Study On Oil Displacement Performance And Evaluation Method Of Nanofluid In Tight Reservoirs

The development of oil and gas exploration and development technologies has brought opportunities for the development of tight reservoirs,making it a hot spot in the global oil and gas development field.For tight reservoirs,fracturing technology is one of the important engineering methods for effective development.The purpose is to obtain effective fractures and seepage channels to improve reservoir seepage.The addition of surfactants to the fracturing fluid can reduce the oil-water interfacial tension and change the wettability of the rock,thereby increasing the crude oil recovery of the tight reservoir.Nano-expulsion system is an emerging technology widely used in the formation of tight reservoir fractures.It has three characteristics: low adsorption loss,reversal of wettability,and maintenance of a certain oil-water interfacial tension.Before nanofluids are applied on site,it is necessary to evaluate their performance.This article takes this as a starting point and designs a series of laboratory experiments to develop a pressure conduction experiment device to evaluate the different properties of nano-liquids.Using a surface interfacial tension test,a set of nanoliquid formulations with a lower surface interfacial tension was screened.Adsorption tests were performed on the selected formulations,and it was found that the adsorption of nano-liquids was less than that of conventional surfactants;at the same time,core fluids were used to evaluate the damage rate of nano-fluids to cores,and nano-liquids were obtained with reduced damage.The results of pressure conduction experiments show that the nano-liquid displacement performance is greatly affected by the multiphase flow,which provides ideas for the subsequent improvement of the formulation.This study provides new ideas for the economic and efficient development of deep oil and gas reservoirs and unconventional tight oil and gas.