WO2016130017A1

WO2016130017A1 - Landing member for wiper apparatus and a system therefore

Info

Publication number: WO2016130017A1
Application number: PCT/NO2016/050019
Authority: WO
Inventors: Ketil Botnmark; Kjell Mikalsen
Original assignee: ¨1/12K Tools As
Priority date: 2015-02-10
Filing date: 2016-02-09
Publication date: 2016-08-18
Also published as: WO2016130017A8; NO20150195A1

Abstract

The present invention concerns a landing system for a wiper apparatus (5) which is adapted for floating on a liquid surface of the drilling mud in the drill string (7) or hanging from a landing seat (9) located in a landing sub (8) by the use of a landing member (1). According to the invention, the landing seat (9) has an inner diameter (ID) which is similar to or greater than the ID of the drill string (7), and wherein the landing member (1) comprises a number of fingers (2) which are arranged to explode and follow the ID of the drill string (7) by the use of biasing members (4) which press the fingers outwards towards the ID of the drill string (7), the fingers (2) of the landing member (1) being adapted to sit on the landing seat (9).

Description

LANDING MEMBER FOR WIPER APPARATUS AND A SYSTEM THEREFORE

The present invention relates to an apparatus for cleaning a drill string of drilling mud and other fluids during tripping of the drill string.

During drilling for hydrocarbons offshore and onshore, it will be necessary at regular intervals to pull up the drill string having a drill bit or another tool affixed thereto. The drill string consists of coupled drill pipes, and when the drill string is pulled out, lengths of three coupled drill pipes are usually extracted at once and placed in a piperack.

These, usually three, pipes are called a stand. The pulling out (tripping) is performed by pulling the drill string up and breaking it stand by stand or pipe by pipe until the whole drill string is pulled out.

In drilling operations, problems often occur due to drilling mud remaining inside drill pipes after pulling up the drill string, caused by poor or lack of cleaning. The mud dries and forms hard flakes and lumps. When the drill pipes are used again, the lumps and particles may be pumped down to the drill bit where they may clog one or more of the nozzles, with the consequence that the drill bit may be damaged. It is also likely to cause problems with downhole tools and engines. In addition, large amounts of waste mud will often end up on the drill deck and on decks in storage areas. This creates unnecessary work with cleaning of decks, deposit of waste, and injuries caused by slippery and soiled decks.

In US 4287948, a wiper for use in a drill string is described. The wiper device floats in the drilling fluid, and during tripping a peripheral ledge on the device wipes the inner wall of the drill string clean of fluid. The apparatus is provided with a mass and a volume such that it can float during tripping on a liquid surface of the drilling mud in the drill string. The apparatus comprises wiper devices.

WO 2006/006872- Al describes internal removal of drilling mud from a drill string by use of a bellows-shaped wiper being attached with weight and volume so that it floats on the surface of the drilling mud in the drill string during tripping. The wiper has at least one channel for allowing drilling mud to pass through.

US 4.671.358-Al describes wiper plugs which are used in cementing procedures, where the wiper part lands and is fixated in a landing shoulder so that the wiper halts and opens a valve for allowing the cement to flow downwards through the valve. A catalogue description from TAM International Inc., 2005 (http://www.lamintl.com) discloses a product "Dart Catcher" with built-in landing profile, so that the wiper lands on a landing seat.

However, when the wiper is used in connection with tripping, situations may occur where the pumps must be activated in full speed, while the wiper is still inside the drill string. As a result, the wiper is pumped downwards until it might be stopped in the drill string, for example 5000 meters downwards. Further, it is an important requirement that the pumping of drilling mud shall continue unhindered, even after the wiper has come to a halt in the drill string.

To meet the challenges in relation to such situations where the pumps are reactivated, it is vital that this does not constitute a hindrance for the drilling fluids which are to be pumped through the drill string. It is also vital that the wiper apparatus is not pumped all the way down to a potential bottom hole assembly, for instance a drill bit, and causes damage there. In addition, it is not desirable that the wiper apparatus is pumped out of the drill string and goes astray down in the well, which might result in damages as well as complicated fishing operations. To avoid pumping the wiper apparatus down into the bottom hole assembly or out of the drill string, a so-called landing sub comprising a landing seat may be mounted. The landing seat may beneficially be formed as an integral part of the longitudinal bore in the landing sub, or alternatively be inserted loosely in the same bore. An embodiment of such a landing seat is discussed in NO 330743. The landing sub is advantageously mounted in the drill string by use of thread connections.

