Unique Application of EM LWD Casing Antenna System to Rocky Mountain Drilling

Abstract

Certain formations in the Rocky Mountains preclude the use of electromagnetic (EM) telemetry due to their inherent resistivities. A new system has been developed that extends the use of EM telemetry systems where they were previously not usable. The system involves installing a special downhole antenna when surface or intermediate casing is run to improve EM signal to noise ratio. The casing antenna system not only allows operators to take advantage of the benefits of EM loggingwhile-drilling (LWD) systems but also extends the drilling depth range where data can be provided.Drilling wells in the Powder River Basin often requires heavy mud weights and the extensive use of lost circulation material (LCM). Unfortunately, these types of muds play havoc on standard mud pulse telemetry systems. Washed equipment and downhole failures related to plugged pulsers often result in multiple trips for failures and excessive nonproductive time (NPT). This new EM LWD system, by contrast, has no moving parts and a through-bore, which allows for higher concentrations of LCM and heavy weighting materials to pass easily through the bottom hole assembly (BHA). The system is combinable with a variety of LWD sensors so the telemetry type proves especially useful in areas that experience high LCM incidents. A key aspect of this system is that it also extends the depth range of where EM LWD systems can operate.Along with a compensated resistivity tool, a unique LWD spectral azimuthal gamma ray (SAGR) sensor, which provides accurate formation evaluation data, high quality gamma ray images and spectral elemental analysis, was used to help geosteer the well to stay in the zone of interest in the reservoir. This paper will examine a case study where the new system was used in an area where drilling with EM was not previously possible. It will describe the basic system design, key operating parameters, provide insight on the drilling problems, and address formation evaluation challenges and solutions.

A Solution to Tough Logging Conditions (Lwf): Intro to Tough Logging Conditions, Logging While Fishing, Operation Procedure and Conditions

“…Although the gap between wireline and LWD offerings continues to narrow, some services are not available while drilling. These include high-data-rate services, such as the FMI formation micro imager coring tool, tools requiring high power, such as sidewall coring tools, and other technologies that have yet to migrate to LWD platforms [10]. Eventually, the rig moves on to drill the next well, and LWD tools can no longer be used for data transmission.…”

“…However, before the widespread acceptance of LWD tools, methods existed for conveying conventional open-hole logging tools at the end of the drill pipe. Among them was the TLC tough logging conditions system [10]. Logging tools, minus the cable, were attached to the end of the drill pipe and pushed to the bottom of the casing.…”