INSPEC44756 - Laserfiche WebLink

Home Browse Search

III. COMMENTS -COMPLIANCE Below are comments on the inspection. The comments include discussion of observations made during the inspection. Comments also describe any enforcement actions taken during the inspection and the facts or evidence supporting the enforcement action. The purpose of this inspection was to observe the permanent sealing operations for a gob vent borehole, to ensure that the agreed upon methane degas borehole sealing procedures aze being followed. Greg Hunt represented the operator in the coordination of the gob vent borehole sealing and inspection. Edward Scartezina of Reclamation, Abandonment and Completion Services (RAGS) performed the field work. The borehole that was to be sealed is designated as GVB-WD-3A. The total depth of this 5.5 inch diameter borehole was 960 feet, with blank casing down to 553 feet The open hole perforated casing ran from 553 feet down to 763 feet. The annulus was cemented from the surface down to 490 feet. Attached to this report is the well completion diagram for GVB-WD-3A, provided by the operator. The day before the field inspection, BRL ran a borehole camera down the hole and recorded the images. The images were reviewed by BRL and the Division on the day of the inspection. The images showed that subsidence-induced shear had affected the borehole casing. There was a small bump in the borehole casing at a depth of 143 feet and a major bump in the casing at a depth of 342 feet. The operator could not get the camera past the casing bump at 342 feet depth. The camera images did not show any areas where the casing was completely sheared off or completely closed. Based on the camera data, a determination was made to place the packer just above the large bump in the casing. Even though this meant that the borehole seal would be well above the perforated casing, there did not seem to be a reasonable way to seal the borehole at a deeper point. The major equipment at the well site consisted of a flatbed trailer, a cement truck and a water truck. On the flatbed trailer were a large spool of 1500 feet of coiled pipe and a small spool of metal cable. A hydraulic power pack powered the two spools. The cement mixture consisted of cement, fly ash and a plasticizer. The fly ash is to give the cement increased resistance to deterioration from sulfur. The plasticizer is to give the cement more fluidity while it is being pumped into the borehole. Four workers were present. The well cap was removed and methane recordings were measured. Methane was coming out of the borehole. A tag weight was lowered into the borehole by cable to find the depth. The tag weight got past the small bump in the casing at a depth of 143 feet but couldn't get past the large bump in the casing at a depth of 342 feet. An inflatable packer was lowered into the hole by cable, with a plastic tube attached, and was set at a depth of 335 feet, confirmed by the cabled tag weight. The packer was set in a section of straight pipe just above the large casing bump to ensure a positive fit in the casing. Carbon dioxide gas was injected into the packer through the plastic tube so that the packer would expand and close off the borehole. The carbon dioxide gas pressure was monitored to ensure that there were no major leaks in the packer. The borehole was monitored for methane again. No methane was coming out of the borehole. With the plastic tube removed, the tag weight was, again, cabled down the hole to get the depth to the packer and to ensure that the packer was still in place. The packer was set at a depth of 335 feet.