Abstract:
A system for forming a seal in a wellbore includes a slurry source, an expandable inflatable element, and a filter. The slurry may contain particles entrained in a fluid carrier. The filter may be configured to separate the particles from the fluid carrier to form a relatively solid body in the inflatable element. The system may include a pump configured to pressurize the slurry. The pump may flow the slurry from a surface location or from a location in the wellbore. The source may be a bailer configured to receive a pressurized fluid from the pump. The system may use a hydraulic disconnect that conveys the slurry from the source to the inflatable element. The hydraulic disconnect may be configured to disconnect the source from the inflatable element upon a predetermined pressure being reached in the inflatable element. The particles may be formed of a compressible material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    1. Field of the Disclosure 
         [0003]    The present invention relates to the selective isolation of wellbores and boreholes drilled in an earthen formation. 
         [0004]    2. Description of the Related Art 
         [0005]    Hydrocarbons such as oil and gas are recovered from a subterranean formation using a wellbore drilled into the formation. During drilling of the wellbore and subsequent completion activities, it may be desirable to isolate one or more sections of the wellbore. Conventionally, packers and bridge plugs may be employed in such circumstances. For instance, an annular space surrounding a wellbore tubular may be sealed by a packer. Traditionally, a packer may use a solid ring of rubber or other elastomer that is compressed against an interior well surface to seal off the annulus. A packer may also use a bladder that is inflated using a liquid or a gas. Bridge plugs are well appliances for obstructing the flow continuity of an entire bore and may also often use solid sealing elements as well as pressurized liquids and gases. Inflatable wellbore sealing devices, such as well packers and bridge plugs, may exhibit a loss in sealing effectiveness over the course of time. This may be due to leakage of the pressurized media used to expand the sealing device or other causes such as mechanical fatigue. 
         [0006]    The present disclosure addresses the need for wellbore sealing devices that may retain their sealing capacity over a greater length of time, as well as and other needs of the prior art. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    In aspects, the present disclosure provides tools and devices that provide dependable zonal isolation for long term installations in wellbore and boreholes. The sealing devices may utilize solid or semi-solid mass that provide the inflation pressure that are generally insensitive to downhole conditions such as temperature changes, and less susceptible to leakage or mechanical creep of the inflated structure. In aspects, the sealing devices of the present disclosure may be expanded to a diameter that may be two to three times greater than the diameter of the bore of the wellbore tubular through which the sealing device is conveyed into the well. Thus, the sealing device may be utilized in a variety of situations to provide selective zonal isolation in a borehole below a wellbore tubular has a diameter that is two to three time greater than the wellbore tubular. 
         [0008]    In aspects, the present disclosure provides a system for forming a seal in a wellbore. The system may include a source containing a slurry having particles entrained in a carrier; an expandable inflatable element having an inlet for receiving the slurry; and a filter positioned at an outlet for the inflatable element. The filter may be configured to separate the particles from the fluid carrier. In one arrangement, the system may include a pump configured to pressurize the slurry. The pump may be configured to flow the slurry from a surface location or from a location in the wellbore. In certain configurations, the source may be a bailer configured to receive a pressurized fluid from the pump. In further arrangements, the system may use a hydraulic disconnect that conveys the slurry from the source to the inflatable element. The hydraulic disconnect may be configured to disconnect the source from the inflatable element upon a predetermined pressure being reached in the inflatable element. In embodiments, the particles may be formed of a compressible material. 
         [0009]    In aspects, the present disclosure provides a method for forming a seal in a wellbore by expanding an inflatable element into sealing engagement with a wellbore structure using a mass of compressible particles. In one embodiment, the method may include positioning a sealing device having an inflatable element in the wellbore; flowing a slurry into the inflatable element, the slurry having particles entrained in a fluid carrier; and flowing the fluid carrier out of the inflatable element while retaining the particles in the inflatable element. The method may include pressurizing the particles retained in the inflatable element. In certain arrangements, the method may include flowing the slurry from a surface location. In other arrangements, the method may include flowing the slurry from a downhole location, such as from a bailer. The method may further utilize terminating the flow of slurry into the inflatable element upon a predetermined pressure being reached in the inflatable element. 
