Patent Publication Number: US-11377933-B2

Title: Shunt tube system for gravel packing operations

Description:
TECHNICAL FIELD 
     The present disclosure relates to shunt tube systems used in gravel packing operations of hydrocarbon well systems. More specifically, this disclosure relates to mixing chambers positioned between sections of shunt tubing in the shunt tube systems used in the gravel packing operations that are external to sand screens. 
     BACKGROUND 
     In hydrocarbon-producing wells, sand screens may be used to filter sand and other debris from production fluids produced from the hydrocarbon well to a surface. To further filter the sand and other debris from the production fluids, an annulus between the sand screen and a wall of the hydrocarbon well may be packed with gravel, sand, or proppant. The gravel, sand, or proppant for a gravel pack filling the annulus may be provided to an appropriate location using multiple shunt tubes. If one of the shunt tubes become blocked or otherwise unusable, a gravel packing operation may continue with one less usable shunt tube. Completing the gravel packing operation with one less usable shunt tube may result in an increase in friction losses in the remaining shunt tubes, and the increased friction losses may limit a maximum achievable gravel packing length of the gravel packing operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an example of a well system that includes a series of sand screens with a shunt system according to some aspects of the present disclosure. 
         FIG. 2  is a side view of the shunt system of  FIG. 1  positioned externally along a portion of a sand screen tubular according to some aspects of the present disclosure. 
         FIG. 3  is a perspective view of a mixing chamber of the shunt system of  FIG. 2  according to some aspects of the present disclosure. 
         FIG. 4  is a flowchart of a process for mixing slurry within the shunt system of  FIG. 1  according to some aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Certain aspects and examples of the disclosure relate to shunt tube systems used for gravel packing operations within a wellbore that are positioned external to a sand screen assembly. Positioning the shunt tubes external to the sand screen assembly may increase an available size of the shunt tubes transporting slurry for the gravel packing operation without occupying space within a tubular of the sand screen assembly used to produce wellbore fluids to a surface of a wellbore. In an example, slurry is defined as a clean carrier fluid with concentrations of particulate (e.g., gravel, sand, or proppant) suspended within the clean carrier fluid. The shunt tube system may include a mixing chamber positioned external to a joint between two sand screen assemblies. In another example, the mixing chamber may be positioned external to a sand screen assembly or in any other external location in relation to the sand screen assembly. Transmission tubes of the shunt system may couple to jumper tubes of the mixing chamber to provide paths for ingress and egress of slurry to and from the mixing chamber. 
     Providing a mixing chamber between two sections of transmission tubes enables mixing of the slurry from multiple parallel transmission tubes at defined intervals. Accordingly, any imbalances in slurry proppant concentration between the multiple parallel transmission tubes may be reduced when the slurry fluids from the multiple parallel transmission tubes are mixed in the mixing chamber and output to downhole sets of parallel transmission tubes. Further, the mixing chamber may enable a bypass of a plug in one of the transmission tubes resulting from a buildup of proppant in the transmission tube. Bypassing the plug with the mixing chamber enables the slurry to continue flowing through the downhole sets of parallel transmission tubes. Providing the bypass to the plug may reduce friction losses in the shunt tube system and improve a maximum achievable gravel packing length by reestablishing a maximum total number of usable transmission tubes after the mixing chamber when one of the transmission tubes along a previous section of a sand screen was rendered unusable due to the plug. 
     Balancing proppant concentrations of transmission tubes and bypassing a plugged transmission tube may result in increased reliability of the shunt tube system. Accordingly, implementing the shunt tube system described herein may result in increases in consistency of a gravel pack around a sand screen within a wellbore. Further, the shunt tube system may provide an increase in reliability of a gravel packing operation within the wellbore. 
     These illustrative examples are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts. The following sections describe various additional features and examples with reference to the drawings in which like numerals indicate like elements, and directional descriptions are used to describe the illustrative aspects but, like the illustrative aspects, should not be used to limit the present disclosure. 
