Investigating the Effect of Fluid and Formation Parameters on Mud Cake Thickness, Filtration Velocity and Invasion Depth

Mud cake formation is a layer of mud emulsion that is formed from the drilling fluids during the drilling operation. Filtration process of drilling mud takes place as the drilling operation in carried out under a certain condition called overbalanced conditions, which means that the pressure of drilling mud injected is higher than the pressure of the formations. Due to this differential in pressure, drilling fluids will tend to be invaded into the porous part of the formation; where by the smaller particles of the drilling fluid will invade further into the formation, while the larger particles will accumulate at front surface of the pore size, creating a layer of mud cake. Understanding the behavior of mud cake thickness is important because it can reduce the mud circulation loss into the formation. Specifically, they are few objectives to be achieved within this project. They are i) to investigate the necessary parameters of the drilling mud properties in order to study the mud cake formation around the wellbore, ii)to investigate the necessary parameters of the drilling mud properties in order to study the mud cake formation around the wellbore. The formation permeability, mud cake permeability, porosity, mud filtrate viscosity, mud cake density, pressure, solid particle concentration in drilling mud, length of core and also the time measured have been identified as the main factors that will manipulate the mud cake thickness, filtration velocity and invasion depth of mud filtrate; meanwhile water-based mud drilling fluid is chosen for a shallow depth well under a static condition with constant pressure and constant low temperature. At the end of this project, it is expected that core with high cake permeability will result in higher mud cake thickness and filtration velocity compared to core with low mud cake permeability.