         [0010]    It should be understood that examples of the more illustrative features of the disclosure have been summarized rather broadly in order that detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the disclosure that will be described hereinafter and which will form the subject of the claims appended hereto. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The advantages and further aspects of the disclosure will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein: 
           [0012]      FIG. 1  is a schematic elevation view of an exemplary production assembly that incorporates sealing devices in accordance with one embodiment of the present disclosure; 
           [0013]      FIGS. 2A-2B  are schematic cross-sectional views of an exemplary sealing device made in accordance with one embodiment of the present disclosure; and 
           [0014]      FIG. 3  illustrates in functional block diagram form one embodiment for a deployment system for a sealing device made in accordance with one embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    The present disclosure relates to devices and methods for controlling production of a hydrocarbon producing well. The present disclosure is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present disclosure with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. Further, while embodiments may be described as having one or more features or a combination of two or more features, such a feature or a combination of features should not be construed as essential unless expressly stated as essential. 
         [0016]    Referring initially to  FIG. 1 , there is shown an exemplary wellbore  10  that has been drilled through the earth  12  and into a formation  14  from which it is desired to produce hydrocarbons. The wellbore  10  is cased by metal casing  16 , as is known in the art, and a number of perforations  18  penetrate and extend into the formation  14  so that production fluids may flow from the formation  14  into the wellbore  10 . The wellbore  10  has a late-stage production assembly, generally indicated at  20 , disposed therein by a tubing string  22  that extends downwardly from a wellhead  24  at the surface  26  of the wellbore  10 . One or packers  28  or bridge plugs  30  may be utilized to selectively seal off or isolate one or more zones or regions of the well  10 . In aspects, an inflatable sealing element  32  for providing zonal isolation in the well  10  may utilize inflation pressure that is substantially insensitive to temperature changes, leakage, and mechanical creep of the inflated structure. In further aspects, the sealing elements  32  may have relatively high expansion capability. That is, the sealing elements  32 , which are conveyed through a bore of the tubing string  22 , may be expanded to a size two to three times greater than a diameter of the bore of the tubing string  22 . Exemplary sealing devices  32  are described below. 
         [0017]    Referring now to  FIGS. 2A-2B , there is illustrated one embodiment of a sealing system  60  made in accordance with the present disclosure. The sealing system  60  may include an inflatable element  62  that can be inflated by a slurry  64  formed of particles  66  having a relatively low elastic modulus. For example, the particles  66 , upon being compressed, can store energy that can be used to expand the inflatable element  62  into a compressive sealing engagement with an adjacent object, such as a surface of a casing  40 . That is, the relatively low elastic modulus of the material allows the particles  66  to behave much like a compressed spring that can apply a biasing force. One exemplary, but not limiting, material for the particles  66  includes elastomers such as nitriles. The slurry may also include a fluid carrier  67  such as water, oil, brine, epoxies or other fluids formulated to convey entrained solids or semi-solids. During use, the particles  66  may be compressed until they are compacted into a relatively low-permeable mass that applies a sealing force via the inflatable element  62  to an adjacent surface. 
         [0018]    The sealing system  60  includes a flow control device  68  for selectively flowing the slurry  64  into the inflatable element  62  and a filter element  70  that allows only the fluid carrier  67  of the slurry  64  to exit the inflatable element  62 . The inflatable element  62  may be a unitary body or a multi-layered body. For example, in embodiments, the inflatable element  62  may include a first layer  62   a  that can be configured to retain a pressurized fluid, a second layer  62   b  that provides strength, and a third layer  62   c  that provides sealing capability. In embodiments, the first layer  62   a  may be formed of a relatively impermeable material such as rubber, the second layer  62   b  may be formed of metal ribs, such as stainless steel ribs, and the third layer  62   c  may be formed of a material such a rubber. The flow control device  68  may be a poppet valve, sliding sleeve valve or other suitable valve. In one suitable arrangement, the valve may be actuated to an open position upon application of a suitable pressure differential and closed when the pressure differential is removed. The filter element  70  may be formed as a perforated mandrel having holes or passages. The holes or passages may be sized to allow passage of only the fluid carrier  67  out of the inflatable element  62 . Additionally, the sealing system  60  may include devices such as a cross-over sub  72  that directs fluid flow from a bore  74  of the inner tubular  75  to an annulus  76 . Thus, the flow control device  68  controls flow into an inlet of the inflatable element  62  and the filter element  70  controls flow out of an outlet of the inflatable element  62 . It should be understood that the illustrated arrangement is only exemplary. For instance, instead of being positioned in a center of the inflatable element  62 , the filter element  70  may be positioned at an axial end of the inflatable element  62 . 
