Integrated Drilling Optimization and Downhole Drilling Dynamics Enables PDC Bits to Drill in the Colorado Region of the San Juan Unconventional Gas Basin

摘要

The San Juan basin is a prolific natural gas play in northwestern New Mexico and southwestern Colorado. For more than four years, all attempts to find a poly crystalline diamond compact (PDC) solution for the northern part of the basin have been unsuccessful or uneconomic; in addition, the performance of insert bits had also reached a plateau of roughly 60 ft/hr. In order to achieve the next step change in drilling performance, it was decided that a drilling optimization process that was integrated with high speed downhole drilling dynamics was required. The optimization process required the cooperation of the client, the directional drilling company, and the optimization company. The team was challenged to find a fixed cutter solution that could drill from surface to total depth (TD) in one run and at over 100 ft/hr; these challenges thus became the project’s two primary objectives. This paper discusses how an optimization process was integrated with high speed, multiple placement, downhole drilling dynamics analysis in order to discover what was limiting the performance of fixed cutter bits. The process involved four phases - analysis, planning, execution, and evaluation - utilizing a four well project. The lessons learned from each well were then applied to the next well in the sequence. From the lessons learned, small changes were made to the drilling assembly after each well in the sequence. These changes were then analyzed on the subsequent well. On each section, the downhole drilling dynamics data was merged with surface data. The analysis of this data demonstrated that the main limiters to drilling performance were poor weight transfer and vibration. On the fourth well in the sequence, a specially designed, six bladed fixed cutter PDC bit drilled the entire 2,858ft of the 7 7/8” section, in one run. The overall rate of penetration (ROP) including connection time, was 102 ft/hr, surpassing the goal of 100 ft/hr.