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~~~-. UNITED STATES ENVIRONMENTAL PROTECTION AGENCY <br />~~~.~ ~ REGION VIII <br />\~\i~f/`/ 999 16th STREET -SUITE 500 <br />DENVER, COLORADO 80202-2466 <br />STEP-RATE TEST PROCEDURE <br />January 12, 1999 <br />PURPOSE: <br />The purpose of this document is to provide a guideline for the acquisition of a Step Rate Test <br />(SRT). These procedures are consistent with acceptable oilfield practices. Test results may be <br />used by the EPA to determine a Maximum Surface Injection Pressure (MSIP) to provide for the <br />protection of the underground sources of drinking water at an injection well having mechanical <br />integrity. Attached is a form that you may copy and use to record step rate test data. <br />Step rate test results must be documented with service company or other appropriate <br />(acceptable) records and/or charts, and the test should be witnessed by an EPA inspector. <br />Arrangements may be made by contacting the EPA Region 8 Underground Injection Control (UIC) <br />offices using the EPA toll free number 1800.227-8917 (ask for extension 6137 or 6155). <br />STEP-RATE TEST PROCEDURE: <br />1) The well should be shut in long enough prior to testing such that the bottom hole pressures <br />approximate shut•in formation pressures. If the shut~in well flows to the surface, the <br />wellhead injection string should be equipped with a gauge and the static surface pressure <br />read and recorded. <br />2) A series of successively higher injection rates are determined using guidelines below, and <br />the elapsed time and pressure values are read and recorded for each rate and time step. <br />Each rate step should last exactly as long as the preceding rate. If stabilized pressure <br />values are not obtained within the rate steps suggested below, the test results may be <br />inconclusive. <br />Formation Permeability (md) <br />5 and <br />10 and <br />Total time per rate-step (min) <br />60 min <br />30 min <br />3) Suggested injection rates: <br />5~ i <br />10°,~ . <br />20~ <br />40~ ~ Of Anticipated Maximum Injection Rate <br />60~, , <br />80~ , <br />100°, ) <br />4) Injection rates should be controlled with a constant flow regulator that has been tested prior <br />to use. A throttling device Is not sufficient. <br />arxwe,.aera,rnp. <br />