This document is an expanded abstract.
Carbonate reservoirs contain a significant part of the world’s oil reserves, and most of them will contain naturally occurring fractures that will impact reservoir performance to various degrees. This paper discusses the importance of establishing an integrated workflow to address the challenges posed by naturally fractured reservoirs. Such a workflow needs to incorporate geomechanical parameters to achieve a consistent model in which fracture intensity is correlated with rock properties. Despite the presence of fractures in most of the reservoirs, the petroleum industry still faces the challenges on how to best implement them in subsurface models. Indeed, many fractured reservoirs are complex and difficult to understand, describe, and model; thus, often models are built focusing only on the matrix properties, or incorporating fractures in a simplistic way. The need for representative reservoir models in increasingly complex fractured reservoirs is the key driver behind the workflow presented in this paper.
Fractured reservoirs represent a major challenge, from reservoir modelling to dynamic simulations; they are also extremely difficult when dealing with less common production mechanisms. The result is often low daily flow rates and low recoveries, so new approaches must be used. The typical industry approach in these cases is the use of Dual Porosity/Dual Permeability formulations to describe the reservoir behavior. This paper describes the essential steps to produce a Dual Porosity simulation model input, which includes (amongst other parameters) fracture porosity and fracture permeability. A workflow (Figure 1) was implemented in a conceptual model to estimate fracture properties as a function of petrophysical properties with the incorporation of geomechanical parameters. The result is a more reliable and consistent model. It incorporates geological and facies concepts, petrophysical and mineralogical models, and rock physics models, to arrive at an estimation of fracture porosity and permeability.
This methodology estimates fracture porosity and fracture permeability as a function of reservoir properties, to incorporate geomechanical features and produce a more consistent model in which fracture intensity is correlated to rock properties.