Carbon dioxide injection and resultant alteration of Weber Sandstone (Pennsylvanian-Permian), Rangely field, Colorado
Geologic interpretations made during the current EOR (enhanced oil recovery) project at Rangely field (Rio Blanco County, Colorado), have made interesting connections between alteration of reservoir mineralogy and texture, changes in produced water composition, and increased production problems. Carbon dioxide is being injected into the Weber Sandstone in portions of Rangely field. The carbon dioxide injection is part of a very successful tertiary recovery project initiated in late 1986. The bottomhole pH of Weber brine has decreased from approximately 7.5 to 4.5 with the addition of CO/sub 2/. Changes in the chemistry of produced water are associated with alteration of reservoir mineralogy. The CO/sub 2/ flood has caused a substantial increase in the concentrations of iron, calcium, magnesium, and strontium in the produced brine. The amount of increase is directly related to the volume of CO/sub 2/ produced in each well. This increase resulted from the dissolution of carbonate cements, authigenic clays, and detrital feldspars. An increase in the calculated scaling potential of the produced water is a result of this change in chemistry. Hypotheses based on the water-chemistry changes were confirmed in pressure-cell and core-flood experiments. Core-flood experiments also indicate no net change in permeability following carbon dioxide injection: the increase in permeability due to the dissolution of carbonate cements is being offset by a decrease caused by migratory clays plugging pore throats. The clays, which coat the authigenic carbonates, are liberated when the carbonates are dissolved.
- Research Organization:
- Chevron U.S.A. Inc., New Orleans, LA (USA)
- OSTI ID:
- 6125922
- Report Number(s):
- CONF-890404-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 73:3; Conference: AAPG annual convention with DPA/EMD Divisions and SEPM, San Antonio, TX, USA, 23 Apr 1989
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COLORADO
PETROLEUM DEPOSITS
OIL WELLS
CARBON DIOXIDE INJECTION
RESERVOIR ROCK
BRINES
CLAYS
ENHANCED RECOVERY
PENNSYLVANIAN PERIOD
PERMEABILITY
PERMIAN PERIOD
PETROLEUM
PH VALUE
POROSITY
SANDSTONES
SEDIMENTARY BASINS
ENERGY SOURCES
FEDERAL REGION VIII
FLUID INJECTION
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
MINERAL RESOURCES
MISCIBLE-PHASE DISPLACEMENT
NORTH AMERICA
PALEOZOIC ERA
RECOVERY
RESOURCES
ROCKS
SEDIMENTARY ROCKS
USA
WELLS
020300* - Petroleum- Drilling & Production