NO20181388A1

NO20181388A1 - A method of depositing a sealant material at a downhole location

Info

Publication number: NO20181388A1
Application number: NO20181388A
Authority: NO
Inventors: Morten Lerbrekk
Original assignee: Tyrfing Innovation As
Priority date: 2018-10-29
Filing date: 2018-10-29
Publication date: 2019-01-14

Abstract

A method of depositing a sealant material at a downhole location, by (a) forming one or more openings in a section of a first downhole tubular; (b) at least partially cracking a frangible material in a portion between said first and second tubulars, said first tubular arranged inside said second tubular, imparting one or more mechanical impacts to at least a portion of said material until cracks or fissures form in the material, to form a space between said tubulars; and (c) filling said sealant material into said space.

Description

A method of depositing a sealant material at a downhole location

Field of the invention

The invention concerns a method of depositing a sealant material at a downhole location.

Background of the invention

Hydrocarbon fluids such as oil and natural gas are obtained from subterranean geologic formations, referred to as reservoirs, by drilling wells that penetrate the reservoirs. Hydrocarbon wells for the exploitation of oil and/or gas from a reservoir normally consist of an upper and outer conductor, which forms the base of the well, an upper casing arranged into and in extension of the conductor, and further down in the well more casings which are arranged into and overlaps the above casing. A production tubing string is located in the middle of the well for transporting petroleum from the bottom of the well to the earth<'>s surface or – in the case of a subsea well – to the seabed. Annuli will then be formed between the different casings.

The use of cementing operations in the extraction of hydrocarbons from subterranean reservoirs is well known. In that context, cementing operations usually mean the preparation and pumping, from an uphole location, cement into one or more zones in a subterranean bore. Cement is widely used as a barrier substance in subterranean wells, to form a seal between nested well casings and between the outer well casing and the surrounding formation (as a part of the well completion), and as a plugging substance inside liners or/and in annuli between downhole tubulars (e.g. when the well is to be plugged and abandoned).

In plugging operations, it is important to place the plugging substance (e.g. concrete, resins, epoxy) as accurately as possible in designated sections in the annuli between downhole tubulars (or between a tubular and the surrounding formation). The plugging substance is normally introduced into the well via production tubing, and is placed in the adjacent annulus through holes or milled-out sections of the liner or casing. The prior art includes a number of tools for forming holes in a tubular, either by drilling, cutting or milling through the tubular wall.

Figure 1 is a schematic illustration of a wellbore W in which a liner (or outer casing) 4 has been installed against a subterranean formation S (cement between outer casing and formation not shown). Nested within the outer casing is an inner casing 5, thus forming an annulus A between the two casings. The annulus is generally filled with cement E, which may have been placed there during a well completion procedure. Figure 1 illustrates a milled-out section M and a drilled section D having a plurality of holes. It should be understood that figure 1 merely is a schematic illustration, and that the wellbore may contain only milled-out sections or drilled sections. In the milled-out section M, a window V has been formed in the inner casing 5 wall, and in the drilled section D, a number of holes H have been formed in the inner casing 5 wall.

However, the cement E frequently contains voids, cavities, cracks and fissures, schematically illustrated in figure 1 by the reference sign C. Therefore, merely filling a sealant through the window V or holes H, may be inadequate in a plugging procedure, as the barrier integrity still is compromised by the voids C. Also, the inner casing is frequently poorly centralized within the outer casing, causing the distance between the casing walls to vary considerably around the casing circumferences. Such eccentric inner casing may be caused by an inadequate completion procedure or by environmental forces during the operation of the well. This eccentricity precludes traditional reaming or milling as a means to remove annular cement, as the milling tools might damage the outer casing wall where the wall-to-wall distance is the shorter and fail to remove the cement where the distance is the greater. It is therefore a need for an apparatus to remove all concrete adjacent to a milled window or drilled hole, prior to injecting the sealant.

