Abstract:
An apparatus to distribute pressurized fluid from one or more sources to multiple wellbores. The apparatus includes a manifold having at least two inlets and at least two outlets. Pressurized fluid is brought into the manifold from opposing directions so that the fluid from one inlet will impinge upon the fluid from the other inlet thereby de-energizing the fluid. Additionally, the manifold is configured such that the cross-sectional area of the inlets is less than the cross-sectional area of the manifold thereby decreasing velocity minimizing the kinetic energy available to erode or otherwise damage equipment, while providing a pressure decrease as the fluid enters the manifold. The outlets are configured such that the cross-sectional area of the outlets providing fluid to a single wellbore is greater than or equal to the cross-sectional area of the inlets such that no pressure increase occurs within the manifold or the outlets as the fluid exits the manifold. Additional velocity reduction enhancements may include angled or camp third turns between the inlet and the manifold or the manifold and an outlet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application Number 62/248,028 that was filed on Oct. 29, 2015. 
     
    
     BACKGROUND 
       [0002]    During the hydraulic fracturing or completion of a wellbore that provides access to subterranean, high pressure pumps, a wellhead assembly and various other types of equipment are installed at the wellbore site to enable safe and efficient stimulation operations to allow for the extraction of hydrocarbons and fluids from subterranean formations. 
         [0003]    The wellhead assembly provides access to the subterranean formation and has various pressure containing components, various casing strings, casing valves, and fluid conduits. During stimulation operations, the wellhead assembly will have a frac stack/tree, which has a series of large bore valves that provide full access to the tubular casing that traverses a subterranean formation. 
         [0004]    Hydraulic fracturing of subterranean formations requires high volumes of fracturing fluids to be pumped to the subterranean formations at high velocities and pressures to fracture the subterranean formation. With emergence of pad drilling, where more than one well exists at a single location providing multiple subterranean access points, a method of operations often referred to as simultaneous operations or zipper frac operations, is used to enhance efficiencies by reducing time and costs to complete each well on a multi-well pad. Simultaneous operations allow for stimulation operations to proceed on one subterranean formation point, while preparing an adjacent subterranean formation(s) for stimulation by running a series of wireline tools to the subterranean formation point where the stimulations operations will proceed after the prior subterranean formation is stimulated completely. 
         [0005]    An apparatus can be used in simultaneous operations that allows for fluid(s) and pressure to be directed to the appropriate subterranean formation while isolating fluid(s) and pressure access to another subterranean formation(s). This apparatus is commonly referred to as a zipper manifold. During pumping operations, the zipper manifold is used to contain pressure and direct the fluid to the appropriate well, while isolating the wells that are not being fractured. The zipper manifold opens/closes a series of valves depending on which well(s) need to be isolated and which well needs the frac fluid directed to it. 
         [0006]    Fluid(s) at a predetermined pressure is pumped into the manifold. A series of open valves direct fluid(s) and pressure to a subterranean formation, while all other valves on the manifold are closed to isolate adjacent subterranean formation(s) from exposure to fluid(s) and pressure. The operations of opening and closing a series of valves to direct and isolate pressure is conducted many times until all subterranean formation points have been stimulated. 
         [0007]    The fluid mixture, volume, velocity and pressure required to fracture subterranean formations is variable depending on the composition of the formation. The combinations of these variables at the subterranean formations dictate the requirements of the horsepower and pumping capacity at the surface. The differential of pressure requirements at the subterranean formation and the requirements at the surface is a result of the fluids undergoing friction loss from the fluids&#39; drag on the inside surface of the pipe, and from obstructions in the fluids&#39; flow path. Obstructions are anything that changes the fluids&#39; velocity and/or direction such as restrictions in the fluids&#39; path, and can occur anywhere in the flow path. 
         [0008]    Many difficulties exist when using a zipper manifold to conduct simultaneous operations, such as friction loss from the inner diameter reduction inside the flow path of the zipper manifold. The choking-down of incoming fluid into the manifold increases the pressure needed to overcome the restriction, increases the fluids&#39; velocity, and creates turbulence in the fluids&#39; velocities. In many instances the fluids are transporting proppant which has an abrasive effect on the equipment. The abrasive effect of the proppant is increased exponentially as a result of increased velocity in the equipment, such as when there is a restriction in the fluid flow as the fluid enters the zipper manifold or passes through the various valves in the zipper manifold. The effects of this dynamic are pressure build-ups, additional strain of upstream equipment, equipment damage/failure, and additional safety risks on the jobsite. 
