Constant-pressure charging of a liquid-dominated geothermal reservoir

Technical Report · Mon Mar 01 04:00:00 EST 1982

DOI:https://doi.org/10.2172/5350603· OSTI ID:5350603

Goyal, K P; Narasimhan, T N

A two-dimensional mathematical model of a fault controlled geothermal reservoir has been developed. Heated water rising in a fault is assumed to charge a reservoir which is overlain by a thin impermeable, thermally conducting cap rock. The mass flow rate or the pressure associated with the charging process at the fault inlet is unknown and can only be estimated. Thus, the pressure in the fault at the bottom of the reservoir is assumed to be prescribed. Quasi-analytic solutions for the distributions of velocity, pressure, and temperature are obtained in the fault-reservoir system for high Rayleigh number flow. In this approximation, the upwelling fluid does not cool off appreciably until it reaches the cold upper boundary of the reservoir and encounters conductive heat loss. The thermal boundary layer, which is thin at the top of the fault, grows outward laterally and occupies the full thickness of the aquifer in the far-field. This study shows that a near isothermal temperature profile, in the aquifer-region close to the fault, can result due to significant horizontal velocities as opposed to the conventional intuitive interpretation of strong vertical mixing due to convection. An interpretation of data from over a dozen wells from East Mesa geothermal field in California seems to qualitatively support the model suggested.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5350603
• Report Number(s): LBL-11836; ON: DE82013876
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150201* -- Geology & Hydrology of Geothermal Systems-- USA-- (-1989)
ANALYTICAL SOLUTION
BOUNDARY LAYERS
EAST MESA GEOTHERMAL FIELD
ENERGY SYSTEMS
GEOLOGIC FAULTS
GEOLOGIC STRUCTURES
GEOTHERMAL FIELDS
GEOTHERMAL SYSTEMS
Geothermal Legacy
HOT-WATER SYSTEMS
HYDROTHERMAL SYSTEMS
LAYERS
MATHEMATICAL MODELS
TWO-DIMENSIONAL CALCULATIONS