WO2018084720A1

WO2018084720A1 - Device for continuous drilling fluid circulation

Info

Publication number: WO2018084720A1
Application number: PCT/NO2017/050286
Authority: WO
Inventors: Odd B. Skjaerseth; Bjørn EILERTSEN
Original assignee: West Drilling Products
Priority date: 2016-11-07
Filing date: 2017-11-07
Publication date: 2018-05-11
Also published as: NO20161762A1; NO343013B1

Abstract

Circulation unit (1) adapted for continuous circulation of drilling fluid during drilling, wherein - an upper chamber (16) is defined upwards by an upper sealing element (133), and through a lower chamber (123) is defined downwards by a lower sealing element (124), and a valve (121) forms an interface between said chambers (16, 123), - said sealing elements (124, 133) seal tightly against the respective pipe (2, 21), - an upper housing section (13) is rotary and axially displaceable in a lower housing section (12), a cylindrical lower portion (134) of the upper housing section (13) sealing slidably against a cylindrical upper portion (126) of the lower housing section (12), - a locking device (132) is adapted to hold a pipe section (21) in a fixed grip during displacement of the pipe section (21) into the lower chamber (123), - several first linear actuators (127) are adapted for displacing the upper housing section (13) relative to the lower housing section (12).

Description

DEVICE FOR CONTINUOUS DRILLING FLUID CIRCULATION

The invention relates to a circulation unit for an arrangement adapted for continuous circulation of drilling fluid during drilling, more specifically a circulation unit wherein a housing is provided with a centre bore adapted to accommodate adjacent portions of pipes to be joined together, the centre bore extends through an upper chamber which is defined upwards by an upper, ring-shaped sealing element, and through a lower chamber which is defined downwards by a lower, ring-shaped sealing element, and wherein a valve forms a closable, fluid-tight interface between said chambers, and wherein said sealing elements are provided with a centre opening which , during expansion of said sealing elements, is closable or seals tightly against the respective pipe by abutment of an inner sealing surface against the pipe.

It is known in the oil and gas drilling industry to take measures for maintaining circulation of drilling fluid in the borehole during extension of a drill string. NO 326427 discloses a system wherein a top drive drilling machine with a hollow drive shaft cooperates with a sluice chamber provided with a pipe-encircling seal, wherein the drill fluid is passed alternately through the drive shaft via a first liquid inlet when a continuous drill string is connected to the drilling machine, and through the sluice chamber via a second liquid inlet when the upper end of the pipe string is arranged in the sluice chamber and is to be joined together with a new pipe section, respectively.

One disadvantage of the prior art according to NO 326427 is that the rotation of the pipe string ceases when the pipe string is to be extended. It is known within the industry that it is an advantage to maintain pipe-string rotation in order both to reduce the risk of the pipe string to get stuck and to improve the productivity, for example increase the drilling capacity by avoiding stop of the drilling operation while the drill string is being extended.

From NO 20100123 an assembly is known wherein, between a first, top driven drilling machine and a borehole, there is arranged a second drilling machine, which is provided with a rotary table adapted to take the weight of a pipe string, a rotary drive unit arranged for continuous rotation of the pipe string, and a fluid chamber which is arranged for, in a fluid communicating way, connecting a pipe string end portion with a drilling fluid plant, the fluid chamber being provided with pipe string ports comprising means adapted for, in a fluid sealing way, closing the pipe string ports, and wherein the second drilling machine is further provided with a power tong adapted for connect- ing/releasing an element with/from the pipe string, the power tong being arranged in the fluid chamber. The disadvantage of this assembly is that the rotary drive unit is directly connected to the fluid chamber (sluice chamber) and the power tong is confined in the fluid chamber. Adaptation of the power tong to the relevant pipe dimension to be handled, has to be done by intervention in the fluid chamber. WO 01 /69034 A2 describes a system adapted for continuous circulation of drilling fluid through a pipe string formed by coiled tubing or by several pipe sections screwed together, wherein an upper, respectively a lower chamber is provided with an upper, respectively a lower sealing apparatus which seals tightly against an upper pipe string element, respectively an underlying pipe element, and the upper or lower chamber is arranged to house said pipe element during joining or discon- nection, and a gate apparatus is arranged between said chamber and is in fluid communication with said chamber. The system may be provided with a device for isolating a pipe section therein from an axial load formed by fluid pressure in the upper and the lower chamber.

