Laserfiche WebLink
Mr. Travis Marshall <br />Mr. David Bird <br />Division of Reclamation, Mining, & Safety <br />May 11, 2011 <br />Page 3 <br />intervals by native geological seals. These seals are aquitards <br />having extremely low vertical and lateral permeability and <br />comprise significant accumulations of kerogen rich strata. <br />Kerogen, like clay, has extremely low permeability that decreases <br />in proportion to the concentration of kerogen. The kerogen-rich <br />seals behave in a ductile fashion such that fractures through the <br />seals are rare except where faulting is present. Like all of <br />Shell's hydrology monitoring wells, the proposed L4 hydrology <br />monitoring well will be open across the L4 water bearing interval <br />(WBI), and cemented above the L4 to preclude cross flow to or <br />from overlying water bearing intervals. <br />• The L4 water bearing interval, being the first WBI above the <br />leach and heater zone, would very likely be the only interval to <br />show indications of a breach of the leach/heater reservoir. In <br />that regard, a single L4 well, downgradient from the project, is <br />sufficient for monitoring. <br />4. As discussed during the February 2, 2011 conference call between Harry Posey and <br />Division staff, the Division will require a pressure test after the production operation has <br />ceased for each well to assure that the integrity of the casing, cement and reservoir <br />containment relative to the overlying L4 WBI are still intact. <br />• Post-production pressure integrity testing is not anticipated for the <br />project. Rather, the ongoing monitoring during the leaching and <br />pyrolysis & production phases of operations are intended to monitor <br />reservoir integrity throughout so that it will be known, at the end of <br />production phase, whether the reservoir containment is preserved. <br />Fluid levels and/or pressure readings will be compared to those in the <br />overlying L4 WBI to ensure separation. <br />5. In Section 6. 2.4 Subsurface Reclamation, it states "Afterwards and after the reservoir is <br />cooled to an average temperature below the boiling point of water at formation pressure <br />the voids generated by leaching, pyrolysis and production will be filled with water. " <br />Please describe the rational for filling the void created by the project with water. <br />Based on recent discussion with the BLM, Shell is maintaining the <br />option to fill or not to fill the reservoir with water, which is <br />consistent with the option to rely on water-assisted cooling or <br />natural cooling. In a much larger commercial-size reservoir <br />development, water added back to the voids would increase structural <br />integrity due to the increased pore pressure of water in the voids. <br />However, in the extant case of the small RDD pilot, because the void <br />radius is so small and the crown so thick, the structural integrity of <br />the crown and leach/heater reservoir is not significantly influenced <br />by water filling. <br />0