Combining Terrestrial Photogrammetry, Applied Sedimentology and Hand-Held Gamma Ray Spectrometry to Characterize the Cretaceous Lower Castlegate Formation, Tuscher Canyon, Utah, U.S.A.

Abstract

Fluvial sandstones create some of the highest net to gross clastic reservoirs in the world but the quality of these reservoirs, and recovery from them, are strongly controlled by depositional style. However, the internal architecture of fluvial sandbodies is difficult to ascertain from down-hole data alone, and the rapid spatial and temporal variations in lithofacies make inter-well correlation of fluvial strata notoriously difficult. This study addresses the key issues of fluvial reservoir connectivity and sandbody architecture at the reservoir scale by using an integrated approach with photogrammetry and pseudo-well log data from the Campanian Lower Castlegate Formation at Tuscher Canyon, Utah, USA.

A 3D reservoir model is constructed using terrestrial photogrammetry combined with sedimentary logging and hand-held gamma ray spectrometry data creating pseudo-well data. This Pseudo-well data is subsequently correlated to a downhole dataset drilled adjacent to the study area, creating a sub-surface analogue.

Analysis of the ~5 km² photogrammetric dataset shows the 20 m to 60 m thick high net to gross Castlegate succession, with an outcrop to area ratio (OAR) of 0.73, indicating exceptional exposure coverage of the study area. Key stratigraphical surfaces are used to create a deterministic framework for an object-based numerical model, with extracted sedimentary architecture statistics from the photogrammetry and measured palaeocurrent indicators forming object vectors that were used to populate the model. Model analysis indicates the complex architecture of the Castlegate was deposited in a highly avulsive, low-sinuosity, bedload-dominated fluvial system.

Further work will simulate fluid flow through the numerical object vector 3D model to understand the internal interactions of facies and sedimentary architecture, and the affects that such architectures have upon fluid migration within a fluvial reservoir. This has important implications for fluid migration at both exploration and production stages in high net to gross fluvial reservoir settings.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018