Delivering commercially attractive geothermal coiled tubing operations

Abstract

Although geothermal coiled tubing (CT) operations are performed globally, making them commercially attractive everywhere is a challenge. This challenge is not new in the geothermal industry. New technology update with the geothermal industry uptake suffers from low project volumes, technically challenging environments, historically low success ratios and the ever-present need to keep costs down. These hurdles keep many well technologies on the fringes of widespread geothermal adoption. Adoption of coiled tubing technology for geothermal well maintenance is no different. Some geographies where CT units (CTU) are readily available, such as New Zealand or the USA perform weekly CTU operations which regularly boast the generation savings they deliver. Other geographies like the Philippines perform ad-hoc operations and seem to only report on failures, unexpected costs, non-productive time and what to do better next time. What is driving these regional successes and failures? How can more locations reach that flash point where CTU workovers become a routine cost-effective maintenance activity? This paper will share & discuss the results of a geothermal CT operational data review. It includes data from 10 years of geothermal CT operations in New Zealand. It will share statistics and discussion surrounding root causes for geothermal CT incidents and CT job costs. It will provide recommendations to well operators on how to reduce their CTU workover costs and job cost variability. The conclusions of this study include reducing CTU equipment & maintenance failures, developing robust procedures & knowledge management (i.e. training & competency). From the job cost data review, the paper discusses CT workover cost & cost variability drivers including well depth and nitrogen volumes required for operations. Finally, the paper discusses the value of after-action reviews; case study analyses; implementing a continuous improvement culture; rig efficiency metrics; and also introduces the concept of applying LEAN manufacturing to CT workovers. For geothermal energy to remain competitive in the global energy market, innovation must be ongoing and deliver generation cost reductions. Uptake of the recommendations presented here presents a great opportunity to achieve this aim.