摘要
The variable-density flow model-SEAWAT Version 4, was used to evaluate the hydrogeological conditions associatedwith hydraulic fracturing （fracking） the limestone oil reservoir in the Lower Cretaceous Sunniland Formation of Southwest Florida.This research contributes to the understanding of the controls on fluid and potential contaminant migration, following high pressurehydraulic fracturing. A hydraulic fracturing treatment used recently in this formation at the Collier-Hogan 20-3H well represents thebase case simulation. Multiple stage fracturing using typical stress periods, a modelled fracture zone radius, and various injectionrates were tested to evaluate the potential for horizontal and vertical fluid migration in and from the reservoir under dynamicconditions, with TDS used as a tracer. Hypothetical scenarios including preferential vertical pathways between the SunnilandFormation and the Lower Floridan aquifer Boulder Zone were also simulated. Results indicate that injected fluids do not migratesignificantly in the lateral and vertical directions beyond the design fractured zone, unless a preferential pathway exists within closeproximity to the fractured zone. In a worst-case scenario under the simulated conditions, vertical heads are approximately 580 metersgreater than static conditions and fluids associated with hydraulic fracturing vertically migrate approximately 500 meters; therefore,the quality of the deepest sources of drinking water is not compromised. Analytical results from a monitoring well installed in theimmediate vicinity of the Collier-Hogan 20-3H well and at the base of the deepest source of drinking water support the conclusionthat impacts from hydraulic fracturing fluids have not migrated into the deepest sources of drinking water.
