Optimization of the composition of materials used for cementing high-enthalpy (150-350 C) geothermal well casing
The cementing materials laid in the casing-formation annulus must be stable and maintain suitable physical characteristics during the entire life of a geothermal well. The purpose of this study is to select the best components for cement formulation according to bottomhole conditions. It determines the long-term behaviour under the combined effect of temperature, pressure, formation fluids and materials already laid in wells or likely to be laid. Bottomhole conditions are simulated by laboratory equipment, specially designed to support high pressures (up to 50 MPa) and temperatures (up to 350 C) and to provide a long-term resistance to aggressive fluids. Various materials have been studied: hydraulic cements standardised by the American Petroleum Institute, experimental hydraulic cements, and thermosetting organic resins. A classification by quality has been drawn up, based on mechanical resistance levels, hardened material permeability and long-term stability. Results depend on bottomhole conditions. In certain cases (200 C approx. vapour) the phenolic-furanic resin-base compositions have proven to be more stable than those prepared with hydraulic binders. Even though development is limited, the application of physical methods (X-ray tomography, scanning microscopy, analysis with Castaing probe) to materials hardened with a hydraulic binder base has made it possible to establish a relationship between the development in the characteristics and the development in the structure.
Bibliographic Reference: EUR 12909 EN (1990) 21 pp., MF, ECU 4
Record Number: 199011044 / Last updated on: 1994-12-01
Original language: en
Available languages: en