Abstract:
A completion system, including a tubular string initially having an substantially constant first dimension and configured to include at least one unexpanded portion having the first dimension and at least one expanded portion having a second dimension larger than the first dimension. The tubular string has at least one opening therein formed at the at least one expanded portion. At least one screen assembly is included having a third dimension and positioned radially adjacent the at least one expanded portion. A radial clearance is formed between the outer dimension of the at least one screen assembly and the second internal dimension of the at least one second portion of the outer tubular string. A method of completing a borehole is also included.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 61/739,606 filed Dec. 19, 2012, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     Screen assemblies are ubiquitous in the downhole drilling and completions industry for enabling solids or particulate to be filtered from a flow of fluid, e.g., hydrocarbons, while enabling production of the fluid. Production and stimulation rates through the screen assemblies can be generally increased by increasing the size of the screen assembly. Additionally, it is well established that certain radial clearances between the outer dimension of the screen assembly and the inner dimension of the casing (or other tubular string) in which the screen assembly is positioned must be maintained in order to support stimulation and/or production at appropriate rates. For example, if the radial gap is undesirably small, there is a severe risk of premature screen outs and/or the sand or particulate in a frac or gravel pack bridging off before filling the annulus about a screen assembly. For the above reasons, it is established practice in the industry to use screen assemblies having dimensions that are significantly smaller than the drift diameter of the casing in order to maintain the aforementioned radial clearance in the range of about at least 0.5 inches. 
     Although maintaining the radial clearance is necessary to support industry accepted production and stimulation rates, it also puts a limit on the maximum possible size of the screen assemblies, which negatively impacts these same rates. The simultaneous use of a larger screen assembly and maintenance of the radial clearance is only possible in these prior systems by using larger casing, but this requires greater material costs and potentially a larger borehole. In view hereof, it is clear that the industry would well receive a system that enables larger screen assemblies to be used within a given size of casing without negatively affecting production and stimulation rates, e.g., by reducing the size of the radial clearance between the screen assembly and the casing to an unacceptable level. 
     SUMMARY 
     A method of completing a borehole, including selectively expanding a tubular string having a substantially continuous first dimension to form at least one expanded portion of the tubular string having a second dimension greater than the first dimension and at least one unexpanded portion of the tubular string having the first dimension; and positioning at least one screen assembly radially proximate to the at least one expanded portion for forming an enlarged radial gap between the at least one screen assembly and the expanded portion of the tubular string. 
     A completion system, including a tubular string having an internal drift dimension and including at least one expanded portion having an expanded internal dimension larger than the internal drift dimension, the tubular string having at least one opening therein formed at the at least one expanded portion; and at least one screen assembly having an outer dimension approximating the internal drift dimension, the at least one screen assembly positioned radially aligned with the at least one expanded portion, wherein the outer dimension and the expanded dimension form a radial clearance therebetween being at least about 0.5 inches. 
