Laboratory investigation of formation damage of an artificial fracture at simulated geothermal conditions

Formation damage mechanisms in a fracture-dominated geothermal reservoir were investigated through the use of simulated fractures. The experiments systematically investigated fracture conductivity impairment resulting from exposure to three discrete fluid systems known to be sources of formation damage. The fluids used included: a clear brine containing suspended solids representative of those produced during drilling; two clear brines of incompatible chemical composition which, when intermingled, produce carbonate scaling and precipitation; and a colloidal drilling fluid containing bentonite clay as the colloid. The test program concentrated on fracture conductivity impairment, not matrix permeability impairment. The test procedures were designed to simulate the infiltration of drilling fluid into the natural fractures of the geothermal reservoir system.