The giant Pinedale gas field, which is approximately 35 miles long and 6 miles wide, is the largest structural feature in the northern Green River Basin of Wyoming, with conservative estimates of in-place natural gas at 159 Tcf. The Pinedale field ranks as the third-largest gas field in the United States by proved reserves. Gas production is primarily from a 5,500 ft-thick "Lance Pool" on top of the Ericson Sandstone. The pay zone consists of Upper Cretaceous sandstones of the Lance Formation, the Upper Mesaverde Group, and a Paleocene "unnamed" unit. The reservoir is classified as tight gas due to its low porosity and micro-Darcy permeability. The lenticular sands and stratigraphic nature of this area make horizontal drilling impractical, and deviated well drilling is prevalent.By 2010, the average drilling time was reduced to 15 days by application of automated vertical-seeking tools with limited availability and poor cost effectiveness. Design and reliability improvements to various downhole tools have further reduced the average drilling time to 12.8 days with a conventional adjustable kick-off sub (AKO) mud motor by 2012. However, due to the various downhole tools involved, a bottomhole assembly (BHA) result analysis is a key step to evaluate the effectiveness of each tool, improve BHA design, identify superior drilling strategy, and eventually optimize the overall drilling performance.Several field cases are presented in this paper to conduct BHA result analysis, and several suggestions are promoted for future operations. These suggestions can reduce bit trip, improve oriented drilling efficiency, increase rotation rate of penetration (ROP) and save substantial financial resources for customers. The valuable information and lessons learned are crucial for Pinedale drilling operations, and they may be readily applied in other tight gas fields with similar characteristics to optimize drilling performance.

Maximizing well productivity and improving drilling efficiency remains a major challenge while drilling horizontal wells in US-land unconventional shale plays in the last few years. Reducing drilling times and eliminating trips for the curve bottomhole assembly (BHA) requires a motor that can be rotated at high RPM in the vertical section while still achieving buildup rate (BUR) in the curve. The challenges of horizontal well drilling in US land led to the recent introduction of a steerable optimized design motor (ODM) with a short bit-to-bend (BTB) distance. These ODMs achieved higher BUR in the curves than the conventional motors at lower adjustable kick-off (AKO) sub angle. Although the planned dogleg severities (DLS) stayed at the similar level, drilling vertical and curve sections of the horizontal wells in the Niobrara shale unconventional play posed additional challenges: – Rotating the BHA in the vertical section with a high AKO angle – Dealing with formation challenges – Holding the toolface to achieve consistent BUR in the curve – Completing the vertical and curve sections in one run The introduction in 2013 of the latest-generation steerable motors (LGSM) with further reduced short BTB distance design helped the operator overcome these challenges. The new system significantly improved drilling performance with excellent directional control. This paper will discuss the design, testing and results of horizontal wells drilled using the LGSM in the Niobrara unconventional shale play.

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.