Influence of drilling fluids on the filtration properties of reservoirs

Currently, during the opening and testing of productive formations, as well as during repair work in wells, specialized water- or oil-based technical fluids are used. All of them are characterized by compatibility to varying degrees with the lithological and physical properties of reservoirs in Western Siberia and have different effects on the filtration properties of the porous reservoir of productive formations. It is known that when using fresh water-based drilling fluids, due to the interaction of the fresh water filtrate with rock cement and some rock-forming minerals, the permeability of the bottom-hole zone changes. The paper presents the results of an experimental study of the effect of drilling fluids on terrigenous rocks of one of the fields. The impact of drilling fluids on the core, with the exception of FLO-PRO and NaCl, led to a decrease in the oil-permeability of core samples. In the core of the terrigenous reservoir, filtering FLO-PRO does not cause a negative result. The curves of permeability changes with increasing filtration pressure before and after FLO-PRO flow are identical in dynamics. According to the results of the study, it can be concluded that technical fluids FLO-PRO and IES (invert emulsion solutions) can be recommended for use as they do not violate the structure of the pore space of the reservoir and do not lead to a significant decrease in oil-permeability of all core layers. (paper)