Optimum acid system for Trengganu offshore gas well acidizing process

Abstract

Formation damage usually occurs drilling operation, chemical treatment and etc. Drilling fluids causes the most common formation damage. In order to repair this damage, a laboratory experiment using matrix acidizing technique were carried out. The successful of this technique depends upon several parameters, such as the reservoir temeprature, acid concentration, mineral composition and acid type. These papers present the results of the laboratory study on optimum acid system for acidizing operation at Offshore Trengganu gas field. In this study, a work used combination of hydrochloric acid (HCI) and hydrofluoric (HF) or mud acid has been carried out using core samples from Offshore Trengganu gas field. The damaged in the cores, which was caused by water base mud, could be removed by acid with certain concentration. The results show that by using the correct type of acid with optimum concentration, permeability increased has been observed. Therefore, the reservoir productivity can be increase significantly. In addition, acid reaction coeeficient (ARC) has been calculated for each type of acid. From ARC results, it can be concluded that mud acid consists of 6% HCI and 1% HF is the most suitable acid system recipe for gas field "A" acidizing job.