EQUIPMENT

The invention relates to a hydraulic fracturing equipment. In terms of hydraulic fracturing technique, the entire profession is in agreement in considering that fracturing is efficacious and controlled when the fractured zone which supports the pressure is not long.

Also, the fact of fracturing a small zone at the same time limits the surface impact of fracturing equipment (fewer pumps, etc.).

Also, there is a need for better control of parameters put in place so that the fracturing campaign proceeds best.

So it is important to modify the fracturing program in progress, as a function of the resulting partial parameters. For instance, following a seismic survey it can be decided to stop the fracturing in progress, to then resume it two zones further on, etc.

Of course, for economic and ecological reasons the aim is to reduce the consumption of water and support agents ("proppant" in English), and to avoid any risk of polluting surrounding layers by fracture propagation.

It can also be requested that chaining the different fracturing phases may not be done necessarily linearly from the bottom up (that is, from the downstream side of the well to the upstream). In fact, it can be advantageous to consider the nature of the terrain and the success or absence of success of fracturing in progress.

Being able to fracture new zones several years after the first instances of fracturing have been completed is also requested.

Naturally, it is also necessary for the fracturing sealing in progress to be faultless, without risk of fracturing the adjacent zone and for this technique to be secure and low-cost to carry out.

The aim of the present is to respond to this demand.

So the invention relates to hydraulic fracturing equipment of the rock of a well by which it is possible to execute a fracturing process.

This hydraulic well-fracturing equipment is characterised in that it comprises, on the one hand: a conduit provided along its external face with at least one pair of expandable metallic tubular sleeves fixedly, connected to the conduit, this conduit having opposite each sleeve at least one opening, known as "first opening" for having the internal space of the conduit communicate with the space delimited by the latter and each sleeve, and opposite the space separating the two sleeves of a same pair at least one other opening known as "second opening", for having the internal space of the conduit communicate with the interior of the well;

a tubular element of a diameter provided to have it engage in said conduit such that there is a free annular space between them;

the wall of this tubular element comprising at least one first through-hole;

the wall being also provided externally with at least two deformable rings located on either side of said first orifice, capable of being applied hermetically against the internal face of said conduit.

According to other non-limiting and advantageous characteristics of this equipment, taken separately or according to any combination:

- the distance between the deformable rings is greater than the distance separating said first openings from said conduit;

- at least two first through-holes are arranged in the longitudinal direction of the element according to two zones whereof the mutual distance is substantially equal to that of the first openings of said conduit;

- the means which prevent said fluid which is funnelled into said second opening from terminating in the space separating the two sleeves consist of a sleeve with sealed ends, fixed on the external wall of said conduit, sleeve which is capable of breaking under predetermined pressure known as "breaking pressure";

- said tubular element comprises at least one second orifice and two pairs of rings, the second orifice being located between the rings opposite the two pairs of rings;

- the two rings are arranged on either side of said first orifices; - the rings of a same pair are separated longitudinally by a distance greater than that which separates the first and the second openings of said conduit;

- said tubular element comprises means capable of blocking its downstream end;

- said means comprise a valve;

- said conduit and said tubular element have mutual immobilisation means;

- said valve is coupled to said mutual immobilisation means such that said valve blocks said end only when said immobilisation means cooperate;

- said tubular element comprises at least one second orifice located between the rings opposite the two pairs of rings;

- said second orifice is provided with a closing member directed axially, which moves from a closing position to an opening position under the effect of a rise in pressure without opposing the longitudinal passage of fluid;

- said member comprises a hollow piston retracted into a closing position by elastically deformable means such as a spring;

- said conduit and said tubular element have mutual immobilisation means in two distinct positions offset longitudinally;

- said means are arranged so as to allow shifting from one position to the other distinct position by sliding of said tubular element relative to said conduit.

Other characteristics and advantages of the invention will emerge from the following detailed description. Reference is made to the attached diagrams, in which:

- Figure 1 is a partial and simplified view, in longitudinal and vertical section, of the horizontal portion of a drilling well wherein the aim is to carry out hydraulic fracturing of the rock, and of a conduit introduced therein;

- Figure 2 is a view similar to the preceding one, but shown over a greater length of well;

- Figure 3 is a view in perspective of a sleeve which equips the conduit of the preceding figures; - Figure 4 is a simplified view, in vertical and longitudinal section, of a tubular element which forms part of the hydraulic fracturing equipment according to the present invention;

- Figure 5 is a view similar to Figure 1 , the tubular element of Figure 4 also being shown;

