The Piceance Basin of western Colorado contains a major gas resource in the tight naturally fractured sandstones, siltstones and coals in the Mesaverde. The objective of the Slant Hole Completion Test, funded by the U.S. Department of Energy, is to evaluate directional and horizontal drilling as an alternate development strategy for these reservoirs.

The well is located 700 ft south of the DOE Multiwell Experiment site in Section 34, T6S, R94W, Garfield County, Colorado. The hole was designed to intersect the paludal Mesaverde at 60° beneath the Multiwell pad and continue north to intersect the Cozzette close to 90°. The well is positioned to drill normal to the regional fracture system. Coring operations included a coal pressure core, 276 ft of conventional core across two paludal sandstones, and 118 ft of conventional core perpendicular to the natural fracture system in the Cozzette.

Drilling operations proceeded as planned through the first build interval, pressure coring, and conventional coring in the 60° hole. Subsequent caving in the coal and in the adjacent naturally fractured siltstone, in conjunction with lost circulation in the Rollins, necessitated prematurely running 7-in. casing below the Rollins. The remaining 800 ft of hole drilled was 6-in. diameter, cased with 4-1/2-in. liner. The high hole angle, in conjunction with the long tangent (60°) section (1,824 ft), made sliding the 4-3/4-in. motors in the second build extremely difficult. Drillpipe conveyed logging operations were successfully conducted in the Cozzette.

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