Installation of a vertical pressure cell at the Priddis Geophysical Observatory

Malcolm B. Bertram, Kevin W. Hall, Donald C. Lawton, Geoff Burton, Peter Wild

Carbon Management Canada and CREWES are in the process of installing a vertical pressure cell in Testhole 4 at the Priddis Geophysical Observatory for the purpose of testing a prototype optical sensor from the University of Victoria that is sensitive to CO₂ concentration. Testhole 4 was drilled in 2007 and cased to a depth of 127 m with PVC casing grouted with bentonite. More recently seismic data quality obtained in the well has appeared to deteriorate in quality, possibly due to bentonite being washed away by ground water. This made it a good candidate for the installation of a vertical pressure cell. Thus far, steel coil tubing with a cap welded onto the bottom has been inserted into the well, and a bell nipple with threads for a flange has been welded onto the top of the coil tubing (Figure 1). The coil tubing will be sealed at the top with access ports for CO₂ and test instrument tubing, allowing the pressure to be taken up to 35 MPa, thereby simulating various reservoir depths. By releasing CO₂ bubbles into the bottom of the coil tubing, the new sensors can be tested and calibrated. The facility continues to be developed.