Patent Grant
8267173
This invention relates, in general, to completing a wellbore that traverses a subterranean hydrocarbon bearing formation and, in particular, to an open hole completion apparatus and method for use of same.
Without limiting the scope of the present invention, its background will be described in relation to fracpack and gravel pack systems for use in completing wellbores in open hole subterranean hydrocarbon bearing formations, as an example.
Fracpacks and gravel packs are commonly performed during the completion of oil and gas wells. During these operations, a completion string including one or more sand control screens is typically run downhole and positioned adjacent to the production interval. A service tool is positioned inside of the completion string to provide a conduit for pumping fluids downhole.
In general, the fracpack operation is used to stimulate well production by pumping liquid under high pressure down the well into the reservoir rock adjacent to the wellbore to create fractures therein. Propping agents or proppants suspended in the high-pressure fluids are used to keep the fractures open, thus facilitating increased flow into the wellbore. In addition, the proppants fill the annulus between the screens and the casing to provide a first layer of filtration, which restricts formation sand migration. The gravel pack operation is commonly used in unconsolidated or loosely consolidated reservoirs for sand control. The gravel pack slurry is pumped down the well into the annulus between the screens and the casing while taking fluid returns to the surface, thereby minimizing fluid loss into the formation. The gravel pack provides a packed sand layer in the wellbore, which restricts formation sand migration.
It has been found, however, that for certain completions, installation of casing and the associated cementing process may be undesirable. For example, in deepwater wells, it may be preferable to complete the wells open hole. One reason for this preference is the risk of experiencing a problem in a cased hole completion that requires the completion to be abandoned. In such a situation, an alternative wellbore may be sidetracked from the existing cased hole wellbore, however, the subsequent wellbore must be completed using smaller diameter equipment. This reduction in hole size not only limits production capabilities but also diminishes the ability to perform desired treatment operations, such as fracpack operations, as the service tool ratings for the smaller diameter tools limits the flow rates and proppants volumes that can be delivered. One way to avoid this problem and to maintain the larger hole size even when a sidetrack is required, is by completing the wells open hole.
It has been found, however, the certain problems arises when gravel packing or fracpacking in open hole environments. For example, when the gravel pack or fracpack slurry is pumped out of the crossover assembly and the closing sleeve, the slurry immediately come in contact with the formation. As the slurry is commonly injected at a location uphole of the particular zone of interest, the liquid portion of the slurry may leak off into an undesired portion of the formation, which dehydrates the slurry and may cause sand bridges to form in the wellbore. These sand bridges not only result in a failed pack but may also cause the service tool to become stuck within the completion string if the slurry dehydration takes place proximate to and inside the closing sleeve.
Therefore, a need has arisen for a system and method of completing open hole wells. A need has also arisen for such a system and method that allows for formation stimulation and sand control in open hole completions. Further, need has arisen for such a system and method that prevents slurry dehydration proximate to and inside the closing sleeve during such treatment operations.
The present invention disclosed herein comprises a system and method of completing open hole wells. The system and method of the present invention allows for formation stimulation and sand control in open hole completions and prevents slurry dehydration proximate to and inside the closing sleeve during such treatment operations.
In one aspect, the present invention is directed to an open hole completion apparatus for use in a wellbore. The apparatus includes an outer tubing string that is at least partially disposed in an open hole portion of the wellbore. The outer tubing string includes at least one sand control screen and a shrouded closing sleeve having at least one fluid port. An inner tubing string is at least partially disposed within the outer tubing string. The inner tubing string includes a crossover assembly having at least one fluid port that is selectively in fluid communication with the at least one fluid port of the shrouded closing sleeve. The shrouded closing sleeve has a shroud that creates a channel with a portion of the outer tubing string by extending over the at least one fluid port of the shrouded closing sleeve toward the at least one sand control screen. With this configuration, when a treatment fluid, such as a fracpack fluid slurry or a gravel pack fluid slurry, is pumped through the inner tubing string, the crossover assembly and the at least one fluid port of the shrouded closing sleeve, the treatment fluid is injected into the wellbore remote from the at least one fluid port of the shrouded closing sleeve.
In one embodiment, the outer tubing string includes first and second packers that are disposed respectively uphole and downhole of the at least one sand control screen and the shrouded closing sleeve that provide zonal isolation for the system. In another embodiment, the shrouded closing sleeve includes a closing sleeve operable to allow and prevent fluid communication between the at least one fluid port of the crossover assembly and the at least one fluid port of the shrouded closing sleeve. In this embodiment, the inner tubing string may be used to operate the closing sleeve between the open and closed positions.