To ensure that drilling mud can flow as freely as possible past a wiper apparatus located in the drill string, a landing cone which is arranged to seat itself in a landing seat according to NO 330743 may be supplied with a central bore which is in connection with a central bore extending longitudinally through the wiper. The landing cone may further be designed with a number of flow channels which reduce the flow area past the landing cone/seat as little as possible.

Below the landing cone the drill pipe has a constriction, a so-called "tool joint", which makes the flow area smaller than further down the drill pipe, where the diameter is larger. In addition to that a constricted "tool joint" reduces the flow area, this constriction and the conventional embodiments of the wiper apparatuses can cause the wiper apparatus to get stuck in the drill pipe.

Even with the measures that are provided in order to ensure that conventional wiper apparatuses to the least possible extent shall prevent drilling mud and other fluids from passing through the drill pipe, the problem remains that conventional wiper apparatus in too great an extent reduce the flow area excessively when located in the drill string. The drill operators want as little loss of flow as possible over the wiper device and with smaller drill pipes with smaller ID, loss of flow over the wiper device must be further reduced if they are to be used.

The object of the present invention is to alleviate the above-mentioned problems in a simple way.

According to the present invention, a wiper apparatus is provided for cleaning a drill string of drilling mud during tripping of the drill string according to the characterizing part of independent claim 1.

Alternative or advantageous embodiments are disclosed in the dependent claims.

The invention will now be explained in further detail with reference to the

accompanying figures which display non-limiting examples of advantageous embodiments of the invention, in which:

Fig. 1 shows a view of an embodiment of the present invention, in which a number of fingers of a wiper member are partly exploded,

Fig. 2 shows a view of the same embodiment as in Fig. 1, in which the fingers are completely exploded and locked,

Fig. 3 shows a view in which a wiper member comprising a landing member is on its way down a drill string,

Fig. 4 shows a view in which the landing member has reached a landing sub and the fingers have been exploded, Fig. 5 shows a view in which the landing member has reached a landing sub and the fingers abut a hooking edge,

Fig. 6 shows the same as fig. 5 in somewhat greater detail,

Fig. 7 shows how the outer surfaces of the fingers have an arc-shape which abuts the ID of the drill string, and

Fig. 8 shows a view in which the fingers of the landing member are completely retracted.

A typical embodiment of a landing member 1 according to the present invention is shown in fig. 1. The landing member 1 comprises a number of fingers 2, a bell-shaped locking member 3 and a spring arrangement 4 which biases the locking member 3. In fig. 1 the fingers 2 are half exploded and the locking member 3 is not in its locking position, fig. 2 shows the locking member 1 fully exploded, the bell-shaped locking member 3 having been slid down into a locking position. Fig. 3 shows a wiper apparatus 5 which comprises the landing member 1 and a number of wiper members 6. The wiper apparatus 5 is located within a drill string 7, wherein a landing sub 8 has been inserted into the drill string 7. The wiper apparatus 5 might also comprise a buoyancy body 3, one or more centering elements 4 in addition to any other elements (not shown).

The buoyancy body might be tubular and may for example have an outer diameter of approx. 2/3 of the inner diameter of the drill string. The buoyancy body may be made of metal, a metal alloy or a composite material. The buoyancy body may be made of aluminum. The buoyancy body may be provided with bursting members which are made to burst if the pressure in the drill string exceeds a predetermined pressure.

Thereby, such bursting members ensure that the buoyancy body, which normally will be hollow and filled with air, will not collapse if the pressure in the drill string increases beyond a predetermined pressure. The pressure in the drill string will increase, for example, if one starts to pump fluids through the drill string.

The wiper apparatus 5 may comprise one or more centering elements which for example are provided in an upper and lower portion of the wiper apparatus 5. The wiper members 6 can also function as centering elements. The terms "upper" and "lower" refer to a conventional vertical orientation of a drill string; however, a diagonal or horizontal orientation is also contemplated. The lower portion of the wiper apparatus 5 may comprise a nose piece (not shown) which for example may be coated with a shock-absorbing material.

