Abstract:
A completion arrangement and methods of using the completion arrangement are described herein. The completion section includes a completion section and impacting formations. The completion section is arranged to be coupled to production tubing, and has means to allow hydrocarbons to pass therein from reservoir rock in which the wellbore is formed. The impacting formations are drivingly moveable relative to the wellbore. The means being arranged to serve as flushing portals, whereby drilling fluid introduced into the production tubing is arranged to flow via the means into a space between the production tubing and the wellbore, and circulate in the space and the impacting formations. One, or both, of the drilling fluid circulating in the space and the impacting formations are arranged to remove obstructing material and formations from the wellbore for return to surface by way of the space, during insertion of the completion arrangement into the wellbore.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a completion arrangement. More particularly, to a completion arrangement for a hydrocarbon and/or an injection well. 
         [0003]    2. Description of the Relevant Art 
         [0004]    When an oil/gas well is drilled, extraction equipment is inserted into an oil/gas reservoir from which oil/gas will be produced to the surface. A bore is drilled into the oil/gas reservoir and production tubing is introduced into the bore. The oil/gas well has then to be “completed”, which entails running a completion section into the well to enable extraction of hydrocarbons from the reservoir for transfer to the surface via the production tubing. It is generally desired that the completion section is ideally located at, or extends into, the bottom (or total depth) of the well. 
         [0005]    A number of “completion” devices exist, for example, “openhole completions”, i.e. where a packer is provided on tubing above an “openhole” (an openhole being an uncased portion of a wellbore), or “inflow control devices”, i.e. a tubing section provided with devices to control flow of fluid from the reservoir to the interior of the tubing section in a producing well and control flow of fluid from the tubing section to the reservoir in an injection well. 
         [0006]    In current completion techniques, when the completion is “run-in” to the well, it is the weight of the completion string that urges the completion to the end of the well. 
         [0007]    However, such techniques are problematic in that the completion may get stuck due to entrained rock and debris accumulated at the head of the completion. Additionally, there may be “burrs” in the openhole section of the well caused by the drilling process, and the completion may also become stuck when it encounters these “burrs”. 
         [0008]    Under the current techniques, if the completion becomes stuck as described above, then remedial actions (such as “jarring” the completion string) are taken to free the completion in an attempt to insert the completion section further into the wellbore. Unfortunately, these remedial actions are not always successful, which leads to the well being completed as is or side-tracked. The problem of the completion becoming stuck is a particular problem in long horizontal wells. 
         [0009]    WO 2008/043985 describes drilling a lower completion into a pre-drilled wellbore with casing liner. A casing liner is a tubular section that conventionally is ‘pushed’ into the pre-drilled hole to total depth. Once to total depth, the casing liner is cemented into place by pumping cement into the space between the reservoir rock and the casing liner (tubular section). The cement is required for structural integrity and to hold the casing liner in place. In order for hydrocarbons to reach the production tubing to flow to the surface, it is necessary that the casing liner be perforated using perforating charges to connect the production tubing space to the reservoir rock. 
         [0010]    The present invention seeks to provide for a completion arrangement having advantages over known such completions. 
       SUMMARY 
       [0011]    In one embodiment, there is provided a completion arrangement for a hydrocarbon wellbore including: a completion section arranged to be coupled to production tubing, and having means to allow hydrocarbons to pass therein from reservoir rock in which the wellbore is formed, the means also arranged to serve as flushing portals, whereby drilling fluid introduced into the production tubing is arranged to flow via the means into a space between the production tubing and the wellbore and circulate in the space; the arrangement further including impacting formations, drivingly moveable relative to the wellbore, wherein one, or both, of the drilling fluid circulating in the space and the impacting formations are arranged to remove obstructing material and formations from the wellbore, for return to surface by way of the space, during insertion of the completion arrangement into the wellbore. 
         [0012]    An advantage of the present invention is that debris around the completion arrangement during an insertion process can be removed by: (i) flushing drilling fluid through the means which, during production, are arranged to allow hydrocarbons to pass into the production tubing from reservoir rock in which the wellbore is formed, but which, during the insertion process, allow drilling fluid to enter a space around the production tubing; and (ii) driving the impacting formations. Thus, with the above two features, the completion section is less likely to become stuck when being “run-in” to the well. 
