Device and method for collecting debris of deposits in a wellbore

The invention relates to a collecting device for collecting debris of deposits while said deposits are being removed from a wellbore wall or an equipment arranged in a wellbore of a subterranean formation in order to improve the recovery of formation fluids and/or gases, said collecting device being configured for being attached to a cleaning device, said cleaning device being configured for removing deposits from a wellbore wall or an equipment arranged in a wellbore. The collecting device comprises a deflector, configured for deflecting falling debris of deposits while said deposits are being removed from said wellbore wall or said equipment, and a debris storing module, connected to said deflector for collecting and storing debris deflected by said deflector.

FIELD OF THE INVENTION

The field of the invention relates to well boring and, more particularly, to a device and a method for removing deposits from a wellbore wall or an equipment arranged in a wellbore of a subterranean formation in order to improve the recovery of formation fluids and/or gases. The device and method according to the invention may advantageously be used to remove deposits from e.g. a wellbore wall, a casing, a tubing or a well completion equipment.

BACKGROUND OF THE INVENTION

In the art of well boring, a borehole is drilled into the earth through an oil or gas producing subterranean formation or, for some purposes, through a water bearing formation or a formation into which water or gas or other liquids are to be injected.

Completion of a well may be carried out in a number of ways dependent upon the nature of the formation of interest. In particular, it is known to arrange a casing into the wellbore to control formation elements. Once installed into the wellbore, the casing is then perforated in a plurality of areas for allowing the passage of oil and/or gas from the formation into the casing. In order to produce formation fluids or gases, completion strings are arranged in the borehole. Such a completion string generally comes as a production tubing which comprises a plurality of different equipment such as e.g. safety valves, sliding side doors, side pocket mandrels, etc.

In any event, after a period of production, injection or transportation of fluids or gases, there is a tendency for the wellbore wall and/or different wellbore equipment to become plugged with various types of deposits like e.g. residues. For example, organic residues like scale, paraffin, asphalts and other gummy residues of petroleum origin often cause plugging problems.

Usually these deposits can cause significant problems, because of their composition and the fact that they can precipitate under certain conditions (pressure, temperature, composition). These materials of mineral or organic origins either together with chemicals from water, normally produced with the oil, such as calcium carbonate, calcium sulfate, barium sulfate, sulfur and the like, or such chemicals themselves have a tendency to form extremely hard deposits on the wellbore wall and/or different parts of wellbore equipment. Such deposits can thus adhere to the wellbore wall and/or various equipment arranged in a borehole or a pipeline, restricting their use seriously and/or reducing or completely preventing the flow of fluids or gases through the completion string or the pipeline. For example, deposits may prevent opening or closing safety valves or sliding side doors, etc.

Such deposits are difficult to dissolve by known chemical means or to dislodge by known mechanical means. For example, chemical treatments, such as, treatments with acids, surface active agents and the like have been utilized in order to clean out scaled wellbore wall or equipment. However, such techniques, while less expensive than a complete workover, are substantially less effective, since they are incapable, in most cases, of dissolving significant amounts of the plugging materials. Another technique, which can be classified as a mechanical technique and has also been suggested for the purpose of cleaning wellbore equipment, includes using brushes, scrapers or pigs. Such technique allows only removing most of the encrusted deposits in areas of the wellbore equipment which are easily accessible. However, brushes, scrapers or pigs are quite inefficient removing encrusted deposits in areas of the wellbore equipment accessible with difficulty or inaccessible. Consequently, it is often necessary to rework the well and replace one or several equipment of the completion string or the pipeline. Such tactics are, of course, both time-consuming and expensive.

Another method used for removing deposits consists in using an electrical discharge generating device which generates shock waves for creating an electrohydraulic effect. More precisely, in an existing solution, the electrical discharge generating device comprises electrodes in between which a high-voltage current is discharged. The discharge of said high-voltage current generates high-energy shock waves that transmit in the borehole toward a well completion equipment and/or a tubing and/or a casing, the wellbore wall and the subterranean formation.

When deposits are removed for an equipment or a wellbore wall using these methods, the deposits fall in the wellbore and may block said wellbore or equipment, therefore reducing or preventing the efficiency of oil recovery.

It is therefore an object of the present invention to provide a device and method for avoiding blocking a wellbore or a wellbore equipment with debris of deposits removed from the wellbore wall and/or a wellbore equipment.

