Carbonate reservoirs contain approximately two-thirds of the world's oil and gas reserves (Al-Anzi et al., 2003). Carbonates often pose a significant problem when it comes to understanding their reservoir quality because of their heterogeneous nature, which is caused by both the variety of processes occurring depositionally and their high susceptibility to diagenetic alterations. In order to fully characterise the behaviour of carbonate rocks in the subsurface is it important to understand their textural heterogeneity and also how faulting can modify their textures. Deformation in fault zones causes the petrophysical properties (e.g. porosity, permeability and velocity) to alter from the background values. For example, fracturing in damage zones surrounding faults increase the permeability, creating conduits to fluids, conversely, fault cores often act as barriers, created by pore occluding processes. However, faulting in carbonate rocks is often complicated by their textural variations, leading to a variety of deformation microstructures, and each will create different petrophysical properties. This thesis aims to understand how faulting effects different carbonate rocks and analyse the controls on any alterations to the petrophysical properties (porosity, permeability and velocity) into the fault zones. Alterations to the permeability are important to unravel in order to assess the fluid flow potential and hydraulic properties of a rock. Understanding the alterations to the velocity can help to better image faults at depth and to provide information on their microstructures.