From the applicant's publications NO 336508 and NO 333982 circulation units are known as well as arrangements for continuous circulation of drilling fluid during drilling, wherein a housing is pro- vided with a centre bore adapted to accommodate a portion of a pipe, and the housing comprises upper and lower sealing elements provided with centre openings which during expansion are clos- able or seal tightly against the pipe by an inner sealing surface resting against the pipe, and wherein each of the sealing elements is fluid-tightly connected to a packing pipe which is in the housing and which is rotatable around the centre axis of the centre bore, the packing pipe being surrounded by a packing assembly fitting tightly between the periphery of the packing pipe and the housing.

When the drilling fluid is circulated at high pressure (typically in the range 5,000-7,500 psi), the pipe which is to be joined to the pipe string, has to be pushed into the circulation unit against the high drilling fluid pressure. When the pushing is done by means of a drilling machine connected to the upper end of the pipe, optionally the assembly of several pipes, there is the risk of the pipe buckling and in worst case breaking, due to the big distance between the lower end of the pipe or pipe assembly, fixedly held in the circulation unit, and the upper end of the pipe or pipe assembly where the pushing force is applied.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art. The object is achieved through the features which are specified in the description below and in the claims that follow.

In the following the term "pipe string" is used as a common term for all types of pipe strings which upon rotation of an end portion form a borehole in the underground by suitable drill bit elements grounding an underground material, and an in-flowing drilling fluid brings the grounded under- ground material out of the borehole by means of a return flow to the surface. Unless it is explicitly mentioned, the term "pipe" is in the following used as a collective term for single pipes, pipe sections assembled from several single pipes, as well as pipe string built up by joining several single pipes or several pipe sections which may be screwed together. "Pipe" may also comprise a so-called liner which is used as a coupling between the pipe string and a rotation unit, optionally adapted for supply of drilling fluid to the pipe string.

A circulation unit is provided, adapted for being disposed between an upper rotation unit, for example a top driven drilling machine, and a lower rotation unit, for example a rotary table or a rotation unit arranged vertically displaceable in a tower, or similar. The circulation unit is connected to the lower rotation unit in a rotationally rigid way, and rotates together with it. Further, the circulation unit is adapted for supply of drilling fluid to an open upper end of a pipe string when said upper end of the pipe string is in a chamber of the circulation unit. The supply takes place through a swivel which surrounds a portion of the lower housing section and is pivotally supported therein.

The circulation unit comprises a housing having a through centre bore. The housing is sectioned, an upper housing section being arranged axially displaceable with regard to a lower housing sec- tion in that a lower portion of the upper housing section is adapted to be accommodated in or accommodating an upper portion of the lower housing section. Seals arranged in one of the housing sections seals tightly against the second one of the housing sections. Several linear actuators, typically in the form of hydraulic cylinders, surround a portion of the housing and connect the upper and the lower housing sections and is adapted at least for pulling the housing together. The upper housing section is pivotable relative to the lower housing section, the end portion of the linear actuators being connected in a ring which is supported in the upper or lower housing section.

The upper housing section is, in an upper portion, provided with a locking device, typically in the form of slips, which is arranged such that it at least upon contraction of the housing may be in locking engagement with a pipe which is led into the housing. In each housing section, a sealing element is arranged being adapted for sealing tightly around a pipe portion. Each of the sealing elements is adapted to close the respective end of the centre bore when a pipe extends through the sealing element, for example by supplying the sealing element with a pressure fluid from an associated pressure supply unit. The sealing elements may be rotata- bly independent of each other. The housing is divided into two chambers by means of a valve which is adapted to, in an open position, form a centre opening which forms a connection between said two chambers, and in a closed position, form a fluid-tight division between said chambers. The valve is preferably a flap valve which at its side edge is attached to the lower housing section, which is supported such that it is downwardly tiltable around a rotation axis perpendicular to the centre axis of the circulation unit, and is provided with a resilient member which is adapted for pressing the flap valve against a valve seat disposed in the lower housing section and surrounds the centre bore. It is an advantage if, above the upper sealing element, radially displaceable support elements are arranged which may be activated when a pipe section is fixedly held in the upper housing section and is to be pushed to connection with the pipe string, full drilling fluid pressure being applied to said sealing element. The support elements may be formed as diametrically opposite plates which are connected to one or more linear actuators, typically in the form of hydraulic cylinders.

Application of pressure fluid to the sealing elements and energy to the linear actuators preferably happen through pipe- and/or wire connections with the lower rotation unit.