SUMMARY OF THE INVENTION

To this end, the present invention concerns a collecting device for collecting debris of deposits while said deposits are being removed from a wellbore wall or an equipment arranged in a wellbore of a subterranean formation in order to improve the recovery of formation fluids and/or gases, said collecting device being configured for being attached to a cleaning device, said cleaning device being configured for removing deposits from a wellbore wall or a wellbore equipment arranged in a wellbore, said collecting device comprising:a deflector configured for deflecting falling debris of deposits while said deposits are being removed from said wellbore wall or said wellbore equipment, anda debris storing module connected to said deflector, said debris storing module being configured for collecting and storing debris deflected by said deflector.

The collecting device according to the invention allows collecting debris falling by gravity when deposits are removed (i.e. cleaned) from a wellbore wall and/or an equipment arranged in a wellbore. Thus, the collecting device allows thus avoiding debris to fall into the wellbore and block said wellbore and/or some wellbore equipment. The device according to the invention also allows extracting quickly deposits from a wellbore.

In a preferred embodiment, the deflector comprises a tubular portion comprising a first end connected to the debris storing module and a second end configured for collecting debris, said tubular portion being adapted to convey debris from said second end into the debris storing module through said first end.

According to an aspect of the invention, the deflector comprises a connecting shaft mounted on the second end of the tubular portion and configured for attaching the collecting device to a cleaning device.

Preferably, the deflector comprises at least one annular portion extending from the second end of the tubular portion.

In an embodiment, the at least one annular portion extends radially from the second end of the tubular portion.

Preferably, the at least one annular portion is flexible or pliable. This allows said at least one annular portion to abut against the surface to be cleaned, for example a casing or the wellbore wall, in order to avoid debris falling between said surface and the deflector into the wellbore.

In an embodiment, the deflector comprises three annular portions extending from the second end of the tubular portion.

Advantageously, the debris storing module comprises at least one tubular section configured for storing debris.

In an embodiment, the debris storing module comprises a plurality of tubular sections connected together along a same longitudinal axis.

Advantageously, each tubular section comprises a plurality of slots for evacuating liquids and/or gases from the inner part of the debris storing module.

In an embodiment, the collecting device further comprises an unloading plug connected to the debris storing module and being configured for switching between a first position in which the unloading plug prevents the debris stored in the debris storing module to leave said debris storing module and a second position in which the unloading plug allows the debris stored in the debris storing module to leave said debris storing module.

According to an aspect of the invention, the unloading plug comprises a trap door allowing the unloading plug to switch (i.e. move) between the first position and the second position (and vice-and-versa).

Advantageously, the trap door is removable to easily evacuate debris stored in the debris storing module.

In a preferred embodiment, the unloading plug comprises a tubular portion delimiting an internal opening, the trap door being configured to be moved between a blocking position, in which the trap door obstructs said internal opening, and a free position in which debris stored into the debris storing module may flow though said internal opening to unload the said debris storing module.

The invention also relates to an assembly for removing deposits from a wellbore wall or an equipment arranged in a wellbore of a subterranean formation and for collecting debris of said deposits, said assembly comprising a cleaning device configured for removing deposits from said wellbore wall or said equipment and a collecting device as previously presented, said collecting device being attached below said cleaning device in order to collect debris from deposits removed by the cleaning device.

According to an embodiment, the cleaning device and the collecting device extend along a same longitudinal axis in order to ease the use of the assembly in the wellbore, in particular to insert or withdraw the assembly from the wellbore.

The invention also relates to a method for collecting debris of deposits in a wellbore of a subterranean formation in order to improve the recovery of formation fluids and/or gases, said method comprising the steps of:removing deposits from a wellbore wall or an equipment arranged in a wellbore using a cleaning device,collecting falling debris of deposits, using a collecting device, as previously presented, attached below said cleaning device, while said deposits are being removed from said wellbore wall or said equipment by the cleaning device.

Advantageously, the collecting step comprises deflecting the debris so that said debris are received by the second end of the tubular portion of the deflector, conveying the debris from the second end of the deflector to the debris storage module through said tubular portion of the deflector and storing the debris into the debris storage module.

In an embodiment, the method further comprises a step of unloading the debris stored in the debris storage module.

