Successful inhibition of deep, hot, sour-gas wells

The sour-gas wells in the Big Escambia Creek (BEC) field of South Alabama have a production environment that consists of 280{degrees} F, 21% H{sub 2}S, 40% CO{sub 2}, and up to 190,000 ppm chlorides in the produced water. The highly corrosive conditions demand the ultimate in a corrosion mitigation program to produce these wells safely and economically. This paper describes the background, technical development, and results of the downhole and gathering-system corrosion inhibition and monitoring programs: continuous downhole inhibition by means of annular injection of a water-dispersible inhibitor in the most aggressive wells; downhole batch treatments with nitrified tubing displacements of an oil-soluble inhibitor in the remaining wells; continuous injection of a water-dispersible inhibitor in the gathering lines to augment the batch treatments and in selected highly corrosive wells; monitoring of inhibitor residuals and plotting of trends to ensure the effectiveness of downhole treatments and to optimize injection rates; and flowline calipers and hydrotests to monitor the gathering-line inhibition programs. The paper also describes the computerized approach used in designing, calculating, and updating both the continuous downhole injection system and the nitrified batch treatments. The success of the inhibition and monitoring program is demonstrated by the tubing life achieved, fieldmore » data on inhibitor residuals, and flowline and downhole calipers. The technical data presented will aid in the design and implementation of successful inhibition program for highly corrosive production.« less