Improved Liner Cementing Techniques for Alaska's Prudhoe Bay Field

Abstract

ABSTRACT This paper describes the current equipment and techniques used to reciprocate and cement liners in Alaska's Prudhoe Bay Field. Liner reciprocation was started in Prudhoe Bay by BP Alaska, Inc., using hydraulic-set hangers during 1976. Liner reciprocation was initially developed to improve mud displacement thereby improving cement bonding in high-angle wells. To date, more than 210 deviated wells have been successfully completed using the methods described in this paper. Typical Prudhoe Bay Unit wells are completed with approximately 1,500 ft of 7 in. 29#/ft L-80 liner hung across 8-1/2 in. open hole at 10,800 ft MD in hole angles up to 67 degrees. Liners are routinely reciprocated while conditioning mud and while circulating and displacing cement slurries. The cement is preceded with a chemical or water pre-flush, and the entire slurry is displaced at turbulent flow rates. The hanger is hydraulically set with a liner wiper plug. Current technology includes the use of the latest recirculating cementing unit as well as liner hanger equipment designed for compactness, low-flow restriction, and high-load capacity. Reciprocating liners in the Prudhoe Bay Unit has resulted in a significant drop in the number of squeeze cement jobs of the liner and/or liner lap. Success has been verified by lap in-flow testing, low-water production rates, and a good cement bonding at the critical oil/ water and gas/oil contacts.