In a preferred embodiment, the unloading step comprises opening or removing a trap door to open the unloading plug and unload the collecting device.

In the accompanying Figures, similar components or features, or both, may have the same or a similar reference label.

DETAILED DESCRIPTION

The Specification, which includes the Summary of Invention, Brief Description of the Drawings and the Detailed Description of the Preferred Embodiments, and the appended Claims refer to particular features (including process or method steps) of the invention. Those of skill in the art understand that the invention includes all possible combinations and uses of particular features described in the Specification. Those of skill in the art understand that the invention is not limited to or by the description of embodiments given in the Specification. The inventive subject matter is not restricted except only in the spirit of the Specification and appended Claims. Those of skill in the art also understand that the terminology used for describing particular embodiments does not limit the scope or breadth of the invention. In interpreting the Specification and appended Claims, all terms should be interpreted in the broadest possible manner consistent with the context of each term. All technical and scientific terms used in the Specification and appended Claims have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs unless defined otherwise. As used in the Specification and appended Claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly indicates otherwise. The verb “comprises” and its conjugated forms should be interpreted as referring to elements, components or steps in a non-exclusive manner. The referenced elements, components or steps may be present, utilized or combined with other elements, components or steps not expressly referenced. The verb “couple” and its conjugated forms means to complete any type of required junction, including electrical, mechanical or fluid, to form a singular object from two or more previously non-joined objects. If a first device couples to a second device, the connection can occur either directly or through a common connector. “Optionally” and its various forms means that the subsequently described event or circumstance may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur. “Operable” and its various forms means fit for its proper functioning and able to be used for its intended use. Spatial terms describe the relative position of an object or a group of objects relative to another object or group of objects. The spatial relationships apply along vertical and horizontal axes. Orientation and relational words including “uphole” and “downhole”; “above” and “below”; “up” and “down” and other like terms are for descriptive convenience and are not limiting unless otherwise indicated. Where the Specification or the appended Claims provide a range of values, it is understood that the interval encompasses each intervening value between the upper limit and the lower limit as well as the upper limit and the lower limit. The invention encompasses and bounds smaller ranges of the interval subject to any specific exclusion provided. Where the Specification and appended Claims reference a method comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously except where the context excludes that possibility.

The invention is described hereunder in reference to a well for producing formation fluids or gases such as e.g. oil. This does not limit the scope of the present invention which may be used with any type of formation.

FIG. 1shows a subterranean formation1comprising a treatment zone3. For example, such a treatment zone3may be made of rock. The treatment zone3may comprise a porous zone that constitutes a reservoir of hydrocarbons, such as oil or gas. The porous zone is accessible through a wellbore5extending from the surface through to the treatment zone3. The treatment zone3interfaces with the wellbore5at wellbore wall5A and extends radially from wellbore5.

In the example illustrated onFIG. 1, a wellbore equipment constituted of a metallic casing7is arranged in the wellbore5. This casing7may comprise perforations that allow creating some flow paths within the treatment zone3adjacent to the wellbore5. In another embodiment, the wellbore equipment could be for example a completion string equipment, a production tubing element or any type of equipment arranged in the wellbore5.

The wellbore5may be partially filled with a liquid, called “wellbore liquid”6that reaches a given wellbore liquid6level in such a manner that some parts of the casing7are arranged above said wellbore liquid level (i.e. in a dry volume of the wellbore5), whereas some parts of the casing7are arranged under the wellbore liquid6level. Alternatively, the wellbore5could be completely dry (i.e. deprived of liquid).

As illustrated onFIG. 1, an electrical discharge generating device10is arranged in the wellbore5. The electrical discharge generating device10is configured for generating electrical discharges that propagate shock waves11(FIG. 12), in particular for cleaning the casing7in order to improve the recovery of formation fluids and/or gases. In this illustrated example, the electrical discharge generating device10constitutes a source of electrohydraulic energy that can be arranged into the wellbore5near (i.e. next to) a part of the casing7that needs cleaning, in particular to remove deposits8stuck on or inside said casing7as shown onFIG. 12.

The electrical discharge generating device10is coupled to a wireline12which is operable to raise and lower said electrical discharge generating device10and to supply power from the surface to said electrical discharge generating device10. A voltage source (not shown) located external of the wellbore5and an electrical circuit (not shown) mounted within said wireline12allow to connect said voltage source to the electrical discharge generating device10. Electrical power is supplied by the low voltage source at a steady and relatively low power from the surface through the wireline12to the downhole electrical discharge generating device10.

