DEVELOPMENT OF OPTIMAL COMPOSITION OF DRILLING FLUID FILLER FOR OPEN HOLE WELL COMPLETION

Abstract

Experimental studies were carried out to determine the effect of inert fillers on the filtration properties of clay cakes during their formation. The sequence of experiments corresponds to the sequence of stages: formation of the main structure of the filter cake (simulation of the opening process by drilling), treatment of the bottomhole zone to restore the initial permeability (for example, during chemical destruction of the filter cakes) and washing out of process fluid filtrates from the bottomhole zone into the well. The solid phase in the drilling fluid can be represented by both structure-forming clay particles and fillers (barite, crushed cuttings, bridging agents, etc.). Moreover, fillers can have individual particles of a size of a colloidal degree of dispersion and significantly affect the filtration performance of drilling suspensions. It is especially important to evaluate the influence of the composition of the solid phase of the clay suspension on the filtration properties at the stage of formation of the main structure of the filter cake. This stage is characterized by a non-stationary filtration process. In essence, the bulk of the studies of filtration processes is carried out in this mode. In our case, it is necessary to determine the dependence of the filtration index of solutions Пр on the composition of the solid phase. In the course of experimental studies, it was confirmed that subsequent filtration through the cakes formed at stage 1 equally depends on the magnitude and nature of the drawdown application, as in stage 1, as well as on the permeability of the filter cake and the clogging zone. Therefore, the research methodology at stage 2 required supplementing experiments with the formation and modification of filter cakes during filtration through permeable sand packs.