Experimental Study on A Drilling Fluid of Powerful Inhibition Film-forming Properties for Trenchless Horizontal Directional Drilling

摘要

Trenchless horizontal directional drilling is the most widely used method in trenchless pipe-laying in China,of which the main formation is Quaternary strata.How to ensure the stability of the hole wall is the key issue to the success of the project in the drilling process.In this paper,a drilling fluid of powerful inhibition based on polyvinyl alcohol (PVA) was researched for trenchless horizontal directional drilling.This type of drilling fluid has a film-forming property,which can form a membrane-like substance if left to stand in air,and have a good effect on the stability of the hole wall in Quaternary strata.The author’s research shows that: the polyvinyl alcohol (PVA) based drilling fluid of powerful inhibition has a better rheology and a stronger compatibility with other drilling fluid material,after investigating and analyzing a series of experiments for this kind of drilling fluids.It can meet the cleaning requirements of long horizontal directional bore hole if used with PAC.Compatibility with SPNH (brown coal resin) can reduce the loss of filtration and get a greater effect on lubrication drag reduction.The film-forming property and wall-protecting effect is particularly obvious when PVA is applied at the amount of 1.5％～3％,especially suitable for trenchless horizontal directional drilling.