摘要：Based on the original fracture initiation location when refracturing technology is applied in low- permeability and ultralow-permeability oil fields, recovery rates are not well improved. Refracturing technology using temporary plugging for fluid diversion can effectively steer fractures and further improve recovery rates. To study the mechanism of refracturing using temporary plugging for diversion and the initiation locations of reoriented fractures, we establish a numerical simulation model of refracturing in old wells in tight sandstone reservoirs and analyze the stress distribution in the fracturing area. A finite element numerical simulation model of the initial fracturing, single-slot refracturing and multislot refracturing is established. The stress distribution of the region near the well is determined during fracturing, and both the fracture initiation point and the impact factors of refracturing technology using temporary plugging for fluid diversion are analyzed. The horizontal in situ stress difference and fluid pressure have significant impacts on the refracture initiation location. When the stress difference is large, forming a single steering joint is easy; when the stress difference is small, forming multiple steering joints is easy. When the liquid pressure is small, cracking at the wellbore is easy; when the liquid pressure is large, initiating at the first fracture body is easy. The results of numerical simulation show that the initiation point of refracture is consistent with that from field tests, which proves that the research results are reasonable. This study proposed a numerical simulation method for predicting the initiation position of refracturing technology using temporary plugging for fluid and analyzed the influencing factors. The research provides basic theories and technical support for reasonable prediction of fracture morphology and formulation of construction design.
关键词：Refracture technology;finite element method;refracture initiation location;horizontal in situ difference;fluid pressure
