Effects of perforation fluid movement on downhole packer with shock loads

Abstract

With the rapid development of oil and gas well production techniques, perforation technologies have made rapid progress, accompanied by perforation safety problems has become an important challenge in the field operation. The shock loads generated during perforating have a strong impact on downhole tools as well as perforation fluid, which poses a threat to the safety of downhole perforating string system, especially for the packer. Firstly, this paper explores the perforation fluid movement mechanism, the calculation model is proposed to describe the two periods of perforation fluid movement. Secondly, the process of perforation with many bullets has been simulated by using the software ANSYS/LS-DYNA. The movement in two periods of perforation fluid can be calculated based on the simulation result, which the set distance of packer needs to be optimized. The propagation attenuation law of shock wave is studied, and a model based on simulation data is proposed to predict the peak pressure of perforation fluid under different perforation conditions. Thirdly, a prediction model for determining the safety distance of the packer has been created by considering the reflection and transmission of shock waves. Finally, the simulated result has been verified by the field case, optimization measures are put forward by combining the design of shock absorption with the safety distance of downhole packer. The results show that the research method in this paper is practical, reasonable and effective, which can provide a theoretical basis for field perforation operation and safety improvement.