Abstract:
A method for drilling and completing a well includes the steps of drilling through a subterranean formation with a drill bit so as to form a well bore having a side wall; applying a consolidating material to the side wall under pressure so that said consolidating material flows into the side wall and provides a coated side wall coated with the consolidating material; and passing a scraping member having a desired profile past the coated side wall so as to provide the coated side wall with the desired profile an apparatus is also provided.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a method and apparatus for drilling and completing a well and, more particularly, to a method and apparatus for simultaneous drilling and completion which allows for simplified drilling and easier data acquisition and transmission. 
     In the industry of producing hydrocarbons such as crude oil and gas from subterranean formations, wells are drilled from a surface location to the hydrocarbon bearing formation so as to allow production of the hydrocarbon. 
     Conventional drilling techniques involve the use of a drilling bit to drill-through various formations utilizing drilling mud which is circulated through a pipe to the drill bit and then back through the well to the surface. The drilling mud helps drill through the desired formation and serves as a vehicle for carrying cuttings from the formation back to the surface. 
     Drilling mud must be carefully weighted so that the weight of the column of fluid in the well is sufficient to balance formation pressure encountered during drilling. If this is not carefully maintained, high pressure formations can cause various undesirable disruptions in the drilling process. On the other hand, if the drilling fluid is too heavy, drilling fluid can invade and adversely affect potentially hydrocarbon producing formations. 
     Conventional wells are drilled in sections. After a particular length of a well is drilled, it is conventional to remove the drilling equipment and position a pipe or casing into the well. This casing is then cemented in place, and further drilling can then be carried out through the cemented cased section of the well. Although the casing resolves any potential problems with formation pressure in the drilled section, it should be readily apparent that this reduces the diameter of the originally-drilled hole, and therefore requires that the next section be drilled with a smaller drill bit. The end result is an ever-decreasing size of the well which of course is not desirable. Further, the need for cementing strings of casing into the well delays the drilling procedure and results in an added expense for the cost of pipe and equipment for positioning same. 
     Horizontal drilling is a development in the drilling art whereby wells are drilled at angles other than substantially vertical so as to reach other desired locations and/or position a well with maximum possible flow area in a producing formation. Unfortunately, horizontal drilling leads to still further complication in connection with positioning and cementing casing into the well. 
     Another disadvantage of conventional drilling techniques is that the casing, when positioned in the hole, is subject to corrosion, and may be adversely affected by erosion as well. Further, the casing can interfere with communication of electronic devices from the well into the formation, for example during logging and other procedures designed to obtain information about the well and formations which the well has been drilled through. 
     Based upon the foregoing, it is clear that the need remains for improved processes and devices for drilling and completing wells. 
     It is therefore the primary object of the present invention to provide such a method and apparatus. 
     It is a further object of the present invention to provide a method and apparatus which eliminates the need for conventional casing. 
     It is still another object of the present invention to provide a method and apparatus whereby the well does not have a gradually decreasing diameter. 
     It is yet another object of the present invention to provide a method and apparatus whereby the well is completed substantially simultaneously with drilling whereby balancing of formation pressure is not necessary. 
     Other objects and advantages of the present invention will appear hereinbelow. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, the foregoing objects and advantages have been attained. 
     According to the invention, a method is provided for drilling and completing a well which method comprises the steps of drilling through a subterranean formation with a drill bit so as to form a well bore having a side wall; applying a consolidating material to said side wall under pressure so that said consolidating material flows into said side wall and provides a coated side wall coated with said consolidating material; and passing a scraping member having a desired profile past said coated side wall so as to provide said coated side wall with said desired profile. 