     A method of completing a borehole, including selectively expanding a tubular string having a substantially continuous first dimension to form at least one expanded portion of the tubular string having a second dimension greater than the first dimension and at least one unexpanded portion of the tubular string having the first dimension; and positioning at least one screen assembly radially proximate to the at least one expanded portion for forming an enlarged radial gap between the at least one screen assembly and the expanded portion of the tubular string. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is a cross-sectional view of a completion system disclosed herein having a liner hung from an upper completion string; 
         FIG. 2  is a cross-sectional view of the completion system of  FIG. 1  being selectively radially expanded to form at least one expanded portion and at least one unexpanded portion; 
         FIG. 3  is a cross-sectional view of the completion system of  FIG. 2  having an annulus between a casing and a borehole being cemented; 
         FIG. 4  is a cross-sectional view of the completion system of  FIG. 3   
         FIG. 5  is a cross-sectional view of the completion system of  FIG. 4  having a screen assembly positioned radially proximate each of the expanded portions for forming an enlarged radial gap between the screen assembly and the corresponding expanded portion; and 
         FIG. 6  is a cross-sectional view of an alternate embodiment disclosed herein wherein an expanded portion corresponds to multiple screen assemblies. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Methods for deploying a downhole production system can be best appreciated in view of  FIGS. 1-5 , in which a completion system  10  is progressively completed. In  FIG. 1 , a casing  12  or other outer tubular of the completion system  10  comprises a production liner  14  or other tubular string that is hung, anchored, or suspended from an upper casing string  16 , which may extend to surface or be a liner or other intermediate casing string. The casing  12  is arranged within a borehole  18 , which is drilled and completed according to any suitable method known or discovered in the art. The borehole  18  may include vertical as well as deviated or horizontal portions. An annulus  20  is formed between the casing  12  and the borehole  18 . As will be better appreciated in view of the below disclosure, the liner  14  in the illustrated embodiment has a restricted inner diameter in relation to the upper casing string  16 , which disadvantageously affects production and stimulation rates. Namely, as discussed in the Background, it is well established that some minimum radial clearance between the casing and any screen assemblies positioned therein must be maintained in order to support production and/or stimulation at acceptable rates. 
     After arranging the casing  12 , e.g., hanging or anchoring the liner  14  from or to the casing string  16 , the liner  14  is selectively radially expanded. By selectively expanded, it is meant that portions of the liner  14  are dimensionally enlarged, i.e., plastically deformed, in the radial direction in order to form at least one expanded portion  22  and at least one unexpanded portion  24 . In the illustrated embodiment, a plurality of the expanded portions  22  is interspaced with the unexpanded portions  24 . The liner  14  has an initial drift dimension (e.g., internal diameter) designated D 1 , which drift dimension D 1  is maintained by the unexpanded portions  24 . The expanded portions  22  are radially expanded to an expanded internal dimension (e.g., internal diameter) designated D 2 , which is greater than the internal drift dimension D 1 . The term drift dimension or drift diameter is used with its ordinary meaning in the art, namely, relating to the effective or minimum dimension of the liner  14 , i.e., such that any component smaller than the drift dimension can be run through the tubular (liner, casing, etc.). In accordance with this understood definition, the drift diameter or dimension D 1  may differ slightly from the actual diameter or dimension of the liner  14 . In the illustrated embodiment, the internal dimension D 2  of the expanded portions  22  is less than the diameter of the casing string  16 , while in another embodiment the internal dimension D 2  may exceed the internal diameter of the upper casing string  16  or another section of the casing  12 . 
     For the purposes of discussion herein, the term expansion is generally interchangeable with swage, deform, enlarge, and other synonyms thereof. Accordingly, the selective expansion of the casing  12 , more specifically of the liner  14  of the casing  12 , can be accomplished by any suitable swage, wedge, cone, or other device that is actuatable or transitionable between a retracted or retractable configuration that enables the device to be run through the liner  14  without deforming the unexpanded portions  24  and a radially extended or supported configuration that enables the expanding device to expand the portions  22 . The actuation or transition between these two configurations could be provided via any suitable mechanism in any suitable manner, e.g., mechanical, hydraulic, electrical, etc. U.S. Pat. No. 6,352,112 (Mills), which patent is incorporated herein by reference in its entirety, provides an example of a selectively supported swage device that could be adapted for selectively expanding the portions  22  of the liner  14  without expanded the unexpanded portions  24 . Those of ordinary skill in the art will recognize that other devices are also suitable for the purpose of selective expansion as described herein. The swaging device could be run into the casing  12  in the same trip as the liner  14 , or a separate trip. The swaging could be performed from bottom-up, from top-down, or combinations thereof for each section desired to be swaged. 
