Maximizing Recovery from Reservoirs with Tar Mats: From Characterization to Production — Joint EAGE/SPE Workshop

9-12 November 2008
Dubai, UAE

One of the challenging aspects of managing oil fields is that reservoirs can contain tar mats (non-movable hydrocarbon saturation). Tar mats are present in many oil reservoirs throughout the world, and they are quite common in Middle-East carbonate reservoirs, including several of the ten largest reservoirs in the world. Tar mats are usually located - but not always - at or near present day oil/water contacts. The tar saturation is commonly unpredictable, at least at the level of detail needed to effectively place injection wells to minimize loss of mobile oil above the tar and to minimize the risk of sidetracking wells to get back above tar. So, one key concern regarding tar mats is their impact on reservoir connectivity and their effect on water flooding.

To have full control of these issues many questions need to be answered: Where are the tar mats located? How many are there? What‘s their horizontal continuity? Do they constitute strong permeability barriers, or only partial? Can we predict tar mats distribution in a reservoir and model them? Placing horizontal injectors just above tar mats may require specific real-time geosteering technology. What are the most effective techniques to achieve optimum placement and maximum injectivity?

An emerging topic in the Middle-East and elsewhere is the technical and economical feasibility of converting tar mats into new reserves. This requires a good understanding of the geochemistry of tar mats, with oil compositional variations and viscosity gradients. What are the best enhanced oil recovery and production methods suited to extract heavy oil from tar mats layers?

From characterization, through modeling, reservoir management, drilling, to production of new reserves, all these topics and questions will be the subject of this workshop.