Abstract
In order to investigate the influence of pore pressure on hydraulic fracturing behavior in the local and whole model, the coupled flow‐stress‐damage (FSD) analysis system RFPA‐Flow was used to study the influence of rock heterogeneity, natural stress ratio, double‐hole spacing, and water pressure gradient on the stress shadow effect. The numerical results show that the tensile crack induced by pore water pressure is significantly affected by the pore water pressure and water pressure gradient. The larger the pore pressure gradient is, the more asymmetrical the crack development pattern and the smaller the instability pressure of the model. In addition, the shape of hydraulic fracture becomes much more irregular with the increase in rock heterogeneity. The number and shape of tip microcracks under the influence of local water pressure are closely related to the homogeneity of rock. Moreover, when the natural stress difference is large, the hydraulic fracture propagates parallel to the maximum principal stress; when the stress field is close and the spacing between two holes is less than 5 times the diameter, the propagation direction of hydraulic fractures between holes is perpendicular to the maximum principal stress. It is found that no hydraulic fractures occur between the two holes when the distance between holes is greater than 5 times the diameter.
Highlights
High-pressure fluid fracturing and mechanical fracturing are the two main approaches to rock cracking, and there are many research studies on the mechanical cracking mechanism of rock
Some field evidence has shown that the influence of pore water pressure on the mechanism of crack initiation and propagation is sometimes unclear. e principle of effective stress is extended to the problem of reservoir fracture, suggesting that the pressure of hydraulic fracture initiation and propagation may decrease with the increase in reservoir pore water pressure. e reopening pressure and propagation pressure of cracks show a decreasing trend when low-rate fluid is injected, which may be because a large amount of fluid has been lost to the reservoir [5]. is conclusion is consistent with the results of laboratory tests
The evolution of hydraulic fracture in a twohole model was numerically investigated using a coupled flow-stress-damage model. e effects of rock homogeneity, stress ratio, hole spacing, and hydraulic pressure gradient were investigated. e characteristics of hydraulic fracture propagation in the two-hole model are the classical issue of stress shadow. e results of this study are different from that of pre-existing studies, and the homogeneity of rock was first considered in the two-hole model fracturing
Summary
High-pressure fluid fracturing and mechanical fracturing are the two main approaches to rock cracking, and there are many research studies on the mechanical cracking mechanism of rock. (2) Case 2: Model stress distribution, pore water pressure distribution, hydraulic fracture morphology, crack propagation path, and fracture pressure were discussed under different rock homogeneity (m 1.5, 3, 5, 1000). (3) Case 3: Study the evolution formation of hydraulic fracture in the double-hole model under different stress ratios (K 0.5, 1, 0.8, 1.5), discuss the influence of compressive stress field on pore water pressure in the overall range, and analyze the evolution law of crack. Geertsma and Detournay believed that the increase in compressive stress field would increase the pore water pressure and resist the generation of hydraulic fracture It can be seen from the calculation results that for the double-hole model, the factors that resist the formation of hydraulic fracture include the distance between the two holes. L=160 mm Figure 10: Morphology of hydraulic fractures with different wellbore spacing (m 2, K 1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