     It is noted that the timing of the swaging process could be different than that described above. For example, in one embodiment, the swaging or expansion of the liner  14  occurs at surface before, or simultaneously with, run-in of the liner  14  as opposed to after it is already set downhole. In one embodiment, the expanded portion is formed by removing wall thickness of the liner  14 , such that the outer dimension remains consistent while the dimensions D 1  and D 2  still differ. Multiple sections of the liner  14  could be coupled together in such an embodiment, e.g., threadedly, to form multiple alternating ones of the portions  22  and  24 . In one embodiment, the expanded and unexpanded portions  22  and  24  are each formed from separate components having different dimensions that are affixed together, e.g., threaded, in order to form the liner  14 , which is then run-into and secured to the upper casing string  16 . 
     The annulus  20  radially about the casing  12  may be cemented according to any suitable technique, e.g., pumping cement down through the interior of the casing  12  (or another tubular run therewith) and forcing it back up through the annulus  20 , thereby filling the annulus  20 . In one embodiment the cementation occurs after expanding the portions  22 , while in another embodiment, the expansion occurs immediately after pumping the cement before it has a chance to cure and harden. In the illustrated embodiment, a liner lap  25  at the junction between the liner  14  and the casing string  16  is specifically not swaged and forms one of the unexpanded portions  24 . Advantageously, not swaging the liner lap  25  during the selective swaging process improves the hydraulic performance of a cement pumping operation that may occur subsequent to the selective swaging process with respect to if the liner lap  25  were also swaged. 
     After cementation, a perforation gun or other assembly for forming openings in the liner  14  is positioned with respect to the expanded portions  22  in the liner  14  and triggered in order to form a plurality of perforations  26  through the liner  14  and the cement in the annulus  20 . Any style of perforating gun could be used and delivered downhole in any desired manner, e.g., coiled tubing, wireline, etc. The perforations  26  provide fluid communication between a downhole formation  28  through which the borehole  18  is formed and an interior passageway  30  of the casing  12 . This fluid communication enables fluid, such as hydrocarbons, to be produced from the downhole formation  28  and/or fluid to delivered to the downhole formation  28 , e.g., in order to stimulate, fracture, or treat the formation to facilitate later production therefrom (generally, “stimulate”). It is noted that in other embodiments, particularly those in which cementation is not required, that the liner  14  or other portion of the casing  12  could be pre-arranged with perforations or other openings in order to save time and avoid an additional perforation trip. 
     Once fluid communication is established, an inner string  34 , e.g., a production string, can be run including one or more screen assemblies  36 . The string  34  and the screen assemblies  36  may resemble a traditional multi-zone frac system or any other system arranged for enabling the stimulation of and/or production from a downhole formation. In the illustrated embodiment, one of the screen assemblies  36  is provided for each of the expanded portions  22 , which may in turn be associated individually with production zones. A packer  38  or other seal device is arranged on the inner string  34  and arranged to engage against each unexpanded portion  24  in order to isolate the screen assemblies  36  and/or their corresponding zones from each other. The screen assemblies  36  are arranged with a filter or mesh  40 , e.g., wire wrap screen, narrow slots, permeable foam, etc., in order to impede the passage of solids, e.g., sand, therethrough while permitting fluid flow. The screen assemblies  36  can each be provided with a first valve  42  arranged for enabling selective fluid communication directly with the formation  28  (bypassing the filter or mesh  40 ), e.g., in order perform a treatment, stimulation, fracturing, or other operation on the formation  28 , and a second valve  44  arranged for enabling selective fluid communication through the mesh or filter  40  of the screen assemblies  36 , e.g., in order to produce fluid from the formation  28  as well as create a circulation flow path for a gravel or frac pack or other stimulation or treatment operation. The valves  42  and  44  can be opened and/or closed due to hydraulic pressure, engagement with a shifting tool, a dropped plug or ball, or in any other desired manner or combinations thereof. 