- Figures 6 and 7 are views similar to Figure 5 showing two successive steps for carrying out a hydraulic fracturing process;

- Figure 8 is substantially identical to Figure 1 and shows a variant embodiment of a conduit in place in the horizontal portion of a well;

- Figure 9 is a view similar to Figure 2;

- Figure 10 is a view similar to Figure 4, showing a variant embodiment different to the tubular element;

- Figures 1 1 , 12 and 13 show the different steps taken to attain fracturing of the rock by using the conduit and tubular element of Figures 8 and 10;

- Figures 14 and 15 show other embodiments of the apparatus of the device according to the invention;

- Figures 16 to 18 illustrate the different steps taken to carry out hydraulic fracturing of the rock of a well, by means of the variant embodiment of Figures 14 and 15.

- Figures 19 and 20 on the one hand, 21 and 22 on the other hand, are views which further illustrate execution of a fracturing process by making use of two more additional variants.

- Figures 23 and 24 on the one hand, 25 and 26 on the other hand, are views of two more variant embodiments of such a process;

- Figure 27 is a view similar to Figure 26, but showing a greater length of conduit.

In the attached figures and for the sake of clarity, only one fraction of the horizontal part of a hydraulic fracturing well A has been shown.

It is of course possible for this horizontal portion to extend over a considerable length. It is attached to a vertical portion terminating in open air via an intermediate portion substantially in an arc of a circle (not shown).

Likewise for reasons of simplification, this well A is shown as constituting a perfect cylinder. This is of course a matter of opinion since its wall, approximately cylindrical, can have a large number of local deformations.

For all the figures, it is considered that the "apex" of the well (terminating in open air) is located to the left of the figures and its base to the right.

As will be evident hereinbelow in the description, fracturing fluid is circulated in the well from the apex to the base, from upstream to downstream.

With reference to Figure 1 , this therefore relates to a portion of well in which containing a metal conduit 1 which has a substantially cylindrical form and which is, for example, kept in place according to the axis X-X' of the well by deformable end sockets which rest against the walls of the well. Any other means known to the expert which auto-centres the conduit 1 relative to the size of the well, can be envisaged.

The expert can also determine the optimal diameter of the conduit 1 to cerate around the latter a free annular space which separates the external wall of the conduit from the wall of the well once it is put in place in the well.

As shown in Figure 1 , the conduit comprises along its external face at least one pair of expandable metallic tubular sleeves referenced 2.

A single pair of these sleeves 2 is seen in Figure 1 . The distance separating them can, for example, be of the order of a metre.

However, in reference to Figure 2 where several of conduit 1 have been assembled and fixed end-to-end, the presence of three pairs of sleeves 2 referenced n, n+1 and n+2 is clear.

By way of indication, if each portion of conduit measures 12 m long, it is possible to position one hundred pairs of metallic sleeves 2 over a length of 1200 m of conduit.

As will be evident later on, this will produce 100 different instances of fracturing, each spaced 12 m.

Still in reference to Figures 1 and 2, it is evident that the conduit 1 has, opposite each sleeve 2, at least one opening 10, called "first opening" which enables communication between the internal space of the conduit 1 and the space delimited by this conduit and each sleeve 2.

A single opening 10 is shown in the figures and still for the sake of clarity. In practice, this can be a set of several openings 10, for example distributed according to circular arrangement which is spaced uniformly and angularly.

Several openings 10 placed according to staggered distribution, or other, are also possible.

As is well known, metallic sleeves 2 comprise relatively ductile metallic material and are connected solidly to the conduit 1 at the level of their ends 20, for example by crimping, by means of screws or by any other fixing means known to the expert, which produce faultless sealing between these ends 20 and the wall of the conduit 1 .

Substantially at mid-distance from the space separating two sleeves of a same pair n, n+1 or n+2, the conduit comprises at least one other opening 3, known as "second opening", which puts the internal space of the conduit 1 in communication with the interior of the well A, and not, as the openings 10, with the interior of the tubular sleeves 2.

Of course, what has been said for the opening 10 also applies for the opening 3 with respect to their number and their arrangement.

However, the conduit is provided along its external face and covering the second opening 3 with an expandable metallic sleeve 30 which is capable of breaking under the effect of internal predetermined pressure, as will be evident hereinbelow.

At least one mechanical weakening zone, such as that illustrated by reference 31 and for example made by removing material, can be provided in this wall. The function of this sleeve especially is being able to break under the effect of predetermined pressure in its internal space. It advantageously has a sinuous path, such that once broken, the corresponding opening will be the widest possible.

