Introduction

The present invention relates to a petroleum well tool for pulling of casing pipes or liner or corresponding pipes in a well.

P oblem statement and background art

Archer (The applicant) has an existing "perforate and wash too!" which is designed for perforating selected parts of easing pipes or liners far washing out the casing pipe / liner am ulus, for subsequent local cementing of a "rock to rock" plug which plugs the well completely. It is a requirement for plugging and abandonment (P&A) of a weil that there are formed two such plugs in the well above each petroleum fluid bearing reservoir zone. Such a fool may be used In determined depth levels below the part of the casing pipe which shall be pulled by means of the method of the present invention.

The second edition of Schlumberger's textbook "Well Cementing" published in 2008, discusses the basic techniques of well cementing, in VVeatharford's brochure "Packer Service Tools" published 2010 is shown a series of weil tools, among those a washing tool ^' for drill pipe string as shown as a part of the tool assembly in Fig, 1.

The same is done in Baker Hugos' Workover Systems brochure, where some illustrations, shown in Sehiumberger's textbook from 2006, are taken from,

US-patent US44S4625

describes a tool for washing the perforated zone In a casing pipe In an oil or gas well with a tube-shaped cylinder which has a passage for through flow, with possibilities of connecting the one end of the cylinder to a drill sting and the other end to a blocking valve. The cylinder has a plurality of apertures through the side wall, A first and a second radially expandable packer surrounds completely and is attached to the cylinder in given positions.

Further, US-patent US4815538 shows a washing loo! connected to the lower end of a pipe string, comprising a cylinder between an upper and a lower connector. The cylinder has two opposite end sections connected to an intermediate section. Each end section has an eiastomeric gasket which ma be fluid fil d with a relatively low liquid pressure. The intermediate section has a blade spring over a lock chamber which may be opened through the blade spring being moved outwardly by means of a higher fluid pressure in the pipe string.

WO2013133718A1 describes a method of removing casing from a well wherein an annulus around the casing and a surrounding body is filled by a mass, comprising:

(A) setting a packer into engagement wth the Inner face of the casing at a first depth, (8) lowering- a string into the well, a cutting tool and a reversibiy sealing .second element connected to the string, the string being fluid-carrying,

(C) forming perforations through the casing by means of a cutting tool at a second depth above the first depth where the first packer is,

(D) expanding the second sealing element against the casing at a third depth,

{£) flowing a fluid through the string and into the annulus via the formed perforations, washing up mass in the annulus and circulating out of the well, and replacing the mass in the annulus with a fluid of lower specific weight.

(F) pulling a length of casing out of the well..

Until present, removal of casing pipes has been conducted by cutting a relatively short section of casing pipes, only a fe meters such as 1 to 5 meters, depending on how stuck the casing pipe, is in the annulus debris or cement, and catches the cut released part of the casing pipe, and pulls It out vertically with raw force by means of a pulling tool or the drill pipe string. This makes it take very long time to remove a casing pipe because each released section becomes so short.

Brief summar of the Invention

The invention is a method for pulling casing pipes liner in a petroleum well, comprising the steps of:

a) perforating an actual section of casing pipes in the well, and subsequently b) washing one or more annul! outside the perforated section to remove debris, particles or cement or other binding substance which would otherwise hold the casing pipe section stuck,

c) cutting the casing pipe within or below the perforated section for releasing It from the lower, remaining part of the casing pipe,

d) Pulling out the released, washed-out part of the casing pipe from the well Advantageous embodiments of the invention is defined in the dependent claims.

Th Invention Is also a petroleum well tool comprising the following features:

- a drill pipe string (5) with

- a perforating tool (1 } arranged to be moved along a desired length of a casing pipe (0) for perforating the desired length of the casing pipe (0) in the well for forming a perforated casing pipe section (Op).

- a wash tool (2) for moving along the perforated casing pipe section (Op) for supply of washing fluid via the drill pipe string (5) for washing out one or ma annuls working through the wall of the perforated section (Op) for releasing it In the annuius, for pulling,

~ a cutting tool (3) for cutting loose the entire or part of the perforated section pipe f 0p) frfr m deeper parts of said casing pipe {ø}

- a grip- and hold tool (4) arranged for pulling the perforated, washed-out part (Op) of said casing pipe out of said weft

In the Norwegian continental shelf alone there are thousands of wells which shall be plugged and abandoned during the next. 10 to 40 years. A considerable advantage of the invention Is that one may pull out far greater lengths of the casing pipe at a time and thus conduct P&A or other corresponding operations much faster and cheaper than with the prio art.

