Studying the Influence of Polymer-Colloid Drilling Fluid on the Pore Space of Rocks

Abstract

Using electron microscopy methods, the effect of polymer-colloidal drilling fluids on the pore space in carbonate reservoirs of an oil and gas condensate field, was studied. It is shown that the impact of polymers included in drilling fluids changes the surface of the pore space of rocks. This affects the technology of developing oil fields and the intensification of oil production. At the same time, due to the deposition of polymer components in the pore space of the rock, the properties of the samples change. This must be taken into account when conducting petrophysical studies on samples, as well as in geophysical studies of the bottom-hole zone using methods with a small study radius. The results of morphological studies in the electron microscope of the pore space of rocks after the impact of polymer-colloidal drilling fluids, are presented. Polymer films formed from drilling fluid components are studied. It has been established that after drilling horizontal wells, the change in the wettability of the pore space is associated with the formation of a polymer film on carbonate crystals. The thickness of this film, measured by the direct method, is 60–200 µm in the studied samples. It is noted that these changes in the future can lead to errors in determining the petrophysical properties.