Abstract:
A method of completing a subterranean well having a well casing extending though an earth formation is provided, including the steps of: suspending an apparatus at a selected depth within the well casing; creating an unbalanced condition within the well casing; forming a lateral bore in the formation by jetting a pressurized fluid from the apparatus through a casing opening in the well casing and into the earth formation; receiving in the well casing through the casing opening fluid and formation debris created from forming the lateral bore; and lifting the fluid and formation debris received by the well casing upwardly through the well casing to the well surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/IB2011/054841, filed Nov. 1, 2011, which is a non-provisional of U.S. Application No. 61/409,622, filed Nov. 3, 2010. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to methods and systems for enhancing heavy oil productivity from unconsolidated sand reservoirs and, in illustrated embodiments thereof, more particularly relates to a method and apparatus for completion of heavy oil unconsolidated sand reservoirs. 
       BACKGROUND OF THE INVENTION 
       [0003]    Heavy oil production with sand is becoming an increasingly used technique for certain types of heavy oil deposits. Allowing sand production can dramatically improve oil recovery compared to the non-sand production process. The advantage of allowing sand production is that the produced sand creates high permeability zones comprising of relatively small channels for the heavy oil to flow through. However, a challenge with heavy oil production with sand is keeping the sand moving freely and consistently into the wellbore. 
         [0004]    Conventional, explosive charge well perforation or completion which creates relatively small diameter holes in the well casing for the production of formation fluid from the reservoir has experienced sporadic success with heavy oil production with sand. This is attributed to experiencing in-flow problems caused by fine sand and clay migration or reservoir sand sloughing that plugs the small diameter casing holes created by the explosive charge perforation completion process. 
         [0005]    In an attempt to improve well productivity, and to alleviate the plugging problems associated with conventional explosive charge perforation, horizontal drilling and horizontal radial water-jetting methods have been implemented in the completion of unconsolidated sand reservoirs. However, each of these methods has achieved nominal success. It is believe the low success is attributed to performing these methods in an overbalanced condition, that is, in a condition in which fluid pressure in the wellbore is maintained higher than the pressure of the reservoir. In this condition, sand loosened from the horizontal drilling and horizontal radial water-jetting is pushed back into the reservoir. It is believed this causes instability in the manufactured bores and results in eventual collapse or closure of the channel due to sand sloughing. 
         [0006]    Considering the advantage of high permeability verse the challenge of high sand production in heavy oil unconsolidated sand reservoirs a need exists for an improved completion method and apparatus that provides an unrestricted near well-bore access in heavy oil sand producing wells. It is to this need that the present invention is directed. 
       SUMMARY OF THE INVENTION 
       [0007]    In carrying out the principles of the present invention, in accordance with representative embodiments thereof, a well casing perforation and formation boring tool and methods of the same for the completion of a subterranean well, and particularly, a heavy oil unconsolidated sand reservoir in an underbalanced condition is provided. 
         [0008]    Embodiments of the present invention also provide for a low impact completion when compared to conventional explosive charge completions, which alleviate concern of damaging cement encasement that is critical in providing isolation from water zones above or below the productive formation. 
         [0009]    Embodiments of the present invention further provide tools and methods for forming a large well-bore access area and a high permeability lateral bore or cavern deep within the reservoir providing enhanced connection between the well and reservoir. The large sand face or reservoir contact area provided by the high permeability bore reduces reservoir fluid velocities and is believed to minimize or eliminate problematic sand and clay production. 
         [0010]    Embodiments of the present invention further provide tools and methods that can be implemented on existing completed wells that are experiencing problematic in-flow or poor production due to near well bore formation damage. 
         [0011]    To achieve these and other advantages, in general, in one aspect, a method of completing a subterranean well extending through an earth formation is provided, including the steps of: creating an underbalanced condition in the well; providing a nozzle in the well; and pumping a pressurized fluid through the nozzle such that a jet of the pressurized fluid ejects from the nozzle and impinges on the earth formation creating a lateral bore in the earth formation. 
         [0012]    The method may further include the steps of: providing a flexible hose to which the nozzle is attached and extending the flexible hose fitted with the nozzle into the earth formation from the well. 
         [0013]    In general, in another aspect, a method of completing a subterranean well having a well casing extending though an earth formation is provided, including the steps of: suspending an apparatus at a selected depth within the well casing; creating an unbalanced condition within the well casing; forming a lateral bore in the formation by jetting a pressurized fluid from the apparatus through a casing opening in the well casing and into the earth formation; receiving in the well casing through the casing opening fluid and formation debris created from forming the lateral bore; and lifting the fluid and formation debris received by the well casing upwardly through the well casing to the well surface. 
