Patent Publication Number: US-7712541-B2

Title: System and method for protecting downhole components during deployment and wellbore conditioning

Description:
BACKGROUND 
   Moving well equipment downhole into a wellbore during an installation process can have damaging effects on a variety of equipment components. This is particularly true of fragile components, sealing components and components susceptible to bending. Such components can be damaged from impacts with the surrounding wellbore, casing, liner or open hole barefoot sections. The impacts can create abrasions or other damage that limits the functionality of the equipment once positioned downhole. Damage also can result from erosion of component material or contamination of the component in a manner that effects its operation. 
   In some applications, downhole equipment components comprise seal elements used to form a seal with other components or with the surrounding wellbore wall, e.g. casing. The seal elements can be damaged as they slide through hundreds or thousands of feet of casing before reaching the final downhole destination. Because the seal elements are formed of a plastic or otherwise softer material, impacts with the surrounding wellbore wall, obstructions or other equipment can damage one or more seal elements and limit the ability of the seal elements to form a satisfactory seal downhole. 
   SUMMARY 
   In general, the present invention provides a technique for protecting components of a well system from damage. Sacrificial material is deployed proximate a susceptible wellbore component to provide temporary protection of the component. The sacrificial material is used to protect wellbore system components during installation of the system to a downhole location. For example, the material can protect susceptible wellbore components from damage due to impacts. However, the sacrificial material also can temporarily protect wellbore components from other potentially damaging effects of the harsh wellbore environment during installation of the system. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
       FIG. 1  is an elevation view of an embodiment of a well equipment system, having at least one susceptible component, as the well equipment system is moved downhole into a wellbore, according to an embodiment of the present invention; 
       FIG. 2  is a partial cross-sectional view of an embodiment of a sacrificial element used to protect one or more components of the well equipment system illustrated in  FIG. 1 , according to an embodiment of the present invention; 
       FIG. 3  is a partial cross-sectional view of another embodiment of the sacrificial element used to protect one or more components of the well equipment system illustrated in  FIG. 1 , according to an embodiment of the present invention; 
       FIG. 4  is a partial cross-sectional view of another embodiment of a sacrificial element used to protect one or more components of the well equipment system illustrated in  FIG. 1 , according to an embodiment of the present invention; 
       FIG. 5  is a side view of the one example of a potentially susceptible wellbore component having seal elements, according to an embodiment of the present invention; 
       FIG. 6  is a side view similar to that of  FIG. 5  showing a sacrificial element deployed adjacent the wellbore component, according to an embodiment of the present invention 
       FIG. 7  is a partial cross-sectional view of another embodiment of a sacrificial element used to protect one or more components of the well equipment system illustrated in  FIG. 1  from premature actuation by temporarily locking the one or more components in a desired state, according to an embodiment of the present invention; and 
       FIG. 8  is a partial cross-sectional view similar to that of  FIG. 7  but showing the one or more components actuated following removal of the sacrificial element, according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variation or modifications from the described embodiments may be possible. 
   The present invention relates to a system and methodology for shielding sensitive well components during, for example, installation operations and early production phases. The potential for damaging well components during a run-in into a wellbore is great, particularly for relatively fragile components, such as seals. Accordingly, the present system and methodology provides temporary protection against impact, e.g. abrasion, erosion, contamination and other environmental effects that can damage sensitive well components. In many applications, the protection is provided as the well components slide through several hundreds or thousands of feet of well casing before reaching their final wellbore destination. 
   Referring generally to  FIG. 1 , an embodiment of a well system  20  is illustrated as it is installed into a wellbore  22 . However, well system  20  also could be positioned at a desired location during, for example, an early production phase. By way of example, well system  20  may comprise a completion  24  having a plurality of well components  26 ,  28 ,  30  and  32 . 
   In the example illustrated, submersible pumping system  20  is designed for deployment in wellbore  22  which has been drilled into a geological formation  34  containing desirable production fluids, such as petroleum. In at least some applications, wellbore  22  is lined with a wellbore casing  36 . A plurality of perforations  37  is formed through wellbore casing  36  to enable flow of fluids between the surrounding formation  34  and the wellbore  22 . 
   At least one of the well components, e.g. well component  30 , is protected by a sacrificial protection element  38 , such as a temporary covering  40  positioned around well component  30 . In this embodiment, the sacrificial protection element  38  protects the component from damage due to abrasion, erosion, contamination or other damage resulting from movement through the wellbore and/or initial operation of the well system  20 . The illustrated temporary covering  40  is at least partially formed of a dissolvable material to enable selective exposure of well component  30  at a desired time within wellbore  22 . Accordingly, one or more well components  30  can be protected with temporary covering  40  during run-in of well system  20  and/or during initial startup procedures once well system  20  is positioned at a desired location within wellbore  22 . Subsequently, the temporary covering  40  is automatically removed to expose the one or more well components  30  for appropriate operation within the wellbore. 
