Polymer gel conformance on oil recovery in fractured medium: Visualization and verification

Canbolat S., PARLAKTUNA M.

JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING, cilt.182, 2019 (SCI-Expanded, Scopus)

Özet

Due to complexity and heterogeneity of the geological patterns of fractured reservoirs recovery estimations are considered to be extremely challenging. These fractures form complicated paths for reservoir characterization and fluid movement that ultimately impacts production performance and recovery. In this study, naturally and artificially fractured cores were used. Using CT scanner images, matrix porosity and saturation calculations were done. Calculated CT porosity was used for CT permeability estimation of each core with a minor relative error %. In the core experiments with different environments (initially oil saturated and water saturated) homogeneous core recovery was more than heterogeneous one due to natural fracture in both cases. The polymer gel decreased the permeability of the core #3 prior to artificial fracture 6 fold, after artificial fracture was 28 fold. As an oil recovery improvement 13.3% original oil in core was produced additional to 33.33% recovery prior to gel application. The effect of polymer gel on core #7 was resulted in permeability decrease 5.5 fold prior to artificial fracture and after artificial fracture was 14 fold with an oil recovery improvement of 14.28% on a 28.57% normal recovery. Flooding was done on core #5 without artificially fracturing. Then, like the other artificially fractured cores, after the polymer gel application, the permeability of the Core #5 decreased 5.3 fold. However, an incremental recovery of 14.30% achieved in addition to 50% normal recovery, ending 64.30% totally. Experimental study quantified the effect of polymer gel injection into artificially fractured sandstone core samples. Permeability measurements before and after gel injection showed the efficiency and conformance. The effect of polymer gel conformance to increase recovery not only by plugging fracture but also increasing sweep efficiency while plugging the permeable path way in the core sweeping the unswept zone.