Mating of a pipe section and the established pipe string during continuous circulation takes place by co-ordinated operation of the lower and the upper rotation unit, and by co-ordinated supply of drilling fluid through the lower chamber of the circulation unit via said swivel and through the upper rotation unit after the feeding into the circulation unit of the pipe section which is to be coupled to the pipe string. As the pressure on both sides of the closed valve is balanced, the valve will open by further displacement of the pipe section. Drilling fluid pressure is applied to the pipe section only after engagement of the locking elements of the upper housing section with the pipe section. Thereafter, the pipe section is pushed towards the open end of the pipe string by contraction of the circulation unit by means of the linear actuators which connect the first and second housing sections. During screwing together of the pipe section and the pipe string, the upper housing section and the pipe string rotate relative to the lower housing section and the pipe string.

The circulation unit is, within the art, also called a continuous circulation unit. The invention is defined by the independent patent claim. The dependent claims define advantageous embodiments of the invention.

The invention more specifically relates to circulation unit for a an arrangement adapted for continuous circulation of drilling fluid during drilling, wherein :

- a housing is provided with a centre bore adapted to accommodate adjacent portions of pipes to be joined together;

- the centre bore extends through an upper chamber which is defined upwards by an upper, ring- shaped sealing element, and through a lower chamber which is defined downwards by a lower, ring-shaped sealing element, and wherein a valve forms a closable, fluid-tight interface between said chambers;

- said sealing elements are provided with a centre opening which, during expansion of said sealing elements, is closable or seals tightly against the respective pipe by abutment of an inner sealing surface against the pipe,

characterised in that:

- an upper housing section is arranged rotary and axially displaceable relative to a lower housing section, a cylindrical lower portion of the upper housing section sealing slidably against a complementary, cylindrical upper portion of the lower housing section; - a locking device adapted to hold a pipe section in a fixed grip at least during displacement of the pipe section into the lower chamber;

- several first linear actuators form connections between the lower housing section and the upper housing section and are adapted for displacing the upper housing section relative to the lower housing section, said first linear actuators being fastened to a ring which is arranged pivotally supported around the centre bore in one of the lower and the upper house sections.

The cylindrical lower portion of the upper housing section may be arranged inside of the cylindrical upper portion of the lower housing section. An advantage of this is that detection and collection of liquid leaking out between the housing sections, are simplified.

At least one of the lower and the upper sealing elements may be rotatably supported in the housing. An advantage of this is that one reduces the wear on the sealing elements due to different rotation speed between pipe and housing in certain phases of the use of the circulation unit.

A sealing element support may be arranged radially displaceable above the upper sealing element. An advantage of this is that the risk of harmful deformation of the upper sealing element at large drilling fluid pressures, is reduced.

The sealing element support may be formed as plate elements having curve shaped inwardly facing end portions, connected to one second linear actuator each.

The lower chamber may be provided with at least one drilling fluid inlet which is in fluid communicating connection with a swivel supported on the outside of the lower housing section.

The first linear actuators may be evenly distributed along the periphery of the housing.

The first linear actuators may be evenly distributed along the periphery of the housing, several axi- ally arranged, cylindrical recesses adapted to accommodate one piston rod each, being formed in the cylindrical upper portion of the lower housing section.

The lower housing section may be provided with a coupling portion adapted for being connected with a lower rotation unit in a rotationally rigid way.

In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein :

Fig. 1 shows in perspective, a circulation unit according to the invention ;

Fig. 2 shows at a smaller scale, a side view of an arrangement according to the invention wherein a pipe string and the circulation unit are rotated by a lower rotation unit, and drilling fluid is supplied via the circulation unit while a pipe section and an up- per rotation unit are being vertically displaced towards the circulation unit and the lower rotation unit;

Fig. 3 shows at a larger scale, an axial section Ill-Ill according to Figure 1 , through the circulation unit in an extended position;

Fig. 4 shows at a larger scale, an axial section corresponding to Figure 3, wherein a pipe string extends from the circulation unit, the circulation unit being in a contracted position, a pipe section is coupled to the pipe string, and the sealing elements of the circulation unit are still sealing tightly against the through going pipes; and

Fig. 5 shows at a smaller scale, the upper rotation unit and the lower rotation unit with the circulation unit arranged in a tower and connected to a drilling fluid plant.

