Case Histories Show Value of Corrosion Inhibitor Squeeze Treatment

Abstract

Introduction The inefficiency of batch treatment down the annulus to prevent corrosion in gas-lift wells led to a search for a better method. Squeezing inhibitor into the formation was attempted and appeared to be an improvement over other methods of treatment. With these other methods it was difficult to get the chemical where it was needed because a high fluid leg would cause a major portion of the chemical to enter the tubing string at the working valve, which was too high to give complete protection. A low fluid leg would cause the chemical to dehydrate and leave a gummy substance on the outside of the tubing and on the inside of the casing. This tendency could be partially overcome by using large amounts of diluent (5 to 10 bbl) with the chemical, but such treatment was time-consuming and expensive. Sticks and pellets were tried with poor results. Theory of Squeeze It was found that some inhibitors would adsorb to sand rapidly and would desorb slowly. Laboratory work indicated that this adsorption-desorption rate was sufficient to warrant field testing. The high chemical concentration (11,000 to 1 million ppm) in contact with the steel during the squeeze is also a factor. Limited field tests to evaluate these two factors have been performed, but are inconclusive. Squeeze Treatment Since Nov. 1954, 60 wells have been squeeze-treated with a total of 160 squeezes. These 60 wells are located in 10 different fields and produce from 19 separate reservoirs. They vary in depth from 3,000 to 12,000 ft. Of the 60 wells, four are natural flowing wells, 47 are gas-lift wells, eight are gas condensate wells, and one is a pumping well. From the information available, it appears that about 150 wells have received this inhibitor squeeze-type treatment. Approximately 350 separate squeeze treatments have been done in these 150 wells. A breakdown of these 150 wells as to method of production is as follows: gas-lift, 85; natural flow, 15; pumping, 20; and gas condensate, 30. Production from these wells, located in Texas, Louisiana and Arkansas, is both sweet and sour. Some are producing from sand and some from lime-stone formations.