Repeated transformation method based on block multi-well physical property and production parameter comparison

Abstract

The invention discloses a repeated transformation method based on block multi-well physical property and production parameter comparison, and belongs to the technical field of oil field exploration and development borehole operation, and the method comprises the following steps: 1, preliminarily determining repeated transformation measures according to the physical property of a target block reservoir; 2, further optimizing repeated reconstruction measures according to the production effect of the adjacent well; and 3, determining the repeated transformation scale according to the number and density of adjacent wells. On the basis of systematization, comprehensiveness and process, the technology is optimized from area (macroscopic) to adjacent well (mesoscopic) to single well (microscopic) and from geology to engineering to production; on the basis of physical property parameters of each well in a target block and the condition of an early-stage transformation process, shaft integrity evaluation is carried out in combination with the production effect of each well.

Description

Technical Field

[0001] This invention relates to the field of downhole operations technology in oilfield exploration and development, specifically to a method for repeated modification based on comparison of physical properties and production parameters of multiple wells in a block. Background Technology

[0002] Current methods for selecting optimal repeated stimulation measures mainly include field experience, geological well selection, production dynamics, and production template curve fitting. Field experience involves comparing and analyzing candidate well construction parameters, reservoir properties, and post-construction effect data; however, this method has certain limitations. Geological well selection focuses on geological conditions and ignores the impact of engineering measures. The production dynamics method cannot distinguish the effects of changes in reservoir properties or well completion damage, primarily prioritizing wells with low production. The production template curve fitting method is more accurate for single-layer evaluation and prioritizes wells with potential. The optimal selection of repeated stimulation measures mainly covers two aspects: exploring stimulated wells and recommending appropriate measures.

[0003] Furthermore, rock expansion technology is a novel reservoir stimulation technology. Invention patent CN 111219176 B, "A Method for Enlarging Reservoirs in Water Injection Wells," describes the implementation method of rock expansion. For low-permeability reservoirs in offshore oilfields, due to the large well depth, excessively high construction pressure poses a wellbore safety risk, and large-span stratification methods are not feasible.

[0004] Combining deflagration and rock expansion technologies is an easy technological innovation for engineers to consider. However, simply combining these two technologies can lead to a series of problems, including longer operation times (deflagration tubing pressurization operation), nozzle jamming accidents (deflagration cable operation), tubing rupture accidents due to prolonged high pressure in rock expansion, and poor operational efficiency due to the crude combination of the two technologies. Furthermore, it fails to effectively utilize the instantaneous high pressure of deflagration to reduce fracture pressure, and the advantage of rock expansion being unrestricted by span modification. It may also exploit the disadvantages of deflagration's limited coverage area per run, the damage to the tubing caused by peak pressure, and the prolonged high pressure buildup in rock expansion.

[0005] Chinese patent CN114135265A, published on March 4, 2022, discloses a low-cost and high-efficiency stimulation process for low-permeability reservoirs in offshore oilfields. The process comprises the following steps: Step 1, selecting optimal stratigraphic locations and stimulation sites; Step 2, calculating the maximum wellbore pressure; if the maximum wellbore pressure is not greater than the formation fracturing pressure at the wellhead, proceed to Step 3; otherwise, proceed directly to Step 4; Step 3, cable deflagration fracturing operation; Step 4, rock stratification and expansion operation; Step 5, stratified acidizing operation; Step 6, pump start-up, residual acid return, and production recovery. This patent is only applicable to low-permeability reservoirs in offshore oilfields, and its applicability is limited. Summary of the Invention

[0006] This invention aims to solve the problems existing in the prior art and provide a method for repeated modification based on the comparison of physical properties and production parameters of multiple wells in a block. Based on the systematization, comprehensiveness, process and optimization of this technology, the method covers the region (macro) - adjacent wells (meso) - single well (micro) and the geology - engineering - production. It is based on the physical property parameters of each well in the target block and the previous modification process, combined with the production effect of each well and the evaluation of wellbore integrity.

[0007] The objective of this invention is achieved through the following technical solution: A method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block includes the following steps: Step 1: Preliminarily determine repeated stimulation measures based on the reservoir properties of the target block; Step 2: Further optimize the repeated modification measures based on the production results of adjacent wells; Step 3: Determine the scale of repeated modification based on the number and density of adjacent wells.

[0008] Preferably, in step one, the quality of unexploited reservoirs is assessed based on the porosity, permeability, and oil and gas saturation of each reservoir in the target block.

[0009] Preferably, when the new reservoir meets the following conditions: permeability > 0.01 mD, porosity > 5%, oil and gas saturation > 40%, and the effective support of the fractures in the modified reservoir is ≥ 30%, and the current daily gas production is less than 10,000 cubic meters, the new formation can be modified by fracturing and acidizing.