   Well component  30  may comprise a variety of components useful in well operations, such as electrical components, e.g. sensors or controls, control lines, seal bores, or flexible elements, such as seal elements. Many seal elements are formed of rubber materials, plastic materials or other relatively soft and/or flexible materials that are susceptible to abrasion and other damage, particularly during run-in of well system  20 . The temporary covering  40  is particularly amenable to protecting such seal materials from impacts along the wellbore that can lead to abrasion or other damage to the seal material, thereby limiting the ability of component  30  to form a desired seal. Sacrificial covering  40  also can be used to shield sensitive components from particle contamination until the components are called upon to perform. Covering  40  also can be used to temporarily fix, e.g. secure, components during installation procedures until covering  40  is removed to allow the desired freedom of movement for the component. 
   Temporary covering  40  may be applied to component or components  30  at various times during the installation process. For example, covering  40  can be wrapped around or otherwise mounted adjacent component  30  before being transported along the surface to the well site at which wellbore  22  has been formed. In this matter, covering  40  can be used to protect the one or more components  30  both before and during installation of well system  20 . Even if protection is not required during run-in, applying covering  40  before surface transport avoids the time and cost otherwise associated with removing covering  40 , because the covering  40  is automatically removed from the component  30  as it is submerged and dissolves within wellbore  22 . Accordingly, protection is maintained until the last possible moment, and rig time is reduced, because no disassembly is required. In some applications, the material and thickness of temporary covering  40  is selected so dissolving of the dissolvable material, and the consequent removal of covering  40  from component  30 , requires a slightly longer period of time than that necessary to run well system  20  to its final depth in wellbore  22 . 
   In  FIGS. 2-4 , examples of temporary coverings  40  are illustrated. Referring first to  FIG. 2 , an embodiment of temporary covering  40  comprises a layer  42  having sufficient thickness to protect component  30  from damage due to impacts with the wall of wellbore  22 . In this embodiment, the thickness of layer  42  is greater than the thickness of a coating and is designed to cushion component  30  against potential impacts during run-in. Layer  42  is formed of a dissolvable material  44  selected to dissolve at a desired rate when exposed to well fluid within wellbore  22 . Accordingly, the dissolving of temporary covering  40  is controlled by submerging dissolvable material  44  in fluids found within wellbore  22  during movement of well system  20  to a desired location within the wellbore. Alternatively, fluid agents also can be added to the wellbore to control the dissolving of material  44 . 
   Layer  42  may be formed as a sleeve  46  that encircles component  30  about its longitudinal axis. In many applications, layer  42  is disposed proximate component  30  and between component  30  and potentially damaging structures, such as the wellbore wall formed by casing  36 . In fact, layer  42  can be adhered directly to an outer surface  48  of component  30 , regardless of whether layer  42  is formed as a sleeve  46  or in some other structural form. 
   In  FIG. 3 , temporary covering  40  comprises an inner layer  50  formed of dissolvable material  44 . Inner layer  50  is covered by a coating  52  designed to prevent exposure of dissolvable material  44  to dissolving fluids until a desired time during the well system installation or operation procedure. Coating  52  can be degraded or otherwise removed by providing an appropriate input downhole. For example, coating  52  can be selected such that it is sensitive to heat. In this embodiment, once the coating  52  is exposed to sufficient heat at a desired depth within wellbore  22 , the coating is degraded which exposes inner layer  50  to well fluids able to dissolve inner layer  50 . In another embodiment, coating  52  can be designed to degrade under sufficient pressure provided either naturally at certain wellbore depths or artificially by applying pressure to the wellbore from, for example, a surface location. In other embodiments, coating  52  can be designed to degrade when exposed to specific chemicals directed downhole. In any of these embodiments, coating  52  prevents the disappearance of inner layer  50  until a specific time period in which the pressure or temperature, for example, causes coating  52  to fail, thus initiating dissolving of inner layer  50 . Once inner layer  50  is dissolved, component  30  is exposed for operation. In this embodiment and other embodiments, the one or more components  30  may comprise a control line  54  that is protected in whole or in part by temporary covering  40 . 
   Referring generally to  FIG. 4 , another example of protective covering  40  is illustrated. In this embodiment, protective covering  40  is formed of a durable sleeve  56  held in place adjacent component  30  by dissolvable structural elements  58 . Durable sleeve  56  is formed of a material that does not dissolve in well fluids, such as a non-dissolvable elastomeric material. Accordingly, when component  30  of well system  20  is moved into wellbore  22  and submerged in well fluid, dissolvable structural elements  58  dissolve and release durable sleeve  56 . At this stage, durable sleeve  56  simply slides away from component  30  to enable proper operation of component  30 . 
