Print this pageCauses of Low Contrast, Low Resistivity in Hydrocarbon Productive Reservoirs of the Rocky Mountain and Mid-Continent Regions
MULLARKEY, JAMES C., and EDWARD D. DOLLY
Thirteen selected examples of hydrocarbon production from low contrast (less than 1.5 times the shale baseline resistivity), low resistivity (nominally less than 10 ohm-meters, most less than 6 ohm-meters) reservoirs are presented in a standardized format. The examples and format are taken from a guidebook published by the Rocky Mountain Association of Geologists and edited by the poster authors that contains 102 examples and six topical papers. Examples of reservoirs that are relatively more conductive or less resistive are presented in clastic carbonate pairs, where possible, organized by the primary cause of the anomalous resistivity. Causes examined in this presentation are clay minerals, water hydrocarbon transition zones, fluid salinities, capillary pressure, thin beds, accessory minerals, microporosity, and unique causes such as zeolite minerals. Cumulative production from the examples, which were taken from nine basins and span five geologic periods from the Ordovician to the Tertiary, totals over 1,960,880 barrels of oil and 23,000,000 mcf of gas.