Patent Publication Number: US-7913765-B2

Title: Water absorbing or dissolving materials used as an in-flow control device and method of use

Description:
BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The disclosure relates generally to systems and methods for selective control of fluid flow into a production string in a wellbore. 
     2. Description of the Related Art 
     Hydrocarbons such as oil and gas are recovered from a subterranean formation using a wellbore drilled into the formation. Such wells are typically completed by placing a casing along the wellbore length and perforating the casing adjacent each such production zone to extract the formation fluids (such as hydrocarbons) into the wellbore. These production zones are sometimes separated from each other by installing a packer between the production zones. Fluid from each production zone entering the wellbore is drawn into a tubing that runs to the surface. It is desirable to have substantially even drainage along the production zone. Uneven drainage may result in undesirable conditions such as an invasive gas cone or water cone. In the instance of an oil-producing well, for example, a gas cone may cause an inflow of gas into the wellbore that could significantly reduce oil production. In like fashion, a water cone may cause an inflow of water into the oil production flow that reduces the amount and quality of the produced oil. Accordingly, it is desired to provide even drainage across a production zone and/or the ability to selectively close off or reduce inflow within production zones experiencing an undesirable influx of water and/or gas. 
     The present disclosure addresses these and other needs of the prior art. 
     SUMMARY OF THE DISCLOSURE 
     In aspects, the present disclosure provides an apparatus for controlling flow of a fluid into a tubular in a wellbore drilled into an earthen formation. In one embodiment, the apparatus includes a flow restriction member positioned along the wellbore tubular that transitions from a first effective density to a second effective density in response to a change in composition of the flowing fluid. In one arrangement, the first effective density is less than the second effective density. In aspects, the flow restriction member may be configured to increase in effective density as a percentage of water in the flowing fluid increases. In embodiments, the flow restriction member may be formed of a water-absorbing material that causes the flow restriction member to increase in density as water is absorbed into a portion of the flow restriction member. The flow restriction member may be formed at least partially of a material that has pores. In aspects, the pores are water permeable but not oil permeable. In another embodiment, the flow restriction member may be formed at least partially of a material that is calibrated to disintegrate when exposed to a selected fluid in the flowing fluid. 
     In aspects, the present disclosure provides a method for producing fluid from a subterranean formation. In one embodiment, the method includes controlling a flow of fluid into a wellbore tubular with a flow restriction member. The flow restriction member is configured to transition from a first effective density to a second effective density in response to a change in composition of the flowing fluid. In aspects, the method may include reducing a flow of water into the wellbore tubular when a percentage of water in the flowing fluid reaches a predetermined value. The method may also include increasing the density of the flow restriction member by absorbing water into the flow restriction member. 
     In aspects, the present disclosure provides a system for controlling a flow of a fluid in a well. The system may include a wellbore tubular positioned in the well and one or more flow restriction members positioned along the wellbore tubular. One or more of these flow restriction members may be configured to transition from a first effective density to a second effective density in response to a change in composition of the flowing fluid. In embodiments, a plurality of flow restriction members are distributed along the wellbore tubular. In aspects, the flow restriction member may be configured to decrease the flow of the fluid in the wellbore tubular when a percentage of water in the flowing fluid reaches a predetermined value. 
     It should be understood that examples of the more important 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 
       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: 
         FIG. 1  is a schematic elevation view of an exemplary multi-zonal wellbore and production assembly which incorporates an inflow control system in accordance with one embodiment of the present disclosure; 
         FIG. 2  is a schematic elevation view of an exemplary open hole production assembly which incorporates an inflow control system in accordance with one embodiment of the present disclosure; 
         FIG. 3  is a schematic cross-sectional view of an exemplary production control device made in accordance with one embodiment of the present disclosure; 
         FIG. 4  is an isometric view of a in-flow control device made in accordance with one embodiment of the present disclosure; 
         FIGS. 5A and 5B  schematically illustrate one embodiment of an in-flow control device that utilizes a water absorbing material in accordance with the present disclosure; and 
         FIGS. 6A and 6B  schematically illustrate one embodiment of an in-flow control device that utilizes a disintegrating material in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. 