       FIG. 1  is a cross-sectional view of an example of a well system  100  according to some aspects. The well system  100  may include a wellbore  102  with a generally vertical section  104  that transitions into a generally horizontal section  106  extending through a subterranean earth formation  108 . In an example, the vertical section  104  may extend in a downhole direction from a portion of the wellbore  102  having a cemented in casing string  110 . A tubular string, such as a production tubing string  112 , may be installed or extended into the wellbore  102 . 
     One or more sand screens  114  and one or more packers  118  may be interconnected along the production tubing string  112 , such as along tubulars  119  positioned along the horizontal section  106  of the wellbore  102 . The tubulars  119  may be attached to a downhole end of the production tubing string  112 . The packers  118  may seal an annulus  120  located between the tubulars  119  and walls of the wellbore  102 . As a result, fluids  122  may be produced from multiple intervals or “pay zones” of the formation  108  through isolated portions of the annulus  120  between adjacent pairs of packers  118 . 
     In an example, the sand screens  114  may be positioned between pairs of the packers  118 . The sand screens  114  may be any type of sand screens that are coupled to the tubulars  119  mechanically or with an adhesive material. In operation, the sand screen  114  may filter the fluids  122  flowing into the tubulars  119  from the formation  108  and through the annulus  120 . 
     While the well system  100  is described as including multiple tubulars  119  and multiple packers  118 , these described components may not be used in every example in which the sand screen  114  is used. For example, the well system  100  may include only an individual tubular  119 . Further, an example using the sand screen  114  may be implemented without the packers  118  isolating the various sections of the formation  108 . 
     To assist the sand screens with filtering the fluids  122  from the formation  108 , the well system  100  may also include a shunt system  126 . The slurry may be diverted from the production string  112  (e.g., using a closing sleeve (not shown)) to an annulus  124  between a wall of the wellbore  102  and the production tubing string  112  when the slurry is at a location within the production tubing string  112  downhole from a gravel pack packer  125 . From the annulus  124 , the slurry is received by the shunt system  126  that functions to both transmit the slurry further downhole and to deposit the slurry around the sand screens  114  to generate a gravel pack within the annulus  120 . The shunt system  126 , which is positioned external to the sand screens  114 , is described in further detail below with respect to  FIGS. 2-4 . The gravel pack generated in the annulus  120  by the shunt system  126  may assist the sand screen  114  in preventing the production of fine particulate or sand from the formation  108 . For example, the gravel pack in the annulus  120  may prevent migration of formation materials from the formation  108  into the tubular  119 . Further, because the shunt system  126  is positioned external to the sand screens  114 , the tubes associated with the shunt system  126  may be larger because the tubes do not take up any space used to produce the production fluid from the wellbore  102 . 
       FIG. 2  is a side view of the shunt system  126  positioned externally along a portion of the tubular  119  including the sand screens  114  according to some aspects. As illustrated, portions of the tubular  119  between the packers  118  may include multiple sand screen sections  202   a  and  202   b . Accordingly, the shunt system  126  may include sets of transport tubes  204   a  and  204   b  and packing tubes  206   a  and  206   b  that correspond with the respective sand screen sections  202   a  and  202   b . To span a joint  208  between the sand screen sections  202   a  and  202   b , a mixing chamber  210  may be installed between the transport tubes  204   a  and the transport tubes  204   b . The mixing chamber  210  may also be positioned in other locations such as directly above one of the sand screens  114 . 
     In an example, the transport tubes  204   a  may receive the slurry from the annulus  124  or from an additional uphole mixing chamber (not shown). As the slurry travels into the transport tubes  204   a , some of the slurry may be diverted into the packing tubes  206   a . The slurry diverted into the packing tubes  206   a  may exit the packing tubes  206   a  at slurry distributors  212   a . In an example, the transport tubes  204   a  include a cross-sectional area that is larger than a cross-sectional are of the packing tubes  206   a.    
     The slurry distributors  212   a  may be holes or nozzles installed along a length of the packing tubes  206   a . In an example, the slurry distributors  212   a  may allow the slurry to exit the packing tubes  206   a  such that the slurry fills the annulus  120  surrounding the tubular  119 . The slurry that fills the annulus  120  may be referred to as a gravel pack. Additionally, a portion of the tubular  119  positioned under the packing tubes  206   a  (e.g., on a side of the tubular  119 ) may be a location of the sand screens  114 . Thus, the gravel pack distributed by the packing tubes  206   a  may work in conjunction with the sand screens  114  to filter unwanted debris from the fluids  122  produced through the production tubing string  112 . 
