Comparison of Geothermal Well Costs for Slim-hole Exploration wells versus Big-hole Exploration wells

Abstract

in the geothermal industry in Indonesia, many geothermal operators using big-hole wells for exploration. understand that well and drilling infrastructure costs for standard and big-hole exploration wells are quite high. High exploration costs and the risks of exploration itself are causing the slow development of geothermal fields in Indonesia. Slim-hole exploration wells in geothermal is one option that can be used to confirm the resource in certain geothermal fields. Two emerging questions are: (i) whether a slim-hole well can deliver the exploration objective and how economic is the cost, (ii) is the use of slim-hole wells an option for exploration planning strategy in the geothermal industry in Indonesia. To answer these questions, we have conducted a literature study regarding the past operation of drilling in exploration projects in Indonesia. We
will break down the cost of drilling services and material in the past operations in Indonesia to get the unit rate data and will adapt these data to calculate the cost of current geothermal slim-hole designs. This paper aims to summarize the information in the literature on slim-hole well costs compared with the cost of big-hole wells using the same subsurface data such as lithology, casing setting depth, reservoir zone, etc. This calculation was conducted by authors over the past several months. Finally, this paper is expected to trigger more discussion among geothermal practitioners about the economics of slim-hole drilling. It is hoped that with the same amount of budget slim-hole wells could deliver more data and increase confidence about the geothermal resource in the area of interest.