Sedimentology and reservoir properties of tabular and erosive offshore transition deposits in wave-dominated, shallow-marine strata: Book Cliffs, USA

Abstract

Facies models for wave-dominated shorelines include an 'offshore transition zone' between shelfal mudstones and nearshore shoreface sandstones. Offshore transition-zone deposits are commonly tabular sandstone beds interbedded with continuous mudstone beds. However, observations from the Blackhawk Formation show that the offshore transition zone locally consists of erosive-based sandstone beds with 'pinch-and-swell' geometries containing steep-walled gutter casts, in areas larger than 6 × 2 km along strike and dip. This increases the amount of sand-on-sand contacts, and leads to improved vertical permeability. Predicting the distribution of erosive offshore transition within the subsurface is therefore desirable. In this study, offshore transition-zone deposits have been studied using virtual outcrops. Tabular offshore transition-zone deposits have continuous sandstone and mudstone beds much longer than 500 m, and erosive offshore transitionzone deposits have discontinuous shales, on average, 60 m long. Reservoir modelling shows a 10-to two-fold increase in vertical permeability in erosive compared to tabular offshore transition deposits, the magnitude decreasing with increasing fraction of shale. Erosive offshore transition deposits occur near distributary channels, subaqueous channels and abrupt bathymetric breaks. A regional study shows that erosive offshore transition-zone deposits are mainly developed where parasequences prograde into deeper water offshore the platform break of the preceding parasequence, are commonly associated with basinal turbidites and may be related to erosion by bypassing turbidity currents.

Coupled ‘storm‐flood’ depositional model: Application to the Miocene–Modern Baram Delta Province, north‐west Borneo

“…Similarly large gutter casts in the Blackhawk Formation (Grassy Member) in Tusher Canyon, Book Cliffs, Utah (cf. Guilpain, ; Eide et al ., ), were measured during the present study which are 0·2 to 2·7 m thick (average 0·6 m) and 0·2 to 5·5 m wide (average 2·0 m) (green points – Fig. A).…”

“…Within the Blackhawk Formation, the scale of storm‐generated sandstone beds (5 to 50 cm thick) and gutter casts (average 0·6 m thick) are similar to those observed in FA‐2 of the Belait Formation (Fig. ) (Guilpain, ; Eide et al ., ). A ca 10 m thick and 4 to 6 km wide zone of gutter casts is associated with interpreted subaqueous channels (e.g.…”

“…A ca 10 m thick and 4 to 6 km wide zone of gutter casts is associated with interpreted subaqueous channels (e.g. Pattison et al ., ), relatively steep bathymetric breaks ( ca 0·5°) and near or seaward of distributary channels (Eide et al ., ). Accordingly, gutter casts and related event beds are interpreted to have formed by river‐fed hyperpycnal flows (Eide et al ., ; cf.…”

Introduction to Vertical Geology thematic issue

“…The first advance led to complex and computational 3D geological modelling [Caumon et al, 2009;Zanchi et al, 2009]. The second has given us access to accurate and high resolution ground surface topography [Shan and Toth, 2008] and real 3D data for obtaining geological information [McCaffrey et al, 2005], leading to true 3D input for models [De Kemp and Sprague, 2003;Eide et al, 2015]. Complementary to 3D surface information from LiDAR or photogrammetry are other remote sensing methods, including LiDAR intensity data [Franceschi et al, 2009] and hyperspectral imaging [Kurz et al, 2011], which are natural additions to virtual outcrop geology.…”

“…Until now, its main application is the 3D modelling of reservoir analogues (Fig. 1), mapping and analysis of sedimentary architecture [Eide et al, 2015], and structural characterisation in order to generate discrete fracture networks (DFN) for reservoir modelling [Wilson et al, 2011]. In natural hazards, the use of 3D data such as high resolution 3D point clouds has been also developed for landslide investigation purposes [Jaboyedoff et al, 2012].…”