Core Drilling

Dry Drilling

A com­mon drilling method is tele­scopic dry core drilling in gran­u­lar soil. This method usu­ally uses a sin­gle tube core bar­rel. Dur­ing each cored sec­tion, the entire drill rod is removed and rein­stalled to extract the drill core. These near-sur­face bore­holes are drilled with the help of cas­ings that inter­lock to sup­port the bore­hole wall. Depend­ing on the geo­log­i­cal sit­u­a­tion and the drilling equip­ment, sec­tions of approx­i­mately 10 to 25 meters can be drilled per pipe sec­tion. The cas­ings are removed once drilling is com­pleted.

This method enables dry core drilling with an ini­tial diam­e­ter of 419 mil­lime­ters. With the tele­scopic cas­ings com­monly used at Stump-BTE Bautech­nik AG and a depth of approx­i­mately 10 to 25 meters per pipe sec­tion, fil­ter wells can be con­structed with the cor­re­spond­ing diam­e­ters and depths.

Wire line core drilling

Core drilling by using the wire line core method is one of the spe­cial­ties of Stump-BTE Bautechnik AG. This drilling method is mainly applied to explore deeper under­ground. Wire line core sys­tems are sim­i­lar in struc­ture to dou­ble-tube core bar­rels. Here, how­ever, the inner sys­tem can be hoisted sep­a­rately from the outer sys­tem using a cable winch. With dou­ble- or triple-tube core bar­rel sys­tems, the mechan­i­cal im­pact on the core is lower than with a sin­gle-tube core bar­rel. The core is pro­tected against the mechan­i­cal impact of the cir­cu­lat­ing flush by the inner tube of the core bar­rel. The flush is chan­neled through an exist­ing annu­lar space between the inner and the outer sys­tem. Flush­ing addi­tives make it pos­si­ble to main­tain the core in its orig­i­nal con­di­tion. Wire line core sys­tems must be driven with a spe­cial rod in order to enable the core in the inner sys­tem to be recov­ered via the cable. Usu­ally, after the core is extracted, the inner tube is rein­serted into the rod string by grav­ity. Pumpable sys­tems are avail­able for inclined drilling.