     In further accordance with the present invention, a drilling assembly for drilling and completing a well has been provided, which assembly comprises a drill bit member having a forward end for drilling through a subterranean formation; a drilling fluid conduit for conveying drilling fluid from surface to said forward end; a recycle conduit for receiving a mixture of said drilling fluid and cuttings from said formation at said drilling end and for conveying said mixture to surface; a consolidating material port positioned behind said forward end for applying consolidating material to walls of a well bore drilled by said forward end; a consolidating material conduit for feeding consolidating material from surface to said consolidating material port; and a consolidating material scraping member having a desired profile and positioned behind said consolidating material port for providing consolidating material on said walls with said desired profile. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A detailed description of a preferred embodiment of the present invention follows, with reference to the attached drawings, wherein: 
     FIG. 1 is a side schematic view of a drilling bit assembly in accordance with the present invention; and 
     FIG. 2 is a side schematic view of a drilling and completing method in accordance with the present invention utilizing the drilling assembly of FIG. 1; and 
     FIGS. 3 a-c  further illustrate the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     The invention relates to a drilling bit assembly and method which advantageously allow for substantially simultaneous drilling and completion of a well. 
     FIG. 1 shows a side schematic view of a drilling assembly  10  in accordance with the present invention. As shown, drilling assembly  10  is preferably a substantially elongate member having a drilling bit  12  defined at one end thereof. Drilling assembly  10  also includes a drilling fluid inlet  14  for feeding drilling fluid to assembly  10 . Drilling fluid is fed to drilling fluid inlet  14  through conventional means, typically through a pipe a portion  16  of which is shown in FIG.  1 . Drilling fluid is conveyed from inlet  14  through assembly  10  to drilling bit  12 , and is preferably discharged from drilling bit  12  through openings  18  so that drilling fluid is contacted with a geological formation through which bit  12  is being used to drill. Drilling assembly  10  also includes an inlet  20  for recycling drilling fluid back to the surface. This is particularly desirable since drilling. fluid entrains formation cuttings and other debris resulting from the drilling operation, and recycling the drilling fluid to the surface allows removal of such debris from the well. Inlet  20  leads to a recycled fluid conduit  22  which is advantageously vented to outside of drilling assembly  10  through outlets  24  as shown. 
     In accordance with the present invention, drilling assembly  10  advantageously is adapted for conveying consolidating material for use in establishing a completed wall along a well being drilled, and this consolidating material advantageously replaces conventional casing and the like and the need for conventionally placing and cementing such casing in the hole. 
     In accordance with the present invention, drilling assembly  10  has a conduit  26  for conveying consolidating material through assembly  10  to one or more ports  28  for feeding consolidating material to a well. As shown, consolidating material ports  28  are positioned behind drilling bit  12  such that consolidating material is disposed on walls of the well bore immediately after drilling. In accordance with the invention, consolidating material is advantageously fed through conduit  26  to ports  28  at a “over pressure”, or a pressure which is designed and selected to minimally exceed formation pressure, such that consolidating material invades or permeates the surrounding formation to an extend sufficient to help anchor consolidating material in place. 
     In further accordance with the invention, drilling assembly  10  further advantageously includes a scraping member  30  positioned behind ports  28  and having a profile, preferably a round profile, which is selected to provide for a final desired profile of the well being drilled and completed. Scraping member  30  is positioned behind ports  28  such that consolidating material coated on walls of the well from ports  28  can then be scraped to provide an inner profile matching the profile of scraping member  30  as desired. Scraping member  30  may advantageously be any suitably-shaped member formed into the outer wall of assembly  10 , or may advantageously be provided as a collar-type member that can be removed from and secured to drilling assembly  10  using conventional means and as desired. 
     FIG. 1 schematically shows the various conduits utilized in accordance with this embodiment of the present invention for independently feeding drilling fluid, recycling drilling fluid and cuttings, and feeding consolidating material. As shown, consolidating material is fed through conduit  26 , which preferably branches into conduits  26   a  and  26   b , each of which lead to ports  28  as desired. Further, recycled fluid conduit  22  passes from inlet  20  through drilling assembly  10  and extends, in this embodiment, between conduits  26   a  and  26   b  and eventually branches off into outlets  24  as shown. In accordance with the invention, drilling assembly  10  has an inner wall  32  defining an inner space through which each of these conduits are positioned. Inner wall  32  defines, in combination with conduits  22  and  26 , an annular space which defines the inlet conduit for drilling fluid. As shown, drilling fluid is introduced between pipe  16  and conduit  26  and flows around conduits  22  and  26  toward drilling bit  12  to openings  18 . 
