Continuous Real-Time Evaluation of Downhole Fluid Pressures During Horizontal Directional Drilling Pilot Bore Operations

摘要

Inadvertent returns during Horizontal Directional Drilling (HDD) operations can result in significant damage tornsurface structures such as roadways, sidewalks, railway tracks, and transformer boxes. Equations such as the Delftrnmodel have been adequately documented for enabling engineers and contractors to calculate allowable overburdenrnpressures during HDD installations in an attempt to better design and construct such projects. Although typicallyrnconservative, little research has been done to validate the accuracy of these predictions. This paper provides anrnoverview of the importance of monitoring and controlling fluid pressures to minimize surface disruptions andrndemonstrates the application of a novel fluid pressure-monitoring tool that enables real-time continuous monitoringrnof drilling fluid pressures during the pilot bore.rnAn analysis of field results of several recent HDD projects using field recorded data is presented as well as arndiscussion on how this data can be used in the field as a means to minimize inadvertent returns. Additionally thernpaper describes how the recorded data can be used to further develop the accuracy of current empirical methods forrnpredicting maximum allowable pressures.