Thermal recovery from a multiple stimulated HDR reservoir

Abstract

A conceptual model is presented to describe thermal recovery from an infinite geological body through an arbitrary number of spherical production zones. The dimensionless parameters of volume averaged fluid recovery temperature ( T ̄ D ), fluid circulation rate ( Q D), thermal porosity ( Φ D) and geometry uniquely define response within dimensionless time ( t D). Dimensionless circulation rate ( Q D) is directly proportional to fluid circulation rate and inversely proportional to the radii of the stimulated zones. Histories of thermal recovery are specifically presented for colinear arrays of stimulated zones produced at uniform fluid circulation rates. In the steady condition, mean recovery temperature ( T ̄ D ) is defined purely in terms of dimensionless circulation rates ( Q D) and the relative production geometry. In steady production, the mean output temperature ( T ̄ D ) reduces with an increase in the number of zones as a natural consequence of thermal interference. In the transient case also, production temperature ( T ̄ D ) for multiple zones reduces as both the number of zones and their mutual proximity increases. These consequences are, significantly, apparent for intermediate values of circulation rate ( Q D) only