水平定向钻进管道敷设地层响应实验分析

在应用水平定向钻进非开挖技术进行近地表管道敷设时,由于上覆地层厚度(C)、钻孔直径(D)和钻井液压力(p)三者无法准确设计,往往会导致地表的变形,进而形成裂缝通道致使地表发生钻井液的溢流.分析了非黏聚力地层的溢流通道形式,同时推导了极限钻井液压力的计算公式.结合室内外实验及应用情况,得出了实测钻井液压力和计算钻井液压力同C/D值的变化规律,即C/D越大,极限钻井液的压力值也就越高.在同一地层中,一般钻井液压力的峰值出现在水平孔段的中间位置.根据C/D值,在保证钻井液不发生溢流的情况下,得出了不同水平孔径范围所对应的上覆地层最小厚度.

Test Analysis of Soil Response in Pipeline Installation by Horizontal Directional Drilling Technology

During the process of pipeline construction the horizontal directional drilling method is used.The drilling fluid intersecting and ground movement always occur when the soil cover depth is lower.The reason is that the soil cover depth(C),horizontal borehole diameter(D) and drilling fluid pressure(p) are hard to calculate accurately.This paper introduces the limited drilling fluid pressure calculation model and the circulation forms in the cohesion and cohesion less soil.The results indicate the relationship between the limited drilling fluid pressure and C/D according to the lab test and field application.The pressure is higher when the C/D increases.The results also show that the maximum drilling fluid pressure always occur at the center of the horizontal drilling track.Under the safe annulus pressure,the paper provides the minimum soil cover depth based on the different borehole diameters.