     It should be noted that drilling bit  12  in accordance with the present invention may be any of numerous different types of drilling bits. For example, drilling bit  12  could be a conventional mechanical drilling bit. In addition, other methods of drilling such as laser or ultrasonic can be used, and any type of drill bit or drilling method would be acceptable in accordance with the invention. 
     In accordance with a preferred embodiment of the present invention, recycled fluid conduit  22  is advantageously provided with a grinding member  34  which is schematically illustrated in FIG.  1 . Grinding member  34  advantageously serves to break up any large portions of cuttings, debris and the like which may be entrained in recycled drilling fluid so as to reduce the size of such debris to a size acceptable for flowing upwardly through drilling assembly  10 . Grinding member  34  may be any suitable conventional devices will be well known to a person of ordinary skill in the art. 
     Recycling fluid conduit  22  may further advantageously be provided with a pump member  36 , which is also schematically illustrated in FIG. 1, for creating vacuum at inlet  20  so as to pull drilling fluid and entrained debris into inlet  20  as desired. 
     Injection ports  28  may suitably be any type of acceptable jet nozzle and the like, which can advantageously be used to distribute consolidating material at the desired over pressure in accordance with the present invention. 
     Turning to FIG. 2, a method for drilling utilizing assembly  10  in accordance with the present invention is illustrated. FIG. 2 shows assembly  10  being used to drill through a formation  38 . Drilling bit  12 , as shown, forms a well bore  40  having a wall  42 . During drilling, drilling fluid  44  is fed to drilling assembly  10  and exits drilling bit  12  through openings  18  to facilitate drilling as desired. Drilling fluid mixes with cuttings and debris to form a mixture  46  which is pulled into inlet  20  and passed through conduit  22  for recycling to the surface. Mixture  46  is then preferably fed through grinding member  34  and pump  36  (both illustrated in FIG.  1 ), if desired and/or necessary and is eventually discharged from drilling assembly  10  through outlets  24  as shown for further recycling up through the completed well. 
     While drilling is being carried out, a consolidating material  48  is advantageously fed to conduit  26  and through conduit branches  26   a  and  26   b  to ports  28  wherein consolidating material  48  is disposed as a coating on wall  42 . As shown, consolidating material  48  is applied at an over pressure such that a portion invades the surrounding formation, and this is illustrated in FIG. 2 by showing an invaded zone  50  into which consolidating material  48  has permeated the formation. Zone  50  advantageously enhances the secure positioning of consolidating material  48  within the well as desired. After application of consolidating material, scraping member  30  passes downwardly and serves to provide consolidated material  48  coated on wall  42  with a desired uniform profile. 
     Depending upon the consolidating material selected and various downhole conditions, it may be desirable to cure consolidating material applied to the well bore before scraping. Curing can be carried out utilizing any of a variety of known external energy techniques such as ultraviolet, heat, laser, electromagnetic and/or microwave curing and the like. 
     From a consideration of the foregoing, it should be readily appreciated that assembly  10  in accordance with the present invention advantageously allows for simultaneous drilling and completion of a well to any desired depth, without the need for casing and the interruption in drilling required for positioning of same. 
     It should further readily be appreciated that a well completed utilizing the assembly and method of the present invention advantageously has enhanced capability for data acquisition and data transmission, thereby allowing for enhanced knowledge of well characteristics. 
