Matthew D. Jackson1,
Howard D. Johnson1,
Ann H. Muggeridge1
(1) Imperial College, London, United Kingdom
(2) University of London, Egham, Surrey, United Kingdom
Abstract: Characterisation, quantification and flow simulation of tidal sandstones: The Barnes High Sandstone Member, Lower Cretaceous Vectis Formation, Isle of Wight, U.K
The efficient recovery of hydrocarbons from tidal sandstone reservoirs is challenging; tidal sandstones contain a complex array of sedimentary heterogeneities, and our understanding of the effect these heterogeneities have on the flow of fluids during recovery is poor. We have used the well-exposed Lower Cretaceous Barnes High Sandstone Member to characterise the small- to intermediate- (centimetre- to metre-) scale sedimentary heterogeneities found within a tidal sandbody, and used simulation to quantify their effect on fluid flow during waterflooding. The outcrop is characterized by several vertically-stacked, upward-coarsening units, and is interpreted as a composite tidal sandbar formed within an incised estuarine valley. The facies are analogous to those found in many subsurface tidal sandstone reservoirs, including the Lower Jurassic Tilje Formation in the Heidrun and Åsgard fields, offshore Norway.
At the small-scale, we have reconstructed the 3-D architecture of flaser, wavy, and lenticular bedding, by serially sectioning large (60cm x 60cm x 20cm) rock specimens; the resulting models preserve the primary depositional geometries and are not based upon synthetic data or stochastic modelling techniques. The models have been used both to quantify the effect on fluid flow of each bedding type during waterflooding, and to derive effective petrophysical properties for use in larger scale simulation models. At the intermediate-scale, we have constructed a detailed 2-D facies model directly from the outcrop, measuring 250m x 6m, and simulated waterflooding through the outcrop using effective petrophysical properties derived from the small-scale models.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana