Drill bit steering

A method of steering a drill bit at the end of a drill string within a borehole to permit drilling of the borehole along a deviated path, the method comprising:

• (a) connecting an upper part of a tubular body to a lower portion of the drill string;
• (b) connecting a lower part of the tubular body to a lower assembly including the drill bit;
• (c) lowering the drill string into position within the borehole such that the drill bit is located at the bottom of the borehole;
• (d) axially aligning the upper and lower parts of the tubular body within the borehole such that the drill bit is aligned with a section of the borehole immediately above the drill bit;
• (e) moving a mandrel axially within the tubular body to a blade out position to move stabilizer blades on the upper part of the tubular body radially outward to engage the borehole wall;
• (f) rotating the drill bit while the upper and lower parts of the tubular body are axially aligned and while the stabilizer blades are move radially outward to drill along substantially a straight path;
• (g) thereafter retracting the stabilizer blades out of engagement with the borehole wall;
• (h) with the stabilizer blades in their retracted positions, pivoting the lower part relative to the upper part to produce an axial bend in the tubular body between the upper and lower parts resulting in tilting of the drill bit;
• and
• (i) rotating the drill bit while the lower part is pivoted relative to the upper part to drill along a deviated path.

A method of steering a drill bit at the end of a drill string within a borehole to permit drilling of the borehole along a deviated path, the method comprising:

• (a) connecting an upper part of a tubular body to a lower portion of the drill string;
• (b) connecting a lower part of the tubular body to a lower assembly including the drill bit;
• (c) mounting radially movable stabilizer blades on the upper part of the tubular body;
• (d) lowering the drill string into position within the borehole such that the drill bit is located at the bottom of the borehole;
• (e) thereafter inwardly retracting the stabilizer blades out of engagement with the borehole wall;
• (f) with the stabilizer blades in their retracted positions, pivoting the lower part relative to the upper part to produce an axial bend in the tubular body between the upper and lower parts resulting in tilting of the drill bit;
• (g) selectively rotating the drill string to orient the bit in a desired direction;
• and
• (h) with the drill bit desirably oriented, rotating the drill bit while the lower part is pivoted relative to the upper part to drill along a deviated path.

Apparatus for steering a drill bit at the end of a drill string within a borehole to permit drilling of the borehole along a deviated path, the apparatus comprising:

• a tubular body having an upper part adapted at its upper end to be coupled to a lower portion of the drill string and a lower part adapted at its lower end to be coupled to a lower assembly including the drill bit, the lower part being pivotable relative to the upper part to produce an axial bend in the tubular body between the upper and lower parts;
• adjustable stabilizer blades mounted on the tubular body and radially movable between extended positions in which the blades engage the borehole wall, and retracted positions in which the blades are radially spaced from the borehole wall;
• and
• a mandrel axially movable within the tubular body for selectively maintaining the lower part in axial alignment with the upper part and thereby maintaining the drill bit in axial alignment with a section of borehole being drilled while simultaneously maintaining the stabilizer blades in their extended positions and for selectively retracting the stabilizer blades to their retracted positions while pivoting causing the lower part relative to pivot relative to the upper part to produce an axial bend in the tubular body and thereby tilt the drill bit out of alignment with the section of borehole being drilled.

Apparatus for steering a drill bit at the end of a drill string within a borehole to permit drilling of the borehole along a deviated path, the apparatus comprising:

• a tubular body having an upper part adapted at its upper end to be coupled to a lower portion of the drill string and a lower part adapted at its lower end to be coupled to a lower assembly including the drill bit, the lower part being pivotable relative to the upper part to produce an axial bend in the tubular body between the upper and lower parts;
• a pivotable member for pivotably connecting the upper part and the lower part for selectively producing an axial bend between the two parts;
• adjustable stabilizer blades mounted on the tubular body above the pivotable member and radially movable between extended positions in which the blades engage the borehole wall, and retracted positions in which the blades are radially spaced from the borehole wall;
• and
• an actuating member moveable to a blade in position for retracting the stabilizer blades to their retracted position while the two parts remain axially aligned, and further movable to a bend position for creating an axial bend between the two parts while the stabilizer blades remain retracted for drilling along a deviated path;
• and
• the actuating member movable to a straight path position for eliminating the axial bend while the stabilizer blades remain retracted, and further movable to a blade out positioned for expanding the stabilizer blades radially outward while the bend remains eliminated for drilling along a straight path.