APPLICATINON OF AN OPTIMIZATION METHOD FOR RESTORATION OF CORE SAMPLES FOR SCAL EXPERIMENTS

摘要

An important aspect of preliminary core preparation for SCAL experiments is the restoration of core sample to its original wettability. The prevalent method for restoration of core sample to either strongly oil-wet or weakly oil-wet is largely dictated by increasing or decreasing the time of aging at reservoir temperature. There is no consistent or reliable method ascribed for a specific sedimentary core sample to restore to its original state which is obtained from preserved core samples. In this study we have identified three important parameters, brine salinity, restoration temperature, and restoration time (age in number of days) as contributing to wettability. The objective of this study was to determine the optimum level of these independent variables (brine salinity, temperature, and age) for restoring wettability. In this paper we use a Box Behnken model of surface response methodology to analyze the effects of brine salinity, temperature and age of conditioning on wettability restoration. The samples for this study include Berea sandstone and Silurian dolomite. The whole aging process was carried out using overburden coreholders and the wettability was experimentally validated using contact angle measurements. A regression model was developed and the adequacy of predicting the output variable (wettability) to nearly all conditions was verified. The study showed a strong influence of brine salinity and temperature towards wettability restoration, which was further confirmed by the regression model. Further 2-D and 3-D surface plots were generated to show the interaction between aging time, temperature, and brine salinity on contact angle.