         [0009]    Thus, any advance which facilitates a less turbulent flow path, reduces fluid velocity, reduces fluid pressure, and minimizes the effects of friction loss when using a zipper manifold to conduct simultaneous operations would provide a competitive advantage in the industry. 
       SUMMARY 
       [0010]    An embodiment of the current invention utilizes a zipper manifold having mixing blocks and multiple lines going to each well increasing the volume of frac fluid that can be pumped through it. The design preferably uses a series of plug valves in addition to at least matching or preferably exceeding the output capacity of the zipper manifold in comparison to the input capacity of the zipper manifold so that the velocity of the fluid through the output valves of the zipper manifold is decreased thereby allowing a net increase in the total fluid throughput, decrease friction loss, decrease turbulent flow, decrease the strain on frac pumps, and decreasing the wear on the zipper manifold and valves as compared to a similar throughput on previous zipper valves. 
         [0011]    The mixing block allows for frac lines to connect at multiple points to facilitate fluid entering the chamber from different directions such as when multiple pumping units are being utilized. The design forces a first portion of the incoming fluid to interact with at least a second portion of the incoming fluid, wherein at least a first fluid stream and at least a second fluid stream are directed substantially towards each other such that as the at least first fluid stream and the at least second fluid stream are brought into contact with one another, both the at least first fluid stream and the at least second fluid stream lose enough energy or are de-energized. By deenergizing the fluid or reducing the velocity of the fluid damage to the internal portions of the manifold due to particulates entrained within the fluid is minimized. Directing the at least first fluid stream towards the second fluid stream causes each fluid stream to act as a buffer for the internal components of the manifold, again preventing damage to the internal portions of the manifold due to entrained particulates within the high velocity fluid. 
         [0012]    Current zipper manifolds typically are delivered to the well site in pieces and assembled at the well site. Typically, such assembly is required due to the size of the outlet valve. By utilizing multiple yet smaller outlet valves where the combined cross-sectional area of the outlet valves is larger than the combined cross-sectional area of the inlet valves, the outlet valves may be pre-mounted onto the manifold and the manifold may then be incorporated into a single skid. In certain instances, multiple skids may be connected in series providing connections to additional wells. 
         [0013]    One embodiment of the zipper manifold has a mixing block. The mixing block has a buffer chamber, a chamber cross-sectional area, a first inlet, a second inlet, a first outlet, and at least a second outlet. The first inlet has a first cross-sectional area and a second inlet has a second cross-sectional area wherein a first cumulative cross-sectional area of the first cross-sectional area and the second cross-sectional area is less than the chamber cross-sectional area. The first outlet has a third cross-sectional area and the at least second outlet has a fourth cross-sectional area wherein a second cumulative cross-sectional area of the outlets is greater than or equal to the cumulative cross-sectional area of the first and second cross-sectional areas. A first fluid stream enters the buffer chamber through the first inlet, a second fluid stream enters the buffer chamber through the second inlet wherein the first fluid stream impinges upon the second fluid stream in a substantially opposing direction. The first fluid stream or the second fluid stream enters the buffer chamber through a flow adapter. The first and second fluid streams have a laminar flow upon entering the buffer chamber. The first outlet and the at least second outlet are chamfered between the junction of the buffer chamber and the outlet. The first outlet and the at least second outlet have at least one removable barrier. The removable barrier is a valve. The removable barrier is remotely actuated. In another embodiment of the zipper manifold the zipper manifold has at least two mixing blocks. In turn the mixing blocks are coupled to form a buffer chamber assembly. The buffer chamber assembly has a first inlet and a second inlet where a first fluid stream and a second fluid stream enter the buffer chamber assembly in substantially opposing directions. Each mixing block has a first outlet and at least a second outlet. The buffer chamber assembly provides access to a first wellbore and at least a second wellbore, where a cumulative cross-sectional area of the outlets connected to the wellbores is greater than the cumulative cross-sectional area of the inlets. The first fluid stream enters the first inlet through a first flow adapter and the second fluid stream enters the second inlet through a second flow adapter. The first fluid stream and the second fluid stream enter the buffer chamber assembly in substantially opposing directions. 