Figure captions

The Invention is illustrated in the attached drawings, wherein: Fig, 1 is a side elevation view of a tool string mounted on a hollow carrier such as a drill pipe string {5} and placed in a relevant part of the casing pipe (0) in a drilled well, and wherein there is a substance in the casing pipe's annuius which prevents pulling out the casing pipe (0) from the well The drill pipe string (S) has a central channel (51 ) for supply of fluid at least to and including the outlet channel (21) in the wash tool (2). In the drill pipe string there is mounted a gripping tool, a wash tool, a perforation gun, and a cutting tool The sequence of the fools (1, 2, 3, 4) may he changed, but the gu (1) may advantageously he mounted lowest in the tool string.

Fig. 2 shows a first or next to first step in the process wherein fhe perforating tool (1) has been lowered to a relevant depth within the casing pipe (0) and perforates the casing pipe {0} so that a perforated casing pipe section (Op) with communication to the annuius i -formed. This process may be repeated several times so as for perforating a desired length or section of the casing pipe (0), e.g. 10 to 100 m of casing pipe. By shot-perforation one will then, in addition to the particles which already are present in the casing pipe annulus, also form fragments during the shooting itself.

Pig. 2B is a genera! overview of a well with a perforated casing pip section (Op) of a casing pipe {0} in the well, ^' wherein the perforated casing pipe section (Op) shall be pulled out after perforation and washing. Fig. 3 illustrates consecutive step of the process wherein the perforation has been conducted, and wherein the wash tool (2) is arranged in a part of the perforated section of the casing pipe (0p) _s and flushes wash fluid through the perforations in the casing pipe (Op), The wash fluid dissolves and / or carries along particles / dissolved matter from the casing pipe's annulus and transports this up with the return current in the drill pipe string annulus up to the surface where they ^* are preferably separated from the liquid. Not far above the actual perforated section (Op) of the casing pipe (0), above residing sections of the casing pipe have been removed. It is assumed that badly consolidated cement also will let Itself wash out from the casing pipe annulus. Fig. 4 illustrates the application of a cutting tool, here a mechanical one, wherein the cutting tool (3) cuts belo or within the perforated, washed free part of the casing pipe (Op), Please notice that the cutting process may be conducted ahead of perforation, ahead of washing, and at least ahead of the pulling itself of the washed free casing pipe (Op) is conducted.. This is conducted by the operator during the planning, or on site.

Fig. 5 Illustrate a gripping - and pulling tool (4) which grips hold in that part of the casing pipe which shall be p lled out. A hammer tool (41 } for fearing loose of the relevant part of the casing pipe may also be integrated in the toot string. The two may be combined. Fig, 8 shows an alternative embodiment of the invention wherein an upper, coarser gripping and pulling tool (42), a so-called "casing spear" is arranged above the lower gripping / pulling tool (4).

Fig, 68 shows an overview of the well similar to in Fig. 28, and shows the perforated easing pipe section and an upper part of the remaining, non-perforated casing pipe (0). A drill pipe string with the cutting tool (3), the washing tool (2), and the lower gripping/pulling tool (4) are S shown with an upper gripping / pulling tool (42) which Is spaced out with drill pipe string between the upper and lower gripping pulling tools (4, 42) corresponding to e length of the perforated casing pipe section (Op). Fig, 7 illustrates that the pulling tool (42) has pull-released the perforated, washed-out casing pipe section (Op) and been released from that. The gripping / pulling tool (4) which is located just above the wash tool (2) has been placed and grips hold near the upper end of the released easing pipe section (Op). Fig. 8 Illustrates- having the gripping / pulling tool just above the washing tool. The perforated, washed-out, released casing pipe section (Op) will hang in the gripping / pulling tool (4) close to the drilling deck and be held after Its upper end of the released casing pipe section (Op), The washing tool and cutting tool which hangs within the casing pipe section (Op) will not extend down to the BOP,

Fig. 9 shows an embodiment of the petroleum well tool, Emb diments of the invention

The invention is a method for pulling casing pipes i liner (0) in a petroleum well, comprising the steps of:

a) perforating an actual section (Op) of said casing pipe (0) in said well by means of a perforating gun (1). and then

b) washing, by means of a washing tool (2) in at least one casing pipe annuius outside the perforated section of said casing pipe (Op) for removing debris material, particles, cement or other bonding substances which otherwise hold said casing pipe section (0) stuck.

c) cutting, by means of a cutting tool (3) said casing pipe within or below the perforated section (Op) for releasing it from the deeper residing, remaining portion of said casing pipe in said well. (If this is not, then, the deepest or last remaining pert of in© casing pipe). This may alternatively be conducted before step (a) or (b).

d) pulling said released, washed-out section of said casing pipe out of said well,

A considerable advantage of the Invention is that one may wash out a considerable length of the casing pipe in one piece, and that the use of the washing fool with swab cups has the effect that even not all portions of the annuius is completely cleaned for debris or cement, then washed-out debris will be able to pass from the casing annuius and into the drill pipe string annuius through perforations above or below the wash took, as opposite of

WO2013/133718 which is dependent from that the annuius is opened all the way from the simp e perforations and ail the way to the free top of the casing, and thus may only wash out short sections of casing.

