Can Geothermal Wells Go Cementless?

Abstract

Due to the high temperature cycles during its life, a geothermal well it is exposed to higher loads compared with conventional oil and gas wells. A conventional well construction utilizes and relies on cement for annular isolation between the casing and the formation, the isolation effectiveness derives from the cement properties behavior in downhole conditions while is setting after a given time. To date only few alternatives to oil well cements have been economically imposed on the market. Effective isolation is not always achieved with cement blends, for this reason alternative technologies such as metallic expandable elements derived from metallic packers can be integrated into casing string and provide the needed seal between casing and formation in the required depths. Given the current tendency in geothermal well construction and completion to use the casing as production string (tubing) rather than adding another string for the production needs, a cementless well construction could enhance the geothermal well construction process while adding achieving maximum well integrity for a much longer time when compared with cement. This paper will present some of the achievements in the well planning of cementless wells using metallic sealing units and will discuss possible future applications in geothermal fields.