Techbits: Seismic-While-Drilling Technology Takes ETW Spotlight

Abstract

Techbits While Seismic-While-Drilling (SWD) methods have been investigated for nearly 30 years as a complete, real-time alternative to conventional vertical-seismic-profiling (VSP) techniques, the industry has yet to accept it beyond a rather narrow scope. Expanding this scope was the focus of a recent SPE Emerging Technology Workshop (ETW) held in League City, Texas. SWD technology, until recently primarily referred to as drill-bit (DB) seismic, began as a method to detect the natural vibration from the end of the drill bit by means of surface geophones, enabling geophysicists and drillers to use these data in real time to optimize drilling efficiency, predict pore pressures ahead of the bit, and verify reservoir models. This technique has been eclipsed by another method, particularly for deepwater offshore drilling applications, which is based on traditional wireline methods that use a standard offshore air-gun seismic source at the surface with suitable receivers or sensors in a downhole tool. This, together with recording and processing capabilities, is part of an enhanced logging-while-drilling (LWD) tool. Nonetheless, proponents of DB/SWD technology believe the technique has untapped potential in certain applications. The ETW was seen as the ideal forum in which to discuss this. ETWs are interactive events designed to give participants a field's-eye view of new technologies and to expedite the adoption of these technologies by publicizing their initial successes as they move from laboratory to field. Andy Hawthorn of Schlumberger helped organize the League City event. "When I got involved, the entire focus was on theory and processing of DB seismic. But because there are still so many limitations with it, we had to include the LWD seismic [LWD/SWD], which has replaced it more successfully on an economic basis." Open Dialogue, Collaboration Promoted According to SWD ETW Chairperson Bob Radtke of Technology International, the workshop's open format encouraged lively discussion and debate on the future of the technology. "We had presentations describing the current state of the art, as well as detailed sections on surface source, downhole source, emerging technologies, and case histories," Radtke said. "In addition, this workshop was unique, in that we had a special keynote speaker, Nansen Saleri." Saleri, manager of Reservoir Management, Saudi Aramco, and a 1991 SPE Distinguished Lecturer, delivered an address titled "The Technology Factor: How It's Changing Upstream Performance." His talk described how the SWD method would be useful for increasing understanding of reservoirs in the Middle East and elsewhere, and indicated that significant producers may be ready to give this technology extensive use. Another special feature of the ETW was the presentation of two "Legends of SWD" awards to Bruce Marion and James Rector for their 1991 demonstration of the first successful use of drill-bit reverse VSP employing drill-bit-correlated data.