100] After a 7-day well closure, all odd-numbered production sections were opened using a switchable cementing sleeve tool, and high-intensity continuous fluid drainage was employed to increase production. The reservoir's development potential was determined based on the test results.

[0101] Example 3:

[0102] Based on Example 1:

[0103] The completion test design for horizontal wells can be completed with 4.5-inch N80 steel grade casing + a switchable cementing sleeve of the same size and steel grade.

[0104] The number of stages of the cementing sliding sleeve mentioned in step S3 is designed according to the logging parameters obtained from different single wells in step S2, with 5, 7, and 9 stages, to achieve 2-stage drive and 3-stage production, 3-stage drive and 4-stage production, and 4-stage drive and 5-stage, that is, the design is that the even-numbered stages in the horizontal section are the displacement stages and the odd-numbered stages are the oil production stages.

[0105] The production section is used to produce oil and obtain crude oil from the reservoir after the whole well is fractured; the displacement section is used to displace the crude oil between the horizontal sections after the whole well is fractured, so as to improve the utilization of crude oil with low charging.

[0106] The location of the cementing sliding sleeve mentioned in step S3 is determined first in the oil production section and then in the oil displacement section, with a designed distance of 38m between the oil production section and the oil displacement section.

[0107] The relative position of the oil displacement section is determined by the design of a distance of 38m between the production section and the oil displacement section. In order to ensure uniform and efficient displacement, the position with good homogeneity (i.e., continuous sandstone section) and low brittleness index is selected as the oil displacement section. At the same time, the wettability of the rock in the oil displacement section is determined.

[0108] The fracture parameters for the oil-producing section are designed as follows: fracture zone length of 210m, fracture zone width of 15m, and fracture thickness of 26μm. 2 • cm flow capacity.

[0109] The matching relationship between fracture width, fracturing fluid displacement, and fracturing fluid viscosity needs to be studied using laboratory physical models or based on field fracture parameter tests. The general principle is to create relatively independent, single fractures, with a recommended displacement of 2.9m. 3 / min, the fracturing fluid viscosity is medium viscosity (15mPa·s) + high viscosity (35mPa·s). The pre-flush fluid and the low sand ratio (13%) use medium viscosity fluid, which forms a fracture bandwidth of 15m with low filtration loss. The high sand ratio stage (17%) uses high viscosity fluid, and the fracture bandwidth is slightly increased.

[0110] Based on the reservoir properties of different oil production sections determined in step S2, and considering the filtration coefficient of the fracturing fluid, the total amount of fluid injected into the formation required for a designed fracture zone length of 210m is determined using the material balance equation. (When using the material balance equation, the fracture height is assumed to be equal.)

[0111] Based on the fracture conductivity requirement (26μm) 2 Based on the long-term flow test of the proppant, the average sand ratio (or sand concentration) and proppant size are designed.

[0112] The displacement fracture design described in step S5 is based on the large differences in reservoir properties (permeability of 32.4 mD) and the formation pressure coefficient of 0.7. The aim is to form uniform displacement and replenish energy, so the displacement section is designed as a linear high-pressure displacement mode. Therefore, the displacement section is designed as a single long, narrow fracture with low conductivity (the horizontal section designed in step S1 is perpendicular to the orientation of the maximum horizontal principal stress, which is conducive to the formation of a single fracture).

[0113] The fracture parameters for the displacement section mentioned in step S5 refer to fracture bandwidth, fracture length, and conductivity. The fracture bandwidth is designed to be 1 / 5 (8m) of the distance between the production section and the displacement section; the fracture length is 1.2 times the length of the production section (252m) to achieve full coverage of crude oil displacement in both the production and displacement sections; the fracture conductivity is 3μm. 2 ·cm.

