An Uncertainty Model for Fault Shape and Location

Per Røe,Frode Georgsen,Petter Abrahamsen

doi:10.1007/s11004-014-9536-z

Per Røe, Frode Georgsen + Show 1 more

Open Access

https://doi.org/10.1007/s11004-014-9536-z

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Journal: Mathematical Geosciences	Publication Date: May 10, 2014
Citations: 36	License type: CC BY 4.0

Affiliation: Norwegian Computing Center

Abstract

Fault models are often based on interpretations of seismic data that are constrained by observations of faults and associated strata in wells. Because of uncertainties in depth migration, seismic interpretations and well data, there often is significant uncertainty in the geometry and position of the faults. Fault uncertainty impacts determinations of reservoir volume, flow properties and well planning. Stochastic simulation of the faults is important for quantifying the uncertainties and minimizing the impacts. In this paper, a framework for representing and modeling uncertainty in fault location and geometry is presented. This framework can be used for prediction and stochastic simulation of fault surfaces, visualization of fault location uncertainty, and assessments of the sensitivity of fault location on reservoir performance. The uncertainty in fault location is represented by a fault uncertainty envelope and a marginal probability distribution. To be able to use standard geostatistical methods, quantile mapping is employed to construct a transformation from the fault surface domain to a transformed domain. Well conditioning is undertaken in the transformed domain using kriging or conditional simulations. The final fault surface is obtained by transforming back to the fault surface domain. Fault location uncertainty can be visualized by transforming the surfaces associated with a given quantile back to the fault surface domain.

Highlights

Thore et al (2002) list several sources of uncertainty when modeling faults based on seismic data, but conclude that the main sources are uncertainty in the seismic interpretation combined with vertical and lateral uncertainty arising from the time-depth migration of the seismic data
The fault-sealing properties and the existence of additional faults are the main sources of uncertainty in reservoir performance, the fault geometry and position have significant effects, especially for wells located near major faults (Irving et al 2010; Rivenæs et al 2005)
The fault uncertainty envelope is shown in purple, and has a variable width of approximately 500 m at the center of the fault, increasing to almost 700 m near the ends of the fault

Summary

Introduction

Faults are generally modeled using seismic data, well data and a knowledge of the local geology. Thore et al (2002) list several sources of uncertainty when modeling faults based on seismic data, but conclude that the main sources are uncertainty in the seismic interpretation combined with vertical and lateral uncertainty arising from the time-depth migration of the seismic data. Thore et al (2002) list several sources of uncertainty when modeling faults based on seismic data, but conclude that the main sources are uncertainty in the seismic interpretation combined with vertical and lateral uncertainty arising from the time-depth migration of the seismic data. The fault-sealing properties and the existence of additional faults are the main sources of uncertainty in reservoir performance, the fault geometry and position have significant effects, especially for wells located near major faults (Irving et al 2010; Rivenæs et al 2005). An uncertainty model for fault position and geometry enables this uncertainty to be updated based on well production data (Cherpeau et al 2012; Irving and Robert 2010; Seiler et al 2010; Suzuki et al 2008)

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