Abstract
The most common reason of formation damage is the drilling operations. Mud invasion is the major problem that affects well productivity in HAOUD BERKAOUI field. As the source of damage is known, different types of acid systems are proposed by service companies to improve the near wellbore formation permeability. Matrix acidizing treatment is successful and economic when either no excess volume or insufficient volume is used. The determination of acid volume is complicated and is generally based on field experience or using rules of thumb. Rules of thumb may not be convenient and always over estimate or underestimate the volume. Selection methods based on laboratory experiments, however, are more close to real estimates since they take into consideration the rock mineralogy.
In this study, laboratory tests are discussed and their results are shown to determine the mineralogy and formation characteristics of HAOUD BERKAOUI field. Acidizing tests of 4 different acids are conducted and discussed to select the optimum fluids. Visual observations of cores using SEM are also used as interpretation tools. Besides, optimum volume is predicted based on the laboratory acid response curves.
Laboratory test results show permeability improvement for 3 systems. However; one system proposed to treat injection wells gave mediocre results. Tests also show the risk of emulsion and/or precipitations for some acids. Acid system 3 with 6% HCl and 1.5% HF is found to be the optimal fluid to treat both injection and production wells. This system presents a good permeability improvement with less damaging precipitates and no risk of emulsion. Guidelines for acid volumes based on 6% HCl -1.5% HF acid are provided and could be used as a starting point in acidizing job design for HAOUDBERKAOUI field.