In the embodiment illustrated the sleeve 30 is fixed to the conduit by the same means as those of the sleeves 2. This is an advantageous variant and it is clear that the sleeve 30 could have its own fixing means.

The material of this sleeve can be advantageously provided to have an elongation rate less than that of the sleeves 2

In reference to Figure 1 , this shows the presence, downstream of the sleeve 2 arranged to the right (that is, downstream of the conduit), of an annular throat 1 1 formed in the internal wall of the conduit 1 and which terminates inside the latter. Its use and function will be referred to later in the description.

It is evident that the downstream end of the conduit 1 is open.

In addition to the conduit 1 , the fracturing equipment according to the invention comprises a tubular element 4 a possible embodiment of which is illustrated in Figure 4.

This is a tubular element of a diameter provided to allow it to be engaged in the conduit 1 such that there is a free annular space between them.

Purely by way of indication, the diameter of this tubular element is less by approximately half that of the conduit.

The wall of this tubular element 4 comprises at least one through-hole 43.

In a particular embodiment these through-holes 43 are arranged, in the longitudinal direction of the element substantially at mid- length, so as to be able to be placed opposite the openings 3 of the conduit 1 , as will be evident hereinbelow.

Also, the external wall is provided with deformable rings 6 which are capable of being applied hermetically against the internal face of the conduit, as will be evident hereinbelow.

These are for example deformable rings of known type, for example in the form of packers capable of being deployed on demand, to be placed against the internal wall of the conduit 10 while producing sealing at this level. They are positioned and fixed to the element 4 by any means known to the expert, for example inside a throat, between two pieces screwed together.

The deformable rings can be « cup packers », that is, lip joints activated by the liquid flow originating for example from the interior of the tool 4 via the orifices 43, in the annular region where they extend.

A particular feature of this embodiment is the fact that there are only two rings 6 whereof the mutual distance is close to the distance from the upstream end 20 of the first sleeve 2 to the downstream end 20 of the second sleeve.

A blocking system 44 is preferably provided at the downstream end of the tubular element 4.

Here this is a system comprising a ball valve 41 , the operation of which will be explained later on in the description. At this level, the external wall of the tubular element 4 is provided with immobilisation means 7 (illustrated schematically) of this element vis-a-vis the conduit 1 , these means 7 being provided with at least one element 70 projecting peripherally intended to cooperate with the above groove 1 1 . These are for example ergots arranged radially relative to the element 4, which tend to be directed towards the exterior under the effect of a spring, not illustrated.

The embodiment in Figures 8 to 1 1 is very similar to the preceding one.

Unless expressed otherwise hereinbelow, the elements common to these two variants will not be described a second time.

The conduit of Figure 8 is identical in all aspects to that of

Figure 1 , if only devoid of sleeve 30. In these conditions the opening 3 is directly in contact with the exterior of the conduit 1 .

A particular feature of the element 4 of Figure 10 is that it comprises two rings 6 arranged on either side of each of the orifices 42, or four in total.

Substantially at mid-length of the tubular element (and therefore at mid-distance from the orifices 42), the embodiment of Figure 10 relates to an opening 43 which, as illustrated in Figures 10 and 1 1 , is blocked by a closing member 5 directed axially.

The latter is capable of moving from a closing position to an opening position under the effect of a rise in pressure in the tubular element 4 without opposing the passage of fluid.

In this case, in the example illustrated in Figure 10, this relates to a hollow piston 50 retracted into a closing position by elastically deformable means such as a helicoidal spring 51 , supported against an annular stop 52 positioned inside the element 4. So, to the extent where the piston is hollow, the fluid which will be conveyed inside the tubular element could circulate from upstream to downstream, passing inside the hollow piston.

But under predetermined pressure conditions, via its front face the emptied cylindrical element forming the hollow piston will then accommodate pressure likely to shift it to an opening position, against the spring 51 . The execution of a fracturing process which makes use of this embodiment of the equipment (and variants hereinbelow) will be described hereinbelow in the description.

The embodiment illustrated in Figures 14 and 15 is similar to the preceding one.

However, with respect to the conduit 1 it is evident that this relates to not only a first throat or groove 1 1 , but also an identical second groove 12 offset longitudinally (towards downstream) of the preceding one.

Also, the tubular element 4 illustrated in Figure 15 differs from the preceding one by the absence of the associated opening member 43 and, of course, closing member 5.