[0010] Preferably, when the new reservoir does not meet the requirements of permeability > 0.01mD, porosity > 5%, oil and gas saturation > 40%, and the effective support of fractures in the modified reservoir is < 30%, and the current daily gas production is 10,000 to 20,000 cubic meters, the old formation is re-modified by fracturing and acidizing.

[0011] Preferably, in step two, the measures for repeated well modification are further determined based on the preliminary plan determined in step one, combined with the initial production, cumulative production, production time, and pressure of adjacent wells.

[0012] Preferably, for wells with a distance greater than 800m from adjacent wells, an initial daily production of more than 100,000 cubic meters, a cumulative production of 20 million cubic meters, a production time of more than 1 year, and a current production pressure greater than 5MPa, a horizontal well is selected for repeated modification by drilling a sidetracked horizontal well in the direction of the adjacent well. After modification, the well is put into production together with the previous producing layer.

[0013] Preferably, for wells with a distance of 400-800m from adjacent wells, an initial daily production of more than 100,000 cubic meters, a cumulative production of 50 million cubic meters, a production time of more than 1 year, and a current production pressure of less than 5MPa, when the fracture conductivity is greater than 3D.cm, the geostress field is broken, the pressure drop rate is reduced, and synchronous fracturing is used to simultaneously modify the current well and adjacent wells.

[0014] Preferably, in step three, the area within 1 km of the current well... 2 Within the area, if there are more than 10 adjacent wells and the fracture conductivity is >3D.cm, a general fracturing method should be used for repeated modification, and the modification scale should be 1.0-1.5 times that of the original design.

[0015] Preferably, within 1km of the current well 2 Within the area, if there are 6-10 adjacent wells with a fracture conductivity >3D.cm, continue production until the total well production in the area drops below 50,000 cubic meters, then repeat the fracturing process using a general approach; within a 1km radius of the current well... 2 Within the area, if there are more than 10 adjacent wells and the fracture conductivity is less than 3D.cm, production will continue until the total well production in the area drops below 50,000 cubic meters, at which point a general fracturing approach will be used for repeated stimulation; within a 1km radius of the current well... 2 Within the specified range, if the number of adjacent wells is less than 5 and the fracture conductivity is greater than 3D.cm, production will continue until the total well production in the area drops below 30,000 cubic meters, at which point a general fracturing approach will be used for repeated stimulation; within a 1km radius of the current well... 2 Within the specified range, if the number of adjacent wells is less than 10 and the fracture conductivity is less than 3D.cm, no repeated modification will be carried out.

[0016] Preferably, in step three, the area within 1 km of the current well... 2 Within the specified range, if the number of adjacent wells is less than 5 and the fracture conductivity is less than 3D.cm, a segmented repeated fracturing method should be adopted for fine and repeated stimulation.

[0017] The beneficial effects of this technical solution are as follows: I. The present invention provides a method for repeated stimulation based on the comparison of physical properties and production parameters of multiple wells in a block. It takes into account the optimization of repeated stimulation well locations and stimulation measures from the perspective of the entire block, and reduces the impact on adjacent wells while ensuring sufficient repeated stimulation of both the already stimulated reservoir and the new reservoir.

[0018] II. This invention provides a method for repeated fracturing based on the comparison of physical properties and production parameters of multiple wells in a block. This method involves fracturing old wells again to stimulate their potential and improve single-well recovery rate and production. Compared with developing new wells, repeated fracturing has a relatively low cost, enabling greater output with less investment, rapidly increasing production, and thus reducing extraction costs. Controlling the attenuation rate and decreasing the rate of decline can appropriately extend the production life of wells and reduce the need to replace wells due to production decline. While improving recovery rate and reducing extraction costs, this method brings significant economic and social benefits. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0020] Example 1 A method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block includes the following steps: Step 1: Preliminarily determine repeated stimulation measures based on the reservoir properties of the target block; Step 2: Further optimize the repeated modification measures based on the production results of adjacent wells; Step 3: Determine the scale of repeated modification based on the number and density of adjacent wells.

[0021] Example 2 The difference between this embodiment and Embodiment 1 is that, in step one, the quality of the unexploited reservoirs is assessed based on the porosity, permeability, and oil and gas saturation of each reservoir in the target block.

[0022] Among them, when the new reservoir meets the following conditions: permeability > 0.01mD, porosity > 5%, oil and gas saturation > 40%, and the effective support of the fractures in the modified reservoir is ≥ 30%, and the current daily gas production is less than 10,000 cubic meters, the new reservoir can be modified by fracturing and acidizing.

