Aminsadegh Paprouschi - Sharif University of Technology
Mohammad Aliahmadi - Sharif University of Technology

Production from fractured reservoirs is mainly done through the fracture, and estimating the depth damaged by drilling mud is of particular importance for repairing the damage through various methods. The mud-filtrate invasion and related formation damage due to drilling fluids can result in the misinterpreted values of rock and fluid properties in the reservoir, affecting the well plan. It is also possible to obtain the fracture's width and permeability by examining the penetration depth of the drilling mud into the channel. In this study, by examining the past studies and research, an attempt has been made to obtain more accurate relationships to estimate the final depth of drilling mud penetration in the fracture. Drilling fluids usually follow Herschel's rheology completely, so by using this fluid rheology model, more real relationships will be obtained for the fluid invasion depth. Then, for opening greater than the drilling mud solid particles' diameter, the fluid enters the fractured causes mud cake, which causes a loss of pressure and a reduction in the final penetration radius of the drilling mud. Also, the penetration radius is not related to the width of the fracture. It is only a function of the mud cake's permeability, the difference between well pressure and formation, well diameter, rheology, and flow properties of drilling fluid. For a channel less than the diameter of the solid particles of the drilling mud, the mud cake is formed outside the fracture, and only mud filtrate is invaded into the fracture, which is a function of well diameter, rheology, and flow properties of drilling fluid filtrate, thickness, and permeability of mud cake.

Drilling Fluid, Rheology, Filtrate, Formation Damage