     Referring initially to  FIG. 1 , there is shown an exemplary wellbore  10  that has been drilled through the earth  12  and into a pair of formations  14 ,  16  from which it is desired to produce hydrocarbons. The wellbore  10  is cased by metal casing, as is known in the art, and a number of perforations  18  penetrate and extend into the formations  14 ,  16  so that production fluids may flow from the formations  14 ,  16  into the wellbore  10 . The wellbore  10  has a deviated, or substantially horizontal leg  19 . 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 . The production assembly  20  defines an internal axial flowbore  28  along its length. An annulus  30  is defined between the production assembly  20  and the wellbore casing. The production assembly  20  has a deviated, generally horizontal portion  32  that extends along the deviated leg  19  of the wellbore  10 . Production devices  34  are positioned at selected points along the production assembly  20 . Optionally, each production device  34  is isolated within the wellbore  10  by a pair of packer devices  36 . Although only two production devices  34  are shown in  FIG. 1 , there may, in fact, be a large number of such production devices arranged in serial fashion along the horizontal portion  32 . 
     Each production device  34  features a production control device  38  that is used to govern one or more aspects of a flow of one or more fluids into the production assembly  20 . As used herein, the term “fluid” or “fluids” includes liquids, gases, hydrocarbons, multi-phase fluids, mixtures of two of more fluids, water, brine, engineered fluids such as drilling mud, fluids injected from the surface such as water, and naturally occurring fluids such as oil and gas. Additionally, references to water should be construed to also include water-based fluids; e.g., brine or salt water. In accordance with embodiments of the present disclosure, the production control device  38  may have a number of alternative constructions that ensure selective operation and controlled fluid flow therethrough. 
       FIG. 2  illustrates an exemplary open hole wellbore arrangement  11  wherein the production devices of the present disclosure may be used. Construction and operation of the open hole wellbore  11  is similar in most respects to the wellbore  10  described previously. However, the wellbore arrangement  11  has an uncased borehole that is directly open to the formations  14 ,  16 . Production fluids, therefore, flow directly from the formations  14 ,  16 , and into the annulus  30  that is defined between the production assembly  21  and the wall of the wellbore  11 . There are no perforations, and open hole packers  36  may be used to isolate the production control devices  38 . The nature of the production control device is such that the fluid flow is directed from the formation  16  directly to the nearest production device  34 , hence resulting in a balanced flow. In some instances, packers maybe omitted from the open hole completion. 
     Referring now to  FIG. 3 , there is shown one embodiment of a production control device  100  for controlling the flow of fluids from a reservoir into a flow bore  102  of a tubular  104  along a production string (e.g., tubing string  22  of  FIG. 1 ). This flow control can be a function of one or more characteristics or parameters of the formation fluid, including water content, fluid velocity, gas content, etc. Furthermore, the control devices  100  can be distributed along a section of a production well to provide fluid control at multiple locations. This can be advantageous, for example, to equalize production flow of oil in situations wherein a greater flow rate is expected at a “heel” of a horizontal well than at the “toe” of the horizontal well. By appropriately configuring the production control devices  100 , such as by pressure equalization or by restricting inflow of gas or water, a well owner can increase the likelihood that an oil bearing reservoir will drain efficiently. Exemplary production control devices are discussed herein below. 
     In one embodiment, the production control device  100  includes a particulate control device  110  for reducing the amount and size of particulates entrained in the fluids, an in-flow control device  120  that controls overall drainage rate from the formation, and a fluid in-flow control device  140  that controls in-flow area based upon the composition of the fluid in the production control device. The particulate control device  110  can include known devices such as sand screens and associated gravel packs and the in-flow control device  120  can utilize devices employing tortuous fluid paths designed to control inflow rate by created pressure drops. These devices have been previously discussed and are generally known in the art. 
     An exemplary in-flow control device  140  is adapted to control the in-flow area based upon the composition (e.g., oil, water, water concentration, etc) of the in-flowing fluid. Moreover, embodiments of the in-flow control device  140  are passive. By “passive,” it is meant that the in-flow control device  140  controls in-flow area without human intervention, intelligent control, or an external power source. Illustrative human intervention includes the use of a work string to manipulate a sliding sleeve or actuate a valve. Illustrative intelligent control includes a control signal transmitted from a downhole or surface source that operates a device that opens or closes a flow path. Illustrative power sources include downhole batteries and conduits conveying pressurized hydraulic fluid or electrical power lines. Embodiments of the present disclosure are, therefore, self-contained, self-regulating and can function as intended without external inputs, other than interaction with the production fluid. 
