GB2172324A

GB2172324A - Drilling apparatus

Info

Publication number: GB2172324A
Application number: GB08606518A
Authority: GB
Inventors: Gordon Douglas; Peter Allen
Original assignee: Cambridge Radiation Tech
Current assignee: Cambridge Radiation Tech
Priority date: 1985-03-16
Filing date: 1986-03-17
Publication date: 1986-09-17
Also published as: GB8606518D0; GB2172324B

Abstract

Drilling apparatus comprising a drilling tube (10) having a drilling bit (12). The tube (10) is deflected by a lateral force which imparts to the tube (10) a curvature, thereby to control the drilling direction. The lateral force is applied by selectively pressurising four flexible actuator bags (42) arranged around the drilling tube (10), the bags being pressurised to a controllable extent in order to provide a controllable magnitude and direction to the lateral face. Hydraulic pressure for the bags (42) is generated by a pump which comprises a further flexible bag (60) (Figure 4), similar to the bags (42), and an eccentric sleeve (58) which rotates with the drilling tube (10) and which causes the pump bag (60) to be cyclically compressed and then relieved of pressure. The four actuator bags (42) and the pump bag are located in a down hole control module (22). <IMAGE>

Description

SPECIFICATION Drilling apparatus Field of the invention This invention relates to drilling apparatus for drilling bore holes in the ground.

Summary ofthe invention According to the invention drilling apparatus com prises aflexible enclosure located in a space defined between two members, the enclosure serving either as an actuator to control the direction of drilling by applying a radial force between the members resulting in radial displacement between the members, or serving as a pump to deliverfluidto actuating means for controlling the direction of drilling, as a result of variation ofthe spacing betweenthe members.

When the flexible enclosure serves as an actuator, the enclosure is one of a plurality of such actuators disposed in said space which is annular. Preferably, the actuators apply a deflecting force which has a controlled magnitude and direction and which deflect a drilling tube ofthe drilling apparatus.

When the flexible enclosure serves as a pump, the spacing between the members conveniently varies as a result of rotation of an eccentric member. The eccentric member may rotate with a drilling tube and the flexible enclosure is located between a bearing sleeve and an outer casing, the bearing sleeve being non-rotatable and being mounted on the eccentric memberbya bearing.

In the preferred embodimentto be described, drilling apparatus has a plurality of actuators, each in the form of a flexible enclosure, and a pump also in the form of a flexible enclosure, the pump supplying fluid to selected actuators at a controlled pressure in dependence upon the required magnitude and direction ofthe deflecting force to be applied to the drilling tube.

Drilling apparatus according to the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa diagrammatic view of the bottom hole assembly of the drilling apparatus, Figure 2 is a detailed view of part of Figure 1, Figure 3 is a sectional view on the line lil-lil of Figure 2, Figure 4 is a detailed view of another part of Figure 1, and Figures 5,6 and 7 are respectively side, end and plan views of a flexible enclosure of the drilling apparatus.

Detailed description ofthe drawings Referring to Figure 1, the drilling apparatus comprises a rotatable drilling tube 10 carrying at its extremity a drilling bit 12. The drilling tube 10 is supported and centred in a bore hole 14 by two stabilisers 16, 18 and bya third, optional stabiliser 20.

Between the stabilisers 18 and 20 is a control module 22 which effects controlled deflection of the drilling tube 1 0to vary the drilling course or direction. In Figure 1, the undeflected drilling tube is indicated at 24, the deflected drilling tube at 26 and the variation in drilling angle at 28. The arrows 30 depict the reaction forces applied by the bore hole wall to the drilling tube 10, but the reaction to the deflecting force is resisted principally within the control module 22, as will be explained.

The module 22 has a cylindrical casing 32 having end seals 34 and enclosing bearings 36,38 and actuating means 40 for deflecting the drilling tube 10.

Referring to Figures 2 and 3,the actuating means 40 comprisefourflexibleenctosuresintheform of bags 42 located in the annular space between the casing 32 and a bearing sleeve 44. The bearing sleeve 44 does not rotate with the drilling tube 10 but is mounted on the latter by bearings 46. Fluid is fed to the bags 42 through hydraulic pipes 48 which communicate with a pump (50, Figure 4) through a valve block and reservoirs unit 52.