         [0014]    In general, in another aspect, a method of completing a subterranean well having a well casing extending through an earth formation is provided, including the steps: providing a well perforation and completion tool including a body having a circumferential wall, an internal axial flow passage extending through an end of the body and terminating through the circumferential sidewall forming a side port, one or more lateral ports extending through the circumferential wall and providing fluid communication between the internal axial flow passage and a position exteriorly of the body, and an abrasive jet perforation nozzle disposed in each of the lateral ports; suspending the well perforation and completion tool at a selected depth within the well casing; pumping a high pressure abrasive fluid through the internal axial flow passage such that a jet of the high pressure fluid ejects out of each of the perforation nozzles to form a perforation in the well casing; moving the well perforation and completion tool in the well casing while maintaining the azimuth position of the well perforation and completion tool relative to the well casing while pumping the high pressure fluid to form a casing slot through the well casing; configuring the well perforation and completion tool for well completion; creating an underbalanced condition in the well casing; extending a hose having attached thereto an excavation nozzle from the apparatus through the side port and through the casing slot and into the earth formation; and pumping a pressurized excavation fluid through the hose such that a jet of the pressurized excavation fluid ejects out of the excavation nozzle and impinges the earth formation to form a lateral bore in the earth formation while extending the hose. 
         [0015]    In general, in another aspect, a casing perforation and formation boring tool for use in connection with the completion of a subterranean well is provided, the tool including: a body having a circumferential wall, an internal axial flow passage extending through an end of the body and terminating through the circumferential sidewall forming a side port, one or more lateral ports extending through the circumferential wall and providing fluid communication between the internal axial flow passage and a position exteriorly of the body, and a landing seat disposed across the internal axial flow passage at a position between the one or more lateral ports; the internal axial flow passage configured to receive a tube therein; the landing seat configured to receive a blanking plug to isolate the one or more lateral ports from the side port; and an abrasive perforation nozzle disposed in each of the one or more lateral ports. 
         [0016]    In an aspect, the tool may also include a flexible hose disposed and extensible within the internal flow passage; a hydraulic excavation nozzle connected to a downhole end of the flexible hose; and a guide wheel guiding the distal end of the flexible hose through the side port. 
         [0017]    In an aspect, the tool may also include a pipe disposed within the internal axial flow passage; a pipe coupling connect to an top hole end of the pipe; and a hydraulic excavation nozzles connected to a downhole end of the pipe, the hydraulic excavation nozzle aligned with the side port and configured to jet a stream of pressurized fluid flowing through the pipe. 
         [0018]    In an aspect, the tool may also include an alignment tab carried by the body and extensible between a retracted position and an extended position. 
         [0019]    There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. 
         [0020]    Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting. 
         [0021]    As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
         [0022]    For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The following drawings illustrate by way of example and are included to provide further understanding of the invention for the purpose of illustrative discussion of the embodiments of the invention. No attempt is made to show structural details of the embodiments in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Identical reference numerals do not necessarily indicate an identical structure. Rather, the same reference numeral may be used to indicate a similar feature of a feature with similar functionality. In the drawings: 
           [0024]      FIGS. 1A-C  are cross-sectional views of successive axial portions of a well casing perforation and formation boring tool embodying principles of an embodiment the present invention, the tool being shown in a first configuration for well casing perforation; 
           [0025]      FIGS. 2A-B  are cross-sectional views of successive axial portions of the well casing perforation and formation boring tool of  FIGS. 1A-C , the tool being shown in a second configuration for formation boring; 
           [0026]      FIGS. 3A-C  are cross-sectional views of successive axial portions of a well casing perforation and formation boring tool embodying principles of another embodiment the present invention, the tool being shown in a first configuration for well casing perforation; 
           [0027]      FIGS. 4A-B  are cross-sectional views of successive axial portions of the well casing perforation and formation boring tool of  FIGS. 3A-C , the tool being shown in a second configuration for formation boring; 
           [0028]      FIG. 5  is a schematic well diagram illustrating a method of perforating a well casing of a subterranean well, the method embodying principles of an embodiment of the invention; 
           [0029]      FIG. 6  is a schematic well diagram illustrating a method of boring a channel into a subterranean formation from the well, the method embodying principles of an embodiment of the invention; 
           [0030]      FIG. 7  is a diagrammatic perspective view of an exemplary hydraulic excavation nozzle; 
           [0031]      FIG. 8  is a diagrammatic rear view of the hydraulic excavation nozzle of  FIG. 7 ; 
           [0032]      FIG. 9  is a schematic tool diagram embodying principles of an embodiment the present invention; and 
           [0033]      FIG. 10  is a schematic tool diagram embodying principles of an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    As a preliminary matter, it should be noted that in this document (including the claims) directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., without departing from the principles of the invention. 
