Date of Award
Engineering and Applied Science
Earth and Environmental Sciences
M. Royhan Gani
Using an integrated dataset comprising outcrop, core, GPR and LiDAR data, this study targets a high-quality outcrop "window" of the upper Cretaceous Blackhawk Formation in the eastern Wasatch Plateau in central Utah, spanning a fairly large spatial (~30 km2 area comprising eight contiguous, and vertical cliff faces) and temporal (~4 my) range. This research provides field-validation and -calibration of a wider range of fluvial heterogeneity: 1) large-scale heterogeneity (10’s of m vertically and 100’s of m laterally), 2) intermediate-scale heterogeneity (1’s of m vertically and 10’s of m laterally), and 3) small-scale heterogeneity (10’s of cm vertically and 1’s of m laterally). These sandbody- to facies-scale heterogeneities generate potential for stratigraphic compartmentalization for analogous fluvial reservoirs and prospects. Moreover, these results specifically constitute an outcrop analog to the producing tight-gas fluvial reservoirs of the adjacent hydrocarbon-prolific Uinta and Piceance Basins of Utah and Colorado, including the giant Jonah Field of Wyoming.
3D virtual outcrop model generated from LiDAR-integration has helped in avulsion-scale (~1's-10's kyr) to basin-fill scale (~100's kyr-1's myr) fluvial sandbody organization analysis down to channel-storey level. This high-resolution analysis has brought several intriguing insights. single-storey sandbodies are preferentially attendant to clustering organization, whereas multi-lateral sandbodies (i.e. channel-belt) show compensational-prone behavior. Sandbody organization is broadly compensational for the lower Blackhawk Formation, where the floodplain facies diversity is the highest. In contrast, floodplain diversity decreases stratigraphically upward such that the upper Blackhawk Formation shows the least heterogeneous floodplain with clustering-prone sandbody organization. In the quest of differentiating autogenic from allogenic signal in dynamic systems where their interplay is complexly intertwined, this study presents two incised-valley examples, where resultant fluvial organization has been interpreted, contrary to conventional wisdom, to be preferentially modulated by a dominant controlling mechanism of autogenic forcing. In filling these incised valley deposits, each of which is up to ~15-20 m thick, the dominating behavior of substrate coal compaction as an autogenic mechanism supplanted allogenic forcing (i.e. sea-level fluctuation).
Sahoo, Hiranya, "4D evolution of fluvial system and channel-fill architecture of the Cretaceous Blackhawk Formation, Wasatch Plateau, Utah: An integrated fluvial rock record analysis" (2013). University of New Orleans Theses and Dissertations. 1771.
Available for download on Thursday, December 20, 2018