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• 1. [Image] Annual Report on the Project to Design and Experimentally Test an Improved Geothermal Drill Bit

  	Progress is reported in a research and development program to design, build, and test an improved geothermal drill bit. The major tasks of the Phase I effort are entitled: failure mechanisms of existing ...
  	Citation × Citation Citation Abstract Copy Title: Annual Report on the Project to Design and Experimentally Test an Improved Geothermal Drill Bit Author: Barker, L.M. Year: 1976 Progress is reported in a research and development program to design, build, and test an improved geothermal drill bit. The major tasks of the Phase I effort are entitled: failure mechanisms of existing bits; new steels and new bearing design; and new seals and lubricants. It appears that a significant gain in drill-bit life can be attained by the use of higher-temperature steels which retain more hardness at temperatures above 260/sup 0/C (500/sup 0/F). Such steels are available, and two research bits of high-temperature steels were made and will shortly be tested in a laboratory-simulated full-scale geothermal drilling environment. Two control bits of the same design, but made with conventional drill bit steels, were also obtained for identical laboratory test runs, so that the performance of the research bits can be meaningfully assessed. Base-line properties of the steels, such as hardness and fracture toughness as functions of temperature, are being measured to further assess the value of the high-temperature steels selected for the research bits. A geothermal test vessel was designed and fabricated in which the full-scale drill bits will be tested. The vessel is capable of temperature to 427/sup 0/C (800/sup 0/F) and pressures to 35 MPa (5,000 psi). Seal and lubrication designs were studied, and the state of the art in high-temperature seals and lubricants was assessed. Some candidate seals and lubricants have been obtained for testing, and others are being procured. In addition, a seal test vessel has been designed and will soon be completed which can simulate the geothermal drilling environment in full-scale testing of seal and lubricant designs and materials. (JGB) Title: Annual Report on the Project to Design and Experimentally Test an Improved Geothermal Drill Bit Author: Barker, L.M. Year: 1976 Progress is reported in a research and development program to design, build, and test an improved geothermal drill bit. The major tasks of the Phase I effort are entitled: failure mechanisms of existing bits; new steels and new bearing design; and new seals and lubricants. It appears that a significant gain in drill-bit life can be attained by the use of higher-temperature steels which retain more hardness at temperatures above 260/sup 0/C (500/sup 0/F). Such steels are available, and two research bits of high-temperature steels were made and will shortly be tested in a laboratory-simulated full-scale geothermal drilling environment. Two control bits of the same design, but made with conventional drill bit steels, were also obtained for identical laboratory test runs, so that the performance of the research bits can be meaningfully assessed. Base-line properties of the steels, such as hardness and fracture toughness as functions of temperature, are being measured to further assess the value of the high-temperature steels selected for the research bits. A geothermal test vessel was designed and fabricated in which the full-scale drill bits will be tested. The vessel is capable of temperature to 427/sup 0/C (800/sup 0/F) and pressures to 35 MPa (5,000 psi). Seal and lubrication designs were studied, and the state of the art in high-temperature seals and lubricants was assessed. Some candidate seals and lubricants have been obtained for testing, and others are being procured. In addition, a seal test vessel has been designed and will soon be completed which can simulate the geothermal drilling environment in full-scale testing of seal and lubricant designs and materials. (JGB) Close

• 2. [Image] Development of the high-temperature redox electrode. Interim report ending March 1980

