Estimation of mineralogy and lithology from geochemical log measurements
- Colorado School of Mines, Golden (USA)
- Exxon Production Research Co., Houston, TX (USA)
Mineralogy, chemistry, and physical properties of core samples from a research well in Grand County, Utah, have been determined to assess the applications of geochemical logging tool measurements to reservoir characterization. The cored interval (over 827 ft or 252 m of continuous core) samples a wide range of lithologies, including subarkose, sublitharenite, litharenite, feldspathic litharenite, quartz wacke, lithic wacke, siltstone, mudstone, and coal. Total clay mineral contents range from 2 to almost 60 wt. go and consist primarily of illite and kaolinite with subordinate ordered, mixed-layer illite/smectite. Dolomite cement is pervasive; locally, large amounts (up to 25 wt.%) of siderite or ankerite are present. Total feldspar minerals comprise 5-18 wt.% with sodium-rich plagioclase slightly more abundant than potassium feldspar. Continuous geochemical well logs of 12 elements (K, U, Th, Al, Si, Ca, Fe, S, Gd, Ti, Cl, and H) were obtained using logging tools that measure neutron capture, neutron activation, and natural gamma-ray activities. Applications of these geochemical log measurements to assess mineralogy and lithology for the research well are complicated by (1) the near compositional colinearity of the assemblage illite + kaolinite + K-feldspar, (2) the presence of dolomite and iron-bearing carbonates, (3) the predominance of Naplagioclase over K-feldspar, and (4) the abundance of sedimentary and metamorphic rock fragments in the litharenite group of lithologies. Because of these mineral and textural features, successful application of the log measurements to reservoir characterization requires calibration to core analyses. Mineral logs calculated using least-squares inversion programs accurately describe changes in mineralogy and mineral proportions once the mineral assemblage is identified. Lithology is best estimated based on these mineral logs.
- OSTI ID:
- 6348037
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:6; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DRILL CORES
GEOCHEMISTRY
MINERALOGY
PHYSICAL PROPERTIES
COAL
DOLOMITE
FELDSPARS
ILLITE
KAOLINITE
SANDSTONES
SILTSTONES
SMECTITE
UTAH
WELL LOGGING
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CARBONATE MINERALS
CARBONATES
CHEMISTRY
CLAYS
ENERGY SOURCES
FEDERAL REGION VIII
FOSSIL FUELS
FUELS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MATERIALS
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
USA
020200* - Petroleum- Reserves
Geology
& Exploration