Abstract: Geologic Interpretations for Reservoir and Fluid-Flow Rate Variations in Northern East Mesa Geothermal Wells

John L. Smith

Completion intervals of geothermal production wells drilled within the northern part of the East Mesa field have been selected to include those parts of the reservoir with temperatures above a thermal threshold of 325°F (163°C). The variations in the permeability-thickness values calculated for completions are reflected in observed differences in well-fluid flow rates.

Detailed studies of the well logs and available geophysical information, including modern Vibroseis data, demonstrate that deltaic reservoir rocks below 2,000 ft (600 m) are a vertically alternating sequence of sandstone and shale units that are stratigraphically correlative but now structurally displaced by gravity faults, folding, and strike-slip faults. Differences in reservoir character and well productivity are explained by a combination of factors that primarily include structural location and a retention of primary matrix porosity.

AAPG Search and Discovery Article #90963©1978 AAPG/SEG/SEPM Pacific Section Meeting, Sacramento, California