Numerical simulation on the initiation and propagation of synchronous perforating fractures in horizontal well clusters

•1. There is a competitive relationship between initiation and propagation of perforated cracks. Perforated cracks will eventually form a crack propagation mode dominated by several main cracks and supplemented by micro cracks.•2. An obvious spatial form associated with asymmetric main cracks and micro cracks derived around them. Parallel perforation crack initiation presents four modes of competitive initiation.•3. With the increase of perforation density, the fracture initiation rate of parallel perforation in the initial stage of fracturing decreases gradually, the number and the complexity of fractures also increase gradually; with the continuous increase of the stress difference, the initiation rate at the initial stage of hydraulic fracturing and the number of the main formed cracks and derived micro cracks all show a decreasing trend. Horizontal well perforation is one of the main factors affecting formation fractures around the wellbore and subsequent hydraulic fractures extending along the predetermined path. In this paper, the RFPA2D-Flow software is used to conduct a numerical simulation study on the initiation and propagation of parallel perforation fractures in the perforation cluster. Then influence of different perforation density and different stress on the initiation and propagation of perforation fractures are studied. The results show that there is a competitive relationship between initiation and propagation of perforated fractures. Three parameters, the initial initiation rate and the length of the hydraulic fracture, and the generated fracture number, are put forward as the indexes to measure the competitive relationship. Perforated fractures will eventually form a fracture propagation mode dominated by several main fractures and supplemented by micro fractures. Then it shows that an obvious spatial form associated with asymmetric main fractures and micro fractures derived around them. Parallel perforation fracture initiation presents four modes of competitive initiation. With the increase of perforation density, the fracture initiation rate of parallel perforation in the initial stage of fracturing decreases gradually, the number and the complexity of fractures also increase gradually; with the continuous increase of the stress difference, the initiation rate at the initial stage of hydraulic fracturing and the number of the main formed fractures and derived micro fractures all show a decreasing trend.