The pump 50 is located in the annular space between the casing 32 and a bearing sleeve 54 which is non-rotatably mounted on the rotatable drilling tube 10 by a bearing 56. Between the drilling tube 10 and the inner race ofthe bearing 56 is located an eccentric sleeve 58 which rotates with the drilling tube 10 and causesthe bearing sleeve 54to oscillate in the radial direction of arrow X in Figure 4, thereby to apply a pumping action to a flexible enclosure or bag 60 ofthe pump. The flexible bag 60 is similar in construction to one ofthe flexible bags 42. An anti-rotation pin 62 interconnecting the casing 32 and the bearing sleeve 54 prevents rotation of these two components.

Figures 5, and 7 showthe construction of a representative bag 42 orthe bag 60. The bag 42 or 60 has a fabric body formed into a tubular configuration, opposite edges being sealed by metallic clamping strips 64, from one of which extends a hydraulic supply or return pipe forming the hydraulic pipe 48.

The magnitude and direction ofthe deflecting force applied by the bags 42to the drilling tube are controlled by appropriate control of the application of hydraulic pressurefrom the pump by 60 tothe actuator bags 42. In order to achieve the required deflecting force, two adjacent bags 42 are individually pressurised to the required extent, and the two remaining bags 42 are completely depressurised, this being achieved by appropriate energisation of the valves in the valve block and reservoirs unit 52.

As mentioned, the deflecting force is applied to the drilling tube, in the desired magnitude and direction, to impart a curvature to the tube, as indicated at 26 in Figure 1. This controlled curvature controls the drilling direction. The reaction to the deflecting force is borne within the casing 32, the bearings 36,38 providing reactive forces on the tube. It will be notedthatthe bore hole wall provides no reactive forces to the tube 10through the intermediary ofthe casing 32.