The upper portion of the wiper apparatus 5 comprises a landing member 1 which is designed to seat itself in a landing seat 9.

According to the present invention, the landing member 1 comprises gripping members in the shape of fingers 2 which are arranged to engage a hooking edge or a landing seat 9 which is arranged in the landing sub 8, ref. fig. 3, 4, 5, 6. This landing seat 9 of the wiper apparatus 5 may be shaped as a shoulder, edge, recesses, slots, pins or the like. The figures show a shoulder or hooking edge. This shoulder is arranged such that the landing sub 8 does not constitute or form a further constriction of the inside of the drill string 7, and preferably minimum corresponding to a ID of the drill string at the connection ends (a typical drilling pipe tends to have a smaller ID at the connection ends than in the middle, see below).

The landing seat 9 may be provided with a conical or other tapering design both over and under the actual edge. The tapering design over the landing seat 9 should be such that the landing member 1 has the time and space to explode and to lock itself to the hooking edge. The tapering design over the landing seat 9 should be such that it contributes to minimizing the risk of tools or other items getting hooked onto the hooking edge.

The actual landing member 1 according to the present invention comprises as mentioned a number of fingers 2 which are arranged to explode and follow the ID of the drill string while the wiper arrangement 5 descends or ascends inside the drill string 7. The fingers 2 are allowed to «flex» in and out such that smaller variations in the ID of the drill string, deposits of impurities and/or cement residue etc. will not lead to that the wiper apparatus 5 is wedged. The fingers 2 may be biased by means of a spring member or other biasing member 4, as the biasing should be loose enough to that the fingers easily can «flex» inwards and outwards.

The fingers 2 are designed as such on the outside, i.e. the side that touches the ID of the drill string ID, that the fingers 2 will not easily get stuck in the drill string 7. A typical design would be an arched design, which is illustrated best in fig. 7. The curvature of the arc could typically be chosen such that the inside of the drill string forms a tangent in relation to the arc curvature 10 of the fingers 2. It could also be a point that the ends of the fingers 2 form a kind of «bow» 11 in downwards direction, such that the fingers can slide more easily over impurities which possibly exist on the inside of the drill string 7. The fingers 2 comprise finger tips 16 designed such that they land on and securely abut the landing seat 9 when the fingers 2 are fully exploded, ref. fig. 5, 6 and 7.

According to an embodiment of the present invention, the fingers 2 balance around a balancing point 12. The balancing point 12 is created by the fastening of the fingers in the tools material, preferably in the shape of a through-going bolt or the like. It should be understood that the balancing point/fastening 12 could be created in alternative ways, for instance by means of pins, constrictions etc.

The other end 13 of the fingers 2, i.e. the end that is not abutting the inner surface of the pipe wall, can according to an embodiment of the present invention be designed such that it cooperates with a biasing and locking member 3. The figures show a potential embodiment of such a biasing and locking member 3 in the shape of a «bell». The inside of the bell is designed such that it contributes to biasing the fingers 2 as long as the fingers are not completely exploded, ref. for instance fig. 7. In the event that the fingers 2 are exploded over a certain point, the bell is designed to slide down over the other end 13 of the fingers 2 and lock these in an exploded state, ref. fig. 2 and 6. This situation will only occur when the landing member 1 and the fingers 2 enter the landing sub 8. Since the ID of the landing sub 8 is greater than the ID of the drill string 7, the fingers 2 will explode over the point that allows the bell 3 to slide down over the other end 13 of the fingers 2 and lock these. Thus, the fingers 2 are locked in an exploded position and when the exploded fingers thereafter reach the hooking member 9, the wiper apparatus 5 will hang where it should.

In order to release the fingers 2 and thus the wiper member 5, the bell 3 must be pulled up/back such that the fingers 2 are allowed to retract again. This can be achieved by pulling in a «fish neck» 14 which is located in the upper end of the wiper arrangement 5. By pulling the fish neck 14 the spring or the biasing member 4 which pressed the bell 3 down over the other end 13 of the fingers, will be pressed together such that the bell 3 is pulled up/back. This is only a sketching of a potential way of releasing a biasing member, as alternative embodiments also may be considered.