         [0014]    The first and second fluid streams have a laminar flow upon entering the buffer chamber assembly. The first outlet and the at least second outlet have at least one removable barrier. The removable barrier is a valve. The removable barrier is remotely actuated. The buffer chamber assembly is mounted on a single skid. 
         [0015]    A method of distributing fluid to a series of wellbores includes pumping a fluid into a mixing block. The mixing block has at least two inlets. Fluid is forced to enter the mixing block through the at least two inlets in substantially opposing directions. Prior to entering the mixing block the fluid has a first pressure and after entering the mixing block the fluid has a second lower pressure. The mixing block selectively distributes fluid from the mixing block to at least two wells. In order to reduce weight from a single massive valve, each well is connected to the mixing block by at least two fluid conduits where each fluid conduit has a valve. The valves are remotely actuated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The features and advantages of certain embodiments will be more readily appreciated when considered in conjunction with the accompanying figures. For a detailed description of the exemplary embodiments, reference will now be made to the accompanying drawings: 
           [0017]      FIG. 1  depicts an end on view of a mixing block. 
           [0018]      FIG. 2  depicts a side view of the mixing block. 
           [0019]      FIG. 3  depicts a top view of the mixing block. 
           [0020]      FIG. 4  depicts a mixing block assembly including outflow valves. 
           [0021]      FIG. 5  depicts a top view of a trailer mounted zipper manifold. 
           [0022]      FIG. 6  depicts a side view of a trailer mounted zipper manifold. 
           [0023]      FIG. 7  depicts a fracturing assembly including multiple pump trucks delivering pressurized fluid to a zipper manifold that in turn is distributing pressurized fluid to multiple wellheads. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The description that follows includes exemplary apparatus, methods, techniques, or instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details. 
         [0025]      FIGS. 1, 2, and 3  depict an embodiment of a mixing block  1 . The mixing block  1  has a first end  4  and a second end  3  where the first end  4  or second end  3  of the mixing block  1  may be connected to either an additional mixing block, such as in the embodiment of  FIG. 4  where mixing block  30  is connected to at least mixing block  29 ,), to a fluid flow adapter such as an injection head, such as in the embodiment of  FIG. 4  where injection head  22  is connected to mixing block  30 . Mixing block  1  has a mixing chamber  2  where fluid flow from the inlets, which may adjacent to the first end  4  and the second end  3 , is directed. Mixing block  1  also has at least one outlet, in this instance outlets  5 ,  6 , and  7 , to allow fluid flow from the mixing chamber  2  to flow to the exterior of the mixing block  1 , typically towards the desired well bore. Generally each outlet has some type of removable barrier usually a valve but it may be a cap or plate between the outlet and fluid conduit. 
         [0026]      FIG. 4  depicts multiple mixing blocks  28 ,  29 , and  30  connected in series. The first mixing block  30  has a buffer chamber  37 . Buffer chamber  37  has a cross-sectional area A, depicted by reference numeral  100 , that is at least equal to or greater than the cumulative cross-sectional areas B  102 , C  104 , D  106 , and D  108  of inlets  23 ,  24 ,  25 , and  26  or any combination thereof. Generally each inlet has some type of flow adapter where the flow adapter is connected between the pump and the inlet on the buffer chamber. The flow adapter allows the connection from a smaller diameter fluid conduit from the pump to the larger diameter of the buffer chamber. In some instances the flow adapter may be formed as a portion of a mixing block inlet. 
