Well track and fracturing transformation integrated method for strata / bedding oil and gas reservoir

Abstract

The invention relates to the technical field of well track and fracturing transformation, in particular to a formation / bedding oil and gas reservoir well track and fracturing transformation integrated method. Comprising the following steps that the thickness of an oil and gas reservoir and the thickness of an upper interlayer and the thickness of a lower interlayer are determined, the position of a high-quality strata / bedding prone to breaking or extending at the strata / bedding position in the oil and gas reservoir is determined, and the drilling well deviation angle of a well track is determined according to the thickness of an oil and gas layer under the condition that it is guaranteed that multiple perforation sections can be designed on a single horizontal section; the whole projection of the well track of the horizontal section of the horizontal well on the horizontal plane is in a U shape, and the well track of the horizontal section of the horizontal well is divided into multiple sections according to needs; the method conforms to the characteristic that fractured fractures are easy to expand along oil and gas reservoir strata / bedding, under the condition that small energy is provided, sufficient extension of the fractures is achieved, the engineering cost is saved, and the method is a sequential design conforming to stratum stress.

Description

Technical Field

[0001] The present invention relates to the technical field of wellbore trajectory and fracturing reconstruction, and particularly relates to an integrated method for wellbore trajectory and fracturing reconstruction of laminated / bedded oil and gas reservoirs. Background Art

[0002] Horizontal well development is the most important development method for reservoirs of tight (shale) oil and gas. Generally, the horizontal wellbore trajectory of a horizontal well is drilled in the middle of the reservoir, parallel to the horizontal direction of the oil and gas reservoir. When fracturing and reconstructing laminated / bedded tight (shale) oil and gas reservoirs, fractures tend to extend along the laminations / bedding planes, and the vertical direction, i.e., the fracture height, is insufficiently reconstructed, resulting in limited reconstruction of the thickness of the oil and gas reservoir, and the effect of the horizontal well development method deteriorates or fails. In order to improve the formation of vertical fractures in laminated / bedded tight (shale) oil and gas reservoirs, generally, the fracturing construction displacement and fracturing fluid volume need to be increased, and the dosage of viscosifier in the fracturing fluid is increased to increase the liquid viscosity, thereby requiring an increase in the wellbore pressure resistance level. Under these measures, the extension of vertically formed fractures is still restricted, and generally, "rich"-shaped fractures will be formed. This fracturing and reconstruction method will, on the one hand, greatly increase the engineering cost, and on the other hand, the number and area of surface well site equipment will also increase. Most importantly, this fracturing method still cannot fundamentally solve the problem of vertical fracture extension.

[0003] During the fracturing and reconstruction process of existing laminated / bedded tight (shale) oil and gas reservoirs, fractures tend to extend along the laminations / bedding planes of the reservoir, forming "rich"-shaped fractures. It is difficult to extend and expand the vertical fracture height of the reservoir, and the reservoir reconstruction is insufficient. Generally, in order to improve the fracture reconstruction effect of the oil and gas reservoir, it is necessary to increase the fracturing construction displacement, fracturing fluid volume, and the dosage of viscosifier in the fracturing fluid to increase the liquid viscosity. These methods will greatly increase the development investment cost of the oil and gas reservoir. Another method is to drill multiple horizontal wells or branched wells in this type of reservoir and improve the fracture reconstruction effect of the oil and gas reservoir. This drilling method has high technical requirements, large investment, and the process technology is not yet very mature, and the implementation risk is large. Summary of the Invention

[0004] In view of the above problems, the present invention starts from the design of the wellbore trajectory and the optimization of fracturing process parameters, drills the wellbore trajectory through the vertical top and bottom of the oil and gas reservoir multiple times, penetrates all the laminations / bedding planes developed in the reservoir, and then optimizes the overall fracturing reconstruction design scheme according to the development of the laminations / bedding planes, so that the fracturing fractures still extend along the easily expandable horizontal direction, and stress interference occurs between multiple parallel horizontal fracture surfaces under high pressure to form complex fractures, thereby realizing the full reconstruction of the reservoir in the horizontal and vertical directions of laminated / bedded tight (shale) oil and gas reservoirs under the condition of low fracturing reconstruction cost, and achieving the purpose of improving the economic benefits of oil and gas field development.

