Kinetic to capillary flow transition during drilling fluid injection through porous medium

A novel experimental study aided with image analysis is used to investigate the flow characteristics such as penetration depth, fluid front velocity, kinetic to capillary transition and wettability behaviour of pressure-induced suspension flow through the dry-dense porous medium. For the three drilling fluid compositions adopted, the penetration response is predominantly governed by the particle size and the specific gravity of the additives present in the suspension. Due to the intricate particle migration/deposition process, the fluid front velocity decreases with an increase in space and time. By utilising fractal analysis, a unique transitional zone based on the linear relationship between the scaled fractal dimension and time is identified which partitions the permeation-dominated kinetic flow and capillary-dominated flow regimes. This transition holds relevance in understanding wellbore instability, drainage control and grouting. Finally, the quantification of the time-dependent contact angle from the fractal analysis revealed that due to the filtration process, the rheological properties of the suspension get altered which impacts the wettability characteristics.