     Continuing with the example, the shunt system  126  may include the transport tubes  204   b  positioned further downhole within the wellbore  102  than the transport tubes  204   a . The transport tubes  204   b  may receive mixed slurry from the mixing chamber  210 , and the mixing chamber  210  may receive unmixed slurry from the individual transport tubes  204   a . Because of the relative positioning of the transport tubes  204   a  within the wellbore  102 , leak-off of clean fluid from the slurry may be more prevalent in a transport tube  204   a  with slurry distributors  212   a  positioned facing a direction  214  toward a lower wall of the wellbore  102  than the slurry distributors  212   a  positioned facing a direction  216  toward an upper wall of the wellbore  102 . The additional clean fluid leak-off experienced by the transport tube  204   a  feeding the slurry distributors  212   a  facing the direction  214  may result in a difference in proppant concentration between the slurry in the two parallel transport tubes  204   a , especially over a length of an entire shunt system  126 . Accordingly, when the unmixed slurry enters the mixing chamber  210  at differing proppant concentrations from the transport tubes  204   a , the mixing chamber  210  may mix the unmixed slurry to provide a more uniform proppant concentration in a mixed slurry provided to the transport tubes  204   b.    
     Mixing the slurry at the mixing chamber  210  may provide each new downhole section of transport tubes  204   b  with similar concentrations of proppant within the slurry. Because of the mixing of slurry within the mixing chamber  210 , the slurry in one branch of the transport tubes  204   b  may avoid becoming more proppant laden than another branch of the transport tubes  204   b  due to clean fluid leak-off based on an orientation of the slurry distributors  212 . Accordingly, the likelihood of the transport tubes  204  plugging with proppant prematurely is reduced when compared to a shunt system without the mixing chamber  210 . 
     Further, the mixing chamber  210  may provide a slurry bypass when one of the transport tubes  204  is plugged with proppant. For example, when one of the transport tubes  204   a  is plugged with proppant, the remaining transport tube  204   a  may still deliver the slurry to the mixing chamber  210 . While the mixing chamber  210  may not mix the slurry from the two transport tubes  204   a  in such an example, the mixing chamber  210  may provide both of the transport tubes  204   b  with the slurry for continued distribution of the slurry to generate gravel packs at downhole locations of the annulus  120 . 
     As with the transport tubes  204   a , as the slurry travels into the transport tubes  204   b  from the mixing chamber  210 , some of the slurry may be diverted into the packing tubes  206   b . The slurry diverted into the packing tubes  206   b  may exit the packing tubes  206   b  at slurry distributors  212   b . In an example, the transport tubes  204   b  include a cross-sectional area that is larger than a cross-sectional are of the packing tubes  206   b.    
     The slurry distributors  212   b  may be holes or nozzles installed along a length of the packing tubes  206   b . In an example, the slurry distributors  212   b  may allow the slurry to exit the packing tubes  206   b  such that the slurry is able to fill the annulus  120  surrounding the tubular  119 . The slurry and deposited gravel that fills the annulus  120  may be referred to as a gravel pack. Additionally, a portion of the tubular  119  positioned under the packing tubes  206   b  (e.g., on the tubular side of the packing tubes  206   b ) may be a location of the sand screens  114 . Thus, the gravel pack distributed by the packing tubes  206   b  may work in conjunction with the sand screens  114  to filter unwanted debris from the fluids  122  produced through the production tubing string  112 . 
