Experimental study on the sealing characteristics of fractured formation by shear thickening fluid

Abstract:

The fracture leakage channel in fractured formation usually has multi-scale characteristics and uncertainty. The drilling fluid leakage problem is particularly prominent in the construction of geological drilling in fractured formation. Shear Thickening Fluid （STF）， as a new type of intelligent material， has excellent properties such as self-sensing， self-adaptation and self-repair， and has been widely used in many fields. In this study， shear thickening fluid was used as a plugging material， and the plugging characteristics of shear thickening fluid were investigated under different dispersed phase concentrations （56.9vol%， 59.2vol% and 61.7vol%）， slit widths （1，2，3，4，5mm） and pressure conditions through the plugging test of API plugging instrument. The plugging test results show that the amount of leakage increases with the increase of seam width and time. When the concentration of nano silica increases in the range of 56.9%~61.7%， the leakage rate will be reduced and the effect of the gap width on the leakage rate will be weakened. When the leakage pressure is 0 MPa， the shear thickening fluid does not produce thickening effect， but leaks out from the seam in the form of liquid. When the pressure increases slightly， the thickening effect will be stimulated， and agglomeration particles will be generated to seal the seam pipe and reduce the leakage rate. When the pressure further increases beyond the bearing capacity of the sealing layer， the shear-thickening fluid is extruded out of the fracture in a plate form. The application of shear-thickening fluid in plugging field is expected to provide innovative solutions for plugging in fractured formation.