| dc.description.abstract | Hydraulic fracturing is a technique extensively used in the oil and gas industry, where water, proppant (sand) and additives are injected into unconventional reservoirs to enhance the recovery of shale hydrocarbon. Because of complex fracture growth in naturally fractured unconventional reservoirs, the ultimate goal of hydraulic fracturing operation should be changed from achieving a desired fracture geometry to maximizing the total fracture surface area (TFSA) for given fracturing resources, as it will allow more drainage area available for oil recovery. Unfortunately, there are no such techniques available to develop pumping schedules to maximize the TFSA for given fracturing resources in naturally fractured unconventional reservoirs. Motivated by this, we developed a model-based pumping schedule by utilizing a recently developed unconventional complex fracture propagation model called Mangrove describing complex fracture networks by accounting for interaction between hydraulic fractures and natural fractures. We demonstrated that by using the proposed control scheme, the TFSA can be greatly enhanced which will increase the cumulative shale oil production volume, compared to the existing pumping schedules. Although some previous studies have developed pumping schedules that maximize gas production for a single-size proppant, there are very few studies that consider the effect of varying proppant diameters across pumping stages on shale gas production.
Motivated by this, we conducted a sensitivity analysis and extended the previous pumping schedule by considering multi-size proppant for simultaneously propagating multiple fractures to maximize shale gas production from unconventional reservoirs. Since the size of injected proppant particles determines the average propped surface area (PSA) and average fracture conductivity (FC), we developed a framework called Sequentially Interlinked Modeling Structure (SIMS) to predict the average PSA, average FC and cumulative shale gas production volume for a given pumping schedule. Then, we used the SIMS framework to obtain a multi-size proppant pumping schedule that maximizes shale gas production. Finally, we demonstrated that obtained pumping schedule gives a gas production volume greater than the values obtained from the existing pumping schedules which consider only single size proppant. | en |
