Evaluation of filter cake mineralogy in extended reach and maximum reservoir contact wells in sandstone reservoirs

Good knowledge of filter cake structure and composition leads to successful selection of drilling fluid that minimizes formations damage and selection of an effective and efficient recipe for removing the filter cake. This study focus on an aspect which was not fully covered in the literature: the chemical characteristics of filter cake formed along the horizontal well, from its heel to its toe. High pressure fluid loss tests were performed using real drilling fluid samples from the field which were collected during drilling horizontal section of a sandstone formation. The mineralogy of the external filter cake formed by fluid loss cell is determined using both Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The results showed that for long horizontal sections, the composition of the filter cake was not constant from its heel to its toe since the small drilled cuttings or particles, that are not completely removed, were mixed with the drilling fluid during circulation and become an integral part of the fabric of the filter cake.