Publications Details

Thermal Expansion, Fluid Flow, and Thermal Shock of Cement and a Cement/Steel Interface at Elevated Pressure and Temperature

Bauer, Stephen J.; Barrow, Perry C.; Kibikas, William M.; Pyatina, Tatiana; Sugama, Toshifumi

A critical parameter for the well integrity in geothermal storage and production wells subjected to frequent thermal cycling is the interface between the steel and cement. In geothermal energy storage and energy production wells an insulating cement sheath is necessary to minimize heat losses through the heat uptake by cooler rock formations with high thermal conductivity. Also critical parameters for the well integrity in geothermal storage and production wells subjected to frequent thermal cycling is the interface between metal casing and cement composite. A team from Sandia and Brookhaven National Labs is evaluating special cement formulations to facilitate use during severe and repeated thermal cycling in geothermal wells; this paper reports on recent finding using these more recently developed cements. For this portion of the laboratory study we report on preliminary results from subjecting this cement to high temperature (T> 200°C), at a confining pressure of 13.8 MPa, and pore water pressure of 10.4 MPa. Building on previous work, we studied two sample types; solid cement and a steel cylinder sheathed with cement. In the first sample type we measured fluid flow at increasing elevated temperatures and pressure. In the second sample type, we flowed water through the inside of the steel cylinder rapidly to develop an inner to outer thermal gradient using this specialized test geometry. In the paper we report on water permeability estimates at elevated temperatures and the results of rapid thermal cycling of a steel/cement interface. Posttest observations of the steel-cement interface reveal insight into the nature of the steel/cement bond.