     Further, the mixing chamber  210  may be fluidly coupled to the transport tubes  204   a  and  204   b  using jumper tubes  218   a  and  218   b . The jumper tubes  218   a  and  218   b  may telescope or be otherwise adjustable such that the mixing chamber  210  and the jumper tubes  218   a  and  218   b  span a distance  220  between the transport tubes  204   a  and the transport tubes  204   b . Moreover, while  FIG. 2  depicts the shunt system  126  including two parallel transport tubes  204   a  attached the two parallel jumper tubes  218   a  of the mixing chamber  210  and two parallel transport tubes  204   b  attached to the two parallel jumper tubes  218   b  of the mixing chamber  210 , more or fewer transport tubes  204  and jumper tubes  218  may be included in the shunt system  126 . For example, the two transport tubes  204   a  may provide slurry to the mixing chamber  210 , but the mixing chamber  210  may output the mixed slurry to only a single transport tube  204   b . In another example, the shunt system  126  may include three or more transport tubes  204   a  that provide slurry to the mixing chamber  210 , and the shunt system  126  may also include three or more transport tubes  204   b  that receive the mixed slurry from the mixing chamber  210 . 
     In an additional example, one or more additional shunt systems  126  may be positioned around the tubular  119 . In such an example, additional sets of transport tubes  204   a  and  204   b , sets of packing tubes  206   a  and  206   b , sets of jumper tubes  218   a  and  218   b , and mixing chambers  210  are positioned along the tubular  119  for distribution of slurry around the sand screens  114  of the tubular  119 . Other numbers and arrangements of transport tubes  204 , packing tubes  206 , jumper tubes  218 , and mixing chamber  210  are also contemplated within the scope of the present disclosure. 
     While the mixing chamber  210  is generally described as being positioned between the jumper tubes  218   a  and  218   b  and spanning the joint  208  between the sand screen sections  202   a  and  202   b , the mixing chamber  210  may be positioned at other locations along the shunt system  126 . In an example, the mixing chamber  210  may be integrated with the transport tubes  204  (e.g., at a position that halves the transport tubes  204 ) while the jumper tubes  218  span the joint  208  between the sand screen sections  202   a  and  202   b . In another example, the mixing chamber  210  may be integrated with the transport tubes  204  (e.g., at the position that halves the transport tubes  204 ) and an additional mixing chamber  210  may be positioned between the jumper tubes  218   a  and  218   b  and spanning the joint  208  between the sand screen sections  202   a  and  202   b.    
       FIG. 3  is a perspective view of the mixing chamber  210  of the shunt system  126  according to some aspects of the present disclosure. As discussed above with respect to  FIG. 2 , the mixing chamber  210  may include or otherwise be attached to jumper tubes  218   a  and  218   b . In another example, the mixing chamber  210  may be coupled directly to transport tubes  204   a  and  204   b  over one of the sane screens  114 , for example. The jumper tubes  218   a  and  218   b  may be telescopically extendable or otherwise adjustable such that ends  302  of the jumper tubes  218   a  and  218   b  are able to mate with ends of the transport tubes  204   a  and  204   b . For example, the jumper tubes  218   a  and  218   b  may each include two or more concentric tubes that provide telescoping functionality of the jumper tubes  218   a  and  218   b  while maintaining structural integrity of the jumper tubes  218   a  and  218   b  during transmission of slurry to and from the mixing chamber  210 . In one or more examples, the jumper tubes  218   a  and  218   b  may be cylindrical tubes or rectangular tubes. Further, the jumper tubes  218   a  and  218   b  may be coupled to the transport tubes  204   a  and  204   b  using a threaded connection, a quick connector, or any other type of suitable connector. 
     A housing  303  of the mixing chamber  210  may span a gap between the jumper tubes  218   a  and  218   b  in any shape. In another example, the housing  303  may extend between two transport tubes  204   a  or  204   b  directly over one of the sand screens  114 . As illustrated, an overhead outline of the housing  303  is rectangular. However, other overhead outline shapes are also contemplated (e.g., circular, oval-shaped, rounded edges, etc.). Further, the example of the housing  303  depicted in  FIG. 3  includes a rounded outer surface  304  (i.e., the surface closest to the wall of the wellbore  102 ) and a rounded inner surface  306  (i.e., the surface closest to the tubular  119 ). A radius of an arc along which the outer surface  304  tracks may be such that the outer surface  304  maintains a constant shortest distance between the outer surface  304  and the tubular  119 . Likewise, a radius of an arc along which the inner surface  306  tracks may also maintain a constant shortest distance between the inner surface  306  and the tubular  119 . However, in other embodiments, the outer surface  304  and the inner surface  306  may not include any curvature. For example, the outer surface  304  and the inner surface  306  may be flat such that the housing  303  is in the shape of a rectangular prism. 
