Corrosion inhibitors for acidizing process in oil and gas sectors

In the petroleum industries, one facet of the development of oil and gas production is the well stimulation. The process involves several aspects, including the acidizing procedure utilized to stimulate the oil well reservoirs. Generally, highly concentrated acids (5-28 wt% hydrochloric acid) are injected into the well for the acidizing stimulation process that makes the environment extremely corrosive to steel structures. In the absence of corrosion inhibitors, the general corrosion rate can be extremely high (>100 mm/yr) and that can increase exponentially with increasing temperature and acid concentration. Acids are also often employed for scale removal treatments (pickling of the well tubing usually done with 15 wt% hydrochloric acid at temperatures up to 140 °F to remove iron oxides and carbonated minerals) and the removal of drilling mud damage in newly drilled wells before being brought into production. Deep wells are characterized by high temperatures and presence of high hydrogen sulfide and carbon dioxide that make the acidizing process extremely difficult. The present chapter provides an account of the techniques used for acidization process, the types of acids, and the major corrosion inhibitors used.