[0114] To improve the displacement of crude oil from macropores, micropores, and pores in the reservoir matrix, the fracturing fluid in the displacement stage is designed to be a low-viscosity fluid with a viscosity of 7 mPa·s. Furthermore, based on the wettability of the oil displacement stage specified in step S2, a fluid type with percolation and displacement functions is selected. If the reservoir wettability is water-wet, 0.08% guar gum + surfactant (such as CF-5C used in Changqing Oilfield) can be selected; if the reservoir wettability is oil-wet, 0.08% guar gum + wetting reversal agent (such as the wetting reversal agent in patent CN107384358B) is selected.

[0115] The construction displacement is designed based on the viscosity and filtration loss coefficient of the selected fracturing fluid, matching an 8m fracture width, and uses a displacement of 1.6m. 3 / min. Sand ratio (or sand concentration) to meet 3μm 2 The required conductivity is 3% (cm). The injected fluid volume must meet the fracture zone length requirement while ensuring the fracture zone pressure coefficient is 0.4 times higher than the reservoir pressure coefficient. A single-stage injection volume of 1400 m³ is recommended. 3 Two to three consecutive injections (designed with low flow rate and multi-stage water injection to control fracture length, increase pressure in the displacement section, and form high-pressure displacement), with a pre-fluid ratio of 50%, and the pre-fluid uses surfactants or wetting reversal agents according to wettability.

[0116] The optimal fracturing method described in step S6 is to first fracture the oil production section and then fracture the oil displacement section.

[0117] The deepest section of the sliding sleeve is opened and the other sections are closed using a switchable cementing sliding sleeve tool (it is normally closed during normal drilling and sliding sleeve installation). After fracturing, this section of the sliding sleeve is closed. The odd-numbered sections of the sliding sleeve from the bottom of the well to the wellhead are opened and closed one by one for fracturing, and continuous fracturing is preferred.

[0118] A switchable cementing sleeve tool is used to open the deepest even-numbered sections of the sleeve, fracturing them one by one and then closing the sleeves. Continuous fracturing is required, with each fracturing stage within a section lasting no more than 2 hours and the interval between stages less than 8 hours. The aim is to maintain a relatively balanced high-pressure oil displacement state in each displacement stage.

[0119] After being sealed for 8 days, all odd-numbered production sections were opened using a switchable cementing sleeve tool, and high-intensity continuous fluid drainage was employed to increase production. The reservoir's development potential was determined based on the test results.

[0120] Example 4:

[0121] Based on Example 1:

[0122] The completion test design for horizontal wells can be completed with 4.5-inch N80 steel grade casing + a switchable cementing sleeve of the same size and steel grade.

[0123] The number of stages of the cementing sliding sleeve mentioned in step S3 is designed according to the logging parameters obtained from different single wells in step S2, with 5, 7, and 9 stages, to achieve 2-stage drive and 3-stage production, 3-stage drive and 4-stage production, and 4-stage drive and 5-stage, that is, the design is that the even-numbered stages in the horizontal section are the displacement stages and the odd-numbered stages are the oil production stages.

[0124] The production section is used to produce oil and obtain crude oil from the reservoir after the whole well is fractured; the displacement section is used to displace the crude oil between the horizontal sections after the whole well is fractured, so as to improve the utilization of crude oil with low charging.

[0125] In step S3, the location of the cementing sliding sleeve is determined first in the oil production section and then in the oil displacement section. The distance between the oil production section and the oil displacement section is designed to be 50m.

[0126] The relative positions of the oil displacement section are determined by designing a distance of 50m between the production section and the oil displacement section. In order to ensure uniform and efficient displacement, the sections with good homogeneity (i.e., continuous sandstone sections) and low brittleness index are selected as the oil displacement sections. At the same time, the wettability of the rocks in the oil displacement sections is determined.

[0127] The fracture parameters for the oil-producing section are designed as follows: fracture zone length of 240m, fracture zone width of 18m, and fracture diameter of 27μm. 2 • cm flow capacity.

