| dc.description.abstract | The goal of this study is to measure fracture conductivity on samples from the Meramec formation, a new unconventional play in Oklahoma. Conductivity samples were sourced from unpreserved downhole core provided by Marathon Oil. The scope of this investigation focused on the effect of produced water on the formation rock and the reduction in fracture conductivity after water exposure. Complementing these tests, each fracture was scanned using a surface profilometer to measure topagraphy, surface area, and roughness, and bulk mineralogy analysis utilizing x-ray diffraction (XRD) was conducted to correlate degree of water impairment to clay composition. In addition, a sieve analysis of the sand was conducted pre- and post-test to determine the amount of proppant crushing.
Tests were conducted using a Modified API RP-61 conductivity apparatus that permits dry nitrogen and reconstituted brine to be flowed through the system. Water conductivity tests were conducted using two different proppant concentrations, 0.2 lb/ft2 and 0.4 lb/ft2, and three sizes of proppant used by Marathon in the field, 20/40, 30/50, and 40/70 mesh sand. A reconstituted brine, representing flow back water, was made from salinity results from a third-party vendor used by Marathon.
Unrecoverable loss of conductivity due to water damage ranged from 24 to 54 percent for the 0.2 lb/ft2 samples, and 16 to 62 percent for 0.4 lb/ft2 samples. It was found that fracture surface topography played an important role in fracture conductivity, and that significant proppant crushing occurred. Additionally, mineralogy was found to vary significantly along the core depth interval, but results were inconsistent when compared to previous studies performed on the Eagle Ford and Barnett formations. These tests provide preliminary results for the Meramec formation, and how water damage affects fracture conductivity. | en |