In the embodiment of Figures 19 and 20 the tubular element 4 is unchanged relative to the variant of Figure 5.

However, the two annular grooves 1 1 and 1 2 of the conduit 1 which has just been described are replaced by a wide annular region 13 forming a reduction in thickness of the wall of the element 1 . Its opposite ends 130 and 131 act as stops, as will be evident hereinbelow.

In the variant embodiment of Figures 21 and 22 the conduit 1 comprises a single annular throat 1 1 , as in the embodiment of Figures 1 and 8.

As for the tubular element 4, it is still devoid of an "intermediate" opening 43 and the means 7 equipping it at its downstream end are likely to shift between two annular stops longitudinally distant from each other. They are referenced 8 in Figure 21 .

Figures 23 and 24 relate to equipment similar to that of Figure

5. However, as will be evident hereinbelow, their mode of use changes.

The same applies for the equipment evident in Figures 25 and

26.

We will now describe the execution of a fracturing process which makes use of the above described material .

This process requires the presence of a conduit 1 such as described hereinabove.

In a first step this process consists of injecting fracturing fluid F under predetermined pressure P1 into the conduit 1 , this fluid being funnelled into the first openings 10 only communicating with the sleeves 2. This pressure is selected such that it is sufficient to cause expansion of the sleeves 2 in the direction of the wall of the well A, so that it is applied hermetically against this wall.

This is for example the state corresponding to Figure 6.

In the process, the pressure P1 prevails inside the sleeves 2 whereas in the space which separates the two sleeves of a same pair delimited by the conduit 1 and the wall of the well, only original pressure P0 prevails.

In a second step, fluid is injected under fracturing pressure P2 different to the first pressure P1 inside the conduit. This fluid is funnelled into the first openings 10 and second openings 3 such that the same pressure P2 prevails on either side of the wall of the sleeves 2.

This corresponds to the situation for example of Figure 7. Because there is no differential pressure between the interior of the sleeves 2 and the annular zone opposite the wall to be fractured, the fracturing is veritably localised at the level of this annular wall and presents no risk of propagation opposite the abovementioned sleeves.

This is the principle of execution of said process.

It is however useful to cover it in greater detail, given the different variant embodiments of the equipment which have been described hereinabove.

Therefore, in reference to Figures 1 , 4 and 5, while the sleeve 1 has been placed in the well, the tubular element 4 is positioned with its downstream end open, that is, without the latter being blocked, to allow free circulation of liquid present in the well.

Once this placement is complete (whereof proper execution can be verified by means of adapted control apparatus), liquid containing a ball which, once in place blocks the valve 41 of the blocking means 44, is sent under first reference pressure.

The immobilisation of the tubular element 4 relative to the conduit 1 is ensured by the means 70 with projecting element(s) which have the capacity to be retracted to slide along the internal wall of the conduit 1 and be engaged and immobilised inside the annular groove 1 1 of the conduit 1 .

This gives the position of Figure 5 in which the second openings 10 of the conduit are opposite the openings 43 of the tubular element, whereas the two rings 6 are respectively opposite the upstream and downstream ends 20 of the two sleeves 2.

As indicated hereinabove, and whereas the rings 6 have been deformed so as to seal the conduit 1 , fluid under first reference pressure P1 is sent inside the element 4.

This liquid circulates through the openings 43 and 10, which deforms the metallic sleeves 2 such that their wall is applied against that of the well A to form a tight joint.

However, when fluid F is sent under second pressure P2, the wall of the sleeves 30 bursts, even before it makes contact with the wall of the well A.

In the process, fracturing pressure P2 balances out on either side of the deformed wall of the sleeves 2, which implements fracturing in a particularly targeted tight manner without risk of transmission of the fracturing to a zone which would not be opposite that intended.

The execution of the variant of Figures 8 and 10 is relatively similar to what has just been described.

The element 4 is immobilised while the first openings 1 0 of the conduit 1 are opposite the openings 42 of the tubular element, whereas the second openings 3 of the conduit 1 are opposite the opening 43 of the element 4.

When fluid under pressure P1 is sent in the element 4, due to the fact that the closing member 5 is a hollow piston the liquid circulates through this piston and enables the second metallic sleeve 2 to be placed under the same pressure P1 .

In any case, this first pressure P1 is insufficient to move the hollow piston of the member 5, such that the openings 43 are blocked.

