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<br />(e) recording and retaining on file the following information: <br />(i) type of fluid used and its gradient, <br />(ii) test duration, <br />(iii) initial pressure, and <br />(iv) final pressure, <br />3.11.14. Pressure Test Failure <br />If the surface casing does not hold pressure, the operator shall rectify the problem before drilling <br />operations are continued. <br />3.12. Drilling Intermediate Hole, Casing, and Cementing <br />The intermediate casing and cement shall: <br />(a) protect equipment and shallower formations from excessive pressures; <br />(b) permanently prevent fluid migration between porous and permeable formations; <br />(c) prevent the shales and unconsolidated material from falling into the open hole and <br />(d) control the maximum anticipated target zone pressure. <br />3.12.1. First Control String <br />The intermediate casing comprising the first control string shall be set and cemented prior to drillinc <br />into the target zone. <br />3.12.2. Aquifer Present <br />Where an aquifer is present in the intermediate hole, the next string of casing shall be cemented in <br />place. Note: In many areas of Ontario more than one aquifer maybe encountered in the <br />intermediate hole. <br />3.12.3. Isolation <br />The operator shall: <br />(a) identify all porous formations during the drilling of a well; <br />(b) pump sufficient cement to separate all porous formations from each other and from the <br />previous casing string; <br />(c) where more than one porous formation is present behind a string of casing, ensure that <br />cement in the casing annulus rises 25 metres above the top of the first fluid show that is <br />encountered below the base of the previous casing; and <br />(d) where good cement returns are not received at surface, identify the top of cement in the <br />casing annulus and provide for an Examiner to certify isolation of all porous zones. <br />3.12.4. Lost Circulation <br />If lost circulation is expected or detected in the drilling of an intermediate hole, the operator shall <br />take necessary measures to isolate the lost circulation zone from any other porous zone <br />encountered in the drilling of the well by: <br />(a) sealing the zone prior to or during the cementing of the casing designed to cover the zone; or <br />(b) if a zone of lost circulation is identified during drilling operations, the operator may plug off this <br />zone immediately. <br />15 <br /> <br />