Evaluating the True Cost of Losing a Bottomhole Assembly

Abstract

Abstract Losing a bottom hole assembly (BHA) is one of the most costly unplanned drilling events that can occur for an operator. Time spent fishing for the lost assembly, the rig time wasted waiting on the mobilization of equipment and people, as well as the additional costs of whipstocks, cement, and directional tools significantly increase the cost of a well and often results in exceeding the approval for expenditure (AFE). The new well plan may also lead to any number of problems with tortuosity and torque-and-drag farther down the wellbore. Typically, these expenses are invoiced individually, obscuring the cumulative cost to reach the same true vertical depth (TVD) as the stuck assembly. Often, one of the largest invoices the operator receives during a stuck BHA event is the replacement cost of the logging while drilling (LWD) technology. This large expense does much to disguise the other costs of sidetracking, leading many operators to consider the risk of losing a high technology LWD tool far greater than the benefits of running it in the hole. As well difficulty increases and the risk of a stuck pipe event grows, operators become hesitant to run larger LWD tool strings in the hole. Unfortunately, this mentality creates a paradox. Many of the new LWD technologies including annular pressure while drilling, formation pressure while drilling, sonic while drilling and seismic while drilling are capable of significantly reducing the risk of a lost-in-hole (LIH) event. In the event this technology is LIH, the additional information to analyze and replan the new wellbore can prove to be invaluable. This paper will analyze data and case studies in the Gulf of Mexico (GOM) to perform a risk analysis that includes the true cost of sidetracking a well, with and without additional LWD technology in the drill string providing key real-time measurements.