Abstract:
A method and apparatus for isolating formation zones preferably with a memory based material formed into an expansion element, with an outer diameter larger than a borehole, adjacent to a radially telescoping perforation element, converting the memory based expansion element to a stable, smaller, run-in diameter, running it into the borehole, then allowing the memory based material to expand and seal against the borehole wall. Expansion can be enhanced by expanding a mandrel on which the expansion element is formed. The expansion element separates two or more groups of outwardly radially telescoping perforation elements, to isolate formation zones and allow the perforation elements to access the isolated zones.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention is in the field of methods and apparatus for isolating one formation zone of an oil or gas well bore from another zone. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is common to drill an oil or gas well bore into and through several different formation zones, where the zones are layered vertically. In such cases, it is typical to isolate each zone from the zones above and below it by installing a packer in the well bore between zones, surrounding a tubular element, such as production piping, which is used to access the various zones. Known systems for achieving this isolation commonly use inflatable or mechanically expandable packers. The inflated packers can be filled with various fluids or even cement. These types of packers can be expensive, and setting them in place can be complicated, since electrical or mechanical systems are usually required for the setting operation. These packers are also less effective in open hole applications than in cased hole applications, because they sometimes do not truly conform to the irregular walls of the open hole, resulting in a limited pressure seal capacity. The problems of expense and complexity are even greater in an application where numerous zones are being accessed by a multi-purpose tool having numerous perforation sections for production of fluid from the well or injection of fluid into the well. This is because numerous packers are required to isolate between zones, and because operation of the numerous perforation sections adds to the overall complexity of operating such a tool. 
       BRIEF SUMMARY OF THE INVENTION 
       [0003]    The present invention is a method and apparatus for isolating between zones with a packer. In the preferred embodiment the packer constructed of memory based material, such as a memory based foam, where the multiple zones are accessed by means of radially telescoping perforation elements. The memory based material is formed onto a base element, such as a mandrel or another tubular element, to form a packer with an outer diameter slightly larger than the downhole diameter in which the packer will be used. The packer is positioned between two sections of radially telescoping perforation elements, in a downhole tool. Two or more packers can be arranged between three or more sections of radially telescoping perforation elements. The memory based material is compressed, such as by elevating a memory based foam to a temperature at which it begins to soften, sometimes called the transition temperature, and the outside diameter of the memory based material is reduced to a smaller diameter, such as by being compressed. Once compressed, the memory based material is then stabilized at that smaller diameter, such as by cooling a memory based foam below the transition temperature, causing it to harden at this desired, smaller, run-in diameter. Then, the tool is run into the hole on a tubular work string, placing each packer at a depth where zonal isolation is required, and placing each section of radially telescoping perforation elements at a depth where zonal access is required. Once each packer is at its respective required zonal isolation depth, the memory based material is then expanded, such as by raising a memory based foam above the transition temperature, causing it to tend to return to its original, larger, outer diameter. Since the original diameter is larger than the hole diameter, the packer conforms to the bore hole and exerts an effective pressure seal on the bore hole wall, between zones. As an alternative, the mandrel or other base element can be hollow, and it can be expanded either before, during, or after the temperature-induced expansion of the foam expansion element. This expansion can be achieved by a mechanical, hydraulic, or hydro-mechanical device. Expansion of the mandrel can enhance the overall expansion achieved with a given amount of memory based material expansion, and it can increase the resultant pressure exerted by the memory based expansion element on the borehole wall, thereby creating a more effective seal. Different packers can be adapted to expand at different temperatures, or through other means adapted to expand at different selected times, as desired by the operator. If desired, cementing of the annulus can also be performed, in the normal fashion. Other alternatives to shape memory packers are envisioned for sealing producing zones such as mechanically or hydraulically set packers, inflatable packers, barriers made of a hardenable material and other designs used downhole to isolate one portion of the wellbore from another. 
