New Coiled-Tubing Cementing Techniques at Prudhoe Developed To Withstand Higher Differential Pressure

Abstract

Summary The successful hydraulic fracturing program at Prudhoe Bay would not have been possible without an effective coiled-tubing-unit (CTU) cement-squeeze program. Many fracture stimulation candidates were wells that had been squeezed previously. Therefore, squeezed perforations were exposed to higher differential pressures during fracturing operations than normally were seen at Prudhoe. At the outset of the fracture stimulation program in 1990, squeeze perforations failed when subjected to fracture job pressures. It quickly became clear that more aggressive CTU squeeze techniques resulting in stronger squeezed perforations would be necessary if the Prudhoe fracture program were to achieve its goals. Arco Alaska Inc. implemented a more aggressive CTU squeeze program in the Eastern Operating Area (EOA) in mid-1990. This paper documents the results of the new squeeze program, in which increased surface coiled-tubing squeeze pressures from 1, 500 to 3, 500 psi for 1 hour were used. More resilient, acid-resistant latex cement also became the standard in late 1990 for squeeze cementing. Implementation of this program has resulted in a squeeze success rate approaching 90%.