A rheophysical study of the non-newtonian behavior of water flow in thin channels

Abstract

The development of low-permeable hydrocarbon reservoirs is becoming an increasingly urgent task, and therefore, the study of the laws of fluid movement in subcapillary pores and microcracks is a crucial scientific and technical problem. The previous experimental studies revealed that a viscous liquid during flow in low-permeable reservoirs exhibits an anomalous non-Newtonian character, accompanied by a violation of the linearity of the filtration process, and, consequently, Darcy's law. It was also established that starting from a certain critical size of the opening of the crack, the flow of a Newtonian fluid (water, viscous oil) becomes non-Newtonian, with the manifestation of an initial pressure gradient and flow locking. In this research work, rheophysical aspects of the non-Newtonian behavior of water during flow in thin rectangular channels are considered experimentally. Using the microchannel model, it is established that the nonlinear rheological effect in the flow of water in micro-slits is mainly caused by the value of the electrokinetic potential of the system, by reducing of which it is possible to significantly weaken the non-Newtonian nature of the fluid. To regulate the electrokinetic potential of the fluid system, an antistatic additive was used, the optimal concentration of which was established experimentally. The optimal concentration is defined to be 0.006 %. Based on the Bingham model, the rheological parameters of water flow were estimated at different micro-slit clearances changed in the range of 10÷25 micrometers, in the absence and presence of an antistatic additive. It is also established that a reduction in the electrical potential of the fluid flow leads to a significant decrease in the yield shear stress during the flow of water in the microchannel