Application of X-ray scanning and tomography to evaluate the filtercake removal efficiency

The removal of the filtercake formed during the drilling operation is essential for a successful cementing job. Nowadays, the use of synthetic base fluids brings the necessity of proceeding new evaluations of the efficiency of the washes in removing the filtercake and to guarantee the wettability inversion of the formation from oil to waterwet. It is presented here the application of X-ray tomographic scanning to evaluate the filtercake removal efficiency performed by different washes. This technique uses a natural core with a perforation, where a filtercake is formed by circulating a drilling fluid. The wash is circulated through this perforation and the filtercake removal efficiency is measured precisely by computer tomography scanning. This procedure enables the filtercake removal visualization during the wash circulation through the formation and from the data obtained from the X-ray tomography it is possible to select the most appropriate wash for a given drilling fluid, as well as to predict the necessary contact time between the wash and the formation to achieve an appropriate filtercake removal.