Control of Sour Crude Corrosion In Kansas Production Operations^⋆

The corrosive portion of Kansas oil fields covers generally all the area west of the Shoestring oil fields in the eastern part of the state. Within this area, the corrosion occurs mainly in wells producing from the Arbuckle limestone. Also, where serious corrosion occurs, there are certain common characteristics in chemical nature of well fluids and in the volumes of these fluids produced. In general, the brine is rather dilute, containing varying amounts of H₂S and CO₂. Release of acid gases from the produced brine brings about rise in pH and deposition of scale in surface equipment and in disposal wells. The oil also contains acid gases and has poor wetting ability. However, as a general rule, sub-surface corrosion does not become particularly troublesome until water is about 85 percent of produced fluid. Relative importance of corrosion, as judged by equipment costs is, in descending order: tubing interior, rods, pump, casing exterior, tubing exterior and casing interior. Tabulation of subsurface costs, due to corrosion, indicate than an over-all average would be near $1800 per well year. The two most popular methods of corrosion control consist of down-hole introduction of oil wetting agents or formaldehyde. Comparison of before and after treating data indicates that these methods accomplish closely similar savings in equipment repair and costs of treating are also roughly equal. Testing costs average in the neighborhood of $120 per well year and corrosion is lessened by approximately 50 percent. The present corrosion prevention practice in Kansas has resultd from many years’ experimentation with resistant materials and methods of well treatment. Experimental resistant materials have included plastic tubing, various alloy rods and tubing, galvanized tubing, plastic-coated and cement-lined tubing. Treating methods have included exclusion of possible oxygen, neutralization agents and protective scale in addition to the formaldehyde and oil wetting agents. A few materials, which probably should be classed as coating compounds, have received limited testing in laboratory and field. Their further development seems a distinct possibility.