  	The oxidation-reduction (known as redox) electrode was studied in a pH range corresponding to that found in a CO/sub 2/-silicate buffered system at temperatures ranging from 100 to 250/sup 0/C. Oxidizing ...
  	Citation × Citation Citation Abstract Copy Title: Development of the high-temperature redox electrode. Interim report ending March 1980 Author: Danielson, M.J. Year: 1980 The oxidation-reduction (known as redox) electrode was studied in a pH range corresponding to that found in a CO/sub 2/-silicate buffered system at temperatures ranging from 100 to 250/sup 0/C. Oxidizing conditions were created by injecting oxygen; the greatest reducing conditions, by using hydrogen. The sulfur system (H/sub 2/S, HS/sup -/, S/sup 2/) was not examined at this time, but future work will include this system since it is an important component of the geothermal brine. Both a platinized platinum (Pt-Pt) and a bare platinum (Pt-foil) electrode respond to the redox environment. The response does not appear to indicate thermodynamic equilibrium with the chemical environment; instead a mixed potential response is indicated. The difference in potential between a strong oxidizing environment (0.4-ppM O/sub 2/) and a strong reducing environment (0.5-atm H/sub 2/) is typically > 1 volt at all temperatures. The magnitude of this response makes the platinum electrode a suitable sensor for continuous monitoring of the geothermal environment for oxygen intrusions. The platinized platinum redox electrode is superior to the bare platinum electrode; PNL-3377 Title: Development of the high-temperature redox electrode. Interim report ending March 1980 Author: Danielson, M.J. Year: 1980 The oxidation-reduction (known as redox) electrode was studied in a pH range corresponding to that found in a CO/sub 2/-silicate buffered system at temperatures ranging from 100 to 250/sup 0/C. Oxidizing conditions were created by injecting oxygen; the greatest reducing conditions, by using hydrogen. The sulfur system (H/sub 2/S, HS/sup -/, S/sup 2/) was not examined at this time, but future work will include this system since it is an important component of the geothermal brine. Both a platinized platinum (Pt-Pt) and a bare platinum (Pt-foil) electrode respond to the redox environment. The response does not appear to indicate thermodynamic equilibrium with the chemical environment; instead a mixed potential response is indicated. The difference in potential between a strong oxidizing environment (0.4-ppM O/sub 2/) and a strong reducing environment (0.5-atm H/sub 2/) is typically > 1 volt at all temperatures. The magnitude of this response makes the platinum electrode a suitable sensor for continuous monitoring of the geothermal environment for oxygen intrusions. The platinized platinum redox electrode is superior to the bare platinum electrode; PNL-3377 Close

• 3. [Image] Field Electrochemical Measurements of Corrosion Characteristics of Materials in Hypersaline Geothermal Brine

  	A flow cell (with appropriate accessories) was developed for use in short-term testing of the corrosion behavior of materials in approximately 100{sup 0}C, hypersaline geothermal brine. The apparatus was ...
  	Citation × Citation Citation Abstract Copy Title: Field Electrochemical Measurements of Corrosion Characteristics of Materials in Hypersaline Geothermal Brine Author: Harrar, J.E. Year: 1977 A flow cell (with appropriate accessories) was developed for use in short-term testing of the corrosion behavior of materials in approximately 100{sup 0}C, hypersaline geothermal brine. The apparatus was designed to accommodate commercial (Petrolite) corrosion measurement equipment and conducted experiments on-line at the Lawrence Livermore Laboratory Test Station in the Salton Sea Geothermal Field. The apparatus also permitted direct readings of corrosion potentials, solution redox potential (E{sub h}), brine flow rate, pH, and temperature. Estimates of general corrosion rates were obtained by the linear polarization resistance technique and from measurements of complete potentiodynamic polarization curves. The latter also afforded predictions of pitting susceptibilities of active-passive type materials. Twenty-two alloys (with various heat treatments) were tested and readily grouped according to general corrosion resistances in acidified hypersaline (approximately 4 M chloride) brine. Especially promising in regard to corrosion resistance-vs-cost is the series of low Cr--Mo steels. Prescaling of materials in unacidified (pH approximately 5.7) brine prior to exposure to acidified (pH 2 to 4.5) brine was found to be beneficial in reducing corrosion rates at 100{sup 0}C Title: Field Electrochemical Measurements of Corrosion Characteristics of Materials in Hypersaline Geothermal Brine Author: Harrar, J.E. Year: 1977 A flow cell (with appropriate accessories) was developed for use in short-term testing of the corrosion behavior of materials in approximately 100{sup 0}C, hypersaline geothermal brine. The apparatus was designed to accommodate commercial (Petrolite) corrosion measurement equipment and conducted experiments on-line at the Lawrence Livermore Laboratory Test Station in the Salton Sea Geothermal Field. The apparatus also permitted direct readings of corrosion potentials, solution redox potential (E{sub h}), brine flow rate, pH, and temperature. Estimates of general corrosion rates were obtained by the linear polarization resistance technique and from measurements of complete potentiodynamic polarization curves. The latter also afforded predictions of pitting susceptibilities of active-passive type materials. Twenty-two alloys (with various heat treatments) were tested and readily grouped according to general corrosion resistances in acidified hypersaline (approximately 4 M chloride) brine. Especially promising in regard to corrosion resistance-vs-cost is the series of low Cr--Mo steels. Prescaling of materials in unacidified (pH approximately 5.7) brine prior to exposure to acidified (pH 2 to 4.5) brine was found to be beneficial in reducing corrosion rates at 100{sup 0}C Close