Distribution of discontinuous mudstone beds within wave-dominated shallow-marine deposits: Star Point Sandstone and Blackhawk Formation, Eastern Utah

Abstract

A B S T R A C TDeposits of wave-dominated shorelines are typically considered to act as relatively simple hydrocarbon reservoirs and are commonly modeled as "tanks of sand." However, important heterogeneities that can act as barriers to fluid flow occur at the parasequence, bedset, and bed scales, especially in viscous oil or low-permeability oil fields. Heterogeneities at the parasequence and bedset scales have been well studied, but discontinuous mudstone beds occurring within the shoreface have received little attention. The Book Cliffs and Wasatch Plateau are among the best-exposed and best-studied deposits of wave-dominated shallow-marine systems in the world. Two parasequences within these outcrops have been studied in detail to investigate the distributions of intrashoreface shales and to propose models for the controls on their distribution. A data set consisting of 30 km (18.6 mi) of virtual outcrops derived from oblique helicoptermounted light detection and ranging (LIDAR) scanning with supporting stratigraphic sections makes it possible to collect a large quantity of accurate geometric data of depositional elements from inaccessible cliffs.Nine-hundred and twenty-one discontinuous mudstone beds were measured. These occur as ellipses with long axes oriented normal to the paleoshoreline. Lengths and widths of these mudstone beds exhibit a lognormal distribution, with means of 21.9 and 13.8 m (71.9 and 45.3 ft), respectively. Within the shoreface

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

“…Within the study area, K4 is incised into by eight distributary channels, one of which feeds a laterally restricted wave-dominated delta (Figs. 4a, 5a, 6; Eide et al 2014). The parasequence thickness varies from 15 to 46 m and the shoreface element thickness varies from 15 to 36 m. The parts of the section with the thickest parasequence do not always correspond to the thickest shoreface deposits.…”

“…The lateral accretion surfaces indicate sustained flow. In the context of a prograding, wave-dominated shoreline fed by multiple deltas developed around fluvial input points (Charvin et al 2010;Eide et al 2014), and significant amounts of gravityflow deposits basinwards (Hampson 2010), erosively based channels within OTZ deposits with evidence for sustained flow are likely to be the deposits of subaqueous channels, cut and filled by hyperpycnal flows fed from distributary channels up-dip, and feeding shelf turbidite systems downdip (Pattison et al 2007). These channels could also be interpreted as incised valley fills, but this seems unlikely due to that there are no evidence for this interval being subject to subaerial exposure, and no evidence for contemporaneous lowstand deposits.…”

“…While this model is robust as a general description and has predictive power in subsurface settings (Hodgetts et al 2001;Bullimore & Helland-Hansen 2009;Went et al 2013), significant complexity and variability exists on the intra-parasequence scale and within the individual facies belts. Intraparasequence complexities n such deposits include the presence of bedsets, which are upwardcoarsening discontinuities related to minor sea-level fluctuations or variations in climate or sediment supply (Storms & Hampson 2005;Sømme et al 2008), the presence of river-dominated deltaic intervals within an otherwise wave-dominated shoreface (Hampson & Storms 2003;Charvin et al 2010;Ainsworth et al 2011;Eide et al 2014) or the presence of discontinuous mudstone beds within shoreface sandstones (Eide et al 2014). …”

LiDAR, UAV or compass-clinometer? Accuracy, coverage and the effects on structural models

“…These detailed 3D reconstructions of outcrop geology are applied to a broad range of studies, including sedimentology and stratigraphy (e.g., Hodgetts et al, 2004;Enge et al, 2010;Fabuel-Perez et al, 2010;Eide and Howell, 2014;Rarity et al, 2014;Rittersbacher et al, 2014), reservoir modelling (e.g., Enge et al, 2007;Rotevatn et al, 2009;Buckley et al, 2010), and structural geology (e.g., Seers and Hodgetts, 2014;Bistacchi et al, 2015, among others). Light Detection and Ranging (LiDAR) has been the principal acquisition technique for deriving virtual outcrops in the last decade (e.g., Pringle et al, 2006;Buckley et al, 2008;Jones et al, 2009), though acquiring this type of detailed 3D spatial data requires expensive instrumentation and significant knowledge of processing workflows.…”

Three-dimensional modeling of clinoforms in shallow-marine reservoirs: Part 2. Impact on fluid flow and hydrocarbon recovery in fluvial-dominated deltaic reservoirs

“…There are few outcrop data sets that quantify the extent or geometry of such barriers along clinoforms (e.g., White and Willis, 2000;Lee et al, 2007;Eide et al, 2014;Hampson et al, 2014). Sensitivity tests indicate that ellipses are suitable objects to represent these barriers for modeling and flow simulation purposes, because they can be described using simple mathematical functions and their abundance and overlap control barrier coverage along clinoforms, provided ellipse dimensions are small relative to the area of the clinoform .…”