Reduction of formation damage in horizontal wellbores by application of nano-enhanced drilling fluids: Experimental and modeling study

Abstract

One of the basic challenges during drilling horizontal wellbores is the damage induced by invasion of mud filtrate into the formation. Addition of nanoparticles to drilling fluids has been recognized as a measure of control and reduction of filtrate invasion, which is the primary mechanism of the aforementioned formation damage. Despite notable advances in composing Nano-enhanced drilling fluids, the role of nanoparticle hydrophobicity on performance of the fluids has not been well studied. This study is based on a combined experimental-numerical methodology. In the experimental section, a procedure to find the optimum composition of Nano-enhanced water-based samples, containing nanoparticles of hydrophilic/hydrophobic silica and lipophilic clay to minimize the formation damage associated with mud circulation is recommended. The main idea was to investigate the effect of hydrophobicity of nanoparticles on damage reduction and furthermore, discover how other properties such as types/concentration of nanoparticles/micro-sized additives, temperature and pressure would affect functionality and characteristics of drilling fluids. In order to more accurately and practically investigate any probable enhancements in performance of fluid samples a particular radial filtration setup was designed and used; then, functionality of mud samples was examined on grain packed porous media at radial flooding flow condition. Results revealed that samples containing 0.2 wt. % hydrophobic nanosilica had the best functionality with returned permeability of 68.4% and 51.1% for the cases of water saturated and oil saturated porous media, respectively. In the modeling section, mass balance and momentum equations were solved simultaneously by using elapsed time data. Permeability as well as thickness of mud cake formed on the wellbore wall were evaluated and compared for different Nano-enhanced mud samples. Results showed that nano-enhanced drilling fluid samples generated thinner mud cakes with lower permeability values during quite shorter period of time. Results of this work might be helpful to better understand the behavior of nano-enhanced drilling fluids in radial porous systems at different conditions of nanoparticles hydrophobicity and applicable to minimize the induced formation damage during drilling of the horizontal section of a production well. • A combined experimental-numerical methodology is used to evaluate any possible enhancement in characteristics of drilling fluid, mud cake and damaging potential. • The effects of hydrophobicity of nanoparticles along with types/concentration of nanoparticles/ micro-sized additives, temperature and pressure on characteristics of drilling fluids are investigated. • A particular radial filtration setup is designed and used to more precisely evaluate the damaging potential of mud samples and to measure permeability recovery after mud filtrate invasion. • Samples containing 0.2 wt. % hydrophobic nanosilica had the best functionality with return permeability of 68.4% and 51.1% in water-saturated and oil-saturated porous media, respectively. • In the modeling section, mass balance and momentum equations are solved simultaneously; permeability and thickness of filter cake are evaluated and compared for each of mud samples.