Patent ID: 6712139
Filing Date: 2004-03-30
Classification: E21B

Abstract:
A method of well casing cathodic current optimization for application of cathodic current to an underground well casing in a field intended to have at least first and second wells, said method comprising the steps of:measuring first drill stem resistances along a first well hole for the first well; correlating the first drill stem resistances to respective types of underground formations having respective resistivity conditions at corresponding positions along the first well hole to generate initial correspondence data; installing a first well casing in the first well hole; conducting a CPET log run on the installed first well casing to generate CPET log data; generating confirmed correspondence data based upon the initial correspondence data and the CPET log data; identifying, by using the confirmed correspondence data, a position of at least one first anodic area on the installed first well casing due to the resistivity conditions of the types of underground formations that are in electrical contact with the installed first well casing; determining, in accordance with said identifying step, at least one first application position on the first well casing and a first amount of cathodic current to be applied to each first application position to avoid corrosion of the first well casing; measuring second drill stem resistances along a second well hole for the second well; predicting, by using the second drill stem resistances and the confirmed correspondence data, a position of at least one second anodic area on a second well casing to be installed in the second well hole due to the resistivity conditions of the types of underground formations that will be in electrical contact with the second well casing when installed; and determining, in accordance with said predicting step, at least one second application position on the second well casing and a second amount of cathodic current to be applied to each second application position to avoid corrosion of the second well casing when installed.