Improving wellbore stability by applying drilling mud with Fe2O3 nanoparticles
Since 90% of all problems related to the wellbore instability occur during drilling through shales, which are mostly consisted of clay minerals, the filtrate from drilling mud penetrate into shale rocks and lead to their destabilization, so the industry is considering the possible application of new types of additives because conventional additives, due to their size, cannot enter in pores of shales, plug them and reduce further filtrate penetration. The oil industry in last few years turns to investigate possible application of nanoparticles because they can enter in small shale pores and plug them, thus increasing the wellbore stability. In this paper the influence of the size (50 nm and between 20 and 30 nm) and concentration (0.5, 1, 3 and 5 wt%) of Fe2O3 nanoparticles on density, rheology, API filtration, and swelling of laboratory prepared pellets in contact with mud without and with nanoparticles was determined. Due to the fact that the rheological properties are significantly increased at higher concentrations, and that smaller particles give better results with an emphasis on increasing the wellbore stability further tests should be carried out with nanoparticles Fe2O3 which size is between 20 and 30 nm in maximum concentration of 1 wt%.