Successful Integration of Electromagnetic MWD-LWD Technology Extends UBD Operation Envelope into Severely Depleted Fields

Abstract The advantages of electromagnetic (EM) telemetry are not always considered when planning drilling operations. This paper examines the execution and lessons learned from the successful implementation of EM-MWD and LWD technology in an underbalanced horizontal drilling application in the Nimr field in Oman. Some of the highlights included the highest daily footage drilled underbalanced, enhanced geosteering through the use of real-time LWD information and significant rig time and cost savings when compared with operations using mud pulse (MP) telemetry. The most significant accomplishment was the demonstration that these wells can be drilled with real-time LWD measurement using standard EM transmission. This is important because it enables underbalanced drilling (UBD) using drillpipe injection with high gas rates, which expands the envelope for UBD operations to severely depleted reservoirs. Petroleum Development Oman's (PDO) standard UBD practice in depleted reservoirs is to avoid severe formation damage and to use real-time LWD for geosteering horizontal multi-lateral wells in the most productive sections of the reservoir. Prior to this well, the application of UBD was generally accomplished using concentric casing gas injection as it was believed that the only viable means of obtaining LWD information was through mud-pulse transmission. The application of EM, LWD, and UBD described in this paper represents an important advance in a stepwise progression for improving PDO's ability to exploit mature reservoirs, especially those that are severely depleted.