However, this approach largely neglects internal heterogeneity and the highly fragmented nature of fluvial three-dimensional bodies (Parker et al., 2013 Van de Lageweg et al., 2013a, b). heterogeneity levels 1 and 2 of Jordan & Pryor, 1992) have had to assume either geostatistical or geometrical body dimensions derived from natural rivers (Pranter et al., 2007). In practice this has the consequence that three-dimensional geomodels developed for flow calculations (i.e. ( 2015).Įfforts to quantify fluvial meander belt architecture until now focused on vertical core data (Paola & Borgman, 1991), ignoring the horizontal dimensions. Modified from Miall ( 1985), Holbrook ( 2001) and Van de Lageweg et al. In this study, the focus is on third-order to sixth-order bounding contacts: bar boundaries, nested channel cuts, channel fill and lateral-accretion element boundaries and the external geometry of meander belt sand bodies.
The hierarchy of fluvial architectural elements. Heterogeneity within individual channel belt sand bodies also impacts performance and efficiency of reservoirs due to an internal architecture with a complex arrangement of contact surfaces, where contrasting grain size, sorting and other lithologic characteristics make for baffles and barriers to flow (Tyler & Finley, 1991 Pranter et al., 2007 Donselaar & Overeem, 2008 Willis & Tang, 2010).
1, sixth-order contacts) stacking patterns and the associated connectivity between individual channel belt sand bodies (Allen, 1978 Leeder, 1978 Bridge & Leeder, 1979 Mackey & Bridge, 1995). heterogeneity levels 1 and 2 of Jordan & Pryor, 1992) primarily depends on channel belt sandbody (i.e. The heterogeneity of fluvial deposits at the scale of a hydrocarbon field (i.e. In essence, fluvial deposits are composed of a number of architectural elements (Miall, 1985 Holbrook, 2001) spanning a wide range of spatial and temporal scales (Fig. Based on this, a set of rules were identified for combining reservoir parameters with the identified probability curves on sandbody dimensions and character, to help create more realistic geomodels for estimating exploration success on the basis of seismic and core data.Ĭharacterization and prediction of the three-dimensional architecture and fluid-flow behaviour of fluvial hydrocarbon reservoirs and drinking water aquifers is challenging because of the various scales of sediment heterogeneity between and within fluvial deposits (Miall, 1988 Jordan & Pryor, 1992 Pranter et al., 2007 Willis & Tang, 2010). Probability curves of preserved architectural characteristics for three dimensions were quantified allowing estimates of bar dimensions, baffle and barrier spacing distributions and container dimensions. A key observation is that the slope and number of lateral-accretion packages within natural point bar deposits can be well predicted from fairly basic observables, a finding subsequently tested on several natural systems. For the first time, the relief of the base of a meander belt is quantified, enabling improved estimates of connectedness of amalgamated meander belts. Meander belt sandbody width-to-thickness ratios between 100 and 200 were observed, which are consistent with reported values of natural meander belts. In this study, three large flume experiments and a numerical model were used to characterize and construct the architecture (referred to as ‘archimetrics’) and sedimentology of meander belt deposits, while taking reworking and partial preservation into account. Three-dimensional architectural data are needed to quantify scales of grain-size heterogeneity, spatial patterns of sedimentation and bar preservation in a direct relationship with the relevant length scales of active river channels. Currently, characterization of meander belt bodies largely relies on idealized vertical profiles and a limited number of analogue models that naively infer architecture from active river dimensions. Fluvial meander belt sediments form some of the most architecturally complex reservoirs in hydrocarbon fields due to multiple scales of heterogeneity inherent in their deposition.
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