[0128] The matching relationship between fracture width, fracturing fluid displacement, and fracturing fluid viscosity needs to be studied using laboratory physical models or based on field fracture parameter tests. The general principle is to create relatively independent, single fractures, with a recommended displacement of 3.0 m³ / s. 3 / min, the fracturing fluid viscosity is medium viscosity (18mPa·s) + high viscosity (35mPa·s). The pre-flush fluid and the low sand ratio (12%) use medium viscosity fluid, which forms a fracture bandwidth of 10m with low filtration loss. The high sand ratio stage (18%) uses high viscosity fluid, and the fracture bandwidth is slightly increased.

[0129] Based on the reservoir properties of different oil production sections determined in step S2, and considering the filtration coefficient of the fracturing fluid, the total amount of fluid injected into the formation required for a designed fracture zone length of 200m is determined using the material balance equation. (When using the material balance equation, the fracture height is assumed to be equal.)

[0130] Based on the fracture conductivity requirement (25μm) 2 Based on the long-term flow test of the proppant, the average sand ratio (or sand concentration) and proppant size are designed.

[0131] The displacement fracture design described in step S5 is based on the large differences in reservoir properties (permeability of 49.7 mD) and the formation pressure coefficient of 0.8. The aim is to achieve uniform displacement and replenish energy, so the displacement section is designed as a linear high-pressure displacement mode. Therefore, the displacement section is designed as a single long, narrow fracture with low conductivity (the horizontal section designed in step S1 is perpendicular to the orientation of the maximum horizontal principal stress, which is conducive to the formation of a single fracture).

[0132] The fracture parameters for the displacement section mentioned in step S5 refer to fracture bandwidth, fracture length, and conductivity. The fracture bandwidth is designed to be 1 / 5 (10m) of the distance between the production section and the displacement section; the fracture length is 1.2 times (290m) of the production section to achieve full coverage of crude oil displacement in both the production and displacement sections; the fracture conductivity is 3μm. 2 ·cm.

[0133] To improve the displacement of crude oil from macropores, micropores, and pores in the reservoir matrix, the fracturing fluid in the displacement stage is designed to be a low-viscosity fluid with a viscosity of 6 mPa·s. Furthermore, based on the wettability of the oil displacement stage specified in step S2, a fluid type with percolation and displacement functions is selected. If the reservoir wettability is water-wet, 0.08% guar gum + surfactant (such as CF-5C used in Changqing Oilfield) can be selected; if the reservoir wettability is oil-wet, 0.08% guar gum + wetting reversal agent (such as the wetting reversal agent in patent CN107384358B) is selected.

[0134] The construction displacement is designed based on the viscosity and filtration loss coefficient of the selected fracturing fluid, matching a fracture width of 10m. A displacement of 1.8m is used. 3 / min. Sand ratio (or sand concentration) to meet 3μm 2 The required conductivity is 5% (cm). The injected fluid volume must meet the fracture zone length requirement while ensuring the fracture zone pressure coefficient is 0.5 times higher than the reservoir pressure coefficient. A single-stage injection volume of 1500 m³ is recommended. 3 Two to three consecutive injections (designed with low flow rate and multi-stage water injection to control fracture length, increase pressure in the displacement section, and form high-pressure displacement), with a pre-fluid ratio of 50%, and the pre-fluid uses surfactants or wetting reversal agents according to wettability.

[0135] The optimal fracturing method described in step S6 is to first fracture the oil production section and then fracture the oil displacement section.

[0136] The deepest section of the sliding sleeve is opened and the other sections are closed using a switchable cementing sliding sleeve tool (it is normally closed during normal drilling and sliding sleeve installation). After fracturing, this section of the sliding sleeve is closed. The odd-numbered sections of the sliding sleeve from the bottom of the well to the wellhead are opened and closed one by one for fracturing, and continuous fracturing is preferred.

