Design and application of green drilling fluid of strong inhibition

Borehole instability problem is always common when intersecting the brittle shale formations using either water-based mud or oil-based mud. An extensive wellbore stability drilling fluid was carried out mainly focused on integrating a variety of anti-collapse technology and the rigorous environmental protection. In this paper, a set of the environmental friendly drilling fluid system of strong inhibition was designed and developed based on the multi-element concept of inhibition, plugging, flocculating and environmental protection, combined with the characteristics and brittle shale and the special environmental requirements. In this system, KCOOH and SIAT are taken as the inhibitors, PAC-LV as the fluid loss agent, KPAM as the flocculant and nano-barite as the weighting and plugging material to improve the quality of mud cake and reduce the solid content of the system.