Borehole Angle Control Device. Final Technical Report

摘要

The invention is a new device for changing the direction of advancement of a borehole being drilled for the discovery or production of oil or gas for example. The new technique involves the inducement of a side force on the bit by pumping a small quantity of formation cuttings, taken from the out-flow in the annulus, selectively to one side of the bit during part of each revolution. Drilling is accomplished by means of a conventional rock bit fitted with a cuttings discharge tube. Drilling fluid containing rock cuttings enters in the intake of a progressive cavity type pump which is powered by a contact roller which contacts the sides of the borehole during part of each revolution at or above the normal point of tangency due to gravity induced sag or bending of the drill string. The fluid containing rock cuttings is discharged selectively to one side of the bit during part of each revolution through the discharge tube. The wedging action of the cuttings between the newly cut wall and the bit cutter pushes the bit in the desired direction, acting like a mini-whipstock. Mathematical demonstrations have shown that a very small side drilling tendency (force) will produce an ample deflection of the borehole. The tool was field tested in July, 1985. It performed guite well in that it did reduce the deviation angle about one degree in 373 feet. Wear patterns observed at several points on the tool make the need for some minor modifications apparent. (ERA citation 11:012672)