ABSTRACT:

The Bahr Essalam field offshore Libya represents a major gas development in the offshore Mediterranean. The timely development of the field is required to provide gas supplies for the West Libya Gas Project. Fifteen wells were planned for the Central platform. To date, sixteen wells have been drilled. Two were drilled and cased through the reservoir. Thirteen were drilled to the top of the reservoir zone, cased, and temporarily suspended. One well was suspended at the 13-3/8 in (340 mm) casing point. Once the platform jacket and deck installation are in place, the production intervals will be drilled and the wells completed. Due to the relatively shallow reservoir depth, a number of high angle wells in excess of 70° of inclination were required. Drilling has progressed in several phases with the first phase encompassing the batch drilling of the 36 in (914 mm) and 23 in (584 mm) sections. This first phase progressed without incident. Problems were encountered, though, in the second phase of the drilling for the 17‑1/2 in (445 mm) and 12-1/4 in (311 mm) hole sections. In the 17‑1/2 in (445 mm) interval, the Mahmoud shale could not be adequately inhibited with water based drilling fluids on the first 7 wells. Such problems as bit balling and stuck pipe occurred. In the 4 wells where water based fluids were utilized in the 12-1/4 in (311 mm) section, the Salambo formation caused similar problems. Based on this experience, a low-toxicity oil mud system was implemented for the remaining wells. This system required special processing and handling equipment for the mud and cuttings to minimize cost and optimize performance. The remaining wells in the project were drilled to target depth without incident. A number of other changes were implemented to improve performance and reduce the likelihood of unplanned events that would result in lost time. The average footage per day increased substantially for the wells drilled with low-toxicity oil mud

This content is only available via PDF.
You can access this article if you purchase or spend a download.