Determination of prohibition mechanism of cationic polymer / SiO2 composite as inhibitor in water using drilling fluid

Abstract

Well drilling is complicated by wellbore inflation caused by saturation and swells in shale. Water-based drilling fluids (WDFs) were used to test the new NS-DD shale inhibitors, which is a nano-silicon dioxide/cationic polymer composite (NS-DD). Shale cuttings rolled restoration evaluations and bentonite inhibition evaluations were utilised to compare the inhibition performance of NS-DD to that of the classic inhibitory (Potassium Chloride) KCl and the widely used inhibitory polyether di-amine (PDA). Even at high temperatures, the inhibitory efficiency of nano silicon-dioxide was superior to that of KCl and PDA. However, when NS-DD was present, the restoration of shale was more than71.8% while hot rolling at 160 °C for 18 h in the occurrence of KCl as well as PDA. The third roll recovery of shale was 28.62 % and 42.15 % correspondingly. According to XRD obtained from WDFs filter cake and shale samples, the NS-DD adsorbs water into the reservoir and causes the shale to expand, therefore blocking water absorption into reservoir and producing shale swelling. This study showed that NS-DD might be used as a shale inhibitor in Water-based drilling fluids.