The following step which is illustrated in Figure 13 is conducted this time under pressure P2 which is greater than pressure P1 and which is capable of moving the hollow piston 5 to make the openings 43 accessible. The liquid is funnelled there, as well as through the orifices 42 and 10.

As in the present case, the fracturing pressure P2 balances out on either side of the deformed wall of the sleeves 2, which implements fracturing in a particularly targeted tight manner without risk of transmission of the fracturing to a zone which would not be as opposite that intended. In the embodiment of Figures 16 to 18, it should be recalled that the tubular element 4 is devoid of openings 43.

Also, for carrying out the fracturing process, this tubular element 4 is positioned so that the mutual immobilisation means 7 are wedged opposite the first peripheral groove 1 1 .

This is a first immobilisation position in which the rings 6 of the element 4 are substantially opposite the ends 20 of each of the sleeves 2, such that when fluid F is sent under the first pressure P1 only the sleeves 2 are accessible and deform to ensure sealing vis-a-vis the wall of the well A.

In a subsequent step, and before pressure P2 is sent to the tubular element 4, it is shifted so that the immobilisation means 7 cooperate this time with the second annular groove 12 which is offset longitudinally from the first groove 1 1 .

In this position, and as illustrated in Figure 18, the rings 6 of the element 4 are then positioned such that they allow communication of the interior of this element with the openings 10 and 3 of the conduit 1 .

In these conditions and as in the preceding embodiment, the pressure P2 can circulate through the abovementioned openings so as to cause fracturing under pressure P2 which is balanced on either side of the wall of the sleeves 2.

The embodiment of Figures 19 and 20 is relatively similar to the preceding one, if only shifting of the element 4 from the first to the second longitudinal position is no longer done by means of the two annular grooves 1 1 and 12, but from the region of minimal thickness 13 whereof the ends 130 and 131 constitute stops for the means 7.

The fracturing can be carried out in the same way as in the preceding embodiment.

As mentioned hereinabove and in reference to Figure 23, this relates to a conduit similar to that illustrated in Figure 5.

In this embodiment however, the sleeve 30 has the particular feature of being provided to break under pressure greater than the expansion pressure P1 of the sleeves 2. However, it can be less than the fracturing pressure P2.

In the step presented in Figure 23 and prior to placing of the element 4, the interior of the conduit 1 is subjected to said pressure P1 such that the fluid is funnelled into the openings 10. This deforms and thrusts the sleeves 2 against the wall A without affecting the handling of the sleeve 30.

Once the pressure P1 stops, the element 4 is placed such that the rings 6 are now opposite the upstream ends of the sleeve 2 located to the left of Figure, and downstream of the sleeve 2 located to the right of the figure.

The interior of the element 4 is then subjected to pressure P2 (greater than P1 ) capable not only of causing "the explosion" of the sleeve 30 but also the fracturing of the rock. This is the situation illustrated in Figure 24.

The embodiment of Figures 25 and 26 contains beforehand a step identical to that of Figure 23.

This gives however a situation in which pressure P3 necessary for breaking / exploding the conduit 3 is greater not only than deformation pressure P1 of the sleeves 2 but also than fracturing pressure P2.

Under pressure P1 , this prior step therefore deforms the sleeves 2 without affecting the sleeve 3.

After relaxing of the pressure and placing of the element 4 in the same position as that of Figure 24, pressure P3 which is sufficient for causing exploding of the sleeve 3 is generated inside the element 4. This is the situation in Figure 25. This pressure is lowered instantly after.

The element 4 is then slid from upstream to downstream, such that neither of the rings 6 is situated opposite the sleeves 2.

Fluid is injected under fracturing pressure P2 into the element 4 so as to fracture the rock. Simultaneously, the same pressure is sent to the annular space which separates the conduit 1 from the element 4 to create pressure equilibrium on either side, capable of avoiding any collapse phenomenon of the wall 4.

It is evident that the ring 6 located downstream of the openings 42 of the element 4 is "activated" so as to create sealing between the upstream and the downstream of the conduit. This is however not necessary for the ring located upstream.

The illustration of Figure 27 shows the importance of having exploding pressure P3 (rupture) of the sleeve 3, which is greater than fracturing pressure. In fact, due to the fact that the process moves from downstream to upstream along the completion (from right to left of Figure 27), it is necessary, when it is proposed to fracture the rock at the level A1 n+1/A2n+1 for the fracturing pressure P2, not to cause rupture of the sleeve 3 located downstream, at the level A1 n/A2n (located on the left of Figure). This is definitely the case here, since the pressure P2 is not sufficient to make this happen.