| 摘要 |
A simple low-cost and highly passive bitless nonrotational nondeviating jam-proof thin-kerf Newtonian hydraulics retrievable core-sampling method and apparatus that advances its circular core kerf through the rock by a combination of high-pressure droplet-impact and abrasive particle-jet effects, and which is independent of the weight of any drillpipe, drill collars, or any other heavy cylindrical conduit or tubular conduit associated with the coring operation. The Newtonian hydraulics features high-pressure solids-free fresh water or solution-weighted brine as the drilling fluid, which excavates rock along the inner periphery of the circular core kerf by droplet-impact effects of the high-pressure and high-velocity circular sheet of drilling fluid and by the abrasive particle-jet effects of the deflected drilling fluid and excavated rock particles along the outer periphery of the circular core kerf. The hydraulic horsepower delivered to the downhole coring apparatus and the hydraulic hoisting capacity of the excavated rock particles to the surface can both be increased considerably by employing high-density solution-weighted brine as the drilling fluid. The use of solution-weighted brine, if chilled at the surface to below the freezing point of the penetrated porefluid, and if circulated in the borehole by means of insulated drillpipe, would also provide the additional advantage of freeze-stabilizing the borehole wall, freeze-stabilizing the excavated core samples, and freeze-entrapment of uncontaminated porefluids in the core samples.
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