Paper presented at SPE International Symposium & Exhibition on Formation Damage Control held in Lafayeete, Louisiana, USA, 15–17 February, 2013
Detrimental Effect of Temperature on Fines Migration in Sandstone and Shale Formations
The present work investigates the impact of high temperature on fines migration and is useful for both sandstone and shale formations at high temperatures. The results show subsequent loss of permeability in clay-containing rocks such as sandstone. Three types of clays are present in sandstone rock used for experiments: kaolinite, illite, and chlorite. Both experimental and theoretical results of conducted coreflood experiments show that the rise in temperature sensitizes fines, and thus decreases sandstone permeability significantly upon the injection of fresh water. Coreflood experiments were performed at 74, 200, and 300°F temperatures. Brine, 5 wt% NaCl was injected at room temperature to determine the initial rock permeability. Next, temperature was applied to the system, and various potential clay stabilizing salts, as well as fresh water flooding, was performed in both forward and reverse directions to confirm plugging. Core effluent was collected during each experiment and analyzed to measure the concentration of key cations using ICP-OES. The experimental results were verified by application of the DLVO theory. The mathematical model was used to evaluate the magnitude and determine the effect of each of the contributing forces. The results show that the double layer repulsion force has the most significant impact, due to change in temperature of the matrix-clay system. Based on the results attained, it can be concluded that fines migration is a serious problem in sandstone formations at high temperatures. High salt concentrations or salts containing high valency cations will be required to mitigate fines migration due to pH changes at higher temperatures. From experimental results obtained, 15 wt% NaCl and 15 wt% HCl solutions were able to preserve permeability in the rock and minimize fines migration at elevated temperatures. This paper will discuss experimental and theoretical studies conducted that highlight the importance of fines migration in high temperature wells.