Preventing Corrosion in Gas-condensate Wells

Abstract

Abstract This paper discusses the most dangerous form of corrosion encountered incondensate well oil production, the discovery of the agent causing thiscorrosion and the remedial chemical treatment proved effective by field use.The injection of ammonium hydroxide, even as little as one quart per day, hasproved effective in preventing gas-condensate well corrosion. The injection of"Bone oil" is applied to wells producing brines containing calcium andmagnesium salts. Introduction The severe corrosion of equipment in high pressure gas condensate wells hasbeen a problem for several years and numerous papers have been presented on thesubject. The term ?gas condensate? or ?distillate well? is applied to a distinctvarieties of hydrocarbon producing well, the characteristics of these wellsbeing high bottom-hole (formation) pressures and temperatures and high gasproduction. These wells usually produce about 40 gal of water per million cubicfeet of gas and the gas contains from 0.1 pct to 2 pct carbon dioxide. In theoperation of this type of well, the operators soon noted severe internalcorrosion of the pipe carrying the production. In some instances the welltubing has been found to be corroded to perforation in eight months. The highwell head pressure of 2500 to 8000 psi makes any weakening of the wellequipment by corrosion extremely hazardous. Bursting of the wells equipmentresults in very expensive repair operations and may result in the loss of thecostly well, or even loss of life. In November 1944, a gas-condensate well in a Gulf Coast field producing from9500'Ft showed a tubing leak. The well was ?killed? by filling it with mudthrough the tubing, and then the tubing was pulled. Corrosion was found to havecaused several perforations in the tubing, Fig. 1. While the mud was beingcirculated to kill the well, a high pressure jet from the corroded hole in thetubing perforated the casing and damaged the well to the extent that the costof repairs amounted to $75,000. In November 1944, another gas-condensate well in a Gulf Coast field producingfrom 11,400'Ft. showed tubing failure. This well had been producing an averageof 2,500,000 cu ft of gas daily for two years. In the workover of this well, itwas found that a hole one inch in diameter had corroded though the tubing andthat corrosion had reduced the wall of the tubing to less than half thestandard thickness over large areas of the interior of the tubing. It was foundthat corrosion had also caused two leaks in the casing. After four months spentin an attempted workover failed to make the well safe for further production, the well was plugged and abandoned at a total low or $300,000.00. T.P. 2229