Technology Focus: Wellbore Construction (May 2008)

Abstract

Technology Focus Well construction involves many disciplines, including casing design, tubing design, downhole-completion equipment, cementing, perforating, and, finally, stimulation. All of these things must be designed and implemented to build a successful economical well. However, the vast majority of the 2007 SPE well-construction papers were cement-related. Because cementing appears to be a recent, but strong, trend, I asked one of Chevron's cementing experts (Robert Carpenter) for his opinion. Below, he talks about why cementing for completions has become a hot topic. "This is evidence of the growing realization that long-term isolation involves more than just pumping some cement spacer and 3,000-psi cement. People are beginning to recognize the stresses placed on the cemented annuli and to grasp the effect of the stresses on long-term annular isolation. We see this in the number of papers by service companies, universities, and now operators relating this concept and their experiences developing and applying cements with greater elasticity and/or self-healing properties. The trend is to use more-elastic-cement designs to prevent tensile-stress-induced microfractures; more recently, one can add cement with self-healing properties. The big interest in recently developed swelling packers also is part of this trend. Newly developed, expanding packers are being used instead of cement and/or to supplement cement to ensure long-term isolation. This trend results from several factors: rising cost of well construction (particularly in deepwater applications) and remedial work, deferred/lost production, and an increased focus on environmental and safety issues. The industry wants to avoid the cost and liability of future annular leaks and sustained casing pressure. All have combined to foster an increased development and adoption of technology to improve long-term annular isolation during well-construction and production operations. On another front, there has been an increased focus on cost-effective remediation and return to service of shut-in or leaking wells. Several of this year's papers detailed large-scale remedial-cementing programs and diagnostic methods used by several operators." My thought is that it does no good to drill a USD-100-million well if, in the end, we cannot isolate the zone of interest. Wellbore Construction additional reading available at the SPE eLibrary: www.spe.org SPE 108973 • "Multitype Application of Cement Packer: Simple and Economical Method of Accessing Bypassed Reservoir Potential" by Muhammad Idris, SPE, Vico Indonesia, et al. SPE 105413 • "Cementing Considerations for Casing While Drilling: Case History" by Robert D. Strickler, SPE, ConocoPhillips, et al. SPE 106765 • "Field Study Results Improve Squeeze-Cementing Success" by Michael Cowan, Shell International E&P.