Evaluation of geothermal drilling fluids using a commercial bentonite and a bentonite/saponite mixture

Technical Report · Sun Feb 01 00:00:00 EST 1987

OSTI ID:6799144

Guven, N; Carney, L L; Ridpath, B E

High temperature properties of two clay fluids, based on commercially available bentonite and a bentonite-saponite mixture, are evaluated at the temperature range 300-600/sup 0/F under appropriate confining pressures up to 16,000 psi. Bentonite fluids exhibit an anomolous viscosity increase in the temperature range 250-400/sup 0/F. This anomolous viscosity is further enhanced by the salts and hydroxide of sodium leading to the gelation of the fluid. Salts and hydroxide of calcium at 1% concentrations are very detrimental to the viscosity, gel strength, and wall-building (filtration) properties of the fluids at all temperatures. Salts of potassium provide a good control over the high temperature gelation of the bentonite fluids but they result in high fluid losses. High and low molecular weight polymers (sodium polyacrylates), and lignite and lignosulfonates at neutral pH range are proved to be valuable mud additives for the high temperature behavior of the bentonite fluids. They maintain the pH of the fluid close to the neutral and thus inhibit the mineral reactions of the smectites in bentonites at high temperatures. These mineral reactions predominate in the alkaline conditions of the fluids in the presence of hydroxides of Na, Ca, and K. Consequently, a large portion of smectites dissolves and new silicate phases precipitate at and above 400/sup 0/F in these fluids. The fluids based on a (1:1) mixture of bentonite and saponite display a high initial viscosity (up to 250/sup 0/F) instead of the viscosity maxima between 150-400/sup 0/F of the bentonite fluids. Therefore, the addition of saponite to the bentonite fluid can provide a balanced viscosity at all the temperatures.

• Research Organization: Texas Tech Univ., Lubbock (USA). Dept. of Geosciences
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6799144
• Report Number(s): SAND-86-7180; ON: DE87009690
• Resource Relation: Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
DRILLING FLUIDS
CHEMICAL COMPOSITION
RHEOLOGY
BENTONITE
CALCIUM HYDROXIDES
POLYMERS
POTASSIUM HYDROXIDES
SALTS
SODIUM HYDROXIDES
TEMPERATURE DEPENDENCE
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CLAYS
FLUIDS
HYDROGEN COMPOUNDS
HYDROXIDES
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
SODIUM COMPOUNDS
420206* - Engineering- Mining & Drilling Equipment & Facilities- (1980-1989)