         [0019]    It should be appreciated that the components of the slurry  64  can be formed of numerous materials. For example, the particles  66  of the slurry  64  can be formed of two or more materials, each of which has a different material property. For instance, the particles  66  may be a mixture of low elastic modulus material, such as elastomers, and relatively hard or incompressible materials such as ceramics. Moreover, the particles may be all of the same shape or different shapes and of the same size or different sizes. The particles  66  may also be ground or pelletized. In still other variants, the particles  66  and fluid carrier  67  may be formulated to interact in a specified manner. For example, the particles  66  may be formed of materials that expand when the fluid carrier  67  is removed. Moreover, the particles  66  may be formulated to expand in response to an applied heat, such as that present in a downhole environment. In still other embodiments, the particles  66  may be formulated to form a generally solid body upon application of a suitable stimulus such as pressure, heat, or chemical agent. That is, instead of a body or mass formed of discrete elements, the particle  66  blend to form a substantially solid body. Thus, it should be appreciated that the sealing force applied by the particles  66  does not necessarily have to be generated by compression. Rather, chemical interactions, molecular interactions, applied heat, or other mechanisms may be used to activate the particles  66  to expand the inflatable element  62  and generate a sealing force. 
         [0020]    Numerous arrangements may be utilized to deploy the sealing device  60  into a wellbore. Illustrative arrangements are discussed below. 
         [0021]    Referring now to  FIG. 3 , there is schematically illustrated one suitable system  80  for deploying the sealing device  60 . The deployment system may include a setting tool  82 , a bailer  84  and a hydraulic disconnect  86 . In one arrangement, the setting tool  82  may be an electric wireline setting tool that is configured to supply pressurized hydraulic fluid. For example, the setting tool  82  may include an electrically activated pump  88 . The pressurized hydraulic fluid supplied by the setting tool  82  may be used to actuate the bailer  84 . The bailer may include a reservoir  90  for storing a quantity of slurry and a piston  92  that may be displaced by the pressurized hydraulic fluid supplied by the setting tool  82 . As the piston  92  is displaced, the slurry is injected through the hydraulic disconnect  86  and into the sealing device  60 . The hydraulic disconnect  86  may be configured to disconnect from the sealing device  60  once a preset pressure is reached. Such an arrangement may protect the sealing device  60  from over-pressurization. After the hydraulic disconnect  86  disconnects from the sealing device  60 . The setting tool  82 , the bailer  84  and the hydraulic disconnect  60  may be retrieved from the wellbore. 
         [0022]    Referring now to  FIGS. 2 and 3 , during an exemplary operation, the deployment system  80  and the sealing device  60  are conveyed via an e-line or wireline  94  into a wellbore and positioned at a selected location. The deployment system  80  and the sealing device  60  may be conveyed through a bore of a production tubular  20  ( FIG. 2 ). Once so positioned, electrical energy conveyed via the wireline  94  may be used to energize and operate the setting tool  82 . The pressurized fluid supplied by the setting tool  82  enables the bailer  84  to inject the slurry via the hydraulic disconnect  86  into the sealing device  60 . The pressurized in-flowing slurry causes the flow control device  68  to open and permit flow into the inflatable element  62 . As long the in-flowing slurry generates a suitable pressure differential, the flow control device  68  allows the slurry  64  to flow into the inflatable element  62 . The in-flow of slurry  64  expands the inflatable element  62 . Additionally, the hydraulic pressure in the inflatable element  62  forces the slurry into the filter element  70 . The filter element  70  allows the liquid carrier  74  to flow into the bore  75  and into flow into the annulus  76  via the cross over sub  72 . The particles  66 , however, remain and accumulate in the inflatable element  62 . The flow of the slurry  64  into the inflatable element  62  continues until a predetermined pressure or degree of compaction is reached inside the internal volume of the inflatable element  62 . This predetermined internal pressure may be utilized to actuate the hydraulic disconnect  86 . That is, the hydraulic disconnect  86  may be calibrated to terminate flow from the bailer  84  to the sealing device  60  once pressure in the inflatable element  62  reaches a predetermined threshold. After the flow of slurry from the bailer  84  stops, the flow control device  68  closes to seal the pressurized particles  66  within the inflatable element  62 . In embodiments, a device such as a piston or sleeve (not shown) may be actuated to mechanically lock the flow control device  68  into the closed position. 
