Trenchless drilling is one of the fastest growing areas for shale shaker use other than drilling oil and gas wells. Trenchless drilling encompasses several areas of use:
• Micro-tunneling—Micro-tunneling has become very popular in Europe and is being used more frequently in the United States. Micro tunneling is the horizontal boring of a large-diameter hole (from 27 inches up to 10 feet) while simultaneously laying pipe. Typically, this technique is used in cities when laying or replacing water and sewer pipe beneath buildings and heavily traveled roads.
To prepare for these operations, large-diameter, vertical holes, or "caissons," are excavated allowing the drilling equipment and hydraulic rams to be set up at the desired depth. The caisson is excavated slightly below the equipment level creating a sump for the returned drilling fluid and associated drilled solids. The returns are pumped to the surface by a submersible pump to a compact solids removal system, which typically consists of a shale shaker and mud cleaner mounted over a small tank.
• River crossing—This technique facilitates running a pipeline under a river. First, a small-diameter hole is directionally drilled under the riverbed. The pipe for the pipeline is then attached to the end of the drill string and pulled back under the river while a larger hole is back-reamed to accomodate the pipe.
When laying large-diameter pipelines, a substantial solids control system must be established with multiple shakers, desanders, desilters, and centrifuges. Additionally, the use of mud cleaners will reduce drilling fluid disposal volumes.
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