Steering system and method

1. A system for steering a drilling device comprising a drill pipe, comprising:

a hoop, sleeved on the drill pipe of the drilling device and having an outer diameter substantially equal to an inner diameter of a hole to be drilled; and

a steering driving mechanism, between the hoop and the drill pipe, for controlling a radial displacement of the drill pipe relative to a center axis of the hole to be drilled while drilling, wherein the steering driving mechanism comprises one or more sub-mechanisms for connecting the hoop and the drill pipe and driving the drill pipe to move inside the hole to be drilled, wherein each of the sub-mechanisms comprises an actuator adjustable in length coupled to the drill pipe, and a link element rotatably coupled to the actuator at a first end thereof and coupled to an inner wall of the hoop at a second end.

2. The system according to claim 1 , wherein a portion of the actuator is fixedly coupled to the drill pipe, and the link element is rotatably coupled to the hoop at a second end thereof.

3. The system according to claim 1 , wherein the actuator comprises a cylinder installed on the drill pipe and a piston rod having one end inside the cylinder and being able to move relative to the cylinder.

4. The system according to claim 3 , wherein the drill pipe has two drill pipe grooves on an outer surface thereof; and the actuator further comprises a connecting support, coupled to an end portion of the piston rod, and perpendicular to the piston rod; two blocks, respectively coupled to two ends of the connecting support, provided in the two drill pipe grooves, and being able to slide in the drill pipe grooves; and at least two hinge supports, respectively fixed on the two blocks, the link element being rotatably coupled to the hinge supports at the first end thereof.

5. The system according to claim 1 , wherein the hoop has at least one hoop groove on an outer surface thereof for mud to pass through.

6. The system according to claim 1 , wherein the steering driving mechanism is able to adjust the radial displacement to a given value based on a current radial displacement and the given value.

7. The system according to claim 1 , further comprising two covers for covering two axial end faces of the hoop, respectively.

8. The system according to claim 1 , wherein the steering driving mechanism comprises three sub-mechanisms arranged with equal intervals around the drill pipe.

9. A drilling method, comprising:

drilling a hole with a drilling device comprising a drill pipe with a hoop sleeved thereon, wherein the hoop has an outer diameter substantially equal to an inner diameter of the hole; and

steering the drilling device while drilling by controlling a radial displacement of the drill pipe relative to an center axis of the hole with a steering driving mechanism between the hoop and the drill pipe, wherein the steering driving mechanism comprises one or more sub-mechanisms, each of which comprises an actuator adjustable in length coupled to the drill pipe, and a link element rotatably coupled to the actuator at a first end thereof and coupled to an inner wall of the hoop at a second end.

10. The drilling method according to claim 9 , wherein steering the drilling device comprises adjusting the length of each actuator to drive the drill pipe to move inside the hole along a direction different from a drilling direction.