[0005] An integrated method for wellbore trajectory and fracturing stimulation in a laminated / stratified oil and gas reservoir of the present invention includes the following steps: (1) Determination of the thickness of the oil and gas reservoir formation and the upper and lower confining beds: Based on the comprehensive electrical logging interpretation result curves of the pilot well or surrounding control wells, determine the development of the laminations / stratifications in the oil and gas reservoir formation, the actual formation thickness, and the thicknesses of the upper and lower confining beds. Then, according to the positional relationship between the target well and the surrounding adjacent wells, use the average value method and the formation distribution prediction method to determine the thickness of the oil and gas reservoir formation and the thicknesses of the upper and lower confining beds; (2) According to the comprehensive electrical logging interpretation result curves in the above step, determine the positions of high-quality laminations / stratifications in the oil and gas reservoir formation that are prone to fracture or extend at the laminations / stratifications. When ensuring that multiple perforation intervals can be designed in a single horizontal section, determine the drilling inclination angle of the wellbore trajectory based on the thickness of the oil and gas layer; (3) The wellbore trajectory of the horizontal section of the horizontal well presents an overall "U" shape in the horizontal plane projection, and the wellbore trajectory of the horizontal section of the horizontal well is divided into multiple sections as needed; (4) Based on the development and thickness of the laminations / stratifications of the oil and gas reservoir formation described in steps (1) and (2), conduct fracture layout simulation with the goal of maximizing the volume of the oil and gas reservoir reformed by the fracturing fractures. According to the thickness of the oil and gas reservoir formation and the positions where the laminations / stratifications are well-developed, optimize and adjust to determine the wellbore trajectory and the positions of the perforation intervals; (5) Preliminary design of the fracturing stimulation technical plan: On the horizontal section of the horizontal wellbore trajectory described in step (4), according to the different positions of the wellbore trajectory divided into multiple sections, conduct fracturing fracture parameter design in the vertical direction. Staggered fracture layout is adopted at the positions where the distance between the fracture lengths formed by the fracturing scale between wellbore trajectories is small or they are interconnected; Large-spacing parallel long fractures are adopted at the positions where the distance between the fracture lengths formed by the fracturing scale between wellbore trajectories is large. Evaluate the thicknesses of the upper and lower confining beds of the oil and gas reservoir formation and the stress difference between the reservoir and the confining beds, and simulate through fracturing design software the length, width, conductivity, reformed volume, and related parameters of the formed fractures. With the goal of maximizing the fracture control degree of the oil and gas reservoir, determine the preliminary fracturing stimulation technical plan; (6) Optimization design of the horizontal wellbore trajectory: Use drilling design software to optimize the different wellbore trajectories described in step (5) with the goal of being able to design multiple perforation intervals in the horizontal section and deploying the perforation intervals on high-quality laminations / stratifications respectively. According to the optimization design results, evaluate the impact of the horizontal wellbore trajectory on the production regime of the oil and gas well. If the construction risk is controllable, the next drilling and completion construction procedure can be carried out. If the construction risk is high, return to re-optimize the horizontal wellbore trajectory using the drilling design software; (7)Determination of the final fracturing reconstruction technical plan: Under the drilling and completion construction conditions described in step (6), the volume fracturing method is used to fracture and reconstruct the horizontal section of the oil and gas reservoir. The horizontal well is optimized and simulated using fracturing design software to determine the final fracturing construction parameters, and an optimized fracturing reconstruction technical plan is obtained.

[0006] Preferably, in step (3), the wellbore trajectory of the horizontal section of the horizontal well is divided into three sections, namely wellbore trajectory section A, wellbore trajectory section B, and wellbore trajectory section C; Wellbore trajectory section A: Gradually extends from the bottom of the oil and gas reservoir to the top of the oil and gas reservoir; Wellbore trajectory section B: Drills from the top of the oil and gas reservoir to the bottom of the reservoir. The drilling inclination angle of wellbore trajectory section B is determined according to the effective seepage radius and reservoir thickness of the oil and gas reservoir. The projection of the drilling direction is perpendicular to the vertical plane of the reservoir of wellbore trajectory section A; Wellbore trajectory section C: Gradually drills from the top of the oil and gas reservoir to the bottom of the oil and gas reservoir, and the drilling direction is parallel to the vertical plane of the reservoir of wellbore trajectory section A.

