Optimized Cased and Perforated Completion Designs Through the Use of API RP-19B Laboratory Testing to Maximize Well Productivity

Abstract

Abstract A detailed perforating study was conducted for a high pressure and high temperature (HPHT) reservoir which provided challenging conditions for conventional perforating. To maximize productivity, a series of API RP-19B Section 2 and Section 4 experiments was conducted to optimize perforation conditions. These results were integrated with mud testing and operational considerations to create an overall completion design for the field. Section 4 tests were performed at static overbalance, static underbalance and dynamic underbalance conditions scaled to field conditions using either mud or base oil as the completion fluid. The core flow efficiency and perforation geometry were evaluated to determine the optimum perforation method to achieve the target skin. The Section 4 apparatus could not achieve absolute field pressure and temperature conditions, therefore to ensure the required perforation geometry could be achieved downhole, Section 2 tests were conducted at the HPHT field conditions of reservoir overburden stress (13,000 psi), reservoir pressure (>11,000 psi) and temperature (>300 F). The results showed that dynamic underbalance removed significant portions of the perforation crushed zone and resulted in high productivity flow even when perforating in mud. Static underbalance was significantly less effective in removing crushed zone damage and overbalanced perforating in mud yielded poor results. Perforation geometry was radically altered upon going from relatively low stress conditions to full HPHT reservoir conditions when the cores were saturated in a light mineral oil. This change in perforation geometry was not observed when the cores were saturated in water, indicating that the fluid compressibility may have a significant impact on perforation geometry under high stress conditions. These results point to the value of conducting Section 2 and Section 4 experiments early in a project's timeline so that the best completion designs can be pursued and ultimately used in the field to maximize well productivity.