The prior art includes WO 2007/010402 A1, which describes methods and tools for i.a. fracturing a cement sheath in a localized zone around a casing. A fracturing force is applied to the cement to generate fractures in the set cement. A controlled load can be applied through the casing and/or sealing plugs for inducing cracks in the cement by means of one or more force or pressure transmitting elements. A contact element can vary in shape, number and position to optimise the process. In one embodiment, the tool applying the force can could be repositioned in the casing and the process repeated or a device could be configured as an (vertical) array of such elements. An alternative to apply controlled pressure is to use explosive devices to increase the hydraulic pressure inside the casing to shatter the cement in the annulus or shaped charges which create a local pressure wave. The explosives may be replaced by electromagnetically operated hammer deployed on a wireline tool. The hammer is placed close to the casing, and is activated, ringing on the casing, the shock waves causing the cement to crack in a known manner. Controlled vibrational energy can also be used to crack the cement. Using a wireline deployed device, a ring can be expanded from a small collar and clamped to the casing. A shaker device of a known or optimized frequency can then excite the casing with sufficient high frequency energy to cause radial cracks. The frequency and magnitude of the vibration can be tailored to the depth and ambient pressure and temperature to optimize the size of the cracks that are formed.

Summary of the invention

The invention is set forth and characterized in the main claims, while the dependent claims describe other characteristics of the invention.

It is thus provided a one-trip downhole tool, configured to be arranged at a location in a first tubular characterized by:

- a tool having a plurality of drilling tools or milling tools configured for forming holes in the first tubular; and

- an apparatus for at least partially cracking a frangible material in a portion between said first tubular and a second tubular, said first tubular arranged inside said second tubular, wherein said apparatus comprises one or more impact devices arranged and configured to impart one or more mechanical impacts to said material.

The tool may comprise a plurality of drilling tools or milling tools arranged in the same plane, substantially perpendicular to the downhole tools longitudinal axis. The drilling tools or milling tools may be arranged in multiple planes substantially perpendicular to the longitudinal axis, and each plane may comprise two or more drilling tools or milling tools. At least one impact device may comprise a vibration generator.

In one embodiment, the apparatus further comprises a plurality of impact devices arranged in the same plane, substantially perpendicular to the downhole tool longitudinal axis. Impact devices may in one embodiment be arranged in multiple planes substantially perpendicular to the longitudinal axis, and each plane may comprise two or more impact devices. The distance between the drilling tools or milling tools planes is identical to the distance between the crushing tool planes. The impact devices may be operated independently of each other.

The tool may in one embodiment comprise a manifold housing comprising movable abutment means which may be extended to support the apparatus against a tubular wall, or the abutment means may be arranged on the apparatus housing. The apparatus housing and flow manifold housing may be integrated into one housing. In one embodiment, the drilling tools or milling tools comprise bores configured for injecting a sealant material from a manifold.

It is also provided a method of of depositing a sealant material at a downhole location, characterized by the steps of:

a) forming one or more openings in a section of a first downhole tubular;

b) at least partially cracking a frangible material in a portion between said first tubular and a second tubular, said first tubular arranged inside said second tubular, imparting one or more mechanical impacts to at least a portion of said material until cracks or fissures form in the material, whereby a space is formed between said tubulars; and c) filling said sealant material into said space. Said steps a, b, c may be performed in a single downhole trip. The one or more mechanical impacts may be vibrations.

In one embodiment, step b is performed by one or more impact devices according to the invention. The material may be concrete or similar frangible material. In one embodiment, the apparatus is arranged inside the first tubular and at least a portion of the at least one impact device is extended through at least one opening in the first tubular wall.

The invention provides an efficient tool and apparatus for breaking down annular cement or other frangible material, without causing any damage to surrounding tubulars. The invention is particularly advantageous if the inner casing and outer casing are not concentric, i.e. when the inner casing is close to or bearing against the liner or casing within which it is nested. Instead of using a traditional reaming or milling to remove annular cement, which might damage the outer casing wall, the mechanical impact forces provided by the invented crushing apparatus will break down the concrete without damaging the casing (steel) wall.

Brief description of the drawings

These and other characteristics of the invention will become clear from the following description of embodiments, given as non-restrictive examples, with reference to the attached schematic drawings, wherein:

Figure 1 is a sectional side view of an embodiment of the invented crushing apparatus, placed in a wellbore;

Figure 2 corresponds to figure 1, and illustrates the invented crushing apparatus in a first mode of operation in the wellbore;

Figure 3 corresponds to figure 1, and illustrates the invented crushing apparatus in a second mode of operation in the wellbore;

Figure 4 illustrates a state of the wellbore following the operation of the invented crushing apparatus, and a tool for filling a barrier substance into the wellbore.

