Abstract
The aim of this paper is to propose an integrated approach to reproduce both facies and diagenetic trends in a static reservoir model based on an outcrop case study. In Wyoming (USA), the Madison Formation (Mississippian) is a thick (up to 350 m) carbonate series, outcropping in several locations of the Bighorn foreland basin.Within these series, nine sedimentary facies have been identified. Based on their vertical stacking pattern, they are organized in small-scale facies sequences: 1) intertidal to supratidal facies sequence; 2) shallow subtidal to intertidal facies sequence; 3) deep subtidal facies sequence. These facies associations have been integrated in a synthetic depositional model, which corresponds to a carbonate ramp progressively evolving towards the most inner part of a platform. This enables to propose a sequence stratigraphy framework for the studied series, that represents at least six third-order sequences (some of them being locally eroded).The diagenetic study has been focused on the identification of the early diagenetic phases. Results from these analyses show the occurrence of several successive early diagenetic phases (micritization, marine calcite cementation, dolomitization, etc.). For modeling purposes, seven “diagenetic imprints” have been defined, each of them corresponding to a succession of diagenetic phases that can coexist in the same sedimentary facies. Moreover, as each sedimentary facies may be affected by several diagenetic imprints, a quantification of these imprints has been realized.A 3D gridded model designed for geostatistical modeling has been constructed in order to reproduce the facies organization of the three first third-order sequences (that are the best documented). The gridding is then based on the four sequence boundaries which have been recognized on every section. The relationships between sedimentary facies and diagenesis have been used to define lithofacies simulation rules. The simulations are based on the plurigaussian and nested algorithms. Finally, a discussion on the distribution of the potential reservoir heterogeneities is proposed, taking into account the sedimentary characteristics (facies, architectures, etc.) and the diagenetic impact.
Highlights
Carbonate reservoir properties are controlled primarily by the sedimentary facies, and are strongly modified by its diagenetic history, early or late (Lézin et al, 2009)
Stochastic Joint Simulation of Facies and Diagenesis: A Case Study on Early Diagenesis of the Madison Formation (Wyoming, USA) — The aim of this paper is to propose an integrated approach to reproduce both facies and diagenetic trends in a static reservoir model based on an outcrop
A thorough description and quantification of both facies and diagenetic phases are necessary inputs for a valid geostatistical modeling of the reservoir properties. It shows the use of such coupled-simulation, as the diagenesis may completely modify the distribution of reservoir facies only based on a facies simulation
Summary
Carbonate reservoir properties are controlled primarily by the sedimentary facies, and are strongly modified by its diagenetic history, early or late (Lézin et al, 2009). This two parameters may subsequently influence the development of the fracture network Diagenesis increases the complexity to characterize and further to model the carbonate reservoirs (Shackelton et al, 2005; Olson et al, 2007; Wennberg et al, 2006). Forward modeling have been used by Whitaker et al (1997) and Patterson et al (2008), to model an early meteoric diagenesis occurring on an isolated carbonate platform. Even if it has been successfully tested to predict the distribution of diagenetic processes (Xiao et Jones, 2006), it is still an ongoing research topic that aims to validate conceptual diagenetic models based on the diagenetic analyses or discuss the influence of the factors involved in a diagenetic process (Whitaker et al, 2004)
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