Environmental Drilling. By: Josh Humphreys October 8,2006. Why Do We Drill??. Environmental Site Characterization Ground Water Monitoring Exploration Petrochemical Exploration Water Well Drilling. Hand Drilling Methods.
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Environmental Drilling By: Josh Humphreys October 8,2006
Why Do We Drill?? • Environmental Site Characterization • Ground Water Monitoring • Exploration • Petrochemical Exploration • Water Well Drilling
Hand Drilling Methods • Probing- Slender steel rod-0.25-0.5 inches in diameter and 3-4 feet long. • Used to locate shallow subsurface obstructions (Boulders, utility conduit, piping e.g.) • When probe is advanced it forces the formation material out of its path by displacing the soil.
Direct Push Boring • Simple, efficient method of obtaining samples and installing wells. • Can be accomplished with out the need of heavy equipment, fluids, and doesn’t produce drill cuttings. • Well suited for shallow borings in soft materials. • Generally small Truck or ATV mounted
Direct Push Boring Cont. • Forced into the soil by direct application of weight of the machine, by the percussive effect of a hydraulic or mechanical hammer. • Some may use a vibratory system to advance the drilling.
Auger Drilling • Utilizes a spiral tool form to convey drilled borehole material to the surface. • Auger Drilling doesn’t normally require the use of circulatory fluids, unless it is used to cope with blowing , heaving or running sands. • Essentially a conveyor with a cutting bit at the bottom to disaggregate formation material, and be lifted to the surface, or forced into the borehole wall.
Bucket Auger • Utilize an auger bucket with cutting teeth attached to a square torque bar that passes through a drive mechanism. • Generally advances 1 to 2 ft., is withdrawn, and contents are discarded in throw away pile. • Depth capacity 30-75 ft. • Large diameter holes 16-48 in. • Commonly used to drill wells, caissons, and building footings.
Continuous-Flight Solid-Stem Augers • Consists of a Plugged Tubluar steel centered shaft, around which a continuous steel strip in the form of a helix is welded. • An individual auger section in known as a “flight”, and is normally 5 ft. long. • Designed to connect to one another by way of safety pin or large bolt ‘u-pin” or “drive clip”. • Torque is transmitted by the rig.
Continuous-Flight Solid-Stem Augers Cont. • Drill cutter heads are attached to the bottom of the auger. • Most of the cutter heads are field replaceable bit types. • Bits are hardened or tungsten carbide steel teeth. • Designed to cut 0.5 inches larger than the auger. WHY??? • Most Successful in dry formations or cohesive materials- not frequently used for well installation.
Hollow Stem Augers • Form of continuous-flight auger in which the helix is wound around, and welded to, a hollow center tube. • When tubes are connected, the hollow stem auger will present a smooth, uniform bore throughout its length. • Can be done with out drilling fluids. • Most common drilling method for monitoring wells.
Rotary drilling rig • Carry their own pumps and operating components. • Power unit, rotation mechanism, feed or retract system, drum hoist, and other features.
Drilling Fluids • Circulation medium can be liquid, water or drilling mud, or is can be a gas, such as air or foam with additives of various types. • Media is forced down through the drill rod and out through the bit and back up between the borehole wall and drill rod. • Cools and lubricates, stabilize the borehole and remove drill bit cuttings.
Wash Boring • Simple, and almost obsolete method of advancing the borehole. • Cut by chopping and twisting action of a bit, and disaggregated formation material is washed to the surface by fluid.
Sonic Drilling • Utilizes high frequency vibration, aided by down pressure and rotation. • Power for drilling is created by sine generator on top of drill mast, with rapidly rotating eccentric, counter balanced weights that are timed to direct 100% of the vibration @ 0 and 180 degrees. • Rotates at 3,000 to 10,800 r/min.
Sonic Drilling Cont. • Developed in the 1970’s for use in mineral exploration, but ineffective. • Later adapted to environmental exploration in the 1990’s and has been very effective. • Drill in mostly unconsolidated formations is very rapid. • Continuous sampling cuts down on costs. • Can go up to 700 ft. can penetrate boulders, construction debris and bedrock to a point.