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PBO Strainmeter Installation Update: A Whole New Frontier! (4)


BRRRRR! Crews woke up to temperatures below freezing, making it hard to roll out of bed and get working in the chilly weather. Regardless, activity at the site began at the usual time of 7am by taking another depth measurement of the borehole. Due to some soft settling of materials at the bottom of the hole, the hole depth measured 506 feet. The big mission today: install enough 6-inch casing to line the entire borehole from bottom to top.

The first piece of casing to go down the hole has a ‘float shoe’ welded onto the end of the 20-foot section. Much like a cap to close off the bottom, the float shoe has a small opening with a one way flow valve that allows wet materials to pass through, but not back up the end of the casing. Once all 506 feet are cased, the drill pipe is inserted into the casing through the bottom of the hole and acts as a transport for cement. Cement is pushed through the pipe and out of the float shoe. Once past the float shoe the cement is forced up the annulus between the 6-inch casing and 8-inch hole and thus cementing all the casing in place.

Just after 8am the first piece of casing with the float shoe was lowered into the top 20 feet of the borehole. The top end of the casing rested on the floor of the rig, and was held in place by a slug and ‘elevator’ to keep it from falling to the bottom of the hole. Next, a second piece of 20 foot 6-inch steel casing was pulled to the top of the rig and centered directly in line with the first pieced of casing. The second piece of casing was slowly lowered so the two ends of the casing meet. After checking to be sure both casing sections are vertical, the two ends are welded together, and lowered down into the hole another 20 feet leaving about a foot and a half sticking out of the floor of the rig to attach the next piece of casing. This process of welding the casing pieces together went smoothly, taking up the entire day at a rate of about 3 pieces per hour. By 4:15pm, all 26 pieces of casing were welded together and settled perfectly in the borehole.

Last modified: Sunday, 11-May-2014 18:02:07 UTC


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