Comparison of Well Completions used in Oil/Gas Wells and Geothermal Wells: a New Approach to Technology Transfer

Abstract

Renewable energy is seen as the future source for meeting the world’s growing demand, with geothermal offering a constant and independent supply. Tapping geothermal energy is not always straightforward as deep drilling is required in order to access this high -temperature resource. Geothermal drilling is expensive and is financed by the operator (usually districts or state representatives) with a long period of debt service before costs can be recovered from the energy sale (heat, electricity or a combination of both). It is reported that the success rate for geothermal wildcat wells is only 25-40%, so a reduction in the exploratory drilling costs would be a major incentive for increased exploitation of this resource.

However, drilling costs are only a part of the total well expenditure. Tubulars can double the total well cost , especially when complex well completions are required. Together, drilling and well completions can account for more than half of the capital cost for a geothermal power project.

This paper presents a comparison of different well completions used for oil, gas and geothermal wells. The study identifies ways in which to facilitate a faster technology transfer from the traditional oil and gas arena to the developing geothermal industry. The study provides engineers with a better understanding of geothermal well completion needs and suggests ways to reduce cost.