Rotary steerable drilling tool and method of control thereof

Patent metadata

Field	Value
Publication number	US-10443307-B2
Application number	US-201816174715-A
Country	US
Kind code	B2
Filing date	Oct 30, 2018
Priority date	Oct 31, 2017
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

The static push-the-bit articulated high-built-rate rotary steerable tool has the main body of a non-rotary measurement and control unit articulated with the main body of a non-rotary actuator, rather than an integral structure. Due to the fact that the drilling tool is easy to bend in a wellbore, the bending stress in an upper portion of the steerable tool is low, and the consumption of the pushing force for bending deformation of the drilling tool is minimized. Since the steering sleeve around the main body of a load-bearing actuator only slides along the well wall in an axial direction without rotational friction there-between, the service life of the steering sleeve is long. Besides, since hydraulic pressure is used instead of pressure difference of mud to act on the pistons to form the pushing force, the pushing force is greatly improved, and the sealing life of the pistons is longer.

First claim

The invention claimed is:

1. A rotary steerable drilling tool, comprising:
a rotary mandrel;
a drill bit shaft connected to a drill bit;
a universal joint having a proximal portion connected to the rotary mandrel and a distal portion connected to the drill bit shaft;
a first non-rotary steering sleeve disposed around the rotary mandrel via an upper mud bearing and a lower mud bearing so that the rotary mandrel is rotatable relative to the first non-rotary steering sleeve;
a second non-rotary steering sleeve extends over the universal joint, wherein the second non-rotary steering sleeve has a distal portion disposed about the drill bit shaft and a proximal portion covering a distal portion of the first non-rotary steering sleeve,
wherein a near-bit-end mud bearing is disposed between the distal portion of the second non-rotary steering sleeve so that the drill bit shaft is rotatable relative to the second non-rotary steering sleeve,
wherein one or more pistons are disposed on the distal portion of the first non-rotary steering sleeve, and, when actuated, the one or more pistons press against an inner surface of the distal portion of the second non-rotary steering sleeve so that the drill bit shaft is deflected around an articulation point defined by the universal joint to adjust a direction of the drill bit shaft, and
wherein the distal portion is disposed closer to the drill bit and the proximal portion is disposed further away from the drill bit.

2. The rotary steerable drilling tool according to claim 1 , wherein the upper mud bearing and the lower mud bearing define an axial direction and a radial direction of the first non-rotary steering sleeve.

3. The rotary steerable drilling tool according to claim 1 , wherein the near-bit-end mud bearing defines an axial direction and a radial direction of the second non-rotary steering sleeve.

4. The rotary steerable drilling tool according to claim 1 , further comprising a bow spring device mounted on the first non-rotary steering sleeve by a retaining cover, wherein, during operation, the bow spring device presses against a wall in a wellbore so that a friction between the bow spring device and the wall limits a speed of rotation of the first non-rotary steering sleeve.

5. The static push-the-bit articulated high-built-rate rotary steerable tool according to claim 1 , wherein a plurality of wear-resistant ribs are mounted on an outer surface of the second non-rotary steering sleeve.

6. The rotary steerable drilling tool according to claim 1 , further comprising: a centering connecting shaft, a first circuit disposed on the rotary mandrel, a central control circuit, wherein, during operation, electric power and communication signals from a measuring-while-drilling instrument (MWD) are transferred to the first circuit via the centering connecting shaft, and the first circuit transfers the electric power and the signals to the central control circuit via a non-contact electric power transmission transformer.

7. The rotary steerable drilling tool according to claim 6 , wherein the first circuit is sealed in a cavity in a proximal portion of the rotary mandrel by a sealing cover plate, and the first circuit is electrically connected with the centering connecting shaft via a connector.

8. The drilling tool according to claim 6 , wherein each of the one or more pistons resides in one of three sets of independent motor pump hydraulic modules affixed on an outer wall of the first non-rotary steering sleeve, wherein each of the three motor pump hydraulic modules has a hydraulic system which generates high-pressure oil to actuate a corresponding piston.

9. The drilling tool according to claim 1 , further comprising a mud turbine generator for generating electric power disposed on an inner shoulder of a drill collar, and electrically connected with an upper-end interface of the rotary steerable tool via a lower-end interface of the mud turbine generator.

10. A method for operating the rotary steerable drilling tool according to claim 6 , comprising:
setting a target tool face in the central control circuit;
determining, by the central control circuit, a current tool face based on signals from acceleration and fluxgate sensors;
calculating, by the central control circuit, a target steering force vector according to the target tool face, and decomposing the target steering force vector into a plurality of forces applied to the one or more pistons;
applying a hydraulic pressure based on each of the plurality of forces to each of the one or more pistons;
acquiring and monitoring, by the central control circuit, a current gravitational tool face value in real time, when the current gravitational tool face value varies, recalculating the target steering force vector and decomposing the recalculated target steering force vector into a plurality of adjusted forces applied to the one or more pistons;
applying an adjusted hydraulic pressure based on each of the plurality of adjusted forces to each of the one or more pistons, whereby controlling the drill bit to follow a pre-determined wellbore trajectory.

Assignees

• Inst Geology & Geophysics Cas

Inventors

• Du Jiansheng
• Di Qingyun
• Wang Zili
• Chen Wenxuan

Classifications

• E21B7/064 Primary

  specially adapted drill bits therefor · CPC title

• E21B7/068

  drilled by a down-hole drilling motor (down-hole drives per se E21B4/00, E21B7/067 takes precedence) · CPC title

• E21B44/00

  Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions · CPC title

• E21B7/062 Primary

  the tool shaft rotating inside a non-rotating guide travelling with the shaft (E21B7/067 and E21B7/068 take precedence) · CPC title

• E21B7/067 Primary

  with means for locking sections of a pipe or of a guide for a shaft in angular relation, e.g. adjustable bent sub · CPC title