Recently, this author was on an HDD project in northwest Idaho where the contractor was failing miserably at installing product line under a road. Soil conditions included rocks and cobble, and the contractor was using a drilling fluid that was not capable of suspending and transporting the drill cuttings to the surface, resulting in stretched ductile, stuck pipe and numerous frackouts. This is a scenario that happens far too often. Having the proper training and understanding of drilling fluids to know if a drilling fluid is capable of performing the task at hand can save contractors a lot of grief and money.
Gel strength/suspension is one of the most important functions of a horizontal directional drilling fluid. In order to make a hole in the ground, dirt must be removed, and drilling fluid returns are the conveyer belt that makes the removal of drill cuttings possible. Therefore, one must have returns, and the drilling fluid must be capable of suspending the soil being encountered.