     Referring now to  FIG. 4 , there is shown one embodiment of an in-flow control device  140  that controls fluid in-flow based upon the composition of the in-flowing fluid. The in-flow control device  140  includes a seal  142 , a body  144  and a flow restriction element  146 . The term “flow restriction element,” “closure element,” “flapper,” are used interchangeable to denote a member suited to blocking or obstructing the flow of a fluid in or to a conduit, passage or opening. The seal  142  prevents fluid flow through the annular flow area between the body  144  and an enclosing structure such as a housing (not shown) or even a wellbore tubular such as casing (not shown). Another seal (not shown) seals off the annular passage between the body  144  and the wellbore tubular  22  ( FIG. 1 ). The body  144  is positioned on a pipe section (not shown) along a wellbore tubular string (not shown) and includes a passage  148  through which fluid must flow prior to entering a wellbore tubular such as the production assembly  22  ( FIG. 1 ). The passage  148 , while shown as slotted, can be of any suitable configuration. The flow restriction element  146  is adapted to restrict fluid flow into the passage  148 . Restriction should be understood to mean a reduction in flow as well as completely blocking flow. The flow restriction element  146 , in one arrangement, is coupled to the body  144  with a suitable hinge  150 . Thus, the flow restriction element  146  rotates or swings between an open position wherein fluid can enter the passage  148  and a closed position wherein fluid is blocked from entering the passage  148 . As explained earlier, fluid does not necessarily have to be completely blocked. For example, the flow restriction element  146  can include one or more channels (not shown) that allow a reduced amount of fluid to enter the passage  148  even when the flow restriction element  146  is in the closed position. A counter weight  152  may be used to assist the rotation of the flow restriction element  146  about the hinge  150 . 
     The flow restriction element  146  moves from the open position to the closed position when the concentration of water, or water cut, increases to a predetermined level. As shown, the flow restriction element  146  is positioned on the “high side”  149  ( FIG. 3 ) of the production string and is in an open position when the flowing fluid is oil and in a closed position when the flowing fluid is partially or wholly formed of water. In one arrangement, the flow restriction element  146  is formed partially or wholly out of a material that increases in density upon exposure to water. For instance, the flow restriction element  146  may have a first effective density less than oil when surrounded by oil and a second effective density greater than water when surrounded by water. Thus, the flow restriction element  146  “floats” in the oil to maintain an open position for the in-flow control device  140  and “sinks” in water to close the in-flow control device  140 . Accordingly, the reaction of the flow restriction element  146  to the composition of the flowing fluid allows the flow restriction element  146  to passively control the fluid in-flow as a function of the composition of the fluid. In one aspect, the term “effective density” refers to density of the flow restriction element  146  as a unit. That is, the mass of the flow restriction element  146  as a whole may increase relative to its volume, which results in a greater effective density. The actual density of the components making up the flow restriction element  146 , however, may not undergo a change in density. Illustrative embodiments of flow restriction elements are described below. 
     In one embodiment, the flow restriction element  146  is partially or wholly formed of a material that absorbs water. This absorption of water may cause the overall density of the flow restriction element  146  to shift from the first effective density less than oil to a second effective density greater than water. 
     Referring now to  FIGS. 5A and 5B , there is shown another embodiment wherein the flow restriction element  146  is formed of a material that has a density greater than water. The flow material element  146  is also formed partially or wholly of a material that has pores  160  that are water permeable but not oil permeable. As shown in  FIG. 5A , the pores  160  of the flow restriction element  146  are initially filled with a relatively light fluid such as air. The relatively light fluid residing in the pores  160  cause the flow restriction element  146  to be positively buoyant in a substantially oil flow. As shown in  FIG. 5B , as the water concentration increases, water molecules penetrate the pores  160  and displace the relatively light fluid. When a threshold value of the relatively light fluid has been displaced, the flow restriction element  146  becomes negatively buoyant and sinks to the closed position. 
