Abstract

Building an accurate static model is critical to understand the reservoir heterogeneity, maintain the production, and optimize new wells locations. The stochastic modelling approach proved significant efficiency as a new and accurate modelling tool. In this case study, we applied the stochastic modelling approach to Sequoia field. The Sequoia Field is a Pliocene gas field, offshore Nile Delta, Egypt. The field is a delta slope, multi-stacked canyon systems with complex turbidity channel-levee deposits. The reservoir architecture commonly is the first priority in a stochastic reservoir model and is usually described in terms of different facies to rock types. The geomodel grid layout was made considering the geological realism. It was constructed from the beginning not to be upscale at the end, on a scale grid design of increment 100×100×1.5m mean. This increment was selected in such a big field to preserve the heterogeneity of the field with respecting to run time and the maximum number of the cell could be run in a dynamic model. The new model built has been used to calculate in-place volumes for Sequoia Field. The integrated structural framework of the model was made using the time and depth converted seismic horizons which used to create horizon model in time and depth domain. And the fault sticks were used to create the fault model and eventually the fault surfaces within the reservoir. The facies volume fractions were calculated from wells and considering the gross rock volumes from magnitude maps and inversion volumes. The reservoir properties like porosity and water saturation volumes were modeled stochastically and co-simulated using correlation coefficients biasing to the facies property. The Stochastic geomodel optimizing on the grid resolution, provide better water predictions and planning of additional wells if needed.

Introduction

This study used the static modeling techniques to understand heterogeneity of sequoia channel in reservoir facies, porosity, permeability and water saturation. Tiab and Donaldson (1996) reported that petrophysics is the science concerned to study of the (physical and chemical) rock properties and interactions with fluids. A number of petrophysical properties; like, porosity, permeability, and saturation will be described. These properties depend on the distribution of other properties such as mineralogy, pore size, or sedimentary fabrics, and on the physical and chemical properties of the solids and fluids. Consequently, petrophysical properties may similar in a homogeneous reservoir or they may vary from one position to another, in a heterogeneous reservoir. Stochastic modeling techniques used to understand heterogeneity of sequoia channel in reservoir properties, and then gas volume can be estimated.

AREA OF STUDY

The Study Area (Sequoia Field) is located on the north-western margin of the Nile Delta, approximately 90km offshore of Alexandria., and approximately covering 90km2 (Fig 1). The field lies across the border between the West Delta Deep Marine Concession and the Rosetta concession.

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