Analyzing Swellable Packer Model Under Miscible Gas Differential Pressure Utilizing Computerized Tomography Scanning

Abstract

The purpose of this project was to confirm the occurrence of and to characterize hydrocarbon gas diffusion through a swollen reduced-scale packer of oil swellable material. The extent and origin of extrusion at the ends of the scaled packer is a key measurement. A quantitative and qualitative analysis was performed to determine if the miscible gas mixture damaged the structure or compromised the capability of the elastomer / swellable packer to hold pressure. Two packers were swollen (separate fixtures) in diesel under conditions similar to downhole pressure and temperature. The test fixtures were limited to an internal pressure of 2000 psi. A 1900 psi differential pressure was applied across the two test samples using the swell fluid. A temperature of 72ºC was maintained for the test. A miscible hydrocarbon gas was then introduced (1900 psi) to one of the test samples to completely displace diesel from the high-pressure side of the test fixture. Pressure and temperature were maintained for approximately 35 days during which regular computed tomography scans were conducted to detect any changes in the density of the swellable rubber element.