[0023] Among them, when the new reservoir does not meet the requirements of permeability > 0.01mD, porosity > 5%, oil and gas saturation > 40%, and the effective support of fractures in the modified reservoir is < 30%, and the current daily gas production is 10,000 to 20,000 cubic meters, the old formation is re-modified by fracturing and acidizing.

[0024] In step two, the measures for repeated well modification are further determined based on the preliminary plan determined in step one, combined with the initial production, cumulative production, production time, and pressure of adjacent wells.

[0025] Among them, wells with a distance of more than 800m from adjacent wells, an initial daily production of more than 100,000 cubic meters, a cumulative production of 20 million cubic meters, a production time of more than 1 year, and a current production pressure of more than 5MPa are selected to be repeatedly modified by side-drilling horizontal wells in the direction of adjacent wells. After the modification is completed, they will be produced together with the previous producing layer.

[0026] The specific method of sidetracking a horizontal well involves first sealing the current wellbore with a bridge plug or cement plug, then drilling a horizontal well by opening a window in the current wellbore, and finally modifying the new wellbore by fracturing and acidizing.

[0027] Among them, for wells with a distance of 400-800m from adjacent wells, an initial daily production of more than 100,000 cubic meters, a cumulative production of 50 million cubic meters, a production time of more than 1 year, and a current production pressure of less than 5MPa, when the fracture conductivity is >3D.cm, the in-situ stress field is broken and the pressure drop rate is reduced (after being modified by fracturing and acidizing, the formation fractures increase and are effectively supported by proppant, increasing the conductivity area and reducing the pressure drop rate), and synchronous fracturing is used to simultaneously modify the current well and adjacent wells.

[0028] The synchronous fracturing method specifically involves fracturing two adjacent wells in a cross-fracturing manner; that is, fracturing one or more sections of one well first, then fracturing one or more sections of the other well, and so on.

[0029] In step three, the area within 1 km of the current well... 2 Within the area, if there are more than 10 adjacent wells and the fracture conductivity is >3D.cm, a general fracturing method should be used for repeated modification, and the modification scale should be 1.0-1.5 times that of the original design.

[0030] The general fracturing method involves repeatedly fracturing the entire reservoir as a single segment without using packers or bridge plugs.

[0031] 1km around the current well 2 Within the range, if there are 6-10 adjacent wells and the fracture conductivity is >3D.cm, continue production until the total well production in the area drops below 50,000 cubic meters, and then repeat the fracturing process using a general fracturing method.

[0032] 1km around the current well 2 Within the area, if there are more than 10 adjacent wells and the fracture conductivity is less than 3D.cm, production will continue until the total well production in the area drops below 50,000 cubic meters, at which point a general fracturing method will be used for repeated fracturing.

[0033] 1km around the current well 2 Within the area, if the number of adjacent wells is less than 5 and the fracture conductivity is greater than 3D.cm, production will continue until the total well production in the area drops below 30,000 cubic meters, at which point a general fracturing method will be used for repeated fracturing.

[0034] 1km around the current well 2 Within the specified range, if the number of adjacent wells is less than 10 and the fracture conductivity is less than 3D.cm, no repeated modification will be carried out.

[0035] In step three, the area within 1 km of the current well... 2Within the specified range, if the number of adjacent wells is less than 5 and the fracture conductivity is less than 3D.cm, a segmented repeated fracturing method should be adopted for fine and repeated stimulation.

[0036] The segmented repeated fracturing method involves dividing a reservoir into several segments using bridge plugs or packers, and then performing reservoir stimulation on each segment separately.

[0037] Example 3 This embodiment employs the repeated modification method described in Embodiment 2, which is based on the comparison of physical properties and production parameters of multiple wells in a block.

[0038] Well A (vertical well) has an undeveloped upper reservoir with a permeability of 0.09 mD, a porosity of 7.5%, and an oil and gas saturation of 46%. The lower, modified reservoir has effective fracture support of 58%, currently producing 0.6 million cubic meters of gas per day. New formations will be stimulated using fracturing and acidizing to stimulate the upper undeveloped reservoir (temporarily sealing the lower reservoir with soluble bridge plugs and other packers, then stimulating the upper reservoir). The well has a 1km radius around it. 2 Within the area, there are 12 adjacent wells with a fracture conductivity of 3.9D.cm. The general fracturing method is used for repeated stimulation, and the stimulation scale should be 1.0-1.5 times that of the original design (proppant scale of 45 cubic meters). After stimulation, an unobstructed flow rate of 80,000 cubic meters is obtained, which is an effective improvement of 40%.

[0039] Example 4 This embodiment employs the repeated modification method described in Embodiment 2, which is based on the comparison of physical properties and production parameters of multiple wells in a block.

