Kaolinite precipitation and dissolution: effects on porosity and permeability
Kaolinite is a common clay mineral that occurs in subsurface sandstones and shales. Kaolinite can form as a product of reactions between minerals and solutions such as the breakdown of feldspars or smectites. In turn, kaolinite can dissolve in reactions that form chlorite or smectite. The precipitation of kaolinite could either augment or diminish porosity and permeability. In addition to natural diagenetic reactions, kaolinite has been observed to form as a result of secondary or tertiary recovery techniques. In such cases, its precipitation can rapidly decrease porosity and permeability, thereby inhibiting production. By measuring the dissolution and precipitation rates of kaolinite, structurally and compositionally the simplest clay, the authors can gain insight into similar processes for other important clay minerals. Such data are sorely needed for modeling diagenetic fluid-rock interactions. Precipitation and dissolution rates of kaolinite were measured in flow-through reaction cells at diagenetic temperatures. The effects of solution composition, solution saturation state, and flow rate were examined. Data collected thus far at 80/degree/C indicate that dissolution rates decrease by as much as an order of magnitude as equilibrium concentrations are approached. Dissolution is congruent as long as the solutions are undersaturated with respect to other phases such as quartz or gibbsite. The kinetics experiments also have proved to be an effective method for determining the solubility of kaolinite, which is requisite for interpreting the rate data. The results obtained in this study demonstrate that the experimental method is highly useful for determining the dissolution and precipitation rates of silicates in solutions of diagenetic interest.
- Research Organization:
- Yale Univ., New Haven, CT (USA)
- OSTI ID:
- 6133035
- Report Number(s):
- CONF-890404-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Vol. 73:3; ISSN AABUD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CHEMICAL REACTION KINETICS
DIAGENESIS
DISSOLUTION
GEOLOGIC DEPOSITS
KAOLINITE
KINETICS
MINERAL RESOURCES
MINERALS
OXYGEN COMPOUNDS
PETROLEUM DEPOSITS
POROSITY
PRECIPITATION
REACTION KINETICS
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SEPARATION PROCESSES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SOLUBILITY