[0137] A switchable cementing sleeve tool is used to open the deepest even-numbered sections of the sleeve, fracturing them one by one and then closing the sleeves. Continuous fracturing is required, with each fracturing stage within a section lasting no more than 2 hours and the interval between stages less than 8 hours. The aim is to maintain a relatively balanced high-pressure oil displacement state in each displacement stage.

[0138] After 10 days of well closure, all odd-numbered production sections were opened using a switchable cementing sleeve tool, and high-intensity continuous fluid drainage was employed to increase production. The reservoir's development potential was determined based on the test results.

[0139] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A method for increasing the production of a single oil well, characterized in that, include: The target exploration well was optimized into a horizontal well, and the key parameters of the horizontal well were optimized. Based on the optimized key parameters of the horizontal well, drill and record important parameters of cuttings throughout the horizontal section; Based on the key cuttings parameters of the entire horizontal section, optimize the number of cementing sleeve stages and the insertion location, and determine the displacement injection section and the oil production section; Based on the displacement injection section and the oil production section, design the fracture parameters, key construction parameters, fracture fluid system and proppant parameters for the oil production section and the displacement section; The fracturing method is designed based on the fracture parameters of the oil production section and the displacement section, key construction parameters, fracturing fluid system and important proppant parameters; The entire well is fractured based on the optimal fracturing method. After fracturing, the well is shut down and the fluid is pumped out to evaluate the reservoir productivity.

2. The method for increasing single-well production of oil wells according to claim 1, characterized in that, The key parameters of the horizontal well include the length of the horizontal section, the drilling azimuth of the horizontal section, and the completion method.

3. The method for increasing single-well production of oil wells according to claim 1, characterized in that, The key parameters of the cuttings in the entire horizontal section include the oil layer drilling rate, physical properties, brittleness, oil content, and wettability of reservoirs in different horizontal sections.

4. The method for increasing single-well production of oil wells according to claim 1, characterized in that, The cementing sleeve has 5, 7, or 9 stages, enabling 2-stage drive and 3-stage production, 3-stage drive and 4-stage production, or 4-stage drive and 5-stage production. In the horizontal section, even-numbered stages are displacement stages, and odd-numbered stages are production stages.

5. The method for increasing single-well production of oil wells according to claim 1, characterized in that, The distance between the oil production section and the displacement section is 30m-50m.

6. The method for increasing single-well production of oil wells according to claim 1, characterized in that, The fracture parameters of the oil-producing section include fracture length, fracture width, and conductivity. The fracture length is 200–240 m, the fracture width is 10–18 m, and the conductivity is greater than or equal to 25 μm. 2 ·cm.

7. The method for increasing single-well production of oil wells according to claim 1, characterized in that, The fracturing method involves fracturing the oil-producing section first, followed by fracturing the oil-displacement section. The fracturing process is as follows: The deepest section of the sliding sleeve is opened using a switchable cementing sleeve tool, and the other sections are closed. After fracturing, the deepest section of the sliding sleeve is closed. The oil production sliding sleeves from the bottom of the well to the wellhead are opened and closed one by one, and continuous fracturing is used. The deepest oil displacement section of the sliding sleeve is opened using a switchable cementing sleeve tool, and the cementing sliding sleeves are closed one by one. The fracturing time for each stage within a section does not exceed 2 hours, and the interval between each section is less than 8 hours.

8. The method for increasing single-well production of oil wells according to claim 1, characterized in that, The proppant used in the oil production section is 20-40 mesh quartz sand or ceramsite, while the proppant used in the displacement section is 40-70 mesh quartz sand.

9. A method for increasing the production of a single oil well according to claim 1, characterized in that, The specific steps for sealing the well after fracturing are as follows: After the well has been closed for 7 to 10 days, all odd-numbered oil production sections are opened using a switchable cementing sleeve tool, and continuous fluid drainage is employed to increase production.

10. An application of the method as described in any one of claims 1-9 in the evaluation of single-well productivity in oil wells.

Images