In one embodiment, the shroud, which may be a thin-walled tubular member, directs the treatment fluid in a downhole direction in the channel, which may be substantially annular. In another embodiment, the shroud extends downhole to a location proximate a first end of the at least one sand control screen, such that when the treatment fluid is pumped through the inner tubing string, the crossover assembly and the at least one fluid port of the shrouded closing sleeve, the treatment fluid is injected into the wellbore proximate the first end of the at least one sand control screen.
In another aspect, the present invention is directed to a shrouded closing sleeve for completing an open hole wellbore. The shrouded closing sleeve includes a tubular housing having at least one fluid port in a sidewall portion thereof. A closing sleeve is operable to allow and prevent fluid communication through the at least one fluid port. A shroud, disposed exteriorly of the tubular housing, creates a channel with a portion of the tubular housing by extending over the at least one fluid port in a first direction, such that when a treatment fluid is pumped from an interior to an exterior of the tubular housing through the at least one fluid port, the treatment fluid travels in the first direction in the channel.
In a further aspect, the present invention is directed to a method for completing an open hole wellbore. The method includes setting a plurality of packers to isolate at lease one zone, pumping a treatment fluid through an inner tubing string, a crossover assembly and at least one fluid port of a shrouded closing sleeve, directing the treatment fluid away from the at least one fluid port in a channel created by a shroud of the shrouded closing sleeve and injecting the treatment fluid into the wellbore remote from the at least one fluid port. The method may be repeated for each of the isolated zones by relocating the inner tubing string, including the crossover assembly, relative to other shrouded closing sleeves and zones in the wellbore.
For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.
In the following description of the representative embodiments of the invention, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In general, “above”, “upper”, “upward” and similar terms refer to a direction toward the earth's surface along a wellbore, and “below”, “lower”, “downward” and similar terms refer to a direction away from the earth's surface along the wellbore. Additionally, the term “upstream” refers to a direction farther from the bottom or end of the wellbore, whether it be vertical, slanted, or horizontal; and the term “downstream” refers to a direction closer to the bottom or end of the wellbore, whether it be vertical, slanted, or horizontal.
Referring initially to
Importantly, even though
Continuing with
Note that, in this specification, the terms “liner” and “casing” are used interchangeably to describe tubular materials, which are used to form protective linings in wellbores. Liners and casings may be made from any material such as metals, plastics, composites, or the like, may be expanded or unexpanded as part of an installation procedure, and may be segmented or continuous. Additionally, it is not necessary for a liner or casing to be cemented in a wellbore. Any type of liner or casing may be used in keeping with the principles of the present invention.
Outer tubing string 56 may include one or more packers 44, 46, 48, 50 that provide zonal isolation for the production of hydrocarbons in certain zones of interest within wellbore 32. When set, packers 44, 46, 48, 50 isolate zones of the annulus between wellbore 32 and outer tubing string 56. In this manner, formation fluids from formation 14 may enter the annulus between wellbore 32 and outer tubing string 56 in between packers 44, 46, between packers 46, 48, and between packers 48, 50. Additionally, fracpack and gravel pack slurries, also known as proppant slurries, may be pumped into the isolated zones provided therebetween.
In addition, outer tubing string 56 includes sand control screen assemblies 38, 40, 42 that are located near the lower end of tubing string 56 and substantially proximal to formation 14. As shown, packers 44, 46, 48, 50 may be located above and below each set of sand control screen assemblies 38, 40, 42.
Further, outer tubing string 56 includes shrouded closing sleeves 66, 68, 70 that provided a pathway such as a channel or an annular area that prevents proppant slurry from contacting the surface of formation 14 until the proppant slurry travels downhole to a desired location, such as near or proximal to one of screen control screen assemblies 38, 40, 42. Preferably, shrouded closing sleeves 66, 68, 70 are each located in a zone of interest defined by packers 44, 46, 48, 50.
It should be understood by those skilled in the art that the open hole fracpack mechanisms of the present invention may be used in a wellbore having any number of zones of interest. For example,
Referring now to
An annulus 86 is formed between casing 34 and outer tubing string 56 that is sealed by gravel pack set packer 82 at its upper or upstream end. Additionally, annulus 86 extends downwardly or downstream through the open hole of wellbore 32 and outer tubing string 56. Another annulus 88 is formed between outer tubing string 56 and a working string referred to herein as an inner tubing string 84. Inner tubing string 84 further includes an inner central passageway 100 for flowing a treatment fluid such as a fracpack or gravel pack fluid slurry referred to herein as a proppant slurry 90 to a particular zone of interest, as further described herein.
As shown, the present open hole fracpack mechanism 80 includes a shrouded closing sleeve 91. Shrouded closing sleeve 91 includes shroud 92, one or more frac ports 94 and a sliding sleeve 96. Shroud 92 is disposed concentrically about the outer surface of outer tubing string 56. Preferably, shroud 92 provides an annular region or other passageway or passageways, which is referred herein as channel 98, between the outer surface of outer tubing string 56 and the inner surface of shroud 92.
