Matrix Acidizing to Improve Injectivity in Carbonate Disposal Wells/Reservoirs with Clay Mineral Damage

Abstract Matrix acidizing is long used in clastic and non-clastic formations to increase productivity in both oil and gas reservoirs. Main goal is always to increase productivity by either dissolving or repairing the near wellbore damage in case of sandstone or by-passing the damage by creation of wormholes in case of carbonates. Standard approach in carbonate formation is acid treatment (HCl) along with other additives which are selected based on characterization of damage in a particular well. Oil or Gas producing wells in Carbonate formations exhibit tendency to deposit various reservoir impurities due to pressure drop and temperature variations at the sandface that may include hydrates, wax, Asphaltenes and various salt deposits. However, in case of injection or disposal wells, the impurities that are contained in produced water may be introduced from external sources. The disposal or injection water usually comes from many wells and is stored in tanks at locations to be mixed, preferably filtered and treated. Due to ineffective surface filtering or colloidal issues, the clay content could be injected in the wells. This impacts the ability to effectively dispose or inject water and may impact net production from a field if alternate sources of water transportation deemed to be expensive. This paper discusses the restoration of injectivity in a carbonate formation disposal well, where filtration of clay fine was not effective. Produced water exhibited colloidal clay fines (