Formation damage during stimulation of sandstone reservoir

Abstract

Formation damage is critical factor in reducing production of oil and gas. This damage effects production at any stage during life of the a well. There could be many reasons of formation damage but this work is describing formation damages in sandstone reservoir during stimulation jobs. This damage took place due to precipitation of colloidal silica, swelling clays, iron bearing cements formed in results of reaction with quartz, iron minerals and clay particles with acid. Reaction products enter into porous media and adversely affect well performance of reservoir. Such damages are necessarily irreversible; the substance get into porous media not necessarily come out. Combination of HCl and HF acids is used to stimulate sandstone acid that have variable sensitivity to different grains of minerals and clay particles. Therefore, sandstone reservoirs need a meticulous designing and execution of acid stimulation job. Good knowledge of reservoir minerals and stimulation solution is valuable information to avoid formation damage during stimulation. This paper describes reactions of acid with different mineral grains. Further explains how to reduce or avoid these reactions.