New Low-Shock Low-Debris Gun Technology with Reliable Gunshock Simulation and Optimization

Abstract

Many high-pressure/high-temperature (HP/HT) gas fields are developed in Northeast China with wells that have pressures reaching 20,000 psi and temperatures up to 180°C. The main difficulty in perforating these wells is the high wellbore pressure, which leads to large gunshock loads when the guns fire. Field operators experienced substantial losses when perforating these HP wells with standard guns; therefore, they needed to minimize the risk of equipment damage due to gunshock and reduce the amount of perforating debris left in the well. To reduce gunshock loads and perforating debris problems, a new low perforating shock and debris (LPSD) gun system was developed specifically for HP/HT wells. Compared with standard guns, LPSD guns produce much less gunshock and negligible amounts of debris; thus, by using LPSD guns operators can minimize gunshock risk and save on cleanup runs. LPSD guns leave almost no debris in the well because LPSD guns retain all the metallic components inside the gun carriers, including the shaped charge cases, which remain virtually intact inside the guns. Complementing the new LPSD gun technology, we use gunshock simulation for shock load reduction and optimization. These are key elements of the perforating job design, and they are critical to prevent equipment damage in HP wells. We show several examples of tool damage resulting from gunshock loads when third-party guns were used. These gunshock problems represented costly losses from equipment damage and nonproductive time. Using gunshock simulation, we show the origin of shock loads and the magnitude of the loads acting on the equipment, resulting in collapsed casing, corkscrewed tubing, and damage to packer mandrels and seals. We compared the performance of LPSD with standard guns under the same perforating conditions, demonstrating that LPSD guns can reduce shock loads significantly, making LPSD guns better suited for all HP wells, including those in Northeast China. The LPSD gun system developed for HP wells significantly reduces the amplitude of the transient pressure waves and associated gunshock loads, and totally reduces the amount of debris. The reduction of gunshock enables perforating wells that otherwise cannot be safely and reliably perforated with standard equipment.