         [0004]    The novel features of this invention, as well as the invention itself, will be best understood from the attached drawings, taken along with the following description, in which similar reference characters refer to similar parts, and in which: 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0005]      FIG. 1  is a perspective view of the preferred memory based packer invention, in its originally formed size and shape and is intended to schematically illustrate the use of alternative barriers in the present invention; 
           [0006]      FIG. 2  is a perspective view of the apparatus shown in  FIG. 1 , reduced to its interim size and shape; 
           [0007]      FIG. 3  is a perspective view of the apparatus shown in  FIG. 1 , expanded to seal against the borehole wall; 
           [0008]      FIGS. 4 and 5  are partial section views of the memory based packer of the present invention, implementing a hydro-mechanical device to expand the mandrel; 
           [0009]      FIGS. 6 and 7  are partial section views of the memory based packer of the present invention, implementing a mechanical device to expand the mandrel; 
           [0010]      FIG. 8  is a partial section view of the memory based packer of the present invention, implementing a hydraulic device to expand the mandrel; 
           [0011]      FIGS. 9 and 10  show a first embodiment of the invention incorporating a memory based packer with a telescoping perforation tool having a solid walled shifting sleeve, some sand control elements, and some fracturing elements; 
           [0012]      FIGS. 11 and 12  show a second embodiment of the invention incorporating a memory based packer with a telescoping perforation tool having a shifting sleeve incorporating a sand control medium, where none of the telescoping elements have a sand control medium; 
           [0013]      FIGS. 13 and 14  show a third embodiment of the invention incorporating a memory based packer with a telescoping perforation tool having a shifting sleeve with ports, some sand control elements, and some fracturing elements; and 
           [0014]      FIGS. 15 and 16  show a fourth embodiment of the invention incorporating a memory based packer with a telescoping perforation tool having a shifting sleeve with some sand control ports, and some fracturing ports. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    As shown in  FIG. 1 , the preferred packer for use in the present invention is a memory based packer  10  having a base element, such as a tubular element or a mandrel  20 , on which is formed a memory based expansion element  30 , such as an element constructed of memory based foam. The mandrel  20  can be any desired length or shape, to suit the desired application, and it can be hollow if required. It can also have any desired connection features, such as threaded ends. The mandrel  20  can be a portion of the tubular body of the overall tool, or it can be a separate tubular element. The expansion element  30  is shown with a cylindrical shape, but this can be varied, such as by means of concave ends or striated areas (not shown), to facilitate deployment, or to enhance the sealing characteristics of the packer. The expansion element  30  is composed of a memory based material, for example, an elastic memory foam such as Tembo™ foam, an open cell syntactic foam manufactured by Composite Technology Development, Inc. This type of foam has the property of being convertible from one size and shape to another size and/or shape, by changing the temperature of the foam. This type of foam can be formed into an article with an original size and shape as desired, such as a cylinder with a desired outer diameter. The foam article thusly formed is then heated to raise its temperature to its transition temperature. As it achieves the transition temperature, the foam softens, allowing the foam article to be reshaped to a desired interim size and shape, such as by being compressed to form a smaller diameter cylinder. The temperature of the foam article is then lowered below the transition temperature, to cause the foam article to retain its interim size and shape. When subsequently raised again to its transition temperature, the foam article will return to its original size and shape. 
         [0016]    In the present invention, the cylindrical memory based expansion element  30  can be originally formed onto the mandrel  20  by wrapping a blanket of the memory based material onto the mandrel  20 , with the desired original outer diameter OD 1 . Alternatively, the process for forming the expansion element  30  on the mandrel  20  can be any other process which results in the expansion element  30  having the desired original diameter, such as by molding the memory based material directly onto the mandrel  20 . The desired original outer diameter OD 1  is larger than the bore hole diameter BHD (shown for reference in  FIG. 1 ) in which the packer  10  will be deployed. For instance, an expansion element  30  having an original outer diameter OD 1  of 10 inches might be formed for use in an 8.5 inch diameter borehole. 