Reference is first made to Figure 1 , wherein the reference numeral 1 denotes a circulation unit comprising a telescopable housing 1 1 formed from a lower and an upper housing section 12, 13 and mutually connected to several linear actuators 127 distributed around the periphery of a mid- portion of the housing 1 1 . The lower housing section 12 is provided with a swivel 14 which in a fluid-sealing way surrounds and is rotatably supported on said housing section 12, and is adapted for connection to a drilling fluid plant (see below). A lower end portion of the lower end section 12 forms a coupling portion 128 against a lower rotation unit (see below).

Reference is now made to Figure 2, wherein the circulation unit 1 is shown connected to a lower rotation unit 3 and cooperates with an upper rotation unit 4 upon connection of a pipe section 21 and a pipe string 2.

Figure 3 shows the circulation unit 1 in greater detail.

The lower housing section 12 of the housing 1 1 forms a lower chamber 123 which upwardly is defined by a valve 121 , here shown as a flap valve having a valve element 121 a which in a side edge is fastened in the housing section 12 by means of a hinge 121 b having a rotation axis across the longitudinal axis of the circulation unit 1 . A resilient member 121 c ensures that the valve element 121 a abuts a valve seat 122 and closes a centre bore 15 which extends centrically through the circulation unit 1 .

The lower chamber 123 is provided with several drilling fluid inlets 123a which are in fluid communication with the swivel 14.

The lower chamber 123 is defined below by a lower sealing element 124. Said sealing element 124 is expandable radially inwards by supplying a pressure fluid in a pressure fluid chamber 124a such that a sealing surface 124c defining a centre opening 124b, may lie sealingly against the through going pipe string 2. Said pressure fluid chamber 124a is in fluid communication with a not shown pressure fluid plant connected to the lower rotation unit 3 via a pressure fluid cable 125a as well as channels (not shown) arranged in the lower housing section 12.

An upper portion 126 of the lower housing section 12 is formed as a cylindrical portion provided with an inner seal 126a in its upper outlet portion. The upper housing section 13 of the housing 1 1 is in an upper end portion provided with an inflow funnel 131 adapted to guide a pipe section 21 into the centre bore 15 of the circulation unit 1 .

Below the inflow funnel 131 , a locking device 132 is arranged, typically in the form of slips adapted to go into locking engagement with a pipe section 21 and prevent the pipe section 21 from being pushed upwards and out of the circulation unit 1 when drilling fluid pressure formed in the circula- tion unit 1 is applied.

A lower portion 134 of the upper housing section 13 is formed as a cylindrical portion provided with an outer sealing 134a in its lower outlet portion. Said cylindrical portion 134 is adapted for, in a telescopic way, being displaced in the cylindrical portion 126 of the lower housing section 12, the sealings 126a, 134 sealing against leakage to the surroundings. The assembled cylindrical portion of the housing 1 1 thereby forms an upper, expandable chamber 16.

The upper chamber 16 is upwardly defined by an upper sealing element 133. Said sealing element 133 is expandable in a radial direction inwardly in that a pressure fluid is supplied to a pressure fluid chamber 133a such that a sealing surface 133c which defines a centre opening 133b may lie sealingly against the through going pipe section 21 . Said pressure fluid chamber 133a is in fluid communication with a not shown pressure fluid plant connected to the lower rotation unit 3 via a pressure fluid cable 125b as well as channels 125d, 137 arranged in the lower and the upper housing sections 12, 13 and a flexible cable 125e connecting the channels 125d, 137.

A bearing ring 135 is via a bearing 135a, here shown as a spherical bearing, rotatably connected in the upper housing section 13. Distributed around the upper cylindrical portion 126 of the lower housing section 12, there are arranged several elongate, cylindrical recesses 127a which together with the complementary piston rods 127b form first linear actuators 127. The piston rods 127b are fixed to the bearing ring 135, and said linear actuators 127 thereby form an axially adjustable connection between the lower and the upper housing sections 12, 13 in order to be able to push a connected pipe section 21 into the upper chamber 15 also when this is subjected to a high drilling fluid pressure from a drilling fluid plant 5 (see Figure 5).

The upper sealing element 133 is provided with an overlying, radially displaceable sealing element support 136, herein shown as several plate elements connected to one second linear actuator 136a each. Said second linear actuators 135a are in fluid communication with a not shown pres- sure fluid plant connected to the lower rotation unit 3 via a pressure fluid cable 125c as well as not shown channels arranged in the lower housing section 12 and not shown flexible cables.

