Fault Facies Modeling: Applications in Various Sedimentary and Fault System Configurations

Muhammad Fachri, Jan Tveranger, Nestor Cardozo, and Sylvie Schueller
Centre for Integrated Petroleum Research, University of Bergen, Bergen, Norway

Fault facies modeling is the process of generating 3D geological objects in the fault envelope in reservoir grid. The modeling is performed to capture reservoir heterogeneity caused by faulting. The conditioning factors for fault facies modeling are a fault product distribution factor (FPDF, a parameter describing the distribution of lithologies in the fault envelope) and a shear strain parameter.

FPDF is generated based on the following variables:
1. Pre-faulting sedimentary facies configuration in the fault envelope
2. Fault displacement model, which is constrained based on the following input variables:
- fault core thickness as a function of fault throw
- footwall and hanging wall damage zone widhts as functions of fault throw
- the displacement percentage accommodated by fault core and damage zones
- the type of displacement function

The strain parameter is generated based on the fault displacement model. The strain parameter, together with the FPDF, is used for creating the probability distribution that serves as an input in stochastic modeling of the fault facies. The fault facies volumetric proportion and spatial distribution in the resulting models can be partly controlled by applying simple manipulations to the fault facies probability distribution.

The modeling technique allowed many synthetic fault envelope models to be built easily by varying the modeling input variables constrained by field data. The resulting models were systematized in matrix form, capturing the variation of both sedimentary and fault system configurations. Currently 64 models have been implemented, each executed in 10 stochastic realizations. Quantitative analysis of the implemented models shows that the application of the modeling technique is able to reproduce natural fault envelope configurations formed under various sedimentary and structural configurations.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas