Oil Well Stimulation based on Hydrochloric Acid in Sandstone & Limestone Formation

Abstract

Permeability and porosity are the reservoir rock’s most important properties which reflect the reservoir’s
productivity. Low permeability reduces fluid flow through the reservoir. So, hydrochloric acidizing is used to
increase the flow by opening up existing channels in the reservoir and creating new channels by dissolving clays.
Experimental work carried out and analyzed the different parameters that affect the performance of hydrochloric
acid in sandstone formations, investigated the increase or decrease of the porosity of sandstone formations after
hydrochloric acidizing, and investigated the effects of the combination of hydrofluoric acid in acidizing
performance. Furthermore, sand-packs were designed to conduct flooding experimentation on sandstone. The sand-
packs were intended to be capable of functioning under a wide range of operating conditions in terms of acid
concentrations, from 7.5 ???????? % to 30 ???????? % for hydrochloric and 1.5 ???????? % to 3 ???????? % for hydrofluoric, and temperature
up to 160 ℉ to perform extensive hydrochloric acidizing procedures. It was absorbed that temperature increased the
rate of reaction of hydrochloric acid; hence, better results were obtained from well-stimulation operations at higher
temperatures. Higher concentrations of hydrochloric acid to stimulate sandstones also increased the rate of reaction
and greater improvements in permeability was achieved. Also, acidizing sandstone with a hydrochloric
concentration of 15 ???????? % and HF of 3 ???????? % showed significant results and high improvements in permeability and
porosity. However, a higher concentration of hydrochloric acid above 15 ???????? % to stimulate sandstones caused the
rock matrix to de-consolidate negatively affecting the overall outcomes of the acidizing process.