# US 10,370,901 B2 · Steering system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,370,901 B2 - Document ID: US10370901B2 - Status: Granted - Kind: B2 - Application number: 14/427,205 - Filed: 2013-09-11 - Published: 2015-08-27 - Granted: 2019-08-06 - Earliest claimed: 2012-09-12 - Assignees: ITI Scotland Limited - Applicants: ITI Scotland Limited - Inventors: Marian Wiercigroch - Web page: https://patentgrep.com/patent/US10370901B2 ## CPC - E21B 7/04: Directional drilling - E21B 7/064: {specially adapted drill bits therefor} - E21B 7/24: Drilling using vibrating or oscillating means, e.g. out-of-balance masses (percussion drilling E21B1/00) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Provided is an apparatus for use in directional drilling, which apparatus comprises: (a) a drill bit; (b) at least one steering actuator capable of exerting a longitudinal force on the drill bit, so as to change the direction of drilling; and/or (c) at least one drill bit steering insert, capable of extending and retracting so as to change the cutting characteristics of the drill bit and thereby change the direction of drilling. Further provided is a method of directional drilling, employing the apparatus of the invention. ## Claims ### Claim 1 An apparatus for use in resonance enhanced directional drilling, which apparatus comprises: (a) a rotary drill bit; (b) an oscillator; (c) a plurality of steering actuators arranged about the axis of rotation of the drill bit, wherein said plurality of steering actuators are capable of driving the oscillator to generate an axial oscillatory load with a varying frequency so as to achieve resonance with a material being drilled and wherein each of the plurality of steering actuators is capable of exerting the axial load on a side of the apparatus; and (d) a resonance enhanced drilling (RED) vibration isolator spring. ### Claim 2 (depends on 1) An apparatus according to claim 1, wherein the steering actuator comprises a piezoelectric element to drive the steering actuators. ### Claim 3 (depends on 1) An apparatus according to claim 1, which apparatus comprises 3, 4, 5, 6, 7, 8, 9, or 10 or more steering actuators. ### Claim 4 (depends on 1) An apparatus according to claim 1, which apparatus does not comprise a main actuator located on the axis of rotation of the rotary drill bit. ### Claim 5 (depends on 1) An apparatus according to claim 1, which apparatus further comprises a RED vibration enhancer spring. ### Claim 6 (depends on 5) An apparatus according to claim 5, wherein the RED vibration isolator spring and the RED vibration enhancer spring comprise a spring system comprising two or more frusto-conical springs arranged in series. ### Claim 7 (depends on 6) An apparatus according to claim 6, wherein the spring system is one such that the force, P, applied to the spring system can be determined according to the following equation: P = 1.1 ⁢ ⁢ E ⁢ ⁢ δ ⁢ ⁢ C R 2 ⁡ [ ( h - δ ) ⁢ ( h - δ 2 ) ⁢ t + t 2 ] wherein t is the thickness of the frusto-conical springs, h is the height of the spring system, R is the radius of the spring system, δ is the displacement on the spring system caused by the force P, E is the Young modulus of the spring system, and C is the constant of the spring system. ### Claim 8 (depends on 6) An apparatus according to claim 6, wherein the frusto-conical springs are Belleville springs. ### Claim 9 (depends on 6) An apparatus according to claim 6, wherein the spring system satisfies the following equation: ω/ωn≥2.3 wherein ω represents an operational frequency of axial vibration of the resonance enhanced drilling apparatus, and ωn represents the natural frequency of the spring system. ### Claim 10 (depends on 6) An apparatus according to claim 6, wherein the spring system satisfies the following equation: 0.6≤ω/ωn≤1.2 wherein ω represents an operational frequency of axial vibration of the resonance enhanced drilling apparatus, and ωn represents the natural frequency of the spring system of the vibration enhancement and/or transmission unit. ### Claim 11 (depends on 5) An apparatus according to claim 5, wherein the RED vibration isolator spring is situated above the oscillator in the drilling apparatus. ### Claim 12 (depends on 5) An apparatus according to claim 5, wherein the RED vibration enhancer spring is situated below the oscillator in the drilling apparatus. ### Claim 13 (depends on 1) An apparatus according to claim 1, wherein the frequency (f) and the dynamic force (Fd) of the oscillator are capable of being controlled by a controller. ### Claim 14 (depends on 13) An apparatus according to claim 13, wherein the frequency (f) and the dynamic force (Fd) of the oscillator are capable of control according to load cell measurements representing changes in the compressive strength (Us) of material being drilled. ### Claim 15 (depends on 1) A method of drilling comprising operating an apparatus as defined in claim 1. ### Claim 16 (depends on 15) A method of drilling according to claim 15, which method comprises operating one or more of the steering actuators and thereby cause a desired change in direction of drilling. ### Claim 17 (depends on 1) A method for resonance enhanced directional drilling using an apparatus as defined in claim 1, the method comprising: controlling frequency (f) of the oscillator in the resonance enhanced drill whereby the frequency (f) is maintained in the range: (D2Us/(8000πAm))1/2≤f≤Sf(D2Us/(8000πAm))1/2 where D is diameter of the drill-bit, Us is compressive strength of material being drilled, A is amplitude of vibration, m is vibrating mass, and Sf is a scaling factor greater than 1; and controlling dynamic force (Fd) of the oscillator in the resonance enhanced rotary drill whereby the dynamic force (Fd) is maintained in the range: [(π/4)D2effUs]≤Fd≤SFd[(π/4)D2effUs] where Deff is an effective diameter of the rotary drill-bit, Us is a compressive strength of material being drilled, and SFd is a scaling factor greater than 1, wherein the frequency (f) and the dynamic force (Fd) of the oscillator are controlled by monitoring signals representing the compressive strength (Us) of the material being drilled and adjusting the frequency (f) and the dynamic force (Fd) of the oscillator using a closed loop real-time feedback mechanism according to changes in the compressive strength (Us) of the material being drilled.