Liner Augmentation of Horizontal Drilling (LAHD FLUTe)

This technique has been developed and field-tested by FLUTe for the primary purpose of providing a clean horizontal hole for sampling the pore fluids. The approach also has special utility in the drilling of horizontal holes in unstable media. The FLUTe liner is used to support the hole in lieu of the usual mud cake on the hole wall. The result is that there is little, if any, mud cake and much less mud invasion of the pore space. In fact, as the hole is reamed to its full size, the drilling fluid can be water, since there is no need for the properties of the common drilling mud other than to remove the cuttings.

The procedure is shown in the drawing sequence: A pilot hole is drilled with the standard procedure, including the normal mud for development of a stable slender hole. After the pilot bit exits the earth, the pilot bit is replaced with a non-rotating pig and the typical reamer. As the reamer cuts the pilot hole and mud cake out, the liner following the reamer supports the borehole wall immediately behind the reamer. The cuttings are forced by the liner to flow out the pilot hole instead of flowing into the reamed hole. When the reamer is fully retracted from the hole, the hole is left fully supported by the pressurized liner.

The liner following the reamer can be a blank liner (without any attachments), or it can be an instrumented liner, as shown, with many sampling ports for pore fluid extraction. The fluid sampling liner is a variation of the Vadose FLUTe System ot the Water FLUTe system modified for this application. The instrumented liner installed behind the reamer can be used immediately as installed.

A blank liner installation is the initial step in installation of a casing or conduit (one technique uses the blank liner to tow a casing into place in the hole). Because the hole will not collapse on a casing inside a liner, and because the friction on the casing is very low within the liner, a relatively inexpensive slotted PVC casing can be used instead of the usual high strength stainless steel casing. The casing installation has been done for exceptionally small holes (e.g., a 4" casing in a 6" hole). The liner can be removed via one of the patented procedures or left in place surrounding the casing.

For information on the application of this technique, please contact FLUTe at .

The photos show a recent installation in a 370 ft. 6" diameter hole beneath a landfill. A liner fitted with 8 sampling ports (each with a 5 ft. sampling interval) was installed from the 48" pressure canister.