Logging While Drilling Cement Evaluation: Case Study in Deep Water Gulf of Guinea

Assessing well integrity through cement bond analysis is recommended and sometimes legally required because the potential risk of a poorly executed cement job on people, assets and environment during- and post well construction can be catastrophic. Traditionally, cement bond logs were acquired with wireline tools. Following advances in tool response modelling and log data processing, Logging While Drilling (LWD) acoustic data for cement bond analysis - acquiring the data while tripping in or tripping out of hole - has become an attractive and viable option to consider over traditional wireline data acquisition. The LWD option comes with the added advantage of substantial savings in rig time while eliminating operational complexity and safety risks associated with additional wireline logging operation particularly in high angle- and extended reach wells. To assess the robustness of the LWD cased hole cement evaluation logs and to validate its application to Deep Water (DW) wells, LWD and wireline acoustic logs were acquired back-to-back in three wells in the DW Gulf of Guinea (GoG), and the bond index estimated from both acquisitions were compared. This paper presents the outcome of the work and provides support to the opportunity to consider LWD acoustic data acquisition for quantitative cement bond evaluation.