In this exemplary embodiment, the electrical discharge generating device10has a substantially cylindrically shape and may comprises, as already described in U.S. Pat. No. 4,345,650 issued to Wesley or U.S. Pat. No. 6,227,293 issued to Huffman, incorporated hereby by reference, a power conversion unit, a power storage unit, a control unit and a discharge unit.

As illustrated onFIG. 1, an example of collecting device20according to the invention is attached to the bottom end10A of the electrical discharge generating device10in order to collect debris8A of deposits8that are removed from the casing7by said electrical discharge generating device10as shown onFIG. 12.

FIGS. 2 to 5show an exemplary embodiment of a collecting device20according to the invention. The collecting device20according to the invention allows collecting debris8A of deposits8while said deposits8are being removed from the casing7in order to improve the recovery of formation fluids and/or gases.

In this example, as illustrated onFIGS. 2 to 5, the collecting device20is of cylindrical shape having a circular section and comprises a plurality of elements. The collecting device20comprises a deflector210and a debris storing module220.

The deflector210is configured for deflecting falling debris8A of deposits8being removed from the casing7by the electrical discharge generating device10.

In reference toFIGS. 5 and 6, the deflector210comprises a tubular portion212comprising a first end212A, adapted to be connected to the debris storing module220via an adapter215, and a second end212B configured for collecting debris8A. The tubular portion212is adapted to convey debris8A from said second end212B through said first end212A into the debris storing module220.

The deflector210comprises a connecting shaft214extending from the second end212B of the tubular portion212and comprising a free end214A which is configured for attaching the collecting device20to the electrical discharge generating device10. For example, the free end214A of the connecting shaft214may comprise a hollow central portion which allow inserting a rod (not shown) protruding from the bottom end10A of the electrical discharge generating device10.

As illustrated onFIG. 6, the second end212B of the tubular portion212comprises an annular flange212B1from which extend three wings213and in which are formed three openings213A delimited between said wings213. The wings213allow reinforcing the deflector210and guiding debris8A toward openings213A into the tubular portion212.

In the example illustrated onFIG. 5, the deflector210comprises three annular portion216mounted around the annular flange212B1and the second end212B of the tubular portion212. The annular portion216aims the debris8A removed from the casing7into the inner flow path of openings213A of the deflector210. The annular portions216are made with a pliable or flexible material such that contact is maintained between the deflector210and the wellbore wall5A or casing7(or deposits8—seeFIG. 12) so that all material is directed into the openings213A and collected by the collecting device20.

As illustrated onFIGS. 2 to 5, the debris storing module220comprises three tubular sections, namely a first tubular section220A, a second tubular section220B and a third tubular section220C connected together along a same longitudinal axis X (FIGS. 2 and 5). In another embodiment, the debris storing module220could comprise more or less than three tubular sections. As illustrated onFIG. 5, each of the first tubular section220A, the second tubular section220B and the third tubular section220C comprises a plurality of slots2200which allow liquids that enter into the debris storing module220via the deflector210to be evacuated. More precisely, the dimensions of the slots2200are adapted to allow liquids that enter into the debris storing module220via the deflector210to be evacuated while debris8A stored inside the first tubular section220A, second tubular section220B and/or third tubular section220C remain inside the debris storing module220.

The debris storing module220is configured to be connected to the deflector210for storing debris8A deflected by said deflector210. To this end, the collecting device20comprises an adapter215, shown onFIG. 7, which allows connecting the first end212A of the tubular portion212of the deflector210to an end220A1of the first tubular section220A as shown onFIG. 5. In this example, the adapter215comprises a first end215A of tubular shape, adapted to receive the first end212A of the tubular portion212of the deflector210, for example by clipping or press-fitting, and a second end215B, also of tubular shape but of a smaller diameter, and which is adapted to be inserted into the corresponding end220A1of the first tubular section220A. In order to fix the end220A1of the first tubular section220A to the second end215B of the adapter215, the adapter215comprises a plurality of pins215C (FIG. 7) which are configured to fit into corresponding plurality of holes (not visible) forms onto the end220A1of the first tubular section220A. The adapter215also comprise two grooved portions215D formed on opposite parts of the side wall of the adapter215for carrying the collecting device20with a lifting tool such as e.g. a crane or a forklift.

