Experimental investigation of rheological properties and formation damage of water-based drilling fluids in the presence of Al2O3, Fe3O4, and TiO2 nanoparticles

Abstract

The successful drilling of the oil and gas wells almost relies upon the drilling fluid properties. Maintaining wellbore stability, transportation, and releasing cuttings at the surface, and controlling formation pressure are the essential functions of the drilling fluid. Improving the rheological properties of the drilling fluid results in an increase in transport power and also provides better stability. One of the new methods to improve different properties of the drilling mud is the application of nanoparticles. Nanoparticles induce favorable effects on the rheological properties of the fluid. Improvement of mud properties yields in better cleaning of the well, the stability of the wellbore, higher drilling bit efficiency, and, consequently, a lower cost in the long run. Therefore, the present study investigates the effect of adding three different nanoparticles including aluminum oxide, iron oxide, and titanium oxide to the drilling fluid in several experiments by measuring rheological properties (plastic viscosity, yield point, filtration rate, gel strength) and also formation damage and permeability reduction. The number of experiments was determined by the experiment design method. The results of the experiments implied that in nanofluids with the weight of 70 pcf, rheological properties were relatively improved in most of the nanofluids samples concentrations. Samples containing iron oxide exhibited a decreasing filtration rate compare to base drilling fluid that indicates increasing stability in the fluid environment. The gel strength (GS) of titanium oxide and aluminum oxide samples has increased appropriately, which shows improvement in attractive forces in the fluid. For the case of the 80 pcf nanofluid, iron oxide indicates appropriate rheological properties and decreasing of filtration rate that all of them represent nanoparticle caused an increasing and improving the stability of fluid. But titanium oxide and aluminum oxide couldn't show significant effects. This phenomenon can be described by the lack of a uniform and thorough mixing of nanoparticles in the drilling fluid under field conditions. Besides, results obtained from the formation damage test equipment demonstrated the 54% reduction in initial permeability of the iron oxide nanoparticle that is the lowest damage between another nanofluid.