         [0013]    In one embodiment, the lower completion can be set into the openhole section without cementing. Once the well is put into production, the hydrocarbon from the reservoir rock is drawn into the space created by the openhole packers. The hydrocarbon then flows from the space, through nozzles in the flow restrictors into the production tubing and then on to the surface. If this particular arrangement was to be cemented, then connection between the production tubing and the reservoir will be required via perforating charges. However, in an embodiment, cementing is not required and the stability of the openhole section is maintained by the strength of the reservoir rock. 
         [0014]    In an embodiment, cementing is not required since the type of lower completion serves a different purpose—this is an openhole completion with openhole packers and flow restrictors. 
         [0015]    The invention is further advantageous in that it enhances completion deployment and allows longer completions to be run, thereby providing completion capabilities for extended reach applications. 
         [0016]    The impacting formations are operable to crush, cut, abrade, scrape, pound or grind material and formations in the wellbore. 
         [0017]    In an embodiment, the means to allow hydrocarbons to pass therein from reservoir rock in which the wellbore is formed may include flow restrictors having at least one nozzle. 
         [0018]    In one embodiment, impacting formations include a drill bit or ream-in shoe. 
         [0019]    Conveniently, the impacting formations are operable by rotating the production tubing, to which the impacting formations are coupled via the completion section. 
         [0020]    In an embodiment, the completion arrangement includes a motor coupled between the completion section and the impacting formations and arranged to control operation of the impacting formations. 
         [0021]    The motor includes a mud motor operable by means of drilling fluid supplied thereto through the production tubing and completion section. 
         [0022]    In one embodiment, drilling fluid further serves to lubricate the impacting formations. 
         [0023]    In one embodiment, there is provided production tubing for a hydrocarbon well that includes a completion arrangement as described above. 
         [0024]    In one embodiment, method of completing a hydrocarbon wellbore, includes inserting a completion arrangement into the wellbore, the completion arrangement including a completion section having means for allowing hydrocarbons to pass therein from reservoir rock in which the wellbore is formed and impacting formations, and the means also arranged to serve as flushing portals whereby drilling fluid introduced into completion section via production tubing is arranged to flow via the means into a space between the completion arrangement and the wellbore and circulate in the space ; and introducing drilling fluid into the completion arrangement for flow via the means into the space and/or driving the impacting formations so as to move relative to the wellbore to remove obstructing material and formations from the wellbore during insertion of the completion arrangement into the wellbore. 
         [0025]    In one embodiment, driving includes rotating the production tubing to drive the impacting formations. 
         [0026]    In one embodiment, the method includes locating a motor between the completion section and the impacting formations, and driving includes activating the motor by means of fluid pumped to the motor via production tubing coupled to the completion section such that the motor can operate the impacting formations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The present invention is described further hereinafter, by way of example only, with reference to the accompanying drawings. 
           [0028]      FIG. 1  illustrates a cross-sectional side view of an oil/gas well or an injection well. 
           [0029]      FIG. 2  illustrates a cross-sectional side view of the well of  FIG. 1  into which the present invention is being introduced. 
           [0030]      FIG. 3  illustrates a cross-section side view of the well of  FIG. 1  with the present invention located partially along the well length. 
           [0031]      FIG. 4  illustrates a cross-section side view of the well of  FIG. 1  with a particular arrangement of the present invention located partially along the well length. 
           [0032]      FIG. 5  illustrates a cross-section side view of the well of  FIG. 1  with the present invention located at total depth. 
           [0033]      FIG. 6  illustrates a cross-section side view of the well of  FIG. 1  with an alternative arrangement of the present invention being introduced to the well. 
       
    
    
       [0034]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawing and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0035]      FIG. 1  illustrates an oil/gas well or injection well  10 . The well  10  includes a wellbore  12  which extends from the surface  14  to oil/gas bearing rock  16 . Part of the wellbore  12  is lined with a production casing  18  to support the walls of the wellbore  12  and prevent collapse of the wellbore  12 . The part of the wellbore  12  which extends into the oil/gas bearing rock  16  includes a so-called openhole section  20  which is not lined with production casing. 
