Water. desalination + reuse

TECHNOLOGY is dependent upon numerous variables including, but not limited to: reservoir temperature, reservoir pressure, the expected value of fracture half-length, and reservoir water sensitivity 5. Examples of fracturing fluids and conditions for their use have been summarized in Table 1. Ideally, the selected fluid system should promote fluid placement, minimize associated risks and maximize posttreatment production economics 6. Although both foam- and oil-based hydraulic fracturing fluids may be utilized within tight-oil developments, for the purpose of this article, the author will be focusing exclusively on the use of water as the base-fluid for hydraulic fracturing as it applies within tight-oil developments throughout the WCSB. FirsT sTEp - OppOrTuNiTY AssEssmENT Looking specifically at water requirements, flowback volumes and activity levels, Table 1. Examples of Fracturing Fluids & Conditions for Their Use Table 2: Penn West Exploration Tight Oil Development Summary & Hydraulic Fracturing Water Requirements Table 3: Penn West Exploration 2011 Tight Oil Development Water-Based Hydraulic Fracturing Overview we are able to gauge the magnitude of potential reuse opportunities within each resource play. Understanding that the volume of water required for hydraulic fracturing throughout the WCSB will vary extensively depending on the "formation depth, formation permeability, in-situ stresses in the pay zone, in-situ stresses in the surrounding layers, formation modulus, reservoir pressure, formation porosity, formation compressibility, and the thickness of the reservoir" 5, page 3, the average tightoil development water requirements utilized by Penn West Exploration in 2011 are provided in Table 2. The volume of water and sand (flowback) that returns through the borehole to surface from hydraulic fracturing stimulations varies predominantly due to the type of fracturing fluid used, the formation's geology and the length of well shutin time between when the well is stimulated and when fluids are flowed back 7. Across Penn West Exploration operations, these flowback volumes range between 5% and 50% of the original fluid volume. Based upon the combination of average water requirements and average flowback volumes per resource play, the cumulative water requirements and flowback volumes anticipated from each tight-oil resource play are summarized in Table 3, page 27. From this data (Table 3), the Carbonates resource August-September 2013 | Desalination & Water Reuse | 27 |

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