Reference is now made to Figure 5, wherein the drilling fluid plant 5 is shown provided with a valve system 51 . A first drilling fluid cable 52 connects the drilling fluid plant 5 with a swivel coupling 41 on the upper rotation unit 4 such that drilling fluid may be supplied to the pipe string 2 through the pipe section 21 when it is connected to the pipe string 2. A second drilling fluid cable 53 connects the drilling fluid plant 5 to the swivel 14 on the circulation unit 1 . A third drilling fluid cable 54 connects the drilling fluid plant 5 to a not shown draining port on the circulation unit 1 .

As soon as the drilling fluid pressure in the lower and the upper chamber 123, 16 has been bal- anced, the valve 121 will open upon application of a force which overcomes the modest force exerted by the resilient member 121 c on the valve element 121 a. Figure 4 shows a valve element 121 a in an open position.

When working with continuous circulation of drilling fluid under high pressure, the pipe section 21 will, during insertion into the circulation unit 1 , be exposed to this fluid pressure when the drilling fluid is supplied via the upper rotation unit 4. By holding the pipe section 21 by means of the locking device 132 in the upper housing section 13 while the housing 1 1 is being contracted in the axial direction by means of the first linear actuators 127, the risk of buckling of the pipe section will be considerably reduced compared to when the pipe section 21 according to prior art is pushed down by means of the upper rotation unit 4, since the distance between the lower end of the pipe section 21 and the point of attack of the pushing force has been drastically reduced by means of the circulation unit 1 according to the present invention.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

P a t e n t c l a i m s 1. Circulation unit (1 ) for an arrangement adapted for continuous circulation of drilling fluid during drilling, wherein:

- a housing (1 1 ) is provided with a centre bore (15) adapted to accommodate adjacent portions of pipes (2, 21 ) to be joined together;

- the centre bore (15) extends through an upper chamber (16) which is defined upwards by an upper, ring-shaped sealing element (133), and through a lower chamber (123) which is defined downwards by a lower, ring-shaped sealing element (124), and wherein a valve (121 ) forms a closable, fluid-tight interface between said chambers (16, 123);

- said sealing elements (124, 133) are provided with a centre opening (124b, 133b) which, during expansion of said sealing elements (124, 133), is closable or seals tightly against the respective pipe (2, 21 ) by abutment of an inner sealing surface (124c, 133c) against the pipe (2, 21 ),

c h a r a c t e r i s e d i n that:

- an upper housing section (13) is arranged rotary and axially displaceable relative to a lower housing section (12), a cylindrical lower portion (134) of the upper housing section (13) sealing slidably against a complementary, cylindrical upper portion (126) of the lower housing section (12);

- a locking device (132) adapted to hold a pipe section (21 ) in a fixed grip at least during displacement of the pipe section (21 ) into the lower chamber (123);

- several first linear actuators (127) form connections between the lower housing section (12) and the upper housing section (13) and are adapted for displacing the upper housing section (13) relative to the lower housing section (12), said first linear actuators (127) being fastened to a ring (135) which is arranged pivotally supported around the centre bore (15) in one of the lower and the upper house sections (12, 13).

2. Circulation unit (1 ) according to claim 1 , wherein the cylindrical lower portion (134) of the upper housing section (13) is arranged inside of the cylindrical upper portion (126) of the lower housing section (12).

3. Circulation unit (1 ) according to claim 1 , wherein at least one of the lower and the upper sealing elements (124, 133) is rotatably supported in the housing (1 1 ).

4. Circulation unit (1 ) according to claim 1 , wherein a sealing element support (136) is arranged radially displaceable above the upper sealing element (133).

5. Circulation unit (1 ) according to claim 4, wherein the sealing element support (136) is formed as plate elements, connected to one second linear actuator (136a) each.

6. Circulation unit (1 ) according to claim 1 , wherein the lower chamber (123) is provided with at least one drilling fluid inlet (123a) which is in fluid communicating connection with a swivel (14) supported on the lower housing section (12).

7. Circulation unit (1 ) according to claim 1 , wherein the first linear actuators (127) are evenly distributed along the periphery of the housing (1 1 ).

8. Circulation unit (1 ) according to claim 1 , wherein the first linear actuators (127) are evenly distributed along the periphery of the housing (1 1 ), several axially arranged, cylindrical recesses (127a) being adapted to accommodate one piston rod (127b) each, being formed in the cylindrical upper portion (126) of the lower housing section (12).

9. Circulation unit (1 ) according to claim 1 , wherein the lower housing section (12) is provided with a coupling portion (128) adapted for being connected with a lower rotation unit (3) in a rotationally rigid way.