Multi-component Coordinated Well Wall Stabilization Water-based Drilling Fluid Research

There are natural fractures in the shale formation, which is easy to collapse and unstable during the drilling process, resulting in a series of downhole complex problems, such as card drilling, hole expansion and so on. Based on the analysis of the rock physical properties and the mechanism of instability of the unstable strata, the anti-collapse drilling fluid technical measures to prevent and control the borehole wall in shale formation are put forward.Through systematic experimental study, obtained the inhibitor combination of KCl and FA367 binary collaboration and synergistic ternary composite plugging agent ECD plus, pitch plugging agent FGL, FT342 plugging agent combination, and collaborative RH220, RH102 solid-liquid lubricant combination. Based on the analysis of the field drilling data, the drilling fluid density needed to stabilize the formation is determined, and the multiple coordinated anti collapse water base drilling fluid system with strong inhibition performance and strong blocking performance is studied.Study on the multiple synergistic anti sloughing drilling fluid field test in well 33-5HF and well 33-6HF Gao miao. The average of the 7 non complex accident block test of horizontal wells in the incidence rate of 3.76%, while the 2 test wells complex accident rate is 0. The anti sloughing drilling fluid improves the Gaomiao Block drilling efficiency and reduce the complex accident rate, field application effect is good, to achieve the effect of wellbore stability.