         [0023]    It should be appreciated that the combination straining the slurry to accumulate particles  66  in the inflatable element  62  and using hydraulic pressure to compress the accumulated particles  66  converts the slurry  64  from a flowable mixture of solids  66  and liquids  67  to a compressed solid or semi-solid mass of particles capable of applying pressure in the useful form of a sealing force against the casing  40 . In the as inflated condition, the first layer  62   a  retains the particles within the inflation element  62 , the second layer  62   b  provides strength protection from the wellbore environment, and the third layer  62   c  forms a seal with the adjacent wall due to the compressive force applied by the mass of particles. It should be appreciated that the use of the slurry  64  allows the inflatable element to expand to a diameter that may be two to three times larger than the bore of the tubular  20  ( FIG. 1 ). 
         [0024]    In one variant of the  FIG. 3  embodiment, the setting tool  82  may include a pump-like device that is configured to flow the slurry into the sealing device  60 . That is, the bailer  84  may be omitted. In another variant of the  FIG. 3  embodiment, the system  80  may be conveyed via a coiled tubing (not shown). In such an arrangement, a downhole pump may be omitted in favor of a surface pump. For instance, the hydraulic pressure in the bore of the coiled tubing may be increased from the surface to actuate or displace the piston  92  of the bailer  84 . Thus, the sealing device  60  may be deployed on rigid carriers such as drill pipe or coiled tubing as well as non-rigid carriers such as e-lines (electric power only) or wirelines (data and power conductors). Additionally, in certain embodiments, a self-contained deployment system, e.g., a system having its own power supply and slurry supply, may be conveyed on a slick-line (no power or data). 
         [0025]    In still other variant, the displacement fluid  89  may directly propels the slurry without the need for a piston  92 . That is, the displacement fluid  89  may contact the slurry. In still another variant, a fluid in the wellbore may be used as the displacement fluid  89 . Such an arrangement may reduce or eliminate the need for fluid to be conveyed from the surface. In still another variant, the return carrier fluid may be utilized is used as the displacement fluid  89 , which would also reduce the amount of fluid to be conveyed from the surface. Thus, in variants, fluids available downhole may be used to supplement a surface conveyed displacement fluid or eliminate the need for a surface conveyed displacement fluid. 
         [0026]    In some embodiments, the sealing device  60  may be permanently installed. In other embodiments, the sealing device  60  may be configured to be retrievable. Numerous arrangements may be used to make the sealing device  60  configurable. For example, the flow control device  68  may be configured to be shifted to an open position by a suitable setting tool. Once shifted into the open position, a fluid carrier may be back-flowed through the filter element  70  into the inflatable element  62  to fluidize the solid or semi-solid mass of particles  66  in the inflatable element  62 . The fluidized particles  66  may then flow out of the inflatable element  62  via the open flow control device  68 . In another embodiment, the particles  66  may be formulated to be dissolved, melted, or disintegrated upon application of a suitable stimulus (e.g., pressure, temperature, chemical agent, etc.). 
         [0027]    From the above, it should be appreciated that sealing devices of the present disclosure, which may be constructed as inflatable packers or bridge plugs as well as other devices, may provide dependable sealing for long term installations. The solid or semi-solid mass in the sealing devices that provide the inflation pressure may be relatively insensitive to downhole conditions such as temperature changes, and less susceptible to leakage or mechanical creep of the inflated structure. 
         [0028]    From the above, it should also be appreciated that sealing devices of the present disclosure may be expanded to a diameter that may be two to three times greater than the diameter of the bore of the wellbore tubular through which the sealing device is conveyed into the well. Thus, the sealing device may be utilized in a variety of situations to provide selective zonal isolation in a borehole below a wellbore tubular has a diameter that is two to three time greater than the wellbore tubular. 
         [0029]    The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention. It is intended that the following claims be interpreted to embrace all such modifications and changes.