Applications, Results, and Lessons Learned From Using Roller Reamers in Hard, Abrasive Formations – The FORGE Project Application

Abstract The expanding geothermal energy market faces unique drilling challenges such as long intervals in hard, abrasive igneous or metamorphic formations at high temperatures. In some cases, drilling is further complicated by significant interfacial severity or a high potential for stick-slip. Drilling at the Department of Energy's Frontier Observatory for Research in Geothermal Energy (FORGE) site in Utah has provided an opportunity for improving drilling performance and reducing dysfunction in a relatively homogeneous granitoid. Activity at this field laboratory has included running and evaluating roller reamers while drilling multiple vertical monitoring wells and two, 65º laterals in high-strength granite at temperatures more than 400ºF. Reamers were run in the bottomhole assemblies (BHAs) of one of the vertical wells as well as in the two deviated wells with vibrational sensors in the drill bits and BHA bodies. Although most drilling experience qualitatively supports the beneficial use of reamers as a mitigation tool, the data collected during this project provided field-based validation and evidence of the merits of using roller reamers in a hard rock environment. A significant amount of data were collected from downhole measurements during the drilling of the production Well 16B(78)-32, enabling a detailed analysis of challenges faced by the reamers and the benefits obtained from their use in the drillstring. While drilling Well 16B(78)-32, downhole drilling parameters were collected continuously at the bit and in the BHAs. This supplemented standard electronic data and extensive logging operations. Vibration information was collected routinely while drilling this well, enabling detailed analyses for developing recommendations to capitalize on the lessons learned during the operations. This paper includes previous experience with roller reamers at Well 16A(78)-32 and Well 78B-32 in the same area and provides lessons learned based on reamer use in these wells.