[0007] The present invention starts from the design of the wellbore trajectory of the horizontal well in the laminated / bedded tight (shale) oil and gas reservoir and the deployment of fracturing fractures, and the optimization of process parameters. The wellbore trajectory is gradually drilled from the bottom of the oil and gas reservoir to the top of the oil and gas reservoir, and then the wellbore drills from the top of the oil and gas reservoir to the bottom of the reservoir along the side of the horizontal section. Then, the wellbore trajectory drills from the bottom of the oil and gas reservoir to the top of the oil and gas reservoir at an equal distance from the original horizontal section, connecting all the laminations / bedding developed in the reservoir. Then, the fracturing reconstruction design plan is optimized according to the development of the laminations / bedding, so as to realize the full reconstruction of the reservoir in the horizontal and vertical directions of the laminated / bedded tight (shale) oil and gas reservoir under the condition of low fracturing reconstruction cost, achieving the purpose of improving the economic benefits of oil and gas field development. At the same time, the range of the oil and gas reservoir controlled by a single well is greatly increased, reducing the later management cost.

[0008] Starting from the characteristics of the oil and gas reservoir, the present invention integrates the design of the wellbore trajectory of the drilling and the optimization of the fracturing reconstruction, so as to maximize the oil and gas production on the basis of reducing costs. To fully reconstruct the vertical permeability of the laminated / bedded tight (shale) oil and gas reservoir, sufficient energy to overcome the formation stress of the reservoir rock must be provided, which requires a large engineering investment and is a reverse design against the formation stress; the present invention conforms to the characteristic that the fracturing fractures are easy to extend along the laminations / bedding of the oil and gas reservoir, and realizes the full extension of the fractures with less energy, saving engineering costs, which is a forward design conforming to the formation stress.

[0009] The wellbore trajectory of the horizontal section of the present invention is designed in a "U" shape. On the one hand, this design method enables vertical small-spacing staggered slotting at positions where the wellbore trajectories are relatively close. The interference between adjacent fractures is conducive to the formation of complex fractures. At positions where the wellbore trajectories are relatively far apart, vertical large-spacing parallel long fractures are used to promote the extension of fractures in the horizontal direction and prevent the vertical fractures from penetrating each other. Thus, the overall full-scale fracture network transformation of the oil and gas reservoir can be realized at low cost. On the other hand, the "U" shape design of the horizontal wellbore trajectory can greatly increase the area of the oil and gas reservoir controlled by a single well, saving well construction and later management costs.

[0010] The integrated design of the wellbore trajectory design and fracturing transformation slotting of the present invention can enable the overall full-scale transformation of the laminated / bedded tight (shale) oil and gas reservoir under the conditions of low displacement, low liquid volume, and low viscosity of the fracturing fluid, improving the economic benefits of oil and gas field development.

[0011] Under the same fracture scale of the laminated / bedded tight (shale) oil and gas reservoir of the present invention, the fracturing cost is greatly reduced, and a multi-layer (plane) fracture network seepage system for effective and full-scale transformation of each laminated / bedded layer is formed, and the oil and gas production is significantly increased.

[0012] The fracturing field construction displacement of the present invention is low, the required well site area is small, and the required equipment is few.

[0013] The fractures of the fracturing transformation of the oil and gas reservoir of the present invention are effectively extended in both the vertical and horizontal directions, and the overall utilization degree of the reservoir is large.

[0014] The wellbore trajectory of the horizontal section of the present invention is designed in a "U" shape, the area of the oil and gas reservoir controlled by a single well is greatly increased, the drilling footage of the vertical well section is reduced, and the management cost of the later oil and gas wells is reduced.

[0015] The requirement for the casing pressure grade of the wellbore of the present invention is reduced, saving well construction costs.

[0016] The requirement for the viscosity of the fracturing fluid of the present invention is reduced, saving material costs. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the wellbore trajectory and transformed fractures in the present invention. Detailed Embodiments

[0018] The present invention will be described below in conjunction with examples.

