Application of water well drilling rig in wire line core drillingin ultra deep soft soil layer

Abstract:

In the regional geological survey project in Qingxu County, Shanxi Province, scientific drilling holes of 800m, 2000m and 3000m are designed to fill the gap in delineation of the Cenozoic floor burial depth, with each hole completed 30m drilled into the bedrock. Full hole coring is required with the core recovery rate ≮85%, the core diameter ≮60mm, and the undisturbed rock sample to be taken with the plastic protective tube. In light of the difficulties such as ultra deep soft soil layer, unknown characteristics and thickness of each group, unknown drilling depth, large diameter high fidelity full hole coring, far lower contract price than the current market cost, with the 800m hole drilled with “water well drilling rig +conventional coring +long open hole section”, and a 640m parametric hole drilled with “core drill+ wire line coring + casing cementing”, an innovative process of “water well drilling rig + wire line coring + long open hole section” was then developed and used to complete the 2000m hole. The core recovery of the hole reached 93%, and the borehole diameter and deviation met the geological requirements, which lays a solid foundation for the smooth construction of the 3000m hole and provides experience and reference for similar projects.