         [0017]    Then, the memory based packer is reduced in diameter, for example by raising the temperature of the expansion element  30  above the transition temperature of the memory based foam material, which causes the foam to soften. At this point, the expansion element  30  is compressed to a smaller interim outer diameter OD 2 . For instance, the expansion element  30  might be compressed to an interim outer diameter OD 2  of 7.5 inches for use in an 8.5 inch diameter borehole. This facilitates running the packer  10  into the borehole. This type of foam may be convertible in this way to an interim size and shape approximately one third the volume of the original size and shape. After compression, the expansion element  30  is lowered below its transition temperature, causing it to retain its smaller interim outer diameter OD 2 . This cooling step can be achieved by exposure to the ambient environment, or by exposure to forced cooling. 
         [0018]    After this diameter reduction, the memory based packer  10  is lowered into the borehole to the desired depth at which zonal isolation is to occur, as shown in  FIG. 2 . Once the packer  10  is located at the desired depth for isolating the borehole, the expansion element  30  is again expanded, such as by being raised to the transition temperature of the foam. As shown in  FIG. 3 , this causes the expansion element  30  to expand to a final outer diameter OD 3 . Because of the properties of the elastic memory foam, the expansion element  30  attempts to return to the original outer diameter OD 1 . However, since the original outer diameter OD 1  was selected to be larger than the borehole diameter BHD, the expansion element  30  can only expand until the final outer diameter OD 3  matches the borehole diameter BHD. This can cause the expansion element  30  to exert a pressure of between 300 and 500 psi on the borehole wall. 
         [0019]    The memory based packer can be adapted to selectively expand at different times; for example, where memory based foam is used, the foam material composition can be formulated to achieve the desired transition temperature. This quality allows the foam to be formulated in anticipation of the desired transition temperature to be used for a given application. For instance, in use with the present invention, the foam material composition can be formulated to have a transition temperature just slightly below the anticipated downhole temperature at the depth at which the packer  10  will be used. This causes the expansion element  30  to expand at the temperature found at the desired depth, and to remain tightly sealed against the bore hole wall. Downhole temperature can be used to expand the expansion element  30 ; alternatively, other means can be used, such as a separate heat source. Such a heat source could be a wireline deployed electric heater, or a battery fed heater. For example, such a heat source could be mounted to the mandrel  20 , incorporated into the mandrel  20 , or otherwise mounted in contact with the foam expansion element  30 . The heater could be controlled from the surface of the well site, or it could be controlled by a timing device or a pressure sensor. Still further, an exothermic reaction could be created by chemicals pumped downhole from the surface, or heat could be generated by any other suitable means. Also, on a tool where several packers  10  are employed, each packer can be formulated to expand at a different temperature, giving the operator individual control of the expansion of each packer. 
         [0020]    As an alternative, if it is desired to enhance the overall amount of packer expansion achievable, in addition to the expansion achievable with a given volume of memory based material, the mandrel  20  itself can be a hollow base element which can be expanded radially. This additional expansion can be achieved by the use of a mechanical, hydraulic, or hydro-mechanical device. For example, as shown in  FIG. 4 , a hydro-mechanical expander  40  can be run into the tubing on a work string, either before, during, or after the memory based expansion of the material. The hydro-mechanical expander  40  can consist essentially of an anchoring device  42 , a hydraulic ram  44 , and a conical pig  46 . Once the conical pig  46  reaches the mandrel  20 , the anchoring device  42  is activated to anchor itself to the tubing. Activation of the anchoring device  42  can be mechanical, electrical, or hydraulic, as is well known in the art. Once the expander  40  is thusly anchored in place, the hydraulic ram  44  can be pressurized to force the conical pig  46  into and through the mandrel  20  of the packer  10 , as shown in  FIG. 5 . Since the outer diameter of the conical pig  46  is selected to be slightly larger than the inner diameter of the mandrel  20 , as the conical pig  46  advances through the mandrel  20 , it radially expands the mandrel  20 . 