     As noted above, fluid production and stimulation rates of a downhole completion are limited by the size, e.g., diameter, of the screen assemblies used. That is, smaller screens are associated with smaller base pipes and/or production strings having relatively restricted internal flow passages therethrough, which restricts fluid flow for production and stimulation. Furthermore, a minimum radial clearance, as noted above, between the outside of the screen assembly and the inner drift dimension of the casing must be maintained in order to support acceptable stimulation and/or production rates. Advantageously, with specific reference to the system  10 , the swaging of the portions  22  of the liner  14  at which the screen assemblies  36  are positioned, enables the outer dimension (e.g., outer diameter) of the screen assemblies, designated D 3  in  FIG. 5 , to approximate or approach the internal drift diameter D 1  of the liner  14  and the unexpanded portions  24 , while still providing the required radial clearance between the screen assemblies and the casing. By the outer dimension D 3  “approximating” the internal dimension D 1  it is not meant that the outer dimension D 3  is some arbitrary amount from the internal dimension D 1 , but is rather meant that the outer dimension D 3  is either at or sufficiently close to the drift dimension D 1  so that the aforementioned necessary minimum radial clearance between the screen assemblies  36  and the liner  14  cannot maintained. However, the dimensions D 1  and D 3  may differ slightly, e.g., due to manufacturing tolerances, to accommodate seal elements (e.g., the packers  38 ), to facilitate run-in of the screen assemblies  36 , etc. In accordance to the above, a gap or clearance  46  is shown in  FIG. 5 , formed as the difference between the dimension D 3  of the screen assemblies  36  and the dimension D 2  of the expanded portions  22 . It is to be appreciated that the Figures are not shown proportionally and that the clearance  46  may be several times or even orders of magnitude larger than the difference between the dimensions D 1  and D 3 . By the dimension D 3  of the screen assemblies  36  approximating the dimension D 1 , the necessary radial clearance  46  between the screen assemblies  36  and the unexpanded portions  24  of the liner  14  is not be maintained, and acceptable production and stimulation rates are only supported by positioning the screen assemblies  36  radially proximate to the expanded portions  22 . In one embodiment, the radial clearance  46  is about at least 0.5 inches, as radial clearances of significantly smaller sizes are not typically tolerated in the downhole industry. 
     An alternate embodiment, designated as a system  10 ′, is shown in  FIG. 6 . In this embodiment, the liner  14  is swaged such that two zones or areas are associated with the same swaged portion, designated as a swaged portion  22 ′. In such an embodiment, if isolation is desired between adjacent screen assemblies, e.g., screen assemblies  36   a  and  36   b , then a packer  38 ′ is required that is larger than the packers  38 . For example, the packer  38 ′ could be swellable in response to a fluid such as water or oil, inflatable, radially extendable due to axial compression or removal of a retaining band, etc., in order to transition from a first size suitable to bypass the unexpanded portions  24  and yet still be able to engage with the expanded portion  22 ′. 
     In view of the foregoing, it is to be appreciated that the current invention is particularly advantageous for gravel and frac pack systems, and other systems for which the industry mandates a sufficient radial clearance (e.g., about half an inch or larger) between the screen assemblies and the outer tubular or casing housing the screen assemblies. Even more particularly to systems similar to those illustrated in which screen assemblies are positioned in a relatively smaller dimensioned string, e.g., the liner  14 , which is hung or suspended from a relatively larger dimensioned upper string, e.g., the upper casing  16 . That is, the relatively smaller dimensioned string, e.g., the liner  14 , in which the screen assemblies are placed would typically result in either the size of the screen assemblies to be reduced or that of the radial gap between the screen assemblies and the inner surface of the casing, but this issue is avoided by the current invention. It is also to be understood that although the current invention is particularly advantageous in such situations, the casing or other outer tubular string may not have a relatively smaller dimensioned string hung from a relatively larger outer dimensioned string. Even in this embodiment, the overall dimension of the casing or outer tubular can be reduced, thereby saving material costs, while still producing at the same rate as a traditional system having a larger outer dimension. That is, the size of the casing or outer tubular only needs to be set as just large enough for the screen assemblies to be located therein without need to accommodate for the radial gap between the screen assemblies and inner dimension of the casing, as the desired radial gap is achieved by the above-described swaging process. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.