Novel Wireline Coring System

Abstract The value of core samples to enhance reservoir evaluation and completion strategies has long been recognized. A large percentage of the cost of coring is the rigtime associated with the tripping of the corebarrels. As rig rates increase, particularly in deepwater areas, the cost of coring becomes prohibitive due to excessive trip costs. A solution to this problem is to trip the core from the well at wireline log recovery speeds, yet still recover the length and diameter of core associated with conventional coring operations. Since the 1960's, international teams which include the United States, Europe, Japan, and Russia, have developed a wireline coring system for recovering 4 to 5-1/4" (101 to 133 mm) diameter, ice and rock cores to 12,000 feet (3,660 m) in Antarctica and Greenland. This paper describes this wireline coring technology. This includes the self-contained fluid circulation, cuttings recovery, instrumentation, core barrel, core catcher, and core bit systems. The operational history for the recovery of both ice and rock cores on multiple wellbores, including the Greenland Ice Sheet Project, is presented and possible oilfield applications, emerging from a recent optimization study, including replicate coring, are discussed.