[0040] Well B (horizontal well) has an undeveloped reservoir with a permeability of 0.015 mD, porosity of 4.2%, and oil and gas saturation of 34.1%. The effective support of the fractured reservoir is 25.8%, and the current daily gas production is 16,000 cubic meters. Therefore, a repeated fracturing scheme (re-stimulating the old formation through fracturing and acidizing) will be adopted. With a distance of 500m from the adjacent well, the initial daily production is 450,000 cubic meters, the cumulative production is 50.28 million cubic meters, and the production time is approximately 3 years. The current production pressure is 3.2 MPa, and the fracture conductivity is 4.3 D·cm. Therefore, a simultaneous fracturing method will be used to simultaneously stimulate both the current well and the adjacent well. Within a 1km radius of the current well... 2 Within the area, there are 11 adjacent wells, which are repeatedly modified using a general fracturing method. The modification scale is 1.0-1.5 times that of the original design. After modification, the unobstructed flow rate is effectively increased by 20%.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, characterized in that, Includes the following steps: Step 1: Preliminarily determine repeated stimulation measures based on the reservoir properties of the target block; Step 2: Further optimize the repeated modification measures based on the production results of adjacent wells; Step 3: Determine the scale of repeated modification based on the number and density of adjacent wells.

2. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 1, is characterized in that: In step one, the quality of unexploited reservoirs is assessed based on the porosity, permeability, and oil and gas saturation of each reservoir in the target block.

3. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 2, is characterized in that: When a new reservoir meets the following conditions: permeability > 0.01 mD, porosity > 5%, oil and gas saturation > 40%, and the effective support of fractures in the modified reservoir is ≥ 30%, and the current daily gas production is less than 10,000 cubic meters, the new reservoir can be modified by fracturing and acidizing.

4. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 2, is characterized in that: When a new reservoir does not meet the requirements of permeability > 0.01 mD, porosity > 5%, oil and gas saturation > 40%, and the effective support of fractures in the modified reservoir is < 30%, and the current daily gas production is 10,000-20,000 cubic meters, the old formation can be re-modified by fracturing and acidizing.

5. A method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 3 or 4, characterized in that: In step two, based on the preliminary plan determined in step one, measures for repeated well modification are further determined by combining the initial production, cumulative production, production time, and pressure of adjacent wells.

6. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 5, is characterized in that: For wells with a distance greater than 800m from adjacent wells, an initial daily production of more than 100,000 cubic meters, a cumulative production of 20 million cubic meters, a production time of more than 1 year, and a current production pressure greater than 5MPa, a horizontal well is selected for repeated modification by drilling a sidetracked horizontal well towards the adjacent well. After modification, the well will be produced together with the previous producing layer.

7. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 5, is characterized in that: When the distance between adjacent wells is 400-800m, the initial daily production is greater than 100,000 cubic meters, the cumulative production is 50 million cubic meters, the production time is more than 1 year, and the current production pressure is less than 5MPa, when the fracture conductivity is greater than 3D.cm, the in-situ stress field is broken, the pressure drop rate is reduced, and the current well and adjacent wells are synchronously modified using the synchronous fracturing method.

8. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 5, is characterized in that: In step three, the current well is within 1km of... 2 Within the area, if there are more than 10 adjacent wells and the fracture conductivity is >3D.cm, a general fracturing method should be used for repeated modification, and the modification scale should be 1.0-1.5 times that of the original design.

9. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 5, is characterized in that: In step three, the current well is within 1km of... 2 Within the range, if the number of adjacent wells is less than 5 and the fracture conductivity is less than 3D.cm, a segmented repeated fracturing method should be adopted for fine and repeated stimulation.

10. The method for repeated stimulation based on comparison of multi-well physical properties and production parameters in a block, as described in claim 5, is characterized in that: 1km around the current well 2 Within the area, with 6-10 adjacent wells and a fracture conductivity >3D.cm, production continues until the total well production in the area drops below 50,000 cubic meters. Then, a general fracturing approach is used for repeated stimulation. Within a 1km radius of the current well... 2 Within the area, if there are more than 10 adjacent wells and the fracture conductivity is less than 3D.cm, production will continue until the total well production in the area drops below 50,000 cubic meters, at which point a general fracturing approach will be used for repeated stimulation; within a 1km radius of the current well... 2 Within the specified range, if the number of adjacent wells is less than 5 and the fracture conductivity is greater than 3D.cm, production will continue until the total well production in the area drops below 30,000 cubic meters, at which point a general fracturing approach will be used for repeated stimulation; within a 1km radius of the current well... 2 Within the specified range, if the number of adjacent wells is less than 10 and the fracture conductivity is less than 3D.cm, no repeated modification will be carried out.