Measuring Cement Thermal Expansion Coefficient and Its Impact Towards Geothermal Well Construction

Abstract

The global energy demand is increasing worldwide, and geothermal is becoming an attractive option due to the untapped resources and being considered an important green energy source. Geothermal wells are challenging due to their depth, which makes the subsurface condition very hostile with respect to temperature and pressure. For the geothermal project to succeed, it is vital to maintain the integrity of the well so that the maximum energy can be produced from it. In that respect, cement plays a crucial role, as different studies have suggested that cement is one of the most critical parameters that control the integrity of the well. Though many cement properties have been investigated by researchers, thermal properties are the least studied parameter. Moreover, the elevated temperature in the geothermal wells makes thermal properties the most important parameter to be considered. Expansion and contraction of the cement due to temperature fluctuation can affect the cement's bonding with the formation and casing and create micro-annuli in the cement matrix. Hence, this paper focuses on measuring the linear thermal expansion of different oil well cements that have been cured for different time periods. The measurement of the thermal expansion was done with the help of a novel apparatus that works on the principle of optical shadowing. The results from this study can be used to find the integrity of the cement through simulations for geothermal wells.