| dc.description.abstract | To further improve a propped fracture’s performance, this study investigated how the distribution of a proppant’s grain size can affect fracture conductivity. The goals of this project were to quantify and explain the impact uniform and non-uniform grain size distribution for 100-mesh proppants have on the propped fracture conductivity measured for fractured shale core samples.
Eagle Ford core collected from an outcrop and Meramec core extracted from downhole conditions were tested in this study. The cores were fractured and propped by two different proppant types: a non-uniformly distributed 100-mesh proppant provided by Marathon Oil and a created 100-mesh proppant with a uniform grain size distribution. To create this proppant, the provided 100-mesh was sieved and the grains collected by the No. 120 pan were used.
A Modified API fracture conductivity cell was utilized to measure the fracture conductivity when dry nitrogen was pumped through the propped fractures. Before the Eagle Ford and Meramec cores were test, preliminary experiments were implemented to analyze and compare the two proppant types. For each proppant, density, specific gravity, void ratio, and porosity were determined.
Although the scope of this investigation was focused on proppant, additional work was done to evaluate the core because rock characteristics and mineralogy also affect fracture conductivity. For all samples, the top and bottom fracture surfaces were scanned using a fracture surface laser profilometer. The data collected by the profilometer was used to model fracture surface topography and quantify the surface volume changes before and after the fracture conductivity experiments. The relationships between proppant embedment, proppant grain size distribution, rock mineralogy, and fracture surface topography were discussed.
From the results yielded in this study, it was concluded that proppant gradation does impact fracture conductivity. Consistently, for the different shale samples, a proppant with grains the same size and shape yielded higher fracture conductivity values than the proppant with a well distributed grain size. The results also indicated poorly distributed proppant was more susceptible to self-channeling than the well distributed proppant with non-uniform grain size distribution.
Therefore, this study offers an insight into the effect proppant grain size distribution has on fracture conductivity. This study also presents the detailed methodology for quantifying fracture conductivity in the laboratory setting. | en |