As shown onFIG. 5, the collecting device20also comprises a first section connector221-1and a second section connector221-2. The first section connector221-1allows connecting the first tubular section220A and the second tubular section220B. The second section connector221-2allows connecting the second tubular section220B and the third tubular section220C.

As illustrated onFIG. 8, a section connector221, such as the first section connector221-1and the second section connector221-2, has a tubular shape and comprises two ends221A,221B adapted to be inserted into a corresponding end of the first tubular section220A, the second tubular section220B and the third tubular section220C. The section connector221is fixed to the first tubular section220A, second tubular section220B and third tubular section220C by clipping using pins221C protruding from ends221A,221B of said section connector221.

In this preferred embodiment, the collecting device20further comprises an unloading plug230that allows evacuating easily the debris8A stored in the debris storage module220, in particular when the debris storage module220is full and/or when the collecting device20is pulled out of the wellbore5.

To this end, the unloading plug230is connected to the debris storing module220and is configured to be placed in a first configuration, in which the unloading plug230prevents the debris8A stored in the debris storing module220to leave said debris storing module220, and a second configuration, in which the unloading plug230allows the debris8A stored in the debris storing module220to leave said debris storing module220.

In reference toFIGS. 9 to 11, the unloading plug230comprises a connecting end231A, a tubular portion231delimiting an internal opening232, a free end231B and a trap door235. In the example illustrated onFIG. 9, the connecting end231A comprises pins233protruding from said connecting end231A, which are configured to engage with holes formed in the end220C1of the third tubular section220C in order to fix the unloading plug230on the third tubular section220C by clipping. As shown onFIG. 11, the tubular portion231comprises a slot234formed in the side wall of said tubular portion231, which is configured for receiving the trap door235.

The trap door235, illustrated onFIG. 10, may be mounted in a removable manner in the slot234of the tubular portion231. In this exemplary embodiment, the trap door235is a one-piece element comprising a plate portion235A and a connection portion235B extending perpendicularly from said plate portion235A and which is configured for receiving a screw236(FIG. 11) allowing fixing the trap door235on the tubular portion231.

Thus, when the trap door235is mounted in the slot234of the tubular portion231, in a position called blocking position, the trap door235obstruct entirely the internal opening232of the tubular portion231to prevent the debris8A from leaving the debris storing module220(first configuration of the unloading plug230).

When the trap door235is removed from the slot234of the tubular portion231(called free position), the internal opening232of the tubular portion231allows debris8A to leave the debris storing module220to empty said debris storing module220from debris8A (second configuration of the unloading plug230).

An exemplary embodiment of the method according to the invention will now be described in reference toFIG. 13.

In a step S1, the connecting shaft214of the collecting device20is first attached to the bottom end10A of the electrical discharge generating device10, extending along the same longitudinal axis X, to form an assembly300which is then lowered inside the casing7down the wellbore5using the wireline12.

When the electrical discharge generating device10is arranged near a portion of the casing7which needs to be cleaned from deposits8, the electrical discharge generating device10is activated to generate electrical discharges that propagate shock waves11to remove deposits8from the casing7internal wall in a step S2.

When debris8A of deposits8being removed fall under the effect of gravity, the deflector210, and in particular the annular portions216, deflect said debris8A, in a step S3, toward the openings213A so that said debris8A go through the tubular portion212up to debris storing module220where the debris8A are stored in a step S4.

The assembly300formed of the electrical discharge generating device10and the collecting device20may then be moved toward another portion of the casing7that needs to be cleaned from deposits8.

When the debris storing module220is full or when the casing7is clean from deposits8or when the debris storing module220is full, the assembly300may be pulled out of the wellbore5and the trap door235may be open, by removing screw236, to unload debris8A stored in the debris storing module220in a step S5.

In the exemplary embodiment described here above, the cleaning device is an electrical discharge generating device. However, in another embodiment, the cleaning device could be any type of device adapted to remove the deposits for a wellbore wall5A or an equipment arranged in a wellbore5.

The device and method according to the invention allow therefore efficiently, rapidly and easily collect deposits that are removed from a wellbore wall and/or a wellbore equipment.