Integrated reservoir modeling sensitivity study for the hydraulic fracturing optimization in the Eagle Ford and Niobrara formations, An

Abstract

There are many intrinsic factors affecting production from unconventional reservoirs such as hydrocarbon in place, pressure, permeability, porosity. In addition, the operational factors also have a strong effect on hydrocarbon production. While we cannot change the intrinsic factors, it is possible to optimize the operational factors to achieve the highest hydrocarbon recovery. Therefore the main focus of this research is to conduct a sensitivity study of different operational factors such as the proppant size, type, concentration and injected fluid volume and type on the hydrocarbon recovery. The formations selected for this investigation are the Eagle Ford and Niobrara. In this research, I conducted an integrated study from reservoir characterization, to stimulation and reservoir simulation, to evaluate the effect of different fluid-proppant combinations on oil production. The log data for the Eagle Ford and the Niobrara were used by previous studies to characterize the formations and build the geological models. Hydraulic fracturing stimulation was then conducted to create the combined discrete fracture network (DFN) for production simulation. The production results from reservoir modeling studies were historically matched to the field production data to validate the accuracy of the models. Then, multiple hydraulic fracturing stimulation scenarios were conducted to evaluate the effect of different factors including fracturing fluid volume and proppant size, type and concentration on oil production. Economic and environmental analyses were conducted in the end before a final fluid-proppant recommendation. I found that for both formations, gel with sand proppant leads to the highest production output. The observations from the case studies for the Eagle Ford suggest that an ideal fluid volume (bbl, per foot of lateral) to proppant mass (lb, per foot of lateral) ratio is close to 2:3. Increasing hydraulic fracturing fluid volume generally increased the recovery, while increasing proppant concentration did not yield a significant improvement in the total oil recovery. Larger proppant led to higher recovery, while a mix of proppants did not improve the oil production. This research suggests that pumping gel with sand proppant will lead to the highest return on investment, while also potentially being the most environmentally-friendly solution. This study could benefit from further research to develop specific tools for even higher accuracy in simulations.