Development of an Improved Cement for Geothermal Wells
- Trabits Group, LLC, Wasilla, AK (United States)
After an oil, gas, or geothermal production well has been drilled, the well must be stabilized with a casing (sections of steel pipe that are joined together) in order to prevent the walls of the well from collapsing. The gap between the casing and the walls of the well is filled with cement, which locks the casing into place. The casing and cementing of geothermal wells is complicated by the harsh conditions of high temperature, high pressure, and a chemical environment (brines with high concentrations of carbon dioxide and sulfuric acid) that degrades conventional Portland cement. During the 1990s and early 2000s, the U.S. Department of Energy’s Geothermal Technologies Office (GTO) provided support for the development of fly-ash-modified calcium aluminate phosphate (CaP) cement, which offers improved resistance to degradation compared with conventional cement. However, the use of CaP cements involves some operational constraints that can increase the cost and complexity of well cementing. In some cases, CaP cements are incompatible with chemical additives that are commonly used to adjust cement setting time. Care must also be taken to ensure that CaP cements do not become contaminated with leftover conventional cement in pumping equipment used in conventional well cementing. With assistance from GTO, Trabits Group, LLC has developed a zeolite-containing cement that performs well in harsh geothermal conditions (thermal stability at temperatures of up to 300°C and resistance to carbonation) and is easy to use (can be easily adjusted with additives and eliminates the need to “sterilize” pumping equipment as with CaP cements). This combination of properties reduces the complexity/cost of well cementing, which will help enable the widespread development of geothermal energy in the United States.
- Research Organization:
- Trabits Group, LLC, Wasilla, AK (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Geothermal Technologies Office
- Contributing Organization:
- University of Alaska Fairbanks
- DOE Contract Number:
- EE0002785
- OSTI ID:
- 1178195
- Report Number(s):
- Final Scientific/Technical Report
- Country of Publication:
- United States
- Language:
- English
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