Publications

This paper presents the results of core flow experiments with high salinityhigh pH (buffered) aqueous completion fluid on sandstones containing migrating and swelling clays.The experiments show that the high salinityihigh pH (buffered) completion fluid is non or less damaging to the sandstones containing predominantly migrating clays (kaolinite). This finding, however, needs to be further verified experimentally using preserved cores. In the case of sandstones containing predominantly swelling clays (smectites), the experiments show that the high salinityhigh pH completion fluid is as damaging to the cores as the normal pH KC1 completion fluid. The relative abundance of expandable clays and their distribution in pore space, i.e., pore lining and filling, and pore size distribution of rock appear to be the controlling factors for the degree of damage.Using examples the paper also addresses the damage to the cores during the core preparation. Highly preserved cores are found to be most suitable for damage studies. Preserving the core's native state (clays and wettability) is absolutely necessary in obtaining meaningful data from the return permeability experiments.