[0019] A certain laminated / bedded shale oil reservoir in the west, with a burial depth of 2000 meters, an oil layer thickness of 20 meters, 6 effective oil-bearing laminations / beds developed in the reservoir, an effective seepage distance of 400 meters, and mud shale with good sealing conditions above and below the reservoir. The implementation steps using this method are as follows: (1)Based on the comprehensive electrical logging interpretation result curves of the pilot well or surrounding control wells, determine that there are 6 effective oil-bearing laminations / bedding planes in the reservoir of this shale oil reservoir, with a formation thickness of 20 meters and an upper and lower interlayer thickness of about 5 meters; (2)According to the logging interpretation results and the positions of high-quality laminations / bedding planes in the reservoir, design that a single horizontal section can have 6 perforation sections, and determine that the drilling inclination angle of the wellbore trajectory is 2 - 2.5 degrees; (3)The wellbore trajectory of the horizontal section of the horizontal well presents an overall "U" shape in the horizontal plane projection, and the wellbore trajectory of the horizontal section of the horizontal well is divided into three sections as needed; Section A of the wellbore trajectory gradually extends from the bottom of the oil and gas reservoir to the top of the reservoir, with a length of approximately 480 - 550 meters; According to the effective seepage radius and reservoir thickness of the oil and gas reservoir, determine that the drilling inclination angle of Section B of the wellbore trajectory is 3 - 3.5 degrees, and the projection of the drilling direction is perpendicular to the vertical plane of the reservoir of Section A of the wellbore trajectory. Drill from the top of the oil and gas reservoir to the bottom of the reservoir, with a length of approximately 350 - 400 meters; The drilling inclination angle of Section C of the wellbore trajectory is 2 - 2.5 degrees, and it gradually drills from the top of the oil and gas reservoir to the bottom of the reservoir, with a length of approximately 480 - 550 meters. The drilling direction is parallel to the vertical plane of the reservoir of Section A of the trajectory; (4)Based on the reservoir thickness of the oil and gas reservoir and the positions where the laminations / bedding planes are well developed, preliminarily determine that the wellbore trajectory length is 1580 meters, including 650 meters for Section A of the wellbore trajectory, with 7 perforation sections, 430 meters for Section B of the wellbore trajectory, with 5 perforation sections, and 500 meters for Section C of the wellbore trajectory, with 6 perforation sections; (5)According to different positions of the trajectory, design the fracture parameters in the vertical direction. Adopt staggered fracture placement at positions where the wellbore trajectories are relatively close, and adopt large-spacing parallel long fractures at positions where the wellbore trajectories are relatively far apart. Use fracture design software to simulate the length, width, conductivity, fracture volume, and related parameters of the formed fractures, and compare the final recovery rates of the schemes; (6)According to the fracture design plan, use drilling design software to optimize the fracture placement and final recovery rate under different wellbore trajectories, evaluate the impact of the horizontal wellbore trajectory on the production regime of the oil and gas well, and determine a drilling plan with controllable construction risks. The horizontal section length is 1450 meters, including 550 meters for Section A of the wellbore trajectory, with 7 perforation sections, 390 meters for Section B of the wellbore trajectory, with 5 perforation sections, and 510 meters for Section C of the wellbore trajectory, with 6 perforation sections; (7)Use fracture design software to optimize the simulation design of the horizontal well, and determine the final fracture construction parameters as follows: the number of fracture stages is 18, the number of perforation clusters is 70, the construction displacement is 6 m3 / min, the fracturing fluid is 18000 m 3 , the proppant is 1300 m 3 , and the viscosity of the fracturing fluid is 30 - 50 mPa.s.

[0020] When this well is transformed using this method, the same degree of fracture control can be achieved while reducing the displacement, that is, reducing the consumption of the pumping displacement. When using a lower viscosity of the fracturing fluid, the fracture can be opened. The interpretation results of the fracturing fracture monitoring data show that the complexity of the fracture has increased by 65%, indicating that each lamina (bedding) developed in the reservoir can be fully transformed, and the degree of reservoir utilization has increased. The comparison of the production data of this well with the production of adjacent wells shows that the average production per well has increased by 2.5 times, and the stimulation effect is significant.