Figure 5 illustrates the invented crushing apparatus connected to a tool for filling a barrier substance into the wellbore;

Figure 6 is a sectional side view of an embodiment of the invented crushing apparatus; the crushing tools shown in retracted positions;

Figures 7a, 7b and 7c are cross-sectional drawings of the invented crushing apparatus, illustrating various crushing tool configurations; the crushing tools shown in extended positions; and

Figure 8 is an enlargement of the region marked “G” in figure 3.

Detailed description of a preferential embodiment

The following description will use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, ”upper”, “lower”, “above”, “below”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are used for the reader’s convenience only and shall not be limiting.

Figure 6 is a schematic drawing of an embodiment of the crushing apparatus 50. Here, the crushing apparatus comprises a housing 51 connected to a flow manifold housing 52. The shapes of the apparatus housing and flow manifold housing are preferably cylindrical having a longitudinal axis of symmetry Y-Y. The housings are dimensioned to fit inside the tubular in which they are intended to be used and formed of a material suited for the environment to which they will be exposed. A drillpipe 3 is connected to the flow manifold housing 52 and configured and dimensioned to extend to an uphole assembly (not shown). The manifold housing comprises movable pads (or slips, or similar abutment means) 53 which may be extended to support the apparatus against a tubular wall. Figure 6 shows the pads 53 in a retracted position. Similar pads (not shown) may additionally or alternatively be arranged elsewhere on the apparatus housing 51. It should be understood that the apparatus housing and flow manifold housing may be integrated into one housing.

Referring additionally to figure 7, the crushing apparatus 50 comprises a plurality of crushing tools 54. Several crushing tools 54 are arranged in the same plane (perpendicular to the tool longitudinal axis Y-Y). In the embodiment illustrated in figure 6 and figure 7a, four crushing tools 54 are arranged at regular intervals in three different planes P1, P2, P3. It should be understood that the invented apparatus may comprise a plurality of crushing tools in fewer or more planes. That is, when assembling the apparatus for a given application, the number of planes (P1to Pn), and hence the length of the apparatus body 51, is determined based on the given requirements.

Figure 7b illustrates an alternative embodiment, in which two crushing tools 54 are arranged in the same plane. Figure 7c illustrates yet another embodiment, in which three crushing tools 54 are arranged in the same plane. A common feature of these embodiments is that the crushing tools 54 are arranged at regular intervals around the apparatus housing 51 periphery and hence provide for a self-centralizing apparatus, without the need for anchors, slips, skids, extending arms, and the like. The invention shall not be limited to these configurations, however, but it should be understood that a crushing apparatus may comprise only one crushing tool 54.

It should be noted that the crushing tools 54 may be extended and retracted (out of and into the apparatus housing 51) independently of each other. Also, the crushing tools 54 may be operated independently of each other. Figure 8 indicates schematically an actuator device 56 for extending and retracting the crushing tool 54 out of and into the housing 51. The actuator device is also used to advance the crushing tool towards the cement E as the cement is breaking up. Required control means, and sensing means (e.g. position sensors, proximity sensors) are not illustrated, as such means are well known in the art. The apparatus may also have a radial dimension such that the distance between the apparatus housing and the casing wall is small. A typical apparatus radial dimension (OD) is 1⁄4” less than the casing inner diameter. This gives a 1/8” clearance on all sides. The invention shall not, however, be limited to such dimensions.

The flow manifold housing 52 may hold a central hydraulic motor (not shown) connected via an axial drive shaft and required gears (not shown) to each of the crushing tools 54. The hydraulic motor is preferably powered by fluids, for example pressurized drill fluids, water or other fluids, supplied via the drillpipe 3 in a manner known in the art. It should be understood that the fluids may be supplied via coiled tubing or other pipe or tubing. Although not illustrated, it should be understood that the crushing tools 54 optionally may be powered by other means, such as electric motors. Alternatively, each crushing tool 54 may be driven by one or more hydraulic motor, in which case hydraulic fluid is supplied from the manifold via hydraulic piping (not shown).

