Apparatus for determining a natural current flow in well casing

• Main Author: WALKOW; ARNOLD M
• Format: Patent
• Language: English
• Published: 14.02.1984
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DETECTING MASSES OR OBJECTS; DIFFUSION TREATMENT OF METALLIC MATERIAL; EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MEASURING; METALLURGY; MINING; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLICMATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASSC23 AND AT LEAST ONEPROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25; NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS; PHYSICS; TESTING

An apparatus for determining the natural current flow in the casing of a well. The apparatus includes earth surface control and recording equipment connected by a cable to an instrument housing. A casing collar locator on the instrument is used to assist in positioning the instrument in the well casing. A plurality of electrodes on the instrument are contactable with the interior of the casing. The earth surface equipment and the electrodes are used to measure voltages and to pass an electrical current through the casing. Measurements of native voltages in the casing and the change in voltage between two locations in the casing during application of a known current are used to determine the casing's resistance at that location in the well and the native current flow between the well casing and the earth formation throughout the well.