DRILLING METHOD

摘要

A method of drilling a borehole from a selected location in an existing wellbore (1) penetrating subterranean earth formation having at least one hydrocarbon bearing zone (3) wherein the existing wellbore is provided with a casing (4) and a hydrocarbon fluid production conduit (6) is arranged in the existing wellbore in sealing relationship with the wall of the casing, the method comprising: passing a remotely controlled electrically operated drilling device (12) from the surface through the hydrocarbon fluid production conduit to the selected location in the existing wellbore; operating the drilling device such that cutting surfaces on the drilling device drill the borehole from the selected location in the existing wellbore thereby generating drill cuttings wherein during operation of the drilling device, a first stream of produced fluid flows directly to the surface through the hydrocarbon fluid production conduit and a second stream of produced fluid is pumped over the cutting surfaces of the drilling device via a remotely controlled electrically operated downhole pumping means and the drill cuttings are transported away from the drilling device entrained in the second stream of produced fluid.