Basic logging while drilling (LWD) measurements have remained the same since their introduction in the late 1980s. But capabilities have expanded-from ultrasonic and density calipers to an increased selection of tool sizes. We review the evolution of hardware, data processing and interpretation that has furthered understanding of the best applications for LWD measurements.
Leaps in computing capability in the last decade have stimulated qualitative changes in the role of resistivity modeling. Computations that took weeks now take minutes. This has helped make resistivity modeling an integral part not only of tool development but also of steering horizontal drilling and investigating anisotropy and other environmental conditions.
Three-dimensional (3D) seismics have handed the explorationist virtually an X-ray view of the subsurface, dramatically improving wildcat and appraisal well success ratios. Land acquisition is harder than marine, but does not compare to the challenge of mixed terrain acquisition, described here for a survey made last year in Europe's busiest port. This article looks at both the acquisition and processing challenges.
Coiled-tubing drilling has the potential to deliver cost-effective slim-hole wells. But before it can become commercially viable, a number of challenges must be met. This article reviews two of the experimental wells drilled so far and the resulting technological agenda.
Recently introduced shear wave logging has opened up new avenues of interpretation, in particular an estimate of pore-fluid compressibility that promises to identify water, oil and gas.
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