         [0035]    Representatively illustrated in  FIGS. 1A-C  is a well casing perforation tool and formation boring tool  10  in accordance with an embodiment of the invention. Tool  10  is shown in a well casing perforation configuration and includes a tool body  12  having an abrasive jet perforation sub  14 , a landing nipple  16 , a jetting shoe  18  and a wiper sub  20  each disposed coaxially and in series from the abrasive jet perforation sub to the wiper sub. Body  12  further includes an internal axial flow passage  22  extending through the abrasive jet perforation sub  14 , the landing nipple  16  and partially through the jetting shoe  18  where the internal axial flow passage includes a lateral bend and extends through the circumferential wall of the jetting shoe forming a side port  24 . 
         [0036]    The abrasive jet perforation sub  14  has at least one, and preferably has a plurality of lateral ports  26  extending through the circumferential wall thereof. In one embodiment, there are three lateral ports  26  arranged in a triangular configuration. In another embodiment, there are four lateral ports  26  arranged in a boxed or diamond configuration. The lateral ports  26  provide fluid communication between the internal axial flow passage  22  and a position exteriorly of the abrasive jet perforation sub  14 . An abrasive jet perforation nozzle  28  is disposed in each of the lateral ports  26  for the passage of the high pressure abrasive cutting fluid used to cut a slot into the well casing and cement encasement as will be further described below. Lateral ports  26  and nozzles  28  are preferably configured to cut a one-inch wide slot through the well casing and cement encasement. 
         [0037]    Further, it is of importance to note, the lateral ports  26  and the side port  24  are disposed on the same side of body  12  and are generally vertically aligned about the circumference of the body. 
         [0038]    Landing nipple  16  connects the abrasive jet perforation sub  14  and the jetting shoe  18  and provides a landing seat  30  across the internal axial flow passage  22  for the reception of a removable blanking plug  40  to seal the internal axial flow passage and isolate the jetting shoe from a flow of fluid through the internal axial flow passage in a well casing perforation operation as will be described in further detail below. The blanking plug  40  may include a fishing neck  41  to permit retrieval of the blanking plug through known methods. 
         [0039]    Jetting shoe  18  is configured to receive the passage of an extensible hydraulic excavator ( FIGS. 2A-C ) that includes a flexible high pressure hose fitted with a high pressure fluid nozzle that is run-in from the well surface in a formation boring operation as will be described in further detail below. The jetting shoe  18  includes a hose guide wheel  32  that is rotatably supported by the body  12  and partially intersects with the internal axial flow passage  22 . The guide wheel  32  serves to guide the flexible high pressure hose run through the internal flow passage  22  with the side port  24  where it can be extend through the side port and into the formation during said formation boring operation. 
         [0040]    Jetting shoe  18  further includes an extensible alignment tab  34  that laterally moves relative to the jetting shoe between a retracted position, shown in  FIG. 2 , and an extending position for registration with a perforation slot cut into the well casing by the abrasive jet perforation sub  14  during said well casing perforation operation. In an embodiment, the alignment tab  34  is biased into the extended position. The alignment tab  34  may be spring biased by one or more coil springs  36 . In a preferred embodiment, alignment tab  34  is disposed vertically below side port  24  with reference to the orientation of the tool  10  as illustrated in the figures. It is important to note, alignment tab  34  is located along the same side of body  12  as the lateral ports  26  and the side port  24  and is generally vertically aligned about the circumference of the body with the lateral ports and the side port. 
         [0041]    Wiper sub  20  is attached to the bottom of the jetting shoe  18  and includes one or more radially extending seal members  38 . The seal member  38  is configured to making a circumferential sealing contact with the internal surface of the well casing and provides well casing isolation from lower completion zones. 
         [0042]    In  FIGS. 2A-B , tool  10  is illustrated in a second configuration which is a formation boring configuration, wherein the blanking plug  40  is removed and an extensible hydraulic excavator  42  is disposed in the internal axial fluid passage  22 . The extensible hydraulic excavator  42  includes a high pressure flexible hose  44  having a hydraulic excavation nozzle  46  fitted at its distal end and is connected at the opposite end to coiled tubing  48 . The high pressure flexible hose  44  is disposed about guide wheel  32  with the hydraulic excavation nozzle  46  aligned with side port  24 . As will be further described, advancement of the coiled tubing  48  at the surface of the well causes the high pressure flexible hose  44  to extend from the jetting shoe  18  through side port  24  as illustrated in dashed line. Similarly, retraction of the coiled tubing  48  causes the high pressure flexible hose  44  to retract into the jetting shoe  18 . Rotating guide wheel  32  ensures the high pressure flexible hose  44  is extended and retracted through side port  24  without being kinked or snagged by the jetting shoe  18 . 