Another advantage is that in an embodiment of the invention ail operations from perforation via washing, releasing _. , and pu!iing out of the well, ma be conducted in one run on a drill pipe- string.

Whether it is a casing pipe (0) or a finer makes no difference,, Other types of pipes in a well may also be imagined. The petroleum we!! is a eli which is formed for petroleum activity, and may also be an exploration well or an injector weli. Alternatively the well may he a geothermai weli

The well may in many instances he dead in advance, plugged below the actual part of the casing pipe, e.g. by means of perforation and injecting of cement "rock to rook" in a P&A phase of the entire or below residing reservoir sections. The present method may also be for removal of casing pipes for slot recovery or new completion of the well, or Intervention,

The step of cutting the casing pipe may be conducted in the sequence described, or ahead of washing, but anyhow ahead of pulling the casing pipe,

The really great advantage of the invention is that one may release casing pipes (0) by perforating and washing over a long section of casing pipe (0) and thus form a long section of perforated, washed - out casing pipes (Op) which may be pulled In one piece when it has been cut free. The pulling out may be conducted by means of a vertical force which is exerted by means of the drill pipe string Itself, It should also be possible to wrench out the perforated, washed-out section of casing pipe (Op).

In an embodiment of the invention it comprises that the perforation of casing pipes (0) is conducted with a perforation gun mounted on a washing tool further mounted (directly or indirectly) on a drill pipe string. An advantage of such arrangement is that the perforation may be conducted across a relevant length of casing pipes (0) which makes perforated casing pipes (Op) which are longer than the perforation gun (1 ) itself, e.g. over a relevant length of 10 to 100 metres. Subsequently one may employ the wash tool (2) which is mounted on the same drill pipe string, across the perforated length of casing pipes (Op) and thus do not have to trip out the drill pipe string (5) for changing operation. The wash process may he conducted stepwise or by continuous movement of the wash fool downwardly or upwardly across the perforated sectio of casing pipes (Op), in an embod men of e invention there is included in the tool sting on the drill pipe string a gripping tool arranged for gripping the perforated, washed-out section of casing pipes (Op). Please notice that parts of the casing pipe (0) which does not comprise substance in the casing i e annuius does not really have to be washed out, but which may form part of the perforated, washed-out casing pipe (Op),

According to an embodiment of the invention there is employed., in the tool string on the drill pipe string (5), a gripping tool (4) arranged for gripping the perforated, washed-out section of (Op). Again, the advantage is that one does not have to trip out the drill pipe string with the tool string in order to mounting or? a gripping tool. The gripping tool may he hydraulic, mechanical, or a combination of such, and It may be enabled for being activated once, or reactivating, A hammer device (41 } is mounted into the tool string and may he arranged for aiding during the release of the washed-out cut part of the casing pipe (Op). This may be integrated with the pulling tool (4).

The process of steps (a) to fd) are conducted in "one single trip" on one and the same drill pipe string. This provides significant operative advantages because one would not have to trip out the drill pipe string between the steps. In such an embodiment the too! may comprise * a drill pipe string (5) with 1.

~ a perforation tool (1 )

~ a washing tool (2) for one or more annuls working through the wall of the perforated section (Op),

- a cutting tool (3) for the relevant, preferably perforated section of the casing pipe (Op)

- a gripping - and pulling tool (4) arranged for pulling the perforated, washed-out part (Op) of the casing pipe out of the well, It is possible to release the gun after perforation for reducing the length of the string for the subsequent washing operation and further work. This may reduce the lateral load on the washing tool and other components, and it may simplify the subsequent work and reduce the nek during the subsequent work, The tool may in an embodiment omit the perforation fool (1) or the cutting tool (3) In order to conduct the simplified (actually less continuous) operations mentioned below. In an embodiment of the Invention the steps of

(a) perforating,

(b) washing,

(o) pulling,

be conducted in one trip on a drill pipe string.

The ste (c) cutting may be conducted in a separate run, anyhow ahead of step (d) pulling, According to n embodiment of the invention the method may be conducted with the following steps:

(a) perforation conducted in one run, and

the steps of

(b) washing

( pulling

conducted in a separate run, on a drill pipe string.

