[First Hit]

Datapages, Inc.Print this page

Click to view posters in PDF format.

 

PSModeling Reservoir Architecture of Isolated Previous HitCarbonateNext Hit Platforms*

By

Phillip Bassant1 and Paul M. (Mitch) Harris1

 

Search and Discovery Article #40294 (2008)

Posted August 7, 2008

 

*Adapted from poster presentation at AAPG International Conference & Exhibition, Paris, France, September 11-14, 2005. See companion article, “Analyzing Reservoir Architecture of Isolated Previous HitCarbonateNext Hit Platforms,” Search and Discovery Article #40295 (2008).

Click to view list of articles adapted from presentations by P.M. (Mitch) Harris or by his co-workers and him at AAPG meetings from 2000 to 2008.

 

1 Chevron Energy Technology Company, San Ramon, California, USA ([email protected]; [email protected])

 

Abstract

Forward stratigraphic modeling of a conceptual isolated Previous HitcarbonateNext Hit platform produces four distinct depositional profiles determined essentially by water depth. The depositional profiles described below have characteristic facies belt dimensions, geometries, facies-proportions and stratigraphic occurrences. These simulations help to predict facies belt geometries and constrain facies belt dimensions for isolated platform reservoirs like those found in the Caspian Basin.

Profile A (shallowest) shows a grainstone shoal margin on the high-energy edge of the platform, 250-500 m wide, with a raised rim and shallow platform interior dominated by packstones. Profile B also shows a high-energy grainstone rim, 500-1000 m wide with no significant margin relief, and a platform interior dominated by packstones. Profile C occurs in a deeper bathymetric setting; high-energy conditions flood the platform, and platform-centered grainstone shoals develop with widths of 2000 – 5000 m. Profile D (deepest profile) has deeper water packstones developed across the platform top, with no grainstone development.

In an aggrading platform with only monotonous Previous HitseaNext Hit-Previous HitlevelNext Hit rise and no Previous HitseaNext Hit-Previous HitlevelNext Hit cyclicity, only profile B develops. This is the stable-state for platform-growth in this model. During Previous HitseaNext Hit-Previous HitlevelNext Hit stillstands, profile A will eventually develop. During a deepening sequence, profiles B, C, and D develop in rapid succession prior to final drowning. Profiles C and D can be considered transient or unstable states, as their productivity rates are too low to keep up with Previous HitseaNext Hit-Previous HitlevelNext Hit rise, and thus are rare during times of monotonous Previous HitseaNext Hit-Previous HitlevelNext Hit rise. However, when Previous HitseaNext Hit-Previous HitlevelNext Hit Previous HitcyclesNext Hit are introduced, unstable profiles C and D may dominate the platform. Grainstones (profile C) or packstones (profile D) can dominate platform-top deposition throughout the cycle, with abrupt shallowing to the raised grainstone rim (profile A) occurring at maximum Previous HitseaNext Hit-Previous HitlevelNext Hit fall.

 

uAbstract

uFigures

uCase model

uSequence stratigraphy

uReference

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

uAbstract

uFigures

uCase model

uSequence stratigraphy

uReference

 

 

Build a Base Case Model

Parameters were chosen to resemble approximately a Carboniferous grain-dominated platform with microbial boundstone slopes like Tengiz.

Input parameters:
Model size = 20 km x 20 km
Cell size = 250 m x 250 m (80 x 80 cells)
Time step = 0.5 Ma for 30 Ma duration
Production rules: depth and energy control on production
Transport rules: downslope transport (gravity)
Accommodation changes: linear (model 1) and cyclic (model 2)

 

Implications for Sequence Stratigraphic Interpretations

Bathymetry alone will not uniquely define the depositional profile for a given system: multiple depositional profiles exist (partly dependent on rate) for the same bathymetry.

In low amplitude accommodation Previous HitcyclesNext Hit, Sequence Boundaries (SB) are 180 degrees out of phase with accommodation cycle (SB occurs at Previous HitseaNext Hit-Previous HitlevelNext Hit highs). Maximum Flooding Surface (MFS) is 90 degrees out of phase with accommodation Previous HitcyclesNext Hit.

In high amplitude accommodation Previous HitcyclesNext Hit, SB and MFS are in phase with accommodation lows and highs, respectively.

 

Reference

Weber, L.J., B.P. Francis, P.M. Harris, and M. Clark, 2003, Stratigraphy, lithofacies, and reservoir distribution, Tengiz field, Kazakhstan: Permo-Carboniferous Previous HitCarbonateTop Platforms and Reefs, SEPM Special Publication 78, p. 351-394.

Return to top.