         [0043]    An alternate embodiment  18   a  of the jetting shoe  18  is shown in  FIGS. 3A-C  and is incorporated in an alternate embodiment  10   a  of the previously described tool  10 . In  FIGS. 3A-C , tool  10   a  is illustrated in the well casing perforation configuration. Further, like reference numbers refer to similar elements of the embodiments, and accordingly, to avoid duplication will not be described here. Jetting shoe  18   a  is devoid of guide wheel  32  and opposed to an extensible hydraulic excavator, jetting shoe  18   a  is fitted a fixed hydraulic excavator  50  that is disposed within internal axial flow passage  22 . Fixed hydraulic excavator  50  includes a fixed stand pipe  52  fitted at the top or surface end with a coil on/off tool  54  and at the opposite end a high pressure hydraulic excavation nozzle  56 . The coil on/off tool  54  permits the downhole connection of a coiled tube with the stand pipe  52  for the delivery of a high pressure fluid to the excavation nozzle  56 . The excavation nozzle  56  is fixedly disposed at side port  24  and is directed to eject a high pressure stream from the side port towards the formation in a formation boring operation. 
         [0044]    In  FIGS. 4A-B , tool  10   a  is illustrated in a second configuration which is a formation boring configuration, wherein the blanking plug  40  is removed and the stand pipe  52  of the fixed hydraulic excavator  50  is connected by coil on/off tool  54  to a length of coiled tubing  58  run into the internal axial flow passage  22 . 
         [0045]    Turning now to  FIG. 5 , well casing perforation will be described utilizing tool  10  configured in the well casing perforation configuration that is illustrated in  FIGS. 1A-C  and discussed above. In  FIG. 5 , there is schematically illustrated a conventional well bore  60  having a well casing  62  and cement encasement  64  extending through an oil bearing formation  66 , and particularly, a heavy oil unconsolidated sand formation. Tool  10  is schematically illustrated for purpose of illustrative clarity, and is connected to a distal end of a length of upset tubing  68  or the like at the top end of the abrasive jet perforation sub  14 . Tool  10  is lowered into the well casing  62  by tubing  68  to a depth at which it is desired to perforate the well casing and the cement encasement  64  and complete a lateral bore into the adjacent formation  66 . Once the tool  10  is positioned at the desired depth, a high pressure abrasive fluid  70  is pumped through tubing  68  and into the internal axial flow passage  22  of the tool. The Blanking plug  40  isolates the jetting shoe  18  from the abrasive jet perforation sub  14  causing the high pressure abrasive fluid  70  to flow through lateral ports  26  and jet out from the perforation nozzles  28  under high pressure and impinge against the wall of the well casing  62  and cement encasement  64 . Tool  10  is then alternately moved upwardly (withdrawn) and downwardly (extended) in the well casing  62  to cut a casing slot  72  through the well casing and cement encasement  64 . Tool  10  is moved a distance corresponding to the desired overall height of the casing slot  72 . Once the casing slot  72  is cut, tool  10  is configured for formation boring by the retrieval of blanking plug  40  for example, by running length of coiled tubing (not shown) through tubing  68  to connect to the blanking plug and withdraw it from tool  10  and pull it to the surface, thereby permitting running of the extensible hydraulic excavator. 
         [0046]    Turning now to  FIG. 6 , formation boring will be described utilizing tool  10  configured in the formation boring configuration that is illustrated in  FIGS. 2A-B  and discussed above. Tool  10  is schematically illustrated for purpose of illustrative clarity, and remains connected to tubing  68 . Tool  10  is moved upwardly (withdrawn) in the well casing  62  causing guide tab  34 , which is pressed against the interior surface of the well casing via the biasing force of springs  36 , to automatically extend into and engage casing slot  72  (as shown here). The engagement of the guide tab  34  with the casing slot  72  registers the side port  24  of the jetting shoe  18  with the casing slot. 
         [0047]    With the guide tab  34  in this position, the extensible hydraulic excavator  42  is connected to tubing  48  and comprising hose  44  and nozzle  46  is run-in through tubing  68  and internal axial flow passage  22 . Upon the nozzle  46  reaching the guide wheel  32 , the nozzle and the hose  44  are fed through the side port  24  and through the casing slot  72 , at which it is positioned and oriented laterally against the formation  66  in which a lateral bore radially extending from the well bore  60  is to be completed. 
