The giant Pinedale anticline gas field, which is approximately 35 miles long and 6 miles wide, contains 159 Tcf of conservatively estimated in-place natural gas. The field ranks as the third-largest gas field in United States by proved reserves. Gas production is primarily from a 5,500-ft thick “Lance Pool” that overlies the top of the Ericson Sandstone Formation. The Lance Pool consists of the Lance Formation, the Upper Mesaverde Group, and a Paleocene “unnamed” unit. The reservoir is classified as tight gas, with low porosity and micro-darcy permeability. Horizontal drilling is not practical and therefore deviated well (S-well) drilling is prevalent, due to the lenticular sands and stratigraphic nature of this area. A typical deviated well has a 5? to 25? inclination in the upper section, then a tangent section varying from 1,000 to 5,000 ft, with a total depth (TD) of around 15,000 ft MD. The extensive reach, long tangent and various formation strata encountered place an extremely challenging drilling environment for directional drilling using a conventional adjustable kick-off sub (AKO), positive displacement motor (PDM), and a polycrystalline diamond compact (PDC) drill bit. However, if proper directional drilling techniques are applied, this approach can accomplish the task in a timely manner and provide outstanding cost effectiveness over automated vertical-seeking tools (Han et al., 2013). This paper discusses difficulties encountered in the Pinedale directional drilling process with a conventional AKO PDM, such as successfully landing in the driller target, predicting the reactive torque under various scenarios, holding the tool face (TF) with a PDC bit, and extensive hole drag. Several practical directional drilling techniques are presented as solutions, such as point-turn-tag, turn-tag-point, tag-turn-point, jerking-while-sliding, counting-number and 6-in.-wiper. These techniques are practical, field-proven and invaluable for Pinedale operations and numerous oil and gas fields with similar directional drilling obstacles. Thorough understanding and mastering of these techniques can substantially increase directional drilling efficiency, reduce drilling time, enhance borehole quality, and improve overall drilling performance.
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