     In one or more examples, an interior of the mixing chamber  210  may be empty. That is, the mixing chamber  210  may include a hollow inner cavity. In another example, blades or baffles may be positioned within the mixing chamber  210  to encourage mixing of the slurry received by the mixing chamber  210  after traveling from inlet ports  308  along inlet fluid paths  309 . Upon mixing within the mixing chamber  210 , the mixed slurry may travel to the outlet ports  310  along outlet fluid paths  312  toward the transport tubes  204   b  positioned downhole from the mixing chamber  210 . 
       FIG. 4  is a flowchart of a process  400  for mixing slurry within the shunt system  126  that is externally mounted to the sand screen sections  202   a  and  202   b  according to some aspects. At block  402 , the process  400  involves receiving slurry from separate shunt tubes (e.g., the jumper tubes  218   a ) of the shunt system  126  at the mixing chamber  210  that is positioned external to the joint  208  between the sand screen sections  202   a  and  202   b . As discussed above with respect to  FIG. 2 , the slurry received from the separate shunt tubes may include varying clean fluid to proppant ratios. That is, one of the shunt tubes may provide slurry that experienced a greater amount of clean fluid leak-off than the other shunt tube. In another example, one of the shunt tubes may not receive any slurry from an associated transport tube  204   a  that is plugged by a buildup of proppant (e.g., due to clean fluid lead-off). In either example, the separate shunt tubes may provide slurry of varying quantities (i.e., different flow rates) and varying clean fluid to proppant ratios. 
     At block  404 , the process  400  involves allowing slurry from the multiple shunt tubes (e.g., the jumper tubes  218   a ) to mix at the mixing chamber  210 . For example, the slurry may enter the mixing chamber from the multiple jumper tubes  218   a  at different flow rates and proppant concentrations. Once in the mixing chamber  210 , the slurry fluids from the multiple jumper tubes  218   a  are encouraged to mix. The encouragement to mix may be provided generally by an open space that allows the slurry fluids to mix. Blades, baffles, or other protuberances may also be positioned within the mixing chamber  210  to generate turbulence that further encourages mixing. 
     At block  406 , the process  400  involves outputting the mixed slurry to one or more additional shunt tubes (e.g., the jumper tubes  218   b ). As the slurry mixes within the mixing chamber  210 , the slurry is transported toward the jumper tubes  218   b . At the jumper tubes  218   b , the mixed slurry may be output toward the transport tubes  204   b . In an example, the mixed slurry provided to the jumper tubes  218   b  may have similar proppant concentrations and similar flow rates due to the mixing of the slurry in the mixing chamber  210 . 
     As the mixed slurry is provided to the transport tubes  204   b , a portion of the mixed slurry in each of the transport tubes  204   b  may be redirected to the packing tubes  206   b . At the packing tubes  206   b , the mixed slurry is distributed into the annulus  120  between the tubular  119  and a wall of the wellbore  102 . The distributed mixed slurry generates a gravel pack within the annulus  120 . 
     In some aspects, systems, devices, and methods for implementing and operating a shunt system for gravel packing operations within a wellbore are provided according to one or more of the following examples: 
     As used below, any reference to a series of examples is to be understood as a reference to each of those examples disjunctively (e.g., “Examples 1-4” is to be understood as “Examples 1, 2, 3, or 4”). 
     Example 1 is a shunt system for a wellbore, the shunt system comprising: a first set of tubes defining a first plurality of fluid paths; a second set of tubes defining a second plurality of fluid paths; and a mixing chamber positioned between the first set of tubes and the second set of tubes to allow slurry from the first plurality of fluid paths to mix together prior to outputting the slurry to the second set of tubes, the shunt system being positionable external to one or more sand screens. 
     Example 2 is the shunt system of example 1, wherein the mixing chamber comprises a first set of jumper tubes attached to the first set of tubes and a second set of jumper tubes attached to the second set of tubes. 
     Example 3 is the shunt system of examples 1 to 2, wherein the first set of tubes and the second set of tubes comprise transport tubes being positionable to transport the slurry through the shunt system. 
