Rt. Bonnecaze et al., PATTERNS OF SEDIMENTATION FROM POLYDISPERSED TURBIDITY CURRENTS, Proceedings - Royal Society. Mathematical, physical and engineering sciences, 452(1953), 1996, pp. 2247-2261
Particle-driven gravity currents, as exemplified by either turbidity c
urrents in the ocean or ignimbrite flows in the atmosphere, are buoyan
cy-driven flows due to the suspension of dense particles in an ambient
fluid. They are formed naturally from sediment-laden outflows from ri
vers into coastal waters, from submarine landslides along coastal shel
ves or as the result of volcanic eruptions. The porous rock and sand o
f both consolidated and unconsolidated oil-reservoirs are often derive
d from the sediment deposited from turbidity currents over geological
time. A knowledge of the genesis of these reservoirs may provide bette
r methods to estimate their porosity and permeability distribution, wh
ich would improve evaluation and management of these valuable resource
s. This paper presents a theoretical model for the dynamics and deposi
tion of a two-dimensional particle-driven gravity current composed of
a polydispersed suspension of dense particles and compares the theoret
ical predictions against data obtained from laboratory experiments. Af
ter developing a scaling analysis of the governing equations, we propo
se a simple algebraic method to Compute the areal density of deposit,
or mass deposited per unit area, and the distribution of particle-size
s within deposits arising from either two-dimensional or axisymmetric
currents. The resulting formulae suggest an inverse method to estimate
the density of deposit and the distribution of particle sizes as a fu
nction of position in a reservoir from a limited number of cores.