Claims

1. An integrated method for wellbore trajectory and fracturing reconstruction of laminated / stratified oil and gas reservoirs, characterized in that, It includes the following steps: (1) Determination of the thickness of the reservoir and the upper and lower barrier beds of the oil and gas reservoir: Based on the comprehensive electrical logging interpretation result curves of the pilot well or the surrounding control wells, determine the development of the laminations / bedding in the reservoir of the oil and gas reservoir, the actual formation thickness, and the thickness of the upper and lower barrier beds. Then, according to the positional relationship between the target well and the surrounding adjacent wells, use the average method and the formation distribution prediction method to determine the thickness of the reservoir of the oil and gas reservoir and the thickness of the upper and lower barrier beds; (2) Based on the comprehensive electrical logging interpretation result curves in the above step, determine the positions of the high-quality laminations / bedding in the reservoir of the oil and gas reservoir that are prone to fracture or extend at the laminations / bedding. When ensuring that multiple perforation intervals can be designed in a single horizontal section, determine the drilling inclination angle of the wellbore trajectory based on the thickness of the oil and gas layers; (3) The wellbore trajectory of the horizontal section of the horizontal well presents an overall "U" shape in the horizontal plane projection, and the wellbore trajectory of the horizontal section of the horizontal well is divided into multiple sections as needed; (4) Based on the development of the laminations / bedding and the thickness of the reservoir of the oil and gas reservoir described in steps (1) and (2), conduct fracture layout simulation with the goal of maximizing the volume of the oil and gas reservoir reformed by the fracturing fractures. According to the thickness of the reservoir of the oil and gas reservoir and the positions where the laminations / bedding develop well, optimize and adjust to determine the wellbore trajectory and the positions of the perforation intervals; (5) Preliminary design of the fracturing transformation technical plan: On the horizontal section of the horizontal wellbore trajectory described in step (4), according to the different positions of the wellbore trajectory divided into multiple sections, conduct fracturing fracture parameter design in the vertical direction. Staggered fracture layout is adopted at positions where the distance between the fracture lengths formed by the fracturing scale between wellbore trajectories is small or they are interconnected; At positions where the distance between the fracture lengths formed by the fracturing scale between wellbore trajectories is large, large-spacing parallel long fractures are adopted. Evaluate the thickness of the upper and lower barrier beds of the reservoir of the oil and gas reservoir and the stress difference between the reservoir and the barrier beds, and simulate through the fracturing design software to form the length, width, conductivity, reformed volume and related parameters of the fractures. With the goal of maximizing the fracture control degree of the oil and gas reservoir, determine the preliminary fracturing transformation technical plan; (6) Optimization design of the horizontal wellbore trajectory: Use the drilling design software to optimize the design of the different wellbore trajectories described in step (5) with the goal that multiple perforation intervals can be designed in the horizontal section and the perforation intervals are respectively deployed on the high-quality laminations / bedding. According to the optimization design results, evaluate the impact of the horizontal wellbore trajectory on the production regime of the oil and gas well. If the construction risk is controllable, the next drilling and completion construction procedure can be carried out. If the construction risk is large, return and use the drilling design software to optimize the design of the horizontal wellbore trajectory again; (7) Determination of the final fracturing transformation technical plan: Under the drilling and completion construction conditions described in step (6), use the volume fracturing method to conduct fracturing transformation on the horizontal section of the reservoir of the oil and gas reservoir. Use the fracturing design software to optimize the simulation design of the horizontal well, determine the final fracturing construction parameters, and obtain the optimized fracturing transformation technical plan.

2. The integrated method for wellbore trajectory and fracturing reconstruction of lamination / stratification oil and gas reservoirs according to claim 1, characterized in that, In step (3), the wellbore trajectory of the horizontal section of the horizontal well is divided into three sections, namely wellbore trajectory section A, wellbore trajectory section B, and wellbore trajectory section C; Wellbore trajectory section A: Gradually extends from the bottom of the reservoir of the oil and gas reservoir to the top of the reservoir of the oil and gas reservoir; Wellbore trajectory section B: Drilling from the top of the hydrocarbon reservoir to the bottom of the reservoir. Determine the wellbore inclination angle of section B according to the effective seepage radius and reservoir thickness of the hydrocarbon reservoir. The projection of the drilling direction is perpendicular to the vertical plane of the reservoir of wellbore trajectory section A. Wellbore trajectory section C: Gradually drilling from the top of the hydrocarbon reservoir to the bottom of the reservoir. The drilling direction is parallel to the vertical plane of the reservoir of wellbore trajectory section A.

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