Research on Simulation and Structural Optimization of the Anchoring Force of Multiple Packers in the Stage Fracturing String

Abstract

The multi-packer staged fracturing string is a key tool for the staged fracturing and exploitation of "three-low" oil and gas reservoirs in the Changqing Gas Field. The magnitude of the packer's anchoring force is closely related to the stability of the staged fracturing string, and directly affects the on - site fracturing operation effect. In response to the problems such as the lack of a quantitative design basis for packer anchoring during the staged fracturing process in the Changqing Oilfield and the difficulty in ensuring the service safety of the staged fracturing string, this paper selects the Y241 compression - type packer and the K344 expansion - type packer. Through theoretical mechanical analysis and finite - element numerical simulation, the distribution characteristics and variation laws of the anchoring force of the compression - type/expansion - type multi - packers in the staged fracturing string are studied. And combined with the on - site fracturing operation technology, the structure of the multi - packer string is optimized. The research results show that: during the first - stage, second - stage, and third - stage fracturing processes, the Y241 packer provides anchoring forces of 640.64 KN, 566.42 KN, and 566.72 KN respectively. The anchoring forces are all insufficient and cannot meet the requirements of staged fracturing. A hydraulic anchor with a pressure capacity of 300 KN needs to be configured throughout the process. For the K344 packer, during the first - stage fracturing, when the operating pressure is greater than 55 MPa, the packer's anchoring force meets the requirements; during the second - stage and third - stage fracturing processes, when the operating pressure is greater than 50 MPa, there is no need to connect a hydraulic anchor. Through the linear interpolation method, the critical values for connecting the hydraulic anchor of the K344 packer during staged fracturing are calculated to be 53.43 MPa, 46.47 MPa, and 46.17 MPa respectively.