1. Drilling apparatus comprising a fiexible enclo- sure located in a space defined between two members, the enclosure serving either as an actuatorto control the direction of drilling by applying a radial force between the members resulting in radial displacement between the members, or serving as a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Drilling apparatus Field of the invention This invention relates to drilling apparatus for drilling bore holes in the ground. Summary ofthe invention According to the invention drilling apparatus com prises aflexible enclosure located in a space defined between two members, the enclosure serving either as an actuator to control the direction of drilling by applying a radial force between the members resulting in radial displacement between the members, or serving as a pump to deliverfluidto actuating means for controlling the direction of drilling, as a result of variation ofthe spacing betweenthe members. When the flexible enclosure serves as an actuator, the enclosure is one of a plurality of such actuators disposed in said space which is annular. Preferably, the actuators apply a deflecting force which has a controlled magnitude and direction and which deflect a drilling tube ofthe drilling apparatus. When the flexible enclosure serves as a pump, the spacing between the members conveniently varies as a result of rotation of an eccentric member. The eccentric member may rotate with a drilling tube and the flexible enclosure is located between a bearing sleeve and an outer casing, the bearing sleeve being non-rotatable and being mounted on the eccentric memberbya bearing. In the preferred embodimentto be described, drilling apparatus has a plurality of actuators, each in the form of a flexible enclosure, and a pump also in the form of a flexible enclosure, the pump supplying fluid to selected actuators at a controlled pressure in dependence upon the required magnitude and direction ofthe deflecting force to be applied to the drilling tube. Drilling apparatus according to the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa diagrammatic view of the bottom hole assembly of the drilling apparatus, Figure 2 is a detailed view of part of Figure 1, Figure 3 is a sectional view on the line lil-lil of Figure 2, Figure 4 is a detailed view of another part of Figure 1, and Figures 5,6 and 7 are respectively side, end and plan views of a flexible enclosure of the drilling apparatus. Detailed description ofthe drawings Referring to Figure 1, the drilling apparatus comprises a rotatable drilling tube 10 carrying at its extremity a drilling bit 12. The drilling tube 10 is supported and centred in a bore hole 14 by two stabilisers 16, 18 and bya third, optional stabiliser 20. Between the stabilisers 18 and 20 is a control module 22 which effects controlled deflection of the drilling tube 1 0to vary the drilling course or direction. In Figure 1, the undeflected drilling tube is indicated at 24, the deflected drilling tube at 26 and the variation in drilling angle at 28. The arrows 30 depict the reaction forces applied by the bore hole wall to the drilling tube 10, but the reaction to the deflecting force is resisted principally within the control module 22, as will be explained. The module 22 has a cylindrical casing 32 having end seals 34 and enclosing bearings 36,38 and actuating means 40 for deflecting the drilling tube 10. Referring to Figures 2 and 3,the actuating means 40 comprisefourflexibleenctosuresintheform of bags 42 located in the annular space between the casing 32 and a bearing sleeve 44. The bearing sleeve 44 does not rotate with the drilling tube 10 but is mounted on the latter by bearings 46. Fluid is fed to the bags 42 through hydraulic pipes 48 which communicate with a pump (50, Figure 4) through a valve block and reservoirs unit 52. The pump 50 is located in the annular space between the casing 32 and a bearing sleeve 54 which is non-rotatably mounted on the rotatable drilling tube 10 by a bearing 56. Between the drilling tube 10 and the inner race ofthe bearing 56 is located an eccentric sleeve 58 which rotates with the drilling tube 10 and causesthe bearing sleeve 54to oscillate in the radial direction of arrow X in Figure 4, thereby to apply a pumping action to a flexible enclosure or bag 60 ofthe pump. The flexible bag 60 is similar in construction to one ofthe flexible bags 42. An anti-rotation pin 62 interconnecting the casing 32 and the bearing sleeve 54 prevents rotation of these two components. Figures 5, and 7 showthe construction of a representative bag 42 orthe bag 60. The bag 42 or 60 has a fabric body formed into a tubular configuration, opposite edges being sealed by metallic clamping strips 64, from one of which extends a hydraulic supply or return pipe forming the hydraulic pipe 48. The magnitude and direction ofthe deflecting force applied by the bags 42to the drilling tube are controlled by appropriate control of the application of hydraulic pressurefrom the pump by 60 tothe actuator bags 42. In order to achieve the required deflecting force, two adjacent bags 42 are individually pressurised to the required extent, and the two remaining bags 42 are completely depressurised, this being achieved by appropriate energisation of the valves in the valve block and reservoirs unit 52. As mentioned, the deflecting force is applied to the drilling tube, in the desired magnitude and direction, to impart a curvature to the tube, as indicated at 26 in Figure 1. This controlled curvature controls the drilling direction. The reaction to the deflecting force is borne within the casing 32, the bearings 36,38 providing reactive forces on the tube. It will be notedthatthe bore hole wall provides no reactive forces to the tube 10through the intermediary ofthe casing 32. CLAIMS

1. Drilling apparatus comprising a fiexible enclo- sure located in a space defined between two members, the enclosure serving either as an actuatorto control the direction of drilling by applying a radial force between the members resulting in radial displacement between the members, or serving as a pump to deiiverfluidto actuating means forcontrolling the direction of drilling, as a result of variation of the spacing between the members.

2. Drilling apparatus accordingto claim 1, wherein the flexible enclosure serves as an actuator and is one of a plurality of such actuators disposed in said space which is annular.

3. Drilling apparatus according to claim 2, wherein the actuators apply a deflecting force which has a controlled magnitude and direction and which deflects a drilling tube ofthe drilling apparatus.

4. Drilling apparatus according to claim 3,wherein there are four actuators equi-angulariy positioned around the longitudinal axis ofthe drilling tube.

5. Drilling apparatus according to claim 3 or4, wherein said members are a casing and a bearing sleeve, the bearing sleeve being non-rotatable and being supported by means of bearings on the drilling tube.

6. Drilling apparatus according to claim 1, wherein the flexible enclosure serves as a pump and the spacing between the members varies as a result of rotation of an eccentric member.

7. Drilling apparatus according to claim 6, wherein the eccentric member rotates with a drilling tube and the flexible enclosure is located between a bearing sleeve and an outer casing, the bearing sleeve being non-rotatable and being mounted on the eccentric member buy a bearing.

8. Drilling apparatus according to claim 6 or7, wherein theflexibie enclosure serving as a pump feeds a plurality of actuators each constituted by a flexible enclosure as specified in any of claims 2 to 5.