         [0021]    As mentioned above, this expansion of the mandrel  20  can be implemented before, during, or after the memory based expansion of the expansion element  30 . It can be seen that radial expansion of the mandrel  20  in this way can enhance the overall expansion possible with the packer  10 . Therefore, for a given amount of memory based material in the expansion element  30 , the final diameter to which the packer  10  can be expanded can be increased, or the pressure exerted by the expanded packer  10  can be increased, or both. For example, a relatively smaller overall diameter packer  10  can be run into the hole, thereby making the running easier, with mandrel expansion being employed to achieve the necessary overall expansion. Or, a relatively larger overall diameter packer  10  can be run into the hole, with mandrel expansion being employed to achieve a higher pressure seal against the borehole wall. 
         [0022]    As a further alternative to use of the hydro-mechanical expander  40 , the mandrel  20  can be expanded by mechanically forcing a conical pig  50  through the mandrel  20  with a work string, as shown in  FIGS. 6 and 7 . Forcing of the pig  50  through the mandrel  20  can be either by pushing with the work string, as shown in  FIG. 6 , or by pulling with the work string, as shown in  FIG. 7 . Still further, the mandrel  20  can be expanded by hydraulically forcing a conical pig  60  through the mandrel  20  with mud pump pressure, as shown in  FIG. 8 . 
         [0023]    While memory based packers are preferred, other barriers used downhole to isolate one portion of the wellbore from another can be used as alternatives. These barriers can be mechanically or hydraulically set packers, inflatables, or materials that can be deposited in an annular space and become firm barriers such as, for example, cement. 
         [0024]    The present invention provides one or more memory based packers  10  between two or more sections of radially telescoping perforating elements, for selectively perforating a well bore liner, fracturing a formation, and producing or injecting fluids, sand-free. Examples of such tools are shown in  FIGS. 9 through 16 . In each of these, the memory based packers  10  are mounted on a tubular tool body having a plurality of radially outwardly telescoping tubular elements. The radially telescoping tubular elements are grouped in two or more groups, separated vertically, to align with the various zones of the formation in which the tool will be used. Packers can be provided between the groups of telescoping tubular elements. A mechanical means can be provided for selectively controlling the hydrostatic fracturing of the formation through one or more of the telescoping elements and for selectively controlling the sand-free injection or production of fluids through one or more of the telescoping elements. Selective expansion of the memory based packers  10  is as described above. 
         [0025]    The apparatus can have a built-in sand control medium in one or more of the telescoping elements, to allow for injection or production, and a check valve in one or more of the telescoping elements, to allow for one way flow to hydrostatically fracture the formation without allowing sand intrusion after fracturing. Vertical isolation of the zones is achieved by placement of one or more memory based packers  10 . 
         [0026]    Other types of telescoping perforation sections used in the apparatus of the present invention, along with the memory based packer, can have a sleeve which shifts between a fracturing position and an injection/production position, to convert the tool between these two types of operation. The sleeve can shift longitudinally or it can rotate. 
         [0027]    In a first shifting-sleeve type, the sleeve can be a solid walled sleeve, as shown in  FIGS. 9 and 10 , which shifts to selectively open and close the different telescoping elements, with some telescoping elements having a built-in sand control medium (which may be referred to in this case as “sand control elements”) and other telescoping elements having no built-in sand control medium (which may be referred to in this case as “fracturing elements”). In this embodiment of the apparatus  100 , the shifting sleeve  16  is a solid walled sleeve as before, but it can be positioned and adapted to shift in front of, as in  FIG. 9 , or away from, as in  FIG. 10 , one or more rows of fracturing elements  12 . It can be seen that the fracturing elements  12  have an open central bore for the passage of proppant laden fracturing fluid. The sand control elements  14  can have any type of built-in sand control medium therein, with examples of metallic beads and screen material being shown in the Figures. Whether or not the shifting sleeve  16  covers the sand control elements  14  when it uncovers the fracturing elements  12  is immaterial to the efficacy of the tool  100 . Isolation between the zones is provided by the expanded memory based packer  10 . 
