--> Abstract: Measuring Autogenic Noise Superimposed on Idealized, Long-Term Distributary Dynamics; #90063 (2007)

Datapages, Inc.Print this page

Measuring Autogenic Noise Superimposed on Idealized, Long-Term Distributary Dynamics

 

Sheets, Benjamin1, David Hoyal1, Tao Sun1 (1) ExxonMobil Upstream Research Company, Houston, TX

 

The long-term average behavior of distributive depositional systems is relatively predictable and linear. The deposits tend to be monotonous, recording slow system re-equilibration via a gradual increase in slope to some regional ‘grade,' and in plan view, the front of the growing deposits will tend towards a radially-symmetric form. Most distributary systems, however, are noisy, producing intrinsic oscillations around the equilibrium trend. Though these oscillations can occur on a variety of time-scales (from minutes to many millennia), this paper is focused on autogenic noise associated with channelization, levee formation, and local overextension of the depositional front beyond the long-term trend. The channelization process leads to a type of ‘landscape inertia,' which is related to both the momentum of channelized flow and a pseudo-inertia associated with depositional landforms such as levees that confine flow to particular courses.

 

Analysis of experimental and numerical simulations of deep water and shallow marine distributive depositional systems indicate that this noisiness is clearly related to autogenic cycles in channel mouth bar formation and distribution. The period and magnitude of the cycles is related to the parameters controlling basin evolution, such as sediment and water discharges, sediment cohesiveness, and accommodation rates. An understanding of distributive autocyclic noise, therefore, has important implications for reservoir characterization and prediction, particularly as deposits associated with this scale of autocyclic behavior are commonly below seismic resolution.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California