Laserfiche WebLink
Specifications for Electrofrac Construction Test Boreholes <br />Installed on the Walls (Ribs) of the Colony Mine Tunnels <br />While exact specifications for Electrofrac construction test boreholes may vary <br />during the course of our research, these boreholes can be described adequately <br />to permit estimation of their abandonment costs. <br />The objective of Electrofrac field experiments is to demonstrate that electrically <br />conductive fractures can be reliably constructed and energized. The typical <br />experiment is illustrated in the diagram below, which was labeled Annex B in <br />ExxonMobil's application for technical revision of MLRB Permit No. M-1980-047. <br />As indicated in the diagram, Electrofrac construction test boreholes will be drilled <br />into the mine ribs. The boreholes will typically be 100 to 200 feet in length and <br />will have a relatively small diameter, perhaps 2 to 4 inches. Other than their <br />longer length, they will be similar to the Fracture Pretest boreholes already <br />drilled, which have been previously described. <br />The Electrofrac construction test boreholes will be cased along some portion of <br />their length. They will be fractured using conventional oil well fracturing <br />techniques and an electrically conductive inert material, such as calcined coke, <br />will be injected into the fractures. <br />In addition to the Electrofrac construction test boreholes, uncased observation <br />and instrumentation boreholes will be drilled adjacent to the electrically <br />conductive fracture boreholes. Because these observation and instrumentation <br />boreholes are not fractured and are similar to conventional mine appraisal holes, <br />they will require no reclamation and will be abandoned "as is." <br />While most of the instrumentation and observation holes will be nearly horizontal <br />and physically close to the Electrofrac fracture, a few may be nearly vertical and <br />at a distance of up to 300-500 feet from the Electrofrac fracture. These holes are <br />likely to be used for passive seismic monitoring. Instrumentation for this <br />monitoring will be cemented into these holes. They will therefore not require any <br />special reclamation and will be abandoned "as is".