Displacement of formation fluids by hydraulic fracturing

Hydraulic fracturing of a geologic formation induces fluid flow within the formation in response to fracturing fluid loss and poroelasticity effects. Thus, hydraulic fracturing displaces the fluids that are distributed within the formation prior to fracturing, and may mobilize contaminants if applied in conjunction with groundwater contamination remediation. Fluid displacement is determined by coupling relations for hydraulic fracture extension to the temporal and spatial superposition of fundamental solutions for point fluid injection and a point dilation. Expressions are developed for three two-dimensional hydraulic fracture models for the limiting cases of high and low fracturing fluid loss to the formation. These results indicate that fluid displacement decreases with distance from the fracture and approaches an axisymmetric variation at greater than two fracture lengths from the well bore. Displacements induced by fluid loss and poroelasticity converge at greater than one fracture length from the fracture surface. Determination of fluid displacement for a hydraulic fracture treatment that may be typical in groundwater contamination remediation returns displacement magnitudes that are not likely to hamper the remediation effort.