Materials for Geothermal Production
Advances in the development of new materials continue to be made in the Geothermal Materials Project. Many successes have already been accrued and the results used commercially. In FY 1991, work was focused on reducing well drilling, fluid transport and energy conversion costs. Specific activities performed included lightweight CO{sub 2}-resistant well cements, thermally conductive and scale resistant protective liner systems, chemical systems for lost circulation control, corrosion mitigation in process components at The Geysers, and elastomer-metal bonding systems. Efforts to transfer the technologies developed in these efforts to other energy-related sectors of the economy continued and considerable success was achieved. Laboratory testing of BNL-developed phosphate modified calcium aluminate cements confirmed their hydrolytic stability in 300 C brine and their resistance to chemical attack by CO{sub 2}. Specimens were found to be >20 times more resistant to carbonation than Class H cement and twice as resistant as unmodified calcium aluminate cements. Testing of thermally conductive polymer cements as potential corrosion resistant liner materials for use in heat exchanger applications was continued. Field test were conducted in flowing hypersaline brine and the results indicated scale deposition rates lower than those on a high alloy steel. Additional tests for bottoming cycle heat exchange use are planned for FY 1992. Progress was also made with chemical systems for lost circulation control. If materials placement is to be performed by pumping through an open drillpipe or through a drillable straddle packer, a bentonite-ammonium polyphosphate-borax-magnesium oxide formulation, containing fibers or particulates when large fissures are encountered, can be used. This system was ready for demonstration in FY 1991, but a suitable test site did not become available. Optimization of this and three other formulations for use with other Sandia National Laboratories developed placement technology is being continued. Work to develop high temperature hydrolytically stable chemical coupling systems needed to bond elastomers to metal reinforcement commenced. Until these become available, it will not be possible to produce many important tools needed to reduce well-drilling costs. To date very promising results have been achieved using high melting point (> 280{sup o}) polyaromatic type adhesives. Compared to the best commercially available coupling systems which will undergo complete disbondment from stainless steel upon exposure for 1 day to brine at 200 C, copolymers made from the polyaromatic materials show no disbondment or loss of bond strength after 5 weeks. Additional work is required to improve the magnitude of the bond and to improve the thixotropic behavior of the adhesives in the liquid state. Cost-shared efforts with operators at the Geysers to evaluate the use of polymer concrete and polymeric liners to mitigate corrosion were continued. Small lined casing sections and full size collection piping tees are being tested. The results to date have been promising and larger-scale tests are planned.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 891895
- Report Number(s):
- CONF-920378-17; TRN: US200622%%541
- Resource Relation:
- Conference: Proceedings, Geothermal Energy and the Utility Market - The Opportunities and Challenges for Expanding Geothermal Energy in a Competitive Supply Market; San Francisco, CA, March 24-26, 1992, Geothermal Program Review X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Geothermal Materials Development, Annual Report FY 1991
Geothermal Materials Development. Annual report FY 1991