   Dissolvable material  44  and coating  52  can be formed from a variety of materials depending on the specific application and environment in which it is used. For example, the materials selected may vary depending on the potential heat and pressures in a given wellbore environment. The materials selected also may depend on the types of well fluids encountered in a given wellbore environment. Examples of dissolvable material  44  comprise highly reactive metals such as calcium, magnesium or alloys thereof, or materials that dissolve in acidic or basic fluids, e.g. aluminum, polymers or specially formulated plastics. Examples of suitable materials used to form coating  52  comprise aluminum or other metals that can be removed with acid or specifically formulated chemicals. Other examples of materials comprise low-temperature plastics or elastomers that fail at higher pressures or temperatures. Additional examples of suitable materials comprise metallic coatings that differ greatly in thermal expansion coefficient relative to their carrier material, such that the coating material fractures and breaks away at elevated temperatures. 
   Referring to  FIGS. 5 and 6 , a specific example of one type of component  30  that is particularly amenable to installation with temporary covering  40  is illustrated. In this embodiment, well component  30  comprises a packer  60  having one or more seal elements  62  positioned to form a seal within wellbore  22 . For example, seal elements  62  may be used to form a seal between a packer body  64  and well casing  36 . In the example illustrated, packer  60  comprises four seal elements  62  that include two downward facing cup seal elements  66  and two upward facing cup seal elements  68 , as best illustrated in  FIG. 5 . For some applications, seal elements  62  are designed in a manner that creates a slight interference against well casing  36 , thus increasing the potential for damage to the seal elements as they slide through several hundreds or several thousands of feet of wellbore casing  36  before reaching the final packer destination. 
   To prevent damage to seal elements  62  and to protect the functionality of packer  60 , covering  40  is applied over well component  30 , as illustrated in  FIG. 6 . Temporary covering  40  provides a protective barrier between seal elements  62  and the surrounding well casing  36  when component  30  is run downhole. A plurality of holes or penetrations  69  may be added to temporary covering  40  to facilitate pressure equalization during run-in and/or during initial pressure cycles. The covering  40  slides along the wellbore wall and serves as a sliding contact to protect the seal elements from the wellbore wall. In the embodiment illustrated in  FIG. 6 , covering  40  can be constructed in the form of sleeve  46  constructed of dissolvable material  44 , as generally illustrated in greater detail in  FIG. 2 . However, the example illustrated in  FIG. 6  also can utilize other embodiments of covering  40 , such as those illustrated in greater detail in  FIGS. 3 and 4 , to protect the one or more seal elements  62 . In this application, temporary covering  40  is designed to protect component  30  and seal elements  62  at least until packer  60  is located at a desired wellbore position for engagement with wellbore casing  36 . After temporary covering  40  dissolves and seal elements  62  are exposed, packer  60  can be actuated to move seal elements  62  against casing  36 . It should be noted that packer  60  may cooperate with other well system components, such as one or more control lines  70  extending longitudinally through the packer. 
   Another embodiment of sacrificial protection element  38  is illustrated in  FIGS. 7 and 8 . In this embodiment, well system  20  comprises a component, e.g. component  28 , having one or more movable parts  72  and one or more fixed parts  74 . Sacrificial protection element  38  is in the form of a temporary element  76  that protects component  28  from premature actuation during transport, running-in hole, or early operation. The temporary element  76  is a dissolvable component that temporarily blocks movement of movable part  72  relative to fixed part  74 , thereby ensuring specific functions of well component  28  become available only after a predetermined amount of time or after other triggering mechanisms have initiated dissolving of temporary element  76 . Once the sacrificial protection element  38  (temporary element  76  in this embodiment) is dissolved, the component can be actuated by relative movement of parts  72  and  74 , as illustrated best in  FIG. 8 . Temporary element  76  can be used to replace, for example, shear shrews or other mechanical locking mechanisms currently used to hold components temporarily in place during transport, run-in, or the early production phase of an operation. 
   The specific components used in well system  20  can vary depending on the actual well application in which the system is used. Similarly, the specific component or components  28 ,  30  protected by sacrificial protection element  38  can vary from one well application to another. Additionally, the specific configuration and formulation of element  38  can be adapted to the specific component covered or otherwise protected, the environmental factors associated with the given well application, and other design considerations. Regardless, sacrificial protection element  38  is designed with sufficient material thickness to provide the component with protection against damage due to impacts and other well related characteristics experienced during the run-in and initial startup procedures and/or with protection against premature actuation of a component before its intended use downhole. 
   Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.