     Referring now to  FIGS. 6A and 6B , there is shown still another embodiment wherein the flow restriction element  146  is formed of a material that has a density greater than water. The flow material element  146  is also formed partially of a disintegrating material  170  that has entrained pores  172 . As shown in  FIG. 6A , the pores  172  of the disintegrating material  170  are filled with a relatively light fluid such as air. The relatively light fluid residing in the pores  172  cause the flow restriction element  146  to be positively buoyant in a substantially oil flow. The disintegrating material  170  is calibrated to dissolve, fracture, or otherwise lose structural integrity as the water cut increases in the flowing fluid and/or the water cut has reached a predetermined threshold. By calibrate or calibrated, it is meant that one or more characteristics relating to the capacity of the element to disintegrate is intentionally tuned or adjusted to occur in a predetermined manner or in response to a predetermined condition or set of conditions. For example, the disintegrating material  170  may be formed of a water soluble metal that reacts and disintegrates when exposed to water. In other embodiments, the disintegrating material  170  may be configured to maintain structural integrity when surrounded in oil, but lose structural integrity as oil concentration drops. As shown in  FIG. 6B , as the water concentration increases or oil concentration decreases, the disintegrating material  170  disintegrates. Because the pores  172  are no longer present, the flow restriction element  146  becomes negatively buoyant and sinks to the closed position. In one aspect, it should be appreciated that the loss of the disintegrating material  170  has increased the effective density of the flow restriction element  146 . 
     It will be appreciated that an in-flow control device  140  utilizing a density sensitive flow restriction member is amenable to numerous variations. For example, referring now to  FIG. 6A , the flow restriction element  146  can be positioned on the “low side”  151  ( FIG. 3 ) of the production string. In one variant, the density of the material forming the flow restriction element  146  can be selected to be less than the density of water and of oil. The disintegrating material  170  is entrained with relatively heavy elements that cause the flow restriction element  146  to have an effective density that is greater than oil. Thus, the flow restriction element  146  sinks to an open position when surrounded by oil. As the water concentration increases or oil concentration decreases, the disintegrating material  170  disintegrates. Because the relatively heavy elements are no longer present, the flow restriction element  146  becomes positively buoyant and floats to the closed position. Accordingly, the flow restriction element  146  “sinks” to an open position when in oil and “floats” to a closed position when in water. 
     It should be appreciated that, for the purposes of the present disclosure, the counter weight may be considered a part of the flow restriction element  146 . Thus, the water absorbing or disintegrating material may be integrated into the counter weight as part of the mechanism to move the flow restriction element  146 . 
     In some embodiments, the in-flow control device  140  can be installed in the wellbore in a manner that ensures that the flow restriction element  146  is immediately in the high side position. In other embodiments, the in-flow control device  140  can be configured to automatically align or orient itself such that the flow restriction element  146  moves into the high side position regardless of the initial position of the in-flow control device  140 . Referring now to  FIG. 4 , for example, the body  144 , which is adapted to freely rotate or spin around the wellbore tubular  22  ( FIG. 1 ), can be configured to have a bottom portion  180  that is heavier than a top portion  182 , the top portion  182  and bottom portion  180  forming a gravity activated orienting member or gravity ring. The flow restriction element  146  is coupled to the top portion  182 . Thus, upon installation in the wellbore, the bottom portion  180  will rotate into a low side position  151  ( FIG. 3 ) in the wellbore, which of course will position the flow restriction element  146  on the high side  149  ( FIG. 3 ) of the wellbore. The weight differential between the top portion and the bottom portion  148  can be caused by adding weights  184  to the bottom portion  148  or removing weight from the top portion  180 . In other embodiments, human intervention can be utilized to appropriately position the in-flow control device  140  or a downhole motor, e.g., hydraulic or electric, can be used to position the in-flow control device  140  in a desired alignment. 
     It should be understood that  FIGS. 1 and 2  are intended to be merely illustrative of the production systems in which the teachings of the present disclosure may be applied. For example, in certain production systems, the wellbores  10 ,  11  may utilize only a casing or liner to convey production fluids to the surface. The teachings of the present disclosure may be applied to control flow those and other wellbore tubulars. 
     For the sake of clarity and brevity, descriptions of most threaded connections between tubular elements, elastomeric seals, such as o-rings, and other well-understood techniques are omitted in the above description. Further, terms such as “valve” are used in their broadest meaning and are not limited to any particular type or configuration. The foregoing description is directed to particular embodiments of the present disclosure 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 of the disclosure.