Parameter optimization of spiral perforations in horizontal well with tight sandstone reservoir

The perforation, a channel connecting wellbore with reservoir, provides the path of oil drainage, reduces the fracturing pressure of reseroir, and determines the direction of fracture propagation. A series of large true tri-axial physical simulation experiments are conducted to study the effects of perforation length, density, diameter, phase and spacing on the characteristics of fracture initiation, behaviors of fracture propagation and fracturing pressure. The experimental results show that the change of perforation parameters affects the perforation spacing, and the distance of two adjacent perforations. It decides the interaction between the two adjacent perforations, and then determines the fracture propagation geometry. The increasing perforation diameter and density reduce the perforation spacing, which is beneficial for fractures to link up with each other and to decrease fracture complexity and fracturing pressure of nearby well bares. The increase of perforation phase, whereas, enlarges the perforation spacing, forming the layered fracture with a high fracturing pressure. In addition, the changes of the perforation length and spacing have no effect on fracture morphology. Thus, according to the experimental results, some theoretical bases and suggestions about the parameter optimization of perforations are put forward for the field operation.