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Mechanical Integrity TestThe purpose of the cavern test is to test the mechanical integrity of the underground storage cavern in accordance with the guidelines set forth by the State and Local regulations. The mechanical integrity test is accomplished by injecting nitrogen into the well casing to below the cemented casing seat, at a test pressure predetermined by the customer, and recording the brine pressure, nitrogen pressure, and interface level throughout a given test period. The customer provides to Sonic Surveys, Inc. the physical description of the well, the maximum operating pressure at the wellhead and casing seat, and the desired test pressure gradient. The customer prepares wellhead to allow nitrogen injection, simultaneous well logging, and attachment of pressure measuring gauges. Sonic Surveys, Inc. attaches pressure recorders and dead weight gauges capable of displaying pressure changes of 1 P.S.I. to both brine and product sides of the wellhead. The calibrated pressure transducer’s signals will be sent to a remote data collection and storage device which will allow continuous monitoring and storage of annulus and tubing pressures. The digital, recorded pressures will be retrieved at the test completion and may be used as a basis for test results, calculations, or conclusions. The cavern is to be pressurized by pumping brine into the well tubing. An inspection of the wellhead will be performed for external corrosion, faulty valves and packing or gasket leaks. The customer will make repairs as needed. A known volume of nitrogen is injected into the well at the desired temperature and pressure.
After a stabilization period determined by the test supervisor, Test Start interface and temperature logs are recorded. The nitrogen pressure rate of decay must be less than 10 psi/ 24 hours. The pressure decay rate may be interpolated for stabilization periods less than 24 hours.
At the end of the specified test period, Test Finish interface and temperature logs are recorded. The test period will not be less than 24 hours but will be sufficient time to ensure a sensitive test. Test sensitivity is determined by a minimum detectable leak rate acceptable to the customer.
A detailed written report of the test procedures, results, and conclusions on the mechanical integrity test will be furnished to the customer.