Noname manuscript No. (will be inserted by the editor) Deep Bed Filtration Modelling of Formation Damage due to Particulate Invasion from Drilling Fluids Edo Boek · Chris Hall · Philippe Tardy Received: date / Accepted: date Abstract A Deep Bed Filtration model has been developed to quantify the effect of solids invasion from drilling fluids on the permeability of rock formations. The calcu- lated particle trapping profile are compared directly with experimental profiles from scanning electron microscopy and synchrotron X-ray sources. The computed perme- ability reduction as a consequence of particle invasion is in broad agreement with experiment. Backflow was modelled by reversing the flow rate, starting off with a situ- ation where all particles either remain trapped or are all released. It appears that the experimentally observed 30 % release of particles upon backflow is reproducible within the limits of the two extreme cases. When erosion is included in the model, a peak in the back flow pressure time series can be observed. This peak may be correlated with the experimentally observed Flow Initiation Pressure (FIP), which is the back flow pressure needed to initiate flow after initial inflow filtration. Finally, we conclude that internal reservoir damage, within the limits of our 1-D single phase DBF model, may contribute to the experimentally observed Flow Initiation Pressure (FIP). Keywords Deep Bed Filtration · Formation Damage · Drilling Fluids Edo Boek Department of Chemical Engineering Imperial College London SW7 2AZ, United Kingdom and Schlumberger Cambridge Research High Cross, Madingley Road Cambridge CB3 0EL, United Kingdom E-mail: e.boek@imperial.ac.uk Christopher Hall Centre for Materials Science and Engineering University of Edinburgh Edinburgh EH9 3JL, United Kingdom Philippe Tardy Schlumberger DIS 322 11th Avenue SW Calgary, AB, T3B 5B1, Canada