The landing member 1 is designed such that fluids can flow on the outside of the landing member 1 when being placed in the landing seat 9. Likewise, the landing seat 9 should be designed to reduce the flow area past the landing seat 9 as little as possible, both with and without the landing member 1 of the wiper apparatus 5 in place in the landing seat 9. For example, instead of the landing seat 9 creating a complete hooking edge, it may comprise a suitable number of, e.g. three or more, appropriately designed pins, cams, longitudinal rails or slits arranged on the inside of a landing sub 8 (not shown).

The number of wiper members 6 arranged may be adapted according to need. It may be appropriate to arrange wiper members 6 with such a spacing that only one, or max. two, of the wiper members 6 are located in the tool joint when the wiper apparatus 5 passes. Further, the wiper members 6 may be designed with different diameters adapted to the normal ID of the drill string, the increased ID through the landing sub 8 and possibly other irregularities which contributes to reduce ID through the drill pipe, respectively.

In use the wiper apparatus 5 is placed in a drill string 7 with an internal surface when tripping (breaking) of the drill string is to be initiated/performed. The drill string 7 contains mud/drilling fluid with a drilling fluid surface, and possibly residues of hydrocarbons, cement, salt water etc. The buoyancy body of the wiper apparatus 1 is provided with a mass and a volume adapted so that the device will stay afloat on the drilling fluid surface. The weight of the wiper apparatus 5 ensures that it falls down to the liquid surface and places the peripheral ledge of the bottom wiper member 6 at a short distance (for example at least approx. 10-15 cm) above the liquid surface.

As the drill string is lifted, the wiper apparatus 5 will always stay on the liquid surface and wipe off the drilling mud that sticks to the inner surface of the drill string 7.

According to one embodiment of the wiper apparatus 5 of the present invention, the length may be approx. 4 m. A typical total weight of the wiper apparatus 5 may be approx. 5 kg. It will be understood that lengths as well as weights may be varied and adapted to the actual use and any special applications.

The wiper apparatus 2 can comprise a spacer 15 between the upper and lower portion of the wiper apparatus 1. This spacer 15 comprises a rod or pipe element having a diameter which is significantly smaller than the smallest ID of the drill string (as previously mentioned, the smallest ID of the drill string is often at tool joint, i.e. the constrictions of the inside of the drill string at each joint of each drill pipe). The tool joint itself often comprises thicker material, which results in a smaller inner diameter. The spacer 15 is provided with such a length that the lower portion of the wiper apparatus 2 will be located where the drill string has the largest ID when the upper portion of the wiper apparatus 2 is located in tool joint. The advantage of such a spacer 15 is particularly evident when the wiper apparatus 1 is seated in the landing seat 10 and fluids need to be pumped down through the drill string.

Because the wiper apparatus 5 at all times will be located on top of the liquid surface, removing the wiper apparatus 5 during tripping of the drill string 7 will normally be easy. Generally, the liquid surface will be slightly above the drill deck when tripping starts. The liquid surface will fall as the drill string is pulled out because the fluid in the well in which the drill string 7 is located will take up the volume that the drill string 7 previously occupied.

If the liquid surface is so low that the wiper apparatus 5 is hard to catch for the operator, retrieving equipment suited for this purpose may be used to retrieve the wiper apparatus 5. This can be achieved by means of a fishing tool which pulls the fish neck 14 of the wiper arrangement.

Drilling mud has a varying self-weight. Accordingly, a favorable embodiment of the apparatus may have replaceable weights / weight elements or varying buoyancy of the buoyancy body.

Claims

1.

A landing member (1) for a wiper apparatus (5), wherein the wiper apparatus (5) is adapted to clean an inside of a drill string (7) of drilling mud or other well fluids under drilling operations, wherein the drill string (7) has an inner diameter (ID), wherein the wiper apparatus (5) further comprises at least one buoyancy body, at least one centering element and at least one wiper member (6),

c h a r a c t e r i z e d i n t h a t the landing member (1) comprises a number of fingers (2) which are arranged to explode and follow the ID of the drill string (7), wherein the landing member (1) comprises biasing members (4) which press the fingers outwards towards the ID of the drill string (7).

