Carbonate Facies Models, Fake or Real? Comparison of the Urgonian Formation South-East France with the Kharaib-Shuaiba Formations Middle East – Insights from the ALBION R&D Project

Abstract

AbstractTypical carbonate reservoir modelling workflow usually requires the definition of a carbonate facies model. It generally consists of a conceptual model that drives the successive stages of populating reservoir models. Intuitively, the process of defining a facies model helps to understand and master carbonate reservoir heterogeneity at all scales. This convenient approach reduces the obvious complexity of carbonate reservoirs. It also supports many scientific and technical activities from stratigraphic well correlation, sedimentology, petrophysical interpretation, identification of key dynamic features and assessment of uncertainties to be captured in numerical reservoir models. In practice, facies models bridge the gap between natural processes (sedimentology, diagenesis) and rock properties at reservoir scale and deliver the elementary bricks for the numerical reservoir models. However, such conceptual models mostly derive from scattered observation data (few wells with cored intervals) rarely supported by physical measurement. This limitation induces significant uncertainties in the definition of sediment profiles, depending on the scale and the concepts used. All models produced are the result of extrapolations and interpretations, from cores data which do not sample the whole space of sedimentation.The interdisciplinary ALBION R&D project aims at studying Urgonian carbonate formation from south-east France, known as a famous analogue of Kharaib & Shuaiba Middle East reservoirs (both of Barremian-Aptian age). The quality of the numerous outcrops, the completeness of the available material (e.g. cores, rock samples, thin sections, various and advanced analyses) and the importance of the published bibliography allowed to define a complete and synthetic facies model to be compared with the ones of Kharaib and Shuaiba formations from the United Arab Emirates. The workflow implemented to realize the facies model on the Urgonian and the Kharaib - Shuaiba formations takes place in four stages: 1) Comprehensive synthesis of the literature; 2) Consistency and ranking of the available data; 3) Creation of the table and facies models; 4) Definition of parameters controlling the occurrence of facies association (e.g. bathymetry, energy). This innovative workflow enforces the coherency between the definition of each facies and the facies association populated in the numerical reservoir model. It makes also possible/easier the comparison between different facies models. These new facies models are embedded within a carbonate infrastructure ranging from the carbonate system (carbonate factory) to the facies of deposits. Facies are characterized by physical quantities such as bathymetry and energy (controlling processes). The construction of these two facies models (representing both sides of the Neo Tethys) drives the definition of numerical modeling rules shared by the two sectors. It opens important perspectives to testing process based and geostatistical numerical modeling methods on the Urgonian outcrop to better control stratigraphic architecture, facies organization in carbonate production prior to applying ascertained modeling rules to Middle East subsurface reservoirs.