Improved oil recovery solution sought in Libya

Horizontal drilling has substantially improved oil recovery rates in recent years, as incremental oil recovery and production rate can improve because of less water coning, larger drained area, and higher sweep efficiency. However, drilling horizontal wells to improve oil recovery can be difficult and has high associated risk in placing the well and steering within the best reservoir zone; sometimes, advanced technology methods are required. One such method is bed boundary detection and mapping using PeriScope service.

The Arabian Gulf Oil Company (AGOCO) was operating in the Messla field in Libya and wanted to enhance oil recovery in one of its wells in the region. The company logged a pilot hole and worked with Schlumberger to evaluate the resulting data as well as develop and deploy a solution that would improve recovery.

Optimal attic interval targeted

Schlumberger petrotechnical experts interpreted the pilot log and delineated the oil column, with results showing a production zone of interest located below a shaly sand layer, which should be avoided. Results also showed that the oil column was narrower than initially mapped. Working in collaboration with AGOCO, the team suggested drilling the top of the reservoir with the PeriScope service in the drillstring. PeriScope bed boundary mapping service enables seeing the reservoir top as the well is being drilled, which helps the drilling trajectory avoid the oil/water contact (OWC) and mitigates the risk of exiting the reservoir from the top. As a result, subsequent sidetracking is eliminated and production enhanced.

Petrophysical Comparison of Conventionally Drilled Offset Wells with PeriScope Service Well

Production improved with high petrophysical quality

Compared with two conventionally drilled offset wells, the well drilled using the PeriScope service produced reserves of higher petrophysical quality. Schlumberger petrophysical interpretation found decreased water saturation and clay volume, while net-to-gross ratio improved. The 2,385-bbl/d production rate of the PeriScope service well was much better than anticipated, and water cut was eliminated. Based on this operational success, the operator expressed interest in using the bed boundary mapping services on future wells to improve oil recovery.