Figure 1 shows an embodiment of the invented crushing apparatus 50 in a wellbore W. In the wellbore, a liner (or outer casing) 4 has been installed against a subterranean formation S (cement between outer casing and formation not shown). Nested within the outer casing is an inner casing 5, thus forming an annulus A between the two casings. The annulus is generally filled with cement E, which was placed there during the well completion procedure. The crushing apparatus 50 is suspended by a non-rotating drillpipe 3 (or other suitable suspension means). It should be understood that the crushing apparatus 50 is stationary with respect to the casing 5 during the operation of the crushing tools 54. The movable pads 53 may be extended to abutment against the casing wall in order to further immobilize the crushing apparatus 50 during the operation of the crushing tools 54. Figure 1 shows these pads in a retracted state.

In figure 1, the crushing apparatus 50 has been positioned adjacent a milled-out section M, where a section of the inner casing 5 wall has been removed (by another tool and process, not shown in figure 1), and a window V has been formed in the annular cement E in the portion B between the inner and outer casings. In figure 2, some of the crushing tools 54 (the lower set of tool are not in operation) have been advanced (extended) into abutment with a portion of the cement E and operated to impart one or more impacts (illustrated by double-headed arrow in figure 8) to the cement E. The crushing tools 54 are operated so as to transmit one or more of percussive impulses into the cement E. The one or more percussions generate fissures F in the cement, causing the affected cement to crack and collapse and a “cleaned” window V’ (see figure 3) will extend all the way between the inner and outer casings.

It should be understood that the part of the crushing tool 54 which is designed to impact the cement may have a blunt shape, as the objective is not to drill into the cement but rather to create cracks, crackles and fissures F in the cement (or other frangible material). To this end, the crushing tool 54 may also be designed to operate at a comparably low impact frequency and high impact force, rather than high impact frequency and low impact force. The crushing tool may for example be a hammer tool, configured to impart one or more of percussive impulses.

The mechanical impact force imparted to the cement by the crushing tool 54 is generated by an impact device 57, schematically illustrated in figure 8. Such device may be any means known in the art, such as mechanical vibrator, for example powered by hydraulics (e.g. well fluids) or by a rotating shaft having a plurality of cams, driving reciprocating pistons. The impact device may thus be controlled (automatically or manually, and/or based on sensor feedback) to generate one or more of percussive movements in the crushing tool 54, and percussion frequency and percussive force may be controlled accordingly.

Figure 3 illustrates another application of the crushing apparatus 50, in which the crushing apparatus 50 has been positioned adjacent a drilled section D, where a plurality of holes in the inner casing 5 wall have been drilled (by another tool and process, not shown in figure 3), and a corresponding number of holes H have been formed in the annular cement E. In figure 3, the crushing tools 54 have been advanced (extended) into respective holes H and into abutment with a portion of the cement E, and operated to impart one or more of percussive impulses (e.g. vibrations) to the cement E. As explained above with reference to figure 2, the crushing tools 54 are operated so as to generate fissures F in the cement, whereby the affected cement eventually will crack and collapse and a “cleaned” space K (see figure 4) will extend all the way between the inner and outer casings.

Thus, by operating the crushing tools 54 in the manner described above, the cavities C in the vicinity of the affected sections are removed, and the annular region is cleaned and prepared for injection of sealant material in order to form a reliable barrier plug. This is illustrated in figure 4, where a sealant material (e.g. cement, resin, epoxy) T has been placed on a plug foundation 55 and also in the cleaned window K, and thus ensuring a reliable barrier.

Figure 4 also illustrates an embodiment of a tool 1 in operation in a wellbore W to fill sealant T (indicated by curved arrows in figure 4) into the casing. In the illustrated embodiment, the tool 1 is conveyed inside the inner casing 5 on a drillpipe 3 extending from an uphole assembly (not shown). The tool comprises a tool housing 2, in which a plurality of filling nozzles 91 are arranged. The tool 1 is connected to a flow manifold housing 10’, for example corresponding to the a flow manifold housing 52 described above. A drillpipe 3 is connected to the flow manifold housing 10’ and configured and dimensioned to extend to an uphole assembly (not shown), and supply the sealant material to the filling nozzles 91. The manifold housing 10’ comprises movable pads (or slips, or similar abutment means) 14 which may be extended to support the apparatus against a tubular wall. Figure 4 shows the pads 14 in a retracted position. It should be understood that the tool housing 2 and flow manifold housing 10’ may be integrated into one housing.

