River Research Group Sloughing Drilling Fluid To Be Home In The Southern Region In Western Sichuan

The shale of TX in southern of Sichuan easily collapse during drilling, at the same time, the development of natural cracks, leading to the occurrence of a series of underground complex issues. Analysis by the instability formation rock propertiesand the mechanism of instability,with analysis and optimization of the drilling-in fluid components and performance, and put forward simultaneously with the plugging and inhibit in the anti-collapse drilling fluid components demand to deal with instability stratigrapHic.Instability stratigrapHic rock properties analysis:the content of clay minerals of mudstone inTX is low, and mainly content is the smectite-illite mixed layer and illite; The absolute of non-clay mineral content is high, and mainly content is quartz and calcite, but feldspar is few.Instability mechanism includes the hydration expansion of smectite-illite mixed layer and illite is severe, and cementation of the seam is poor, and large differences between clay and non-clay mineral in hydration capacity, and hydration stress became higher, which caused by the mud filtrate made the deep shale hydrated along cracks, and then improved the collapse stress and made the strata instability.To optimize the on-site drilling fluid by shale rolling recovery experiments, improved hot-rolling of large pieces of rock samples experiments, swelling experiments, immersion test and sand bed experiments, on the evaluation of the dispersion, inhibitoty and closure, and then came to the right optimization formulation, which include based pulp+2%KCl+1%SMC+1%RLC-101, and proposed anti-collapse measures.ZJ001-X4well Held applications with indoor track showed that, anti-collapse drilling liquid, which appropriate increased density (1.62g/cm3to1.65g/cm3), and added about3%(volume percent) anti-blocking agent (such as RLC-101the NRII. FRH. PHD), and supplemented with1%sullbnated lignite treatment agent (such as the SMC. RSTF) and2%sulfonated phenolic resin treatment agent (such as JD-6. SMP-1). could balance formation pressure, and block the bedding and fracture, and reduce the los in high temperature and high pressure. Compared with the contrast well, after suppression and blocking combination into wells pulp, the blockage drilling and reaming frequency significantly became lower, and rate of hole enlargement has been effectively improved, and the borehole became relatively regular, and can normal drilling and drill clown in the end.