         [0036]      FIG. 2  illustrates the same oil/gas well  10 , but with extraction equipment partially introduced into the well in a “running-in” process, i.e. the process whereby extraction equipment is delivered to the oil/gas producing region of the well. This equipment includes production tubing  22  which is located within the production casing  18  and which is formed of a series of tubing sections connected together by means of couplers  24  arranged to couple adjacent sections of tubing sections together. The extraction equipment further includes a completion section  26  coupled to an end of the production tubing  22  and which is arranged, upon well completion, to reside in the portion of the wellbore  18  (i.e. the openhole section  20 ) extending into the oil/gas bearing rock  16 . The completion section  26  is arranged such that fluid can permeate from the surrounding oil/gas bearing rock into an interior section of the completion section  26  such that the fluid can be transferred to the surface  14  via the production tubing  22 . Vice versa for an injection well: the injected fluid is pumped from surface into the production tubing  22  and permeates through the completion section  26  into the reservoir rock  16 . 
         [0037]    In addition to the production tubing  22  and the completion section  26 , the illustrated embodiment of the completion arrangement of the invention includes a drill bit  28  coupled to an end of the completion section  26  remote from the end coupled to the production tubing  22 . The drill bit  28  is located at the “front” face of the completion section  26 , i.e. the face of the completion section  26  which is foremost with respect to its direction of travel into the openhole section  20 . 
         [0038]      FIG. 3  illustrates the same oil/gas well  10  as  FIGS. 1 and 2 . The features illustrated in  FIG. 3  which correspond to features already described in relation to  FIGS. 1 and 2  are denoted by like reference numerals. 
         [0039]    The illustration of  FIG. 3  differs from that of  FIG. 2  in that the production tubing  22  extends further into the wellbore  12 . In  FIG. 2 , the completion section  26  and drill bit  28  are located within the production casing  18  of the lined section of the wellbore  12 . However, in  FIG. 3 , the completion section  26  and drill bit  28  have been inserted further so as to extend into the openhole section  20  of the wellbore  12 . 
         [0040]    The completion section  26  preferably includes a number of different combinations of extraction devices, valves, sensors, measurements, mechanical and swellable packers etc. In a particular arrangement as illustrated in  FIG. 4 , which shows a detailed view of the completion section  26  to illustrate the features thereof, the completion section  26  is made up of openhole swellable packers  200  (for openhole compartmentalisation) and Inflow Control devices (“flow restrictors”  202 ) which serve two purposes: (i) during the “running in” procedure, drilling fluid  204  is pumped from surface down to the drill bit  28  (or ream-in shoe) to circulate and lubricate the completion section  26  during deployment; and (ii) during a production phase, hydrocarbons can enter the completion section  26  from reservoir rock surrounding the completion section  26 , via the flow restrictors  202  and pass therefrom to the surface via production tubing  22  attached to the completion section  26 . Since the flow restrictor  202  is formed with a plurality of nozzles  206  arranged to allow drilling fluid  204  to be injected through the production tubing  22  into a space  208  (which may be annular) around production tubing  22 , this aids in a lubricating process to ease the passage of the completion section  26  into the wellbore. Should the lubrication process fail, or be inadequate to remove debris, etc. and the completion section  26  becomes stuck, the completion section  26  can be rotated by means of surface control (or by a downhole mud motor—see  FIG. 5  and the description relating thereto). However the rotational capability is secondary to the fact that drilling fluid is being flushed across the entire completion section  26 , rather than merely at the drill bit  28 . By efficiently flushing and lubricating across the entire lower completion, this may reduce the need to rotate the drill bit  28 . Debris is carried along the space  208  to surface and since the flow restrictors  200  are passing fluid from the production tubing  22  into the space  208 , this aids in the flushing process. 
