First Application of a Lightweight Salt Slurry to Help Cement Longest Intermediate Casing across Salt Section and Improve Well Economics: Case History from the Gulf of Suez

摘要

This paper highlights a successful cement job in which more than 1,300 bbl of cement slurry was pumped to help cement the longest 9 5/8-in. casing in a highly deviated and washed out wellbore in the Gulf of Suez (GOS). This novel slurry design aided efficient cementing across a massive salt section, while mitigating the risks associated with using a multiple-stage cementing tool in highly deviated wells. To access most of the reservoirs in the GOS, operators must drill through a salt section with a thickness sometimes greater than 1000 m. This section is covered with 9 5/8-in. intermediate casing, which is generally cemented in two stages using a multiple-stage cementing tool. Conventional salt slurries of 15.8- to 16-lbm/gal are generally used to cover the salt section. Any failure with the multiple-stage tool can lead to expensive remedial work and can cause salt instability resulting from longer exposure, which can lead to salt creeping or loss of the well. The success ratio of multiple-stage tools is not high, especially in highly deviated wells; therefore, it was necessary to find a new approach to help mitigate the risks associated with using multiple-stage tools. High-strength, low-density (HSLD) slurries have been successful in replacing conventional 15.8- to 16-lbm/gal slurries across the production zones. With this in mind, lightweight salt slurries were designed to replace conventional salt slurries across the salt section. Because this is the longest intermediate casing in the GOS to date for the operator, it was logistically favorable because the lightweight slurries helped reduce the amount of dry cement required to meet the rig capability. The cost of the multiple-stage tool, additional dry cement, dry-cement-transportation costs, and rig costs for waiting on cement (WOC) for the second stage were either completely eliminated or minimized with this solution, resulting in a total savings in excess of USD 100K.