Figure 5 illustrates a configuration in which the crushing apparatus 50 is connected to a tool 1 having a plurality of penetration units 9, for example drilling tools or milling tools capable of forming a hole in the inner casing wall in a controlled manned, without damaging other parts of the wall. The tool 1 may be a unitary body or be made up of several individual tool modules. In the illustrated embodiment, the penetration units 9 are arranged in the same plane (perpendicular to the tool longitudinal axis Y-Y), similarly to the configuration of the crushing tool 54 as described above. In the embodiment illustrated in figure 5, four (only three shown; the fourth unit is hidden) penetration units 9 are arranged, at regular intervals, in three different planes Q1, Q2, Q3. It should be understood that the tool 1 may comprise a plurality of penetration units 9 in fewer or more planes. That is, when assembling the tool for a given application, the number of planes (Q1to Qn), and hence the length of the tool, is determined based on the given requirements (e.g. the length of casing to be perforated). The tool is configured such that penetration units 9 within each plane may be operated independently of each other.

The penetration units 9 may be extended and retracted (out of and into the tool housing) independently of each other. Required control means and sensing means are not illustrated, as such means are known in the art. During operation, the tool 1 is stationary with respect to the casing wall, and is suspended by the crushing tool 54 which is suspended by a non-rotating drillpipe 3, or other suitable suspension means. Although not illustrated in figure 5, movable pads or slips may be fitted to the tool in order to immobilize the tool during the operation of the penetration units. The penetration units 9 may be powered by one or more hydraulic motors (not shown), powered by e.g. pressurized drill fluids, water or other fluids, supplied via the drillpipe 3 in a manner known in the art. It should be understood that the fluids may be supplied via coiled tubing or other pipe or tubing. Although not illustrated, it should be understood that the penetration unit optionally may be powered by other means, such as electric motors.

In operation, the tool 1 may be activated such that the penetration units 9 form multiple holes H in the inner casing wall, thus providing access to the annulus A (see figure 1). The penetration units 9 are only extended sufficiently far to penetrate the inner casing wall, but not as far as to the outer casing 4.

Figure 5 illustrates a configuration in which a sealant material (e.g. cement, resin, epoxy) is filled into the cleaned space K generated by the crushing apparatus 50 as described above. In this operation, the sealant material is injected from a manifold and through bores (not shown) in the penetration units 9 into the annular space K.

It should be understood that the tool 1 and penetration units 9 may be used to form the holes H described above with reference to figure 1 and figure 3. The combination of the crushing apparatus 50 and tool 1 may therefore be used to – in one trip – perforate the inner casing to make holes H in the casing wall (using the tool 1), crack cement or other frangible material between the holes H and the outer casing (using the crushing apparatus 50), and fill or inject a sealant material into the cleaned space K (using the tool 1). Therefore, the distance between the penetration unit planes (Q1to Qn) is preferably identical with the distance between the crushing tool planes (P1to Pn).

Although the invention has been described with reference to a well plugging procedure, it should not be limited to such procedure.

Although the invention has been described with reference to an inner casing and an outer casing, it should be understood that the invention is equally applicable to intermediate casings and liners and between an outer casing an a subterranean formation.

Claims

1. A method of depositing a sealant material (T) at a downhole location, characterized by the steps of:

a) forming one or more openings (V, C) in a section (M, D) of a first downhole tubular (5);

b) at least partially cracking a frangible material (E) in a portion (B) between said first tubular (5) and a second tubular (4), said first tubular (5) arranged inside said second tubular (4), imparting one or more mechanical impacts to at least a portion of said material until cracks or fissures (F) form in the material (E), whereby a space (K) is formed between said tubulars; and

c) filling said sealant material (T) into said space (K).

2. The method of claim 1, wherein said steps a, b, c are performed in a single downhole trip.

3. The method of any one of claims 1-2, wherein the one or more mechanical impacts are vibrations.

4. The method of any one of claims 1-3, wherein step b is performed by one or more impact devices (54) of the a downhole tool, configured to be arranged at a location in a first tubular (5) and comprising:

- a tool (1) having a plurality of drilling tools or milling tools (9) configured for forming holes in the first tubular (5); and

- an apparatus (50) for at least partially cracking a frangible material (E) in a portion (B) between said first tubular (5) and a second tubular (4), said first tubular (5) arranged inside said second tubular (4), wherein said apparatus comprises one or more impact devices (54) arranged and configured to impart one or more mechanical impacts to said material.

5. The method of any one of claims 1-4, wherein the material is concrete or similar frangible material.