Innovative seismic workflows for characterizing unconventional shale resource plays
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2019-08-16
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Abstract
Over the last five to seven years the characterization and exploitation of shale formations have led to a more dominating role for the engineers, ahead of geoscientists. A common perception is that in shale formations of interest, horizontal wells can be drilled anywhere in any direction, and completed at regular intervals along their lengths, a process referred to as ‘factory drilling’. The economics of such shale plays may have been the driving factor for such practices, but studies have shown that factory drilling should be replaced with smart drilling, which entails optimum placement and stimulation of the laterals, resulting in more uniform production. Reservoir quality (RQ) defined by organic richness, effective porosity, fluid saturation, pore pressure and gas-in-place, and completion quality (CQ) represented by in-situ stress field, mineralogy (clay content and type), and the presence of natural fractures as well as their orientation, must be considered in planning strategic hydraulic stimulation for increasing the total production of a horizontal well. As many of these properties can be estimated from seismic data, they can be integrated by introducing the concept of shale capacity, which is defined as the ability of a shale play to produce hydrocarbons, once it gets fractured. In this thesis, the usual challenges faced by geoscientists in computing individual components of shale capacity and their solutions have been highlighted by considering different datasets from different basins in North America. For instance, an important property of the formation of interest is its brittleness, and the usual criterion for its determination is to look for pockets that exhibit low Poisson’s ratio and high Young’s modulus. Though not difficult to compute, this combination is not found to be favourable in every shale play. Consequently, after highlighting the fallacy in following such a criterion a new attribute is proposed that makes use of strain energy density and fracture toughness. While the former controls fracture initiation, the iii propagation of fractures is governed by the latter. As hydraulic fracturing comprises both these properties, it is firmly believed that the new proposed attributes could be used to highlight the favorable intervals for fracturing. This work is followed by an alternative way of integrating key parameters of shale capacity, helping understand the variability in the well performance. It is firmly believed that geoscientists can not only stay relevant but can play a crucial role in improving the overall completion effectiveness and economics of shale plays.
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Sharma, R. K. (2019). Innovative seismic workflows for characterizing unconventional shale resource plays (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.