2.

A landing member (1) according to claim 1, wherein the landing member (1) comprises a locking member (3) which locks the fingers (2) in an exploded state when the ID of the drill string (7) exceeds a predefined diameter.

3.

A landing member (1) according to claim 2, wherein the landing member (1) is adapted to land on and hang from a landing seat (9) which is arranged in a landing sub (8) which forms a part of the drill string (7), wherein the landing seat (9) has a greater ID than the ID of the drill string (20).

4.

A landing member (1) according to claim 3, wherein the ID of the landing sub (8) on the surface of the landing seat (9) extends outwards in a direction towards the landing seat (9).

5.

A landing member (1) according to claim 3 or 4, wherein the landing seat (9) comprises one or more shoulders, edges, recesses, slots or pins, or a combination thereof.

6.

A landing member (1) according to claim 2, wherein the locking member (3) has a bell- shape with an inner ID which is essentially conical or tapered in design, the inside of the bell further having a locking function which serves to lock the fingers (2) in a exploded state when the ID of the drill string exceeds a predefined diameter.

7.

A landing member (1) according to claim 6, wherein the locking member (3) is biased by means of a spring device (4), hydraulic device, pressurized gas device, or by means of the self-weight of the wiper member (5).

8.

A landing member (1) according to claim 7, wherein the locking member (3) and fingers (2) are released by pulling or manipulating a fish neck (14).

9.

A landing member (1) according to claim 1, wherein the fingers (2) balance around a balancing point (12).

10.

A landing member (1) according to claim 1, wherein the outer surface of the fingers (2) which abut the ID of the drill string (7) essentially are arc-shaped (10) such that the ID of the drill string substantially tangentially abuts the outer surfaces of the fingers (2) when the fingers (2) are not completely exploded and locked.

11.

A landing member (1) according to claim 10, wherein the fingers (2) further comprise finger tips (16) designed such that they securely abut the landing seat (9).

12.

A landing seat (9) arranged in a landing sub (8) which is connected to a drill string (7), c h a r a c t e r i z e d i n t h a t the landing seat (9) has an ID which is similar or greater than the ID of the drill string (7), wherein the ID of the landing sub (8) somewhere on upper side of the landing seat (9) expands in the direction towards the landing seat (9).

13.

The landing seat (9) according to claim 12, wherein the landing seat (9) comprises one or more shoulders, edges, recesses, slots or pins, or a combination thereof.

14.

The landing seat (9) according to claim 12, wherein the landing seat (9) is adapted to be arranged on a wiper apparatus (5), wherein the wiper apparatus (5) is adapted for cleaning an inside of the drill string (7) of drilling mud or other well fluids under drilling operations, wherein the wiper apparatus (5) further comprises a landing member

(1) , at least one buoyancy body, at least one centering element and at least one wiper member (6), wherein the landing member (1) comprises a number of fingers (2) which are adapted for exploding and following the ID of the drill string, wherein the fingers

(2) comprise finger tips (16) which are designed such that they land on and securely abut the landing seat (9) when the fingers (2) are completely exploded.

15.

A system for cleaning the inside of a drill string of drilling mud or other well fluids under drilling operations, wherein the system comprises a wiper apparatus (5) which is adapted for floating on a liquid surface of the drilling mud in the drill string (7) or hanging from a landing seat (9), wherein the drill string (7) has an inner diameter (ID), wherein the landing seat (9) is arranged in a landing sub (8), wherein the wiper apparatus (8) comprises a landing member, at least one buoyancy member, at least one centering member and at least one wiper member (6),

c h a r a c t e r i z e d i n t h a t the landing seat (9) has an ID which is similar to or greater than the ID of the drill string (7), wherein the ID of the landing sub (8) somewhere on the upper side of the landing seat (9) expands in the direction towards the landing seat (9), and wherein the landing member (1) comprises a number of fingers (2) which are arranged to explode and follow the ID of the drill string (7) ID, wherein the landing member (1) comprises biasing members (4) which press the fingers outwards towards the ID of the drill string (7), the fingers (2) of the landing member (1) being adapted to sit on the landing seat (9).