A cluster spacing optimization method for staged multi-cluster fracturing of horizontal wells in low-permeability oil and gas reservoirs
A technology for low-permeability oil and gas reservoirs and horizontal wells, which is applied in earthwork drilling, wellbore/well components, production fluids, etc., and can solve the problem of inaccurate reflection, changes in pore pressure and pore elastic stress, and inability to obtain cluster spacing optimization results And other issues
Active Publication Date: 2017-05-17
SOUTHWEST PETROLEUM UNIV
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Problems solved by technology
However, the induced stress field model of hydraulic fractures established by analytical solution and 2D displacement discontinuity method cannot accurately reflect the induced stress field distribution of three-dimensional hydraulic fractures in the reservoir under actual conditions, and the existence of hydraulic fractures will not only generate Induced stress, which also causes changes in pore pressure and poroelastic stress in the formation
At the same time, when the original horizontal stress difference in the formation is large, there may not be a stress reversal point, and the stress reversal radius is used as the optimal cluster spacing, which does not fully consider the stimulation effect of the reservoir after fracturing
It can be seen that the existing cluster spacing optimization method cannot obtain an ideal cluster spacing optimization result.
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[0091] The present invention will be described in further detail below in conjunction with the accompanying drawings and field application examples.
[0092] Taking a horizontal well (XP well) in a tight sandstone reservoir in an eastern oilfield as an example, the well was drilled to a depth of 3919m, a vertical depth of 2091.7-2105.6m, a horizontal section length of 1619m, an average porosity of 8.3%, and an average permeability of 0.77 mD is low porosity and ultra-low permeability reservoir, and other basic parameters are shown in Table 1 below.
[0093]At present, domestic low-permeability oil and gas reservoir horizontal well segmented multi-cluster fracturing technology is limited by reservoir geological conditions and construction tools and equipment. Usually, 2-3 clusters are used for fracturing in a single stage. Here The example wells in the well were also optimized for cluster spacing in accordance with the conventional scale of 2-3 clusters in a single section. Ho...
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The invention discloses a cluster interval optimizing method for segmental multi-cluster fracturing of a horizontal well of a low-permeability oil and gas reservoir. The cluster interval optimizing method for segmental multi-cluster fracturing of the horizontal well of the low-permeability oil and gas reservoir sequentially comprises the following steps that (1) the induced stress generated by hydraulic fractures in a stratum is calculated; (2) the formation pore pressure after fracturing liquid is leaked off is calculated; (3) formation pore elastic stress after the fracturing liquid is leaked off is calculated; (4) the three induced stress fields and the original ground stress field are superposed, so that a new ground stress field is obtained; (5) facture network waves and the region area are calculated; and (6) a relation curve chart of the fracture cluster interval, the fracture network waves and the region area is drawn with the cluster interval being used as x-coordinates and the fracture network waves and region areas being used as y-coordinates, and the optimal cluster interval is determined. According to the cluster interval optimizing method for segmental multi-cluster fracturing of the horizontal well of the low-permeability oil and gas reservoir, the interference effect of the hydraulic fractures on the original ground stress field is considered, the expanding and shear fracturing behaviors of natural fractures under a complex ground stress field condition are also considered, and the novel cluster interval optimizing method is formed with the optimization goal of obtaining the maximum fracture network wave and the maximum region area; and the novel cluster interval optimizing method is more objective, accurate and practical.
Description
technical field [0001] The invention belongs to the field of oil and gas field development, and in particular relates to a cluster spacing optimization method for segmented multi-cluster fracturing of horizontal wells in low-permeability oil and gas reservoirs. Background technique [0002] In recent years, the progress and large-scale application of staged multi-cluster fracturing technology for horizontal wells in unconventional fields at home and abroad have enabled low-permeability oil and gas resources such as shale oil, shale gas, tight sandstone oil, and tight sandstone gas to be developed efficiently and economically. Have a revolutionary effect. Horizontal well staged multi-cluster fracturing technology refers to dividing the horizontal well into multiple stages and performing fracturing step by step during fracturing, and performing multi-cluster perforation at a certain interval in each fracturing stage. The perforation clusters in the same fracturing stage perfo...
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IPC IPC(8): E21B43/26
CPCE21B43/26
Inventor 赵金洲许文俊李勇明刘作磊
Owner SOUTHWEST PETROLEUM UNIV