Frac ports 94 are disposed through outer tubing string 56, thus providing a passageway for proppant slurry 90 to flow into channel 98 of shroud 92. As can be seen, shroud 92 is attached, affixed, formed or may be integral with outer tubing string 56 just above or upstream of frac ports 94, thus providing a pathway for proppant slurry 90 to flow outward from frac ports 94, through channel 98 and downward or downstream to opening 154 of shroud 92.
Open hole fracpack mechanism 80 further includes a closing sleeve 96 that is slidably positioned or disposed between outer tubing string 56 and inner tubing string 84 such that it may be actuated to move relative to frac ports 94 for opening and closing the passageway provided by frac ports 94. As illustrated in
Open hole fracpack mechanism 80 further includes a sand control screen assembly 102 for filtering proppant from proppant slurry 90. Sand control screen assembly preferably includes a screen portion 104 and a base pipe 106 that may provide a channel 108 therebetween such that filtered fluid 148 is transmitted to one end of sand control screen assembly 102 where a valve 110 is located. The upstream or upper end of sand control screen assembly is shown located substantially proximal to opening 154 of shroud 92. As shown in
Open hole fracpack mechanism 80 also includes a pair of packers 111, 112 for sealing annulus 86 to provide zonal isolation. Packers 111, 112 may be any type of packer commonly used and known by those skilled in the art, however, swellable packers that expand upon contact with an activation fluid may be preferred in the open hole environment due to the non-uniform and uneven surface of the formation.
In a lower portion of the illustrated open hole fracpack mechanism 80, as best seen in
Frac ports 118 are disposed through outer tubing string 56, thus providing a passageway for proppant slurry 90 to flow into channel 152 of shroud 120. As can be seen, shroud 120 is attached, affixed, formed or may be integral with outer tubing string 56 just above or upstream of frac ports 118, thus providing a pathway for proppant slurry 90 to flow outward from frac ports 118, through channel 152 and downward or downstream to opening 156 of shroud 120.
Closing sleeve 122 is slidably positioned or disposed between outer tubing string 56 and inner tubing string 84 such that it may be actuated to move relative to frac ports 118 for opening and closing the passageway provided by frac ports 118. As illustrated in
Open hole fracpack mechanism 80 further includes a sand control screen assembly 128 for filtering proppant 150 from proppant slurry 90. Sand control screen assembly 128 preferably includes a screen portion 132 and a base pipe 130 that may provide a channel 131 therebetween such that filtered fluid 148 is transmitted to one end of sand control screen assembly 128 where a valve 134 is located. The upstream or upper end of sand control screen assembly 128 is shown located substantially proximal to opening 156 of shroud 120. As shown in
Open hole fracpack mechanism 80 also includes a pair of packers 112, 136 for sealing annulus 86 and to provide zonal isolation. Packers 112, 136 may be any type of packer commonly used and known by those skilled in the art, however, swellable packers the expand upon contact with an activation fluid may be preferred in the open hole environment due to the non-uniform and uneven surface of the formation.
Open hole fracpack mechanism 80 includes a crossover assembly 114 positioned within inner tubing string 84. Crossover assembly 114 may be selectable to move fluids, such as proppant slurry 90 from inner central passageway 100 to annulus 88, for example. Crossover assembly 114 may also be selectable to move fluids from inner central passageway 100 to annulus 86 as further described below. Preferably, crossover assembly 114 is sealed against outer tubing string 56 by one or more seal elements 116 to provide a fluid tight engagement therebetween. In the illustrated embodiment, three seal elements 116 are shown; however, any number of seal elements may be used. In addition, open hole fracpack mechanism 80 includes one or more seal elements 146 slidably disposed between inner tubing string 84 and outer tubing string 56. In this manner, proppant slurry 90 flowing from crossover assembly 114 is forced through frac ports 118.
In
As shown in
As noted above/open hole fracpack mechanism 80 may include any number of shrouds 92, 120 and they preferably include a portion that extends radially outwardly from outer tubing string 56. They may be sealed, formed, fastened, or otherwise affixed to the outer surface of outer tubing string 56 at a location that is proximal but upstream of frac ports 94, 118. As noted above, they may extend radially outward from this point where they are sealed or joined to outer tubing string 56. This radial extension may be substantially perpendicular or slanted relative to outer tubing string 56.
