A Single Treatment Controls Scale, Emulsions, and Corrosion From the Producing Formation to the Disposal Sand

A blend of an organic phosphate, a wetting agent, and a corrosion inhibitor has been successfully squeezed into producing oil and gas wells to control scale and corrosion throughout the production and disposal systems. Both barium sulfate and calcium carbonate deposition have been reduced. Unusually good corrosion inhibition results in extremely low concentrations of iron in the water. Plugging by iron compounds is thereby considerable Plugging by iron compounds is thereby considerable reduced. The single treatment precludes the use of surface injection facilities for chemicals and the attendant maintenance costs of chemical pumps. Cleaner oil and cleaner water have resulted because of the detergent action of the wetting agent used to couple the scale and corrosion inhibitors. Productivity increases have been achieved in Productivity increases have been achieved in several wells. Service operations on producing and disposal wells have been reduced; injection rates have been maintained for longer periods. Introduction The concept of squeeze treatment with a combination chemical, soluble in brine, grew in stages. The chemical was developed first to improve salt water quality for subsurface injection. The water was extremely corrosive (up to 100 MPY), had high scaling tendencies (CaCO3), and was loaded with oil-wet solids and entrained oil. Mechanical separation was not achieving the desired quality although some improvements were obtained. An organic phosphate, a wetting agent, and a cation corrosion inhibitor were found which achieved the desired water quality and which reduced the scale and corrosion problems sharply. Three chemical injectors were required at each of several locations. These injectors required careful supervision since the varying dosage resulted in different refill frequencies for each injector. The loss of several hours to several days of treatment could nullify the effect of prior treatment and reduce the effect of subsequent treatment for some time. It was decided that a blend of the three compounds would reduce mechanical, labor, and supervisory problems by two-thirds. The blend worked well, but surface chemical injection was still fraught with the usual maladies such as inoperative pumps and empty chemical reservoirs. It was then decided that if the chemical could be squeezed into the producing formation, that it would return a period of several days to several weeks. At first, the thought of squeezing with water into an oil-producing formation was disturbing, but further evaluation indicated that a squeeze treatment could be safely performed. The additional benefits gained from the squeeze treatment were varied and numerous.