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DETECTING WATER FLOW BEHIND PIPE IN INJECTION WELLS
Citation:
Thornhill*, J. T. AND B. G. Benefield. DETECTING WATER FLOW BEHIND PIPE IN INJECTION WELLS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-92/041, 1992.
Impact/Purpose:
Information.
Description:
Regulations of the Environmental Protection Agency require that an injection well exhibit both internal and external mechanical integrity. The external mechanical integrity consideration is that there is no significant fluid movement into an underground source of drinking water through vertical channels adjacent to the injection well bore. The oxygen activation method for detecting flow behind pipe employs a measurement technique in which a stable isotope of oxygen is temporarily converted to an unstable nitrogen isotope. Unstable nitrogen-16 decays with a half-life of 7.13 seconds and acts as a radioactive tracer to enable measurement of flow of water-bearing fluid past a series of detectors. Thirteen tests have been conducted at the Mechanical Integrity Testing and Training Facility to determine the accuracy and reliability of this method. his technique has also been applied commercially in almost two hundred privately owned wells. The oxygen activation technique, which is a modification of an existing technique, provides, in many instances, a more accurate and precise method for detecting flow behind casing both related to injection and not related to injection (interformational flow).