The wetting of a surface by a liquid is a crucial part of many natural and industrial processes. Despite numerous existing studies, some elements of wetting-dewetting such as contact angle variation are still poorly understood. Knowledge of contact angle behavior during the flow is necessary for modeling fluid displacements in capillary-dominated flows. In the context of multi-phase flow in porous medium, the lack of direct contact angle measurements inside pores (in-situ), adds to the ambiguity. This work consists of performing in-situ contact angle measurements on X-ray micro-computed tomography images of multi-phase fluid systems during quasi-static flow and investigating the effects of pore geometry and interfacial forces on contact angle. An algorithm enabled automated analysis of contact angle throughout the three-dimensional images. Observations revealed two unique contact angle variation patterns for oil (dodecane)-water and air-water systems with larger hysteresis for the oil-water. Introduction of a third phase (air) and altering surface chemistry (wettability) of a portion of solid phase, influenced oil-water contact angle near unaltered surfaces, but the overall trend remained the same. Results of this investigation show that contact angle correlates with the variations of fluid-fluid interfacial curvature and the pore radius at the wetting front.