     Still further, the method and assembly of the present invention allow for substantially immediate completion of the well, as it is drilled, thereby greatly reducing the chance for problems incurred due to high pressure formations, and reducing and/or avoiding the need for carefully monitoring of fluid densities and the like. 
     The consolidating material used in accordance with the present invention may be any suitable material. The consolidating material is preferably a set table or curable material which is environmentally friendly, and which can be handled and injected in a fluid phase. Further, it is preferred that the consolidating material have a cementing agent which has a controllable and short curing time, preferably which can be controlled by pH and/or-water concentration, and which can be enhanced by means of external energy sources such as ultraviolet, heat, laser, electromagnetic wave and the like. The consolidating material may further suitably have elasticity properties which can be controlled or tailored by varying amounts of specific components, and is further preferably an electrically conductive structure, that is, a structure which does not interfere with communication of electronic devices within the well. Suitable electrical conducting structure would include cementing agent, lithic matrix and ceramic coating. 
     Consolidating material preferably has a collapse resistance of greater than about 1 Mpa, an internal yield resistance of greater than about 60 Mpa, low porosity and permeability (preferably as close to zero as possible), and a curing time of less than about 1 hour. 
     When permeable formations are being drilled through, the over pressure utilized is sufficient to partially invade the surrounding formation and anchor or secure the consolidating material in place. When drilling through low or non-permeable formations, it may be desirable to select the consolidating material so as to have adhesive qualities so as to anchor the material in place utilizing adhesive mechanisms instead. 
     As shown in FIG. 2, well bore  40  is drilled having a diameter conforming to the size of drilling bit  12 , and the completed well has a single diameter the entire length of the well which is smaller than the diameter of the well bore by the thickness of completing material disposed on wall  42  in accordance with the present invention. 
     Upon completion of the well, the drill bit or tool must be removed through a hole which is of a narrow diameter than that through which the bit has drilled. Alternatively, the drill bit may be left in the hole. 
     In accordance with one embodiment of the invention, a drill bit structure is provided which has a collapsible outside diameter such that cutting elements, debris inlet, drilling seal, and the like of the tool can be longitudinally stretched or lengthened and diametrically withdrawn so as to allow drilling bit  12  to be removed. 
     FIGS. 3 a, b  and  c  show one embodiment of such a drill bit  12 . 
     In this embodiment, drill bit  12  has drilling seal members  60  which are provided in segments, and are adapted for radial expansion and contraction. Longitudinally positionable sealing wedges  62  are provided which can be positioned between drilling seals  60  (FIG. 3 c ), or removed from position between drilling seals  60  (FIGS. 3 a ,  3   b ), to allow the drilling tool to be expanded or withdrawn as desired. Coupling legs  64  can advantageously be cooperated with different members  66  of the drill string and used to control the diameter of. the drilling tool. In the embodiment shown in FIGS. 3 a-c , drill string  66  is connected to a stretchable or resilient element  68  which is connected to drilling seal members  60 . Upon upward movement of drill string  66 , stretchable element  68  stretches longitudinally while coupling legs  64  pull sealing wedges  62  from between drilling seal members  60 . Once the sealing wedges  62  are removed from between drilling seals  60 , as shown in FIG. 3 b , drilling seal member  60  can then collapse radially inwardly to the position as shown in FIG. 3 a , at which point the drilling tool can be removed through the hole. Thus, drilling bit  12  in this embodiment is positionable between a relatively large diameter drilling configuration (FIG. 3 c ) and a relatively small diameter removal configuration (FIG. 3 a ) whereby bit  12  can be removed from a hole completed according to the invention. 
     Alternatively, a disconnect member can be positioned between the drill string and the drilling bit, which can be used to disconnect and leave the drill bit portion of the drilling assembly at the bottom of the hole, if preferable. In some instances, this may be desirable based upon a cost analysis for the drilling bit as compared to the cost of conventional tubing, cementing and the like. Any conventional disconnect structure would be used for this purpose. 
     It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope as defined by the claims.