         [0048]    At this point, the well bore  60  is placed into an underbalanced condition, wherein the pressure within the well casing  62  is lower than the formation pressure, by a continuous injection of stable foam through tubing  68  and the internal axial flow passage  22  where it is ejected from the side port  24 . The stable foam  74  is returned to the surface through well casing  62 . Once the stable foam  74  is initially returned to the surface, pressurized fluid, such as, for example water is then pumped through tubing  48 , through hose  44  and jetted from nozzle  46  where it impinges against the unconsolidated sand formation  66  forming a lateral bore  76  therein. The underbalanced condition of the well bore  60 , as result of the injection of stable town  74 , causes sand slurry and fluids, admixed with the stable foam, to flow outwardly from the lateral bore  76  and into the well casing  62  through the casing slot  72 . Once in the well casing  62 , the sand slurry, fluid and stable foam are further mixed within a mixing chamber  78  defined by a lateral recessed profile  80  in the exterior circumferential wall of the jetting shoe  18  and the well casing  72 . The recessed profile  80  is further illustrated in  FIG. 1B  by the region bounded by the dashed lines. At this point, the stable foam, sand and fluid slurry is lifted to the surface of the well bore  60 . 
         [0049]    The hose  44  and nozzle  46  are fed continuously into the unconsolidated sand formation  66  from the tool  10  until a lateral bore  76  reaches a desired radial depth from the well bore  60 . The hose  44  and nozzle  46  may be alternately withdrawn and extended (guided by guide wheel  32 ) to achieve the desired radial depth, which may be up to 150-feet. As this operation continues, an increasing volume of sand is flushed into the well casing  62  creating a high permeability bore  76  deep into the unconsolidated sand formation  66 . 
         [0050]    Once bore  76  reaches a desired depth, water jetting injection is terminated, and the hose  44  and nozzle  46  are withdrawn into the jetting shoe  18  and the excavator  42  is withdrawn from tool  10  and pulled to the surface. Stable foam injection continues until the surface returns are clear of sand providing an indication that completion at this interval is finished, and at which point, the stable foam injection is terminated. Tool  10  is then withdrawn slowly causing the alignment tab  34  to be retracted once it reaches the top of the casing slot  72 . Tool  10  may be withdrawn a certain distance to align the tool with another completion zone or may be completely withdrawn from the well bore  60 . In multiple completions with tool  10 , the lowest or deepest zone would be completed first with successive zones being completed at the tool is withdrawn. The wiper sub  20  isolates completed zones as the tool  10  is withdrawn and is operated to complete a subsequent zone. 
         [0051]    The above description in reference to methods of operating tool  10  and the above description of tool  10   a  with reference to  FIGS. 3A-C  and  FIGS. 4A-B  are believed to be sufficient to understand the operation of tool  10 . a . The main distinction being the fixed excavator  50  of tool  10   a  is disposed within the internal axial flow passage  22  prior to tool  10   a  being run-in to the well casing  62 . Of course, the fixed excavator  50  does not extend a hose or excavation nozzle radially into the formation as does the extensible excavator  42  of tool  10   a . Accordingly, tool  10  is considered to be primarily used for deep formation penetration and tool  10   a  is considered to be primarily used for shallow formation penetration. 
         [0052]    Further, it should be noted excavation nozzles  46  and  56  may be of any known type or conventional in the art. In an embodiment, and for example, as illustrated in  FIGS. 7 and 8 , nozzle  46  may include one more thruster discharge ports  78  disposed on a rearward end of the nozzle. Thruster discharge ports  78  operate to jet streams of fluid from the nozzle  46  in a rearwardly direction relative to the nozzle which causes the nozzle  46  to be propelled in a forwardly direction. Nozzle  46  also includes one or more excavation discharge ports  80  disposed on a forwarded end of the nozzle. Ports  80  operate to jet streams of fluid from the nozzle  46  in a forwardly direction relative to the nozzle for the purpose of hydraulic excavating material disposed forward of the nozzle. 
         [0053]    With reference to  FIG. 9 , the jetting shoe  18  can be configured to be run-in separately of the abrasive perforation sub  14  and the nipple  16 , in restoring or cleaning operations in existing wells to improve well production by cleaning casing perforations or further opening of formation bores. In such a configuration, tubing  68  would be connected to the jetting shoe  18  to lower the jetting shoe in the well casing to the desired depth. Extensible excavator  42  would be operated as discussed above, in either an underbalanced or overbalanced well condition. Jetting shoe  18   a  can be configured similarly to jetting shoe  18  as shown in  FIG. 10 . 
         [0054]    A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.