The longitudinal portion of shrouds 92, 120 extends from this point downwardly or downstream to a point that is substantially proximal to sand control screen assemblies 102, 128, respectively. The longitudinal portion of shrouds 92, 120 extend substantially parallel to wellbore 32 to a point where the openings 154, 156 are proximal to a zone of interest. For example, the zones of interest relative to
It should be understood by those skilled in the art that the longitudinal portions of the shrouds of the present invention may be any length desired so long as they are of sufficient length to inject the proppant slurry to a location in the wellbore that is remote from the frac ports of the shrouded closing sleeves, i.e., a location in the wellbore sufficiently distant from the frac ports that dehydration of the proppant slurry does not occur at or near the frac ports. For example, the length of the longitudinal portions of shrouds of the present invention may extend for several sections of tubing making up the outer tubing string or may be only a few feet, depending on factors such as completion string configuration, formation characteristics, the type of proppant slurry to be pumped, the flow rate and pressure at which the proppant slurry will be delivered and the like.
Shrouds 92, 120 may be formed separately and then affixed to outer tubing string 56 prior to running it into wellbore 32. In another example, shrouds 92, 120 may be formed as a unitary part of outer tubing string 56. Generally, shrouds 92, 120 are of a substantially cylindrical shape reflecting the outer tubing string 56 in which they are disposed about. Preferably, they are thin-walled and made from a material, such as steel, that is sufficiently rigid to run into wellbore 32 along with outer tubing string 56 without becoming deformed.
In one embodiment, closing sleeves 96, 122 may be actuated by lifting or otherwise moving inner tubing string 84 upstream such that shifters actuate closing sleeves 96, 122. In another embodiment, closing sleeves 96, 122 may be actuated remotely by wired or wireless communication to a remote motor or actuator, for example.
Seal elements 116, 146 may consist of any suitable sealing element or elements, such as a packing stack with one or more O-rings either alone or in combination with backup rings and the like. In various embodiments, seal elements 116, 146 may comprise AFLAS® O-rings with PEEK back-ups, Viton® O-rings, nitrile O-rings or hydrogenated nitrile O-rings or other suitable seal.
Referring collectively to
When inner tubing string 84 is initially run into wellbore 32, a float shoe 141 is attached to its lower end. In the illustrated embodiment, inner tubing string 84 may be attached to float shoe 141 using plug 142, which initially provides a seal in a profile 143 and is preferably coupled to float shoe 141 with pins or other suitable attachment members. After this assembly is positioned at the desired depth, outer tubing string 56 may be run to its desired depth and attached to the upper end of float shoe 141. Once in this configuration, a downward force on inner tubing string 84 may be used to shear the pins, thus freeing plug 142 from float shoe 141. Inner tubing string 84 may now move upwardly within outer tubing string 56. Preferably, inner tubing string 84 is moved upwardly to position plug 142 in the radially expanded region 144 of float shoe 142. In this position, fluid may be circulated through float shoe 141 as desired. Once packers 112 and 136 are set, inner tubing string 84 is moved upwardly to position plug 142 in profile 145 providing a seal therein. Further upward movement inner tubing string 84 releases plug 142, as best seen in
In one embodiment, inner tubing string 84 may be further lifted or picked up further such that shifter 126 opens closing sleeve 122 and shifter 138 opens valve 134. Once these elements are opened, inner tubing string 84 may be lowered downstream to a position as best seen in
During the lowering operation, seal elements 116 and seal elements 146 seal between inner tubing string 84 and outer tubing string 56. Proppant slurry 90 is then pumped down inner central passageway 100 to crossover assembly 114 where it crosses over to channel 152 via opened closing sleeve 122 and frac ports 118. Proppant slurry 90 then flows between shroud 120 and outer tubing string 56 as shown in
The proppant 150 contained within proppant slurry 90 is now deposited or packed between formation 14 and sand control screen assembly 128, the results of which are depicted in
Once a first zone of interest has been treated, inner tubing string 84 may be picked up or lifted to the next zone of interest as best seen in
The proppant contained within proppant slurry 90 is now deposited or packed between formation 14 and sand control screen assembly 102 (not shown). The fluid portion of proppant slurry 90 is filtered through sand control screen assembly 102. Filtered fluid 148 then flows to opened port 110 where it exits and flows into annulus 88 and then toward open end 140 of inner tubing string 84. Filtered fluid 148 then flows up through inner central passageway 100 toward crossover assembly 114 where it crosses over to annulus 88 and then flows further upward or upstream where it may exit annulus 88 into annulus 86 via an exit port (not shown) located above gravel pack set packer 82, for example. This operation may continue until a desired amount of proppant has been deposited or packed between sand control screen assembly 102 and formation 14.
Although, the above operations have been described relative to a fracpacking operation, the present open hole fracpack mechanism 80 may be used in gravel packing operations as well. In one embodiment, shrouds 92, 120 direct proppant slurry 90 to substantially the top or upstream portion of sand control screen assembly 128 and sand control screen assembly 102, respectively, but fluid returns are allowed during the entire operation resulting in the packing of the wellbore regions surrounding sand control screen assembly 128 and sand control screen assembly 102 without fracturing the formation.
While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.
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