Research And Application Of Anti-collapse Drilling Fluid In DZ-BH-03 Exploration Hole Of Chongqing-kunming High-speed Rail

As China's infrastructure has entered a new peak,railway construction has entered a period of vigorous development as an important part of infrastructure construction.Geotechnical investigation is the preliminary work of railway construction and an important part.It provides hydrographic and engineering geological data for railway designers and provides information and evidence for railway design.Core drilling is one of the commonly used means of railway survey,and its engineering volume has also shown explosive growth.Mud shale formation is often encountered during the drilling process.The loose fracture and hydration expansion of the shale is the main influencing factor of the instability of the borehole wall,which often leads to collapse of the pore wall,reduction of diameter and stuck drill.accident.Core drilling often encounters shale formations,loosely fractured formations,and water-sensitive formations.Drilling into these formations often leads to accidents such as reduced diameters,stuck drills,and collapsed walls.The DZ-BH-03 survey hole of the Buktun high-speed railway BH tunnel is in the northwest wing of the upper male block.Due to the regional structure,the local bedrock is completely twisted and then heavy cementation occurs.The strata belong to the Triassic Upper Xujiahe Formation(T3x)sandstone and shale coal seam.Because the shale,coal seam and other strata are easy to hydrate and expand and disperse,the nature is unstable,and the borehole also passes through multiple fault rupture zones,which leads to frequent accidents when drilling DZ-BH-03 survey holes using conventional drilling fluid.The specific performance is that the diameter of the hole is seriously reduced,the collapse of the hole is often caused,and the heart rate is very low.Therefore,in order to prevent the problem of poor anti-collapse performance of the drilling fluid used in the DZ-BH-03 survey hole,the drilling fluid optimization formula with good rheological property,easy flow regulation,low fluid loss and strong anti-collapse performance was studied.It is imminent.This article is based on the optimization formula of anti-collapse drilling fluid to carry out the following research work:(1)Firstly,the status quo of research on the mechanism of borehole instability at home and abroad and the research status of anti-collapse drilling fluid are reviewed,focusing on the shale hydration mechanism and the inhibition of shale hydration measures.Based on the analysis of the instability mechanism of mud shale formation and the hydration mechanism of clay minerals,the performance requirements and technical points of DZ-BH-03 drilling fluid for BH tunnel were proposed.On the basis of the widely used non-dispersible low solid phase polymer drilling fluid,the bentonite addition was screened by comparative test to determine that water + 4% bentonite was used as the soil slurry for the subsequent test.By adding suitable admixtures,flocculant FA-367,diluent XY-27,inhibitor NH4-HPAN,fluid loss additive JT-888 and asphalt plugging agent FT-1,each has better performance.The basic combination of components.(2)On the basis of the basic combination,using the orthogonal test analysis method,four kinds of anti-collapse drilling fluid optimization formulas were selected according to four different principles,and then the drilling fluid requirements were drilled according to the DZ-BH-03 prospecting hole drilling site.Under the premise of anti-collapse and fluid loss requirements,the anti-collapse drilling fluid formula most suitable for on-site use was screened out.(3)Awakened the indoor test for the optimal formula of anti-collapse drilling fluid,and quantitatively investigated its rheological properties,fluid loss performance,inhibition performance,lubrication performance,etc.The test results show that the anticollapse drilling fluid is the most The excellent formula can well meet the basic requirements of DZ-BH-03 survey hole core drilling.(4)Combined with the on-site construction process,the optimized anti-collapse drilling fluid optimization formula is applied to the DZ-BH-03 survey hole drilling site of the Bukun high-speed railway BH tunnel.After use,the situation in the hole gradually returned to normal,and there were no serious complications such as serious drilling fluid loss and collapse of the collapsed hole.The mechanical drilling speed increased to 5 times and the core take-up rate also increased significantly.This indicates that the optimized formula of the anti-collapse drilling fluid has a good stability effect on the pore wall of the DZ-BH-03 exploration hole,and it has a certain effect on the preparation and use of the drilling fluid when drilling the carbon shale and fault rupture zone in the future.Guiding significance.