         [0028]    In a second shifting-sleeve type of the apparatus  100 , as shown in  FIGS. 11 and 12 , the sleeve itself can be a sand control medium, such as a screen, which shifts to selectively convert the telescoping elements between the fracturing mode and the injection/production mode. In this embodiment, none of the telescoping elements would have a built-in sand control medium. This longitudinally sliding shifting sleeve  16  is constructed principally of a sand control medium such as a screen.  FIG. 11  shows the sleeve  16  positioned in front of the telescoping elements  12 , for injection or production of fluid.  FIG. 12  shows the sleeve  16  positioned away from the telescoping elements  12 , for pumping of proppant laden fluid into the formation. In this embodiment, none of the telescoping elements has a built-in sand control medium. Isolation between the zones is provided by the expanded memory based packer  10 . 
         [0029]    In a third shifting-sleeve type, as shown in  FIGS. 13 and 14 , the sleeve can have ports which are shifted to selectively open and close the different telescoping elements, with some telescoping elements having a built-in sand control medium (which may be referred to in this case as “sand control elements”) and other telescoping elements having no built-in sand control medium (which may be referred to in this case as “fracturing elements”). In this embodiment of the apparatus  100 , the sleeve shifts to selectively place the ports over either the “sand control elements” or the “fracturing elements”. This shifting sleeve  16  is a longitudinally shifting solid walled sleeve having a plurality of ports  24 . The sleeve  16  shifts longitudinally to position the ports  24  either in front of or away from the fracturing elements  12 .  FIG. 13  shows the ports  24  of the sleeve  16  positioned away from the fracturing elements  12 , for injection or production of fluid through the sand control elements  14 .  FIG. 14  shows the ports  24  of the sleeve  16  positioned in front of the fracturing elements  12 , for pumping of proppant laden fluid into the formation. In this embodiment, the fracturing elements  12  have an open central bore for the passage of proppant laden fracturing fluid. The sand control elements  14  can have any type of built-in sand control medium therein. Here again, whether or not the shifting sleeve  16  covers the sand control elements  14  when it uncovers the fracturing elements  12  is immaterial to the efficacy of the tool  10 . Isolation between the zones is provided by the expanded memory based packer  10 . 
         [0030]    In a fourth shifting-sleeve type, as shown in  FIGS. 15 and 16 , the sleeve can have ports, some of which contain a sand control medium (which may be referred to in this case as “sand control ports”) and some of which do not (which may be referred to in this case as “fracturing ports”). In this embodiment of the apparatus  100 , none of the telescoping elements would have a built-in sand control medium, and the sleeve shifts to selectively place either the “sand control ports” or the “fracturing ports” over the telescoping elements. This shifting sleeve  16  is a rotationally shifting solid walled sleeve having a plurality of ports  24 ,  26 . A first plurality of the ports  26  (the sand control ports) have a sand control medium incorporated therein, while a second plurality of ports  24  (the fracturing ports) have no sand control medium therein. The sleeve  16  shifts rotationally to position either the fracturing ports  24  or the sand control ports  26  in front of the telescoping elements  12 .  FIG. 15  shows the fracturing ports  24  of the sleeve  16  positioned in front of the elements  12 , for pumping of proppant laden fluid into the formation.  FIG. 16  shows the sand control ports  26  of the sleeve  16  positioned in front of the telescoping elements  12 , for injection or production of fluid through the elements  12 . In this embodiment, all of the telescoping elements  12  have an open central bore; none of the telescoping elements has a built-in sand control medium. Isolation between the zones is provided by the expanded memory based packer  10 . 
         [0031]    It should be understood that a rotationally shifting type of sleeve, as shown in  FIGS. 15 and 16 , could be used with only open ports, as shown in  FIGS. 13 and 14 , with both fracturing elements  12  and sand control elements  14 , without departing from the present invention. It should be further understood that a longitudinally shifting type of sleeve, as shown in  FIGS. 13 and 14 , could be used with both open ports and sand control ports, as shown in  FIGS. 15 and 16 , with only open telescoping elements  12 , without departing from the present invention. 
         [0032]    While the particular invention as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages hereinbefore stated, it is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.