         [0041]    The illustrations of  FIGS. 2 ,  3  and  4  are merely schematic “snapshots” of the process of introducing extraction equipment into the well, and the progress of the extraction equipment on its route to the position as illustrated in  FIG. 5 . 
         [0042]    Turning now to  FIG. 5  in detail, there is illustrated the same oil/gas well  10  as in  FIGS. 1 to 4 . Again, features corresponding to those already described are denoted by like reference numerals. 
         [0043]    Here, the completion section  26  and drill bit  28  have reached total depth, i.e. the maximum extent to which the bore has previously been drilled. Once the completion section  26  and drill bit  28  have reached the total depth, the well  10  is effectively “complete” and an oil/gas extraction process can commence without limitation that might occur due to incomplete insertion of the production tubing and completion section. 
         [0044]    The lubrication process has been described above. Now the operation of the drill bit  28  found in the illustrated embodiments of the invention will now be described in more detail. 
         [0045]    As described above, in conventional processes where an oil/gas well is “completed”, the extraction equipment (including a completion section) is introduced into the wellbore, and it is the weight of the completion section and production tubing that urges the completion towards the end of the well (i.e. total depth) and pulls the production tubing behind it. However, and as mentioned above, the presence of “burrs” on the walls of the openhole section of the well which were introduced by the drilling process, or the accumulation of debris in front of the completion section, may cause the completion section to become stuck. Remedial actions (e.g. “jarring”) are possible which can free the completion section for further insertion into the wellbore, but these are not always effective and the well may therefore have to be completed without the completion section reaching total depth. 
         [0046]    By providing a drill bit  28  at the head of the completion section  26 , this allows the completion section  26  to be drilled, or rather reamed into position in the wellbore should the lubrication process fail at some point to ease passage of the completion section into the well. Thus, in the illustrations of  FIGS. 3 to 5  where the completion section  26  and drill bit  28  are in the openhole section  20  of the wellbore  12 , the drill bit can be operated to, for example, remove “burrs” from the walls of the openhole section  20  and/or to remove debris from in front of the combined drill/completion section for transfer to, and removal at, the surface  14 . As noted above, such process is secondary to the main process of providing lubrication by way of drilling fluid  204  passing through nozzles  26  of the flow restrictors  200 . Thus, these features aid in the flushing process to carry debris to surface and to efficiently lubricate the space during deployment. 
         [0047]    In a preferable arrangement, the drill bit  28  is rotated by rotating the production tubing  22  at the surface  14  when the drill bit  28  has reached a pre-detemined depth (e.g. when it has entered the openhole section  20 ). By activating the drill bit, the openhole section  20  is drilled/reamed and this allows the completion section  26  to reach total depth without becoming stuck. 
         [0048]    Another arrangement of the present invention is illustrated in  FIG. 6 . The same well  10  as illustrated in the previous figures is shown and reference numerals for like features remain the same. However, in the arrangement of  FIG. 6 , a motor (preferably a mud motor  30  as illustrated) is provided between the completion section  26  and drill bit  28 . 
         [0049]    The mud motor  30  is arranged to drive and control operation of the drill bit  28  and eliminates the requirement to rotate the production tubing  22  at surface  14  to operate the drill bit  28 . 
         [0050]    It should be appreciated that the drill bit  28  and/or the motor  30  is intended to remain in place once its final depth has been reached. 
         [0051]    The mud motor  30  operates by means of fluid pumped from the surface through the production tubing  22  (denoted by arrows A). This fluid activates the mud motor  30  which, in turn, operates the drill bit  28 . The drill bit  28  preferably includes a number of nozzles  32  to allow the drilling fluid to exit a face of the drill bit  28 . After the drilling fluid has exited through the nozzles  32 , and through nozzles  206  in the flow restrictor  200 , it can lubricate the drill bit  28  and carry the debris from the face of the drill bit  28  back through the space between the production tubing  22  and the walls of the openhole section  20  and between the production tubing  22  and the production casing  28  to the surface  14  (this is indicated by arrows B). 
         [0052]    Advantages of the present invention have been described above although the present invention is particularly advantageous when used in the completion of horizontal wells. 
         [0053]    Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.