     Example 4 is the shunt system of examples 1 to 3, further comprising: a first set of transport tubes and a second set of transport tubes, wherein the first set of tubes and the second set of tubes are jumper tubes mate with the first set of transport tubes and the second set of transport tubes. 
     Example 5 is the shunt system of examples 1 to 4, wherein the first set of tubes comprises: at least two transport tubes being positionable to transport the slurry to the mixing chamber; and at least two packing tubes being positionable to transport the slurry to an annulus between the one or more sand screens and a wall of the wellbore. 
     Example 6 is the shunt system of example 5, wherein the second set of tubes comprises: at least two additional transport tubes being positionable to receive a mixed slurry from the mixing chamber; and at least two additional packing tubes being positionable to transport the mixed slurry to the annulus between the one or more sand screens and the wall of the wellbore. 
     Example 7 is the shunt system of examples 5 to 6, wherein the at least two packing tubes comprise a first cross-section with a first cross-sectional area, and the at least two transport tubes comprise a second cross-section with a second cross-sectional area that is larger than the first cross-sectional area. 
     Example 8 is the shunt system of examples 5 to 7, wherein a first packing tube of the two packing tubes is fluidly coupled to a first transport tube of the two transport tubes; and a second packing tube of the two packing tubes is fluidly coupled to a second transport tube of the two transport tubes. 
     Example 9 is the shunt system of examples 1 to 8, wherein the mixing chamber is positionable external to a joint between two sand screens of the one or more sand screens. 
     Example 10 is a mixing chamber for a shunt system for delivering slurry to sand screens, the mixing chamber comprising: a first inlet port for a first tube defining a first inlet fluid path; a second inlet port for a second tube defining a second inlet fluid path; a first outlet port for a third tube defining a first outlet fluid path; a second outlet port for a fourth tube defining a second outlet fluid path; and a housing defining an area in which fluid from the first inlet fluid path and the second inlet fluid path is mixable prior to flowing through the first outlet port or the second outlet port, wherein the mixing chamber is positionable external to one or more sand screens. 
     Example 11 is the mixing chamber of example 10, wherein the mixing chamber is positionable over a joint between two sand screens of the one or more sand screens. 
     Example 12 is the mixing chamber of examples 10 to 11, wherein the first inlet port and the second inlet port are positionable to receive slurry from a first transport tube and a second transport tube, and the first outlet port and the second outlet port are positionable to transmit slurry to a third transport tube and a fourth transport tube. 
     Example 13 is the mixing chamber of examples 10 to 12, wherein the first tube, the second tube, the third tube, and the fourth tube comprise telescoping jumper tubes that are positionable to extend between the housing and a set of transport tubes. 
     Example 14 is the mixing chamber of examples 10 to 13, wherein the housing comprises an inner surface curvature and an outer surface curvature that are each positionable to maintain a constant shortest distance of an inner surface and an outer surface of the housing to the one or more sand screens. 
     Example 15 is the mixing chamber of examples 10 to 14, wherein the first outlet port and the second outlet port are positioned in relation to the housing such that the first outlet port and the second outlet port receive substantially similar amounts of the slurry from the housing. 
     Example 16 is the mixing chamber of examples 10 to 15, wherein the housing comprises blades or baffles positioned within the area to encourage mixing of the fluid from the first inlet fluid path and the second inlet fluid path. 
     Example 17 is a method comprising: pumping slurry through separate tubes to a mixing chamber; allowing the slurry from the separate tubes to mix in the mixing chamber that is external to one or more screens; and outputting mixed slurry to one or more output tubes through outlet ports of the mixing chamber. 
     Example 18 is the method of example 17, wherein outputting the mixed slurry to the one or more output tubes comprises outputting the mixed slurry to one or more transport tubes and to one or more packing tubes. 
     Example 19 is the method of examples 17 to 18, further comprising: packing an annulus between the one or more screens and a wall of a wellbore with the mixed slurry. 
     Example 20 is the method of examples 17 to 19, wherein the separate tubes comprise at least two jumper tubes coupled between the mixing chamber and at least two transport tubes of a shunt system. 
     The foregoing description of certain examples, including illustrated examples, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art without departing from the scope of the disclosure.