| dc.description.abstract | The coupling of the technologies of the horizontal drilling and hydraulic fracturing operations has enabled the economic development of the shale oil and gas reservoirs and led to the recent significant increase in the U.S. hydrocarbon production and reserve. The literature review revealed the importance of the fracture conductivity which is usually sacrificed in the hydraulic fracturing operation. The objective of this study is to experimentally evaluate the damaging mechanisms to fracture conductivity associated with the use of ceramic, sand, and resin-coated sand proppants in the hydraulic fracturing of Eagle Ford shale formations.
The combined effect of proppant crushing, compaction, and embedment mechanisms is assessed by the measurements of the fracture width and proppant porosity at stress conditions using a new procedure that allows the direct measurement of the propped fracture width at simulated downhole conditions. Furthermore, the proppant diagenesis mechanism is assessed by studying the chemical interactions between the proppant, the fluid, and the formation, using, high-pressure/high-temperature (HP/HT) aging cells, and, the post-aging analyses of the solids and fluids using scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscopy (EDS) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES).
The study presents tables of the values of the fracture width and the proppant porosity for different proppant types and concentrations. The 20/40-mesh resin-coated sand at concentration 0.2 lb/ft^2 showed the highest reduction in fracture width and proppant porosity of 25.88 and 44.16%, respectively, while the 40/70-mesh ceramic proppant at 0.6 lb/ft^2 showed the minimum reduction of 5.68 and 7.88%, respectively, at 8000 psia closure stress. Furthermore, the diagenesis process was found more profoundly in the case of ceramic proppant; and the chemical interactions between the proppant, the formation, and the fluid led to the precipitation of CaSOv4 and the overgrowth of different zeolite minerals on the proppant surface.
The study contributes to the understanding of the proppant-related fracture conductivity damaging mechanisms. The results can be used in the hydraulic fracturing design, the production forecasting models, and the proppant selection process for an improved fracture conductivity, and hence, an improved hydrocarbon production from the Eagle Ford shale formations. | |