Here the step of (a) perforation be- conducted on wireline, coil d tubing or drill pipe string. The step of (b) washing and folfd] pulling should preferably be conducted on a drill pipe string. The step of (e) cutting may be conducted ahead of (a). perforation or (h) washing.. In an embodiment of the method according to the Invention the washing may be conducted with a wash tool (2) arranged to isolate with gaskets (22, 23} against the perforated section of the casing pipe (Op) and for and for flushing wash Hold out through the perforation which have been formed. The wash fluid is supplied via the drill pipe string's central channel (51 ). The big issue is to perforate a long section of the casing pipe, for subsequently running the wash tool for forming flushing nozzles from the perforations, thereby washing behind the entire perforated section, thereby enabling pulling out long sections,

In an embodiment of the invention's method 11 is isolated by means of the gaskets (22, 23} out against the casing pipe's liner's inner wall above and preferably also below the wash tool's outlet channel (21 } within the perforated section (Op). It Is essential that at least one gasket (22) is used above the outlet channel (21 ) and that the drill pipe string's (5} annulus may receive flushed-out material and dissolved material which is brought out to the surface of the well. According to an embodiment of method of the invention the cutting may be conducted mechanically by means of a hy&rauiieaify driven tool, or explosively (by means of a round- peripherally shooting perforating gun* or chemically.

The different tools (1), (2), (3) ₍ and {4} may be so-called bail-operated or flow / hvdrauSically operated.

Fig, 8 shows an alternative embodiment of the invention wherein an upper, coarser gripping / pulling tool (42), e.g. a so-called casing spear (42) Is arranged above the lower gripping / pulling tool (4), This pulling tool ma be employed for the mechanical detachment of th perforated, washed-out casing section (Op),

Fig. 6 shows an alternative embodiment of the Invention wherein an upper, coarser gripping / pulling tool (42), a so-called casing spear (42) Is arranged above the lower gripping / pulling tool (4).

Fig. 6B shows an overview of the well similar to in Fig. 28, and shows the perforated casing pip section and a part of the remaining , non-perforated casing pipe (0), A drill pipe string with the cutting tool (3) , the washing tool (2) and the lower gripping / pulling tool (4) is shown with an upper gripping / pulling tool (42) which is spaced out with drill pipe string between the upper and lower gripping / pulling tools (4, 42) corresponding to the length of the perforated / washed out casign pipe section (Op). Thus one may, when the wash process has been conducted, and if the wash tool is situated at the lower part, of the washed-out casing pipe section (Op), avoid having to trip out drill pipe string until the wash tool and the lower pulling tool (4) Is in level with ^' the upper part of the washed-out casing pipe sectbn{0p), one will already have an upper pulling tool (42) ready in the desired level for pulling loose the casing pipe section (Op), Thus one may pressure test the wash tool in blank casing in the top of the remaining easing pipe section (0) below the washed-out casing pipe section (Op) for testing whether the wash tool's swab cups (22, 23) have been intact during the entire washing process ahead of deciding to pull out the washed-out casing pipe section (Op). Further, one avoids having to pull the wash tool up through the entire casing pipe section (Op) with the risk of damaging the swap cups (22, 23) before one shall grip hold with the lowe pulling tool (4).

Fig. 7 illustrates that the pulling tool (42) has pulled and detached the perforated, washed-out casing pipe section (Op) and been released from it, and pulled some distance upwardly until the gripping / pulling tool (4) which is just above the washing tool (2) and near the upper end of the released casing pipe section (Op). The perforation guns are usually dropped after firing as described above, so those will also not be any hinder either.

The method according to an embodiment of the Invention comprises, as explained above, that there is arranged an upper, coarser pulling tool (42) above the gripping pulling fool (4), wherein said coarser pulling tool is employed after the washing in step (h) for pulling and detaching the perforated, washed-out casing pipe section (Op) to be released and elevated so as for the gripping / pullin too! to catch hold near an upper end of the released casing pipe section (0p) _; whereby step (d) of pulling the released, washed-out casing pipe section (Op) out of the well.

Fig. S illustrates the purpose of having the gripping / pulling tool Just above the washing tool; the perforated, washed out, released casing pipe section (Op) will hang from the gripping / puling tool {4} near the drilling deck and be held at its upper end of the released casing pipe section (Op), The wash tool and the cutting tool which hangs within the casing pipe section (Op) will not extend down to the BOP, so there is only one pipe siring down through the BOP, not two.. Thus the safety Is maintained because shear rams of the BOP may cut through the single casing pipe (Op) which extends through the BOP, Fig. 9 shows an embodiment of the petroleum well tool comprising a series of assembled one or more perforation guns ( 1), cutting tools (3), washing tools (2), gripping and pulling tool (4), drill pipe space ouf sections, and the second gripping /pulling tool (42), hammer tool (41), accelerator, and connection to the drill pipe string.