Paper: CO2 H2O Corrosion

This paper contains a discussion, with examples, on how one type-of casing inspection survey is used to identify the depth and circumferential extent of casing corrosion. Corrosion results from one or more of a family of electrochemical processes. Some of these electrochemical processes will be generally described in the later topics. The Dresser Atlas casing inspection log and casing evaluation logs (for the detection of corrosion) provide such information as: 1. Whether the corrosion is external or internal. 2. The degree to which the pipe's wall thickness is reduced by the corrosion. 3. The circumferential extent of the corrosion. 4. Whether corrosion is general or isolated. 5. Basis for monitoring corrosion and effectiveness of cathodic protection of chemical treatment. Corrosion is an electrochemical process that involves chemical reactions and the flow of electricity. Corrosion requires an anode, a cathode and an electrically conductive path between the anode and cathode. In the west Texas-New Mexico area there are many zones with differing electrical potentials with which the casing forms the electrical coupling. These conditions represent the prime cause of external corrosion. With the addition of CO2 inside the casing internal problems as CO, + water = corrosion can be expected. This paper will show a way, though the use of Vertilog, to monitor corrosion activity and assist in evaluating the techniques to combat such problems.