         [0027]    The cumulative cross-sectional area areas B  102 , C  104 , D  106 , and D  108  of each of the inlets  23 ,  24 ,  25 , and  26  is preferably less than or equal to the cross-sectional area A  100  of the mixing chamber  2 . By increasing the cross-sectional area A  100  of the mixing chamber as compared to the cumulative cross-sectional areas B  102 , C  104 , D  106 , and D  108  of inlets  23 ,  24 ,  25 , and  26  the velocity of the fluid decreases as the fluid enters the mixing chamber. The decrease in velocity reduces the kinetic energy available to erode or otherwise damage the mixing block  1 . An additional benefit of increasing the cross-sectional area of the mixing chamber  2  as compared to the inlets  23 ,  24 ,  25 , and  26  is a reduction in pressure buildup as the fluid moves from the inlets  23 ,  24 ,  25 , and  26  into the mixing chamber  2 . The reduction in pressure build up reduces wear and tear on the pumps and reduces the amount of power required to pump the frac fluid into the wellbore. 
         [0028]    The outlets  132 ,  134 ,  136 ,  138 ,  140 ,  142 ,  144 , and  146  respectively have cross-sectional areas F  110 , G  112 , H  114 ,  1   116 , J  118 , K  120 , L  122 , M  124 , and N  126  whereby the cumulative cross-sectional areas of the open lines leading to a wellbore such as cross-sectional area F  110 , G  112 , H  114 ,  1   116 , J  118 , K  120 , L  122 , M  124 , and N  126  are greater than or equal to the cumulative cross-sectional areas B  102 , C  104 , D  106 , and D  108  of inlets  23 ,  24 ,  25 , and  26  thereby preventing a velocity increase through the outlets  132 ,  134 ,  136 ,  138 ,  140 ,  142 ,  144 , and  146 , and any associated valves in fluid communication with the outlets  132 ,  134 ,  136 ,  138 ,  140 ,  142 ,  144 , and  146 . It may be desirable that he combined cross-sectional area of the exit lines from each mixing block  28  ,  29 , or  30  be at least equal to or greater than the combined cross-sectional area of the cross-sectional area B  102 , C  104 , D  106 , and D  108  of inlets  23 ,  24 ,  25 , and  26 . 
         [0029]    The angled or chamfered joints  41 ,  42 , and  43  allow fluid leaving the mixing chamber  37  to maintain a laminar flow as the fluid exits the mixing chamber  37 . Each of the first mixing block  30 , second mixing block  29 , and third mixing block  28  are designed to connect the flow path to a desired frac stack positioned on the wellhead. Preferably each mixing block  28 ,  29 , and  30  is connected to a single frac wellhead. When multiple mixing blocks are coupled together they become a zipper manifold assembly. In certain instances a single mixing block may be formed incorporating the features of multiple mixing boxes bolted together thereby becoming a zipper manifold assembly. 
         [0030]    In many instances the mixing block  1  is designed such that fluid enters the mixing block  1  from both the first end  4  and the second end  3  thereby causing the fluid from each end to impinge upon the fluid entering from the other end. As the fluid from one end impacts the fluid from the other end the fluid is de-energized inside buffer chamber  2 . Additionally, the fluid already in the mixing block  1  tends to buffer and de-energize any fluid subsequently entering the mixing block  1 . 
         [0031]    An example of a three well zipper manifold design having a first mixing block  30 , second mixing block  29 , and third mixing block  28  is provided in  FIG. 4  in accordance with an embodiment of the pressure containing equipment, and a mounting system of the multiple mixing block zipper manifold mounted on a mounting system  44  shown on  FIG. 5 . Focusing on the embodiment on  FIG. 4 , any combination of injection points  23 ,  24 ,  25 , and/or  26 , can be used to connect the flow path from the frac missile  55  in  FIG. 7  to the multiple mixing block zipper manifold assembly  9 . The frac missile  55  is used to connect multiple frac pumps  54  to a centralized output. The combined cross-sectional area of the combination of incoming lines  56 ,  57 ,  58 , and  59  provided on  FIG. 7 , must not exceed the cross-sectional area of any of the mixing chambers  35 ,  36 , and/or  37  in  FIG. 4 . The coupling devices for the inlets  23 ,  24 ,  25 , or  26  can be threaded, studded, or any other coupling device. 
         [0032]    The multiple mixing block zipper manifold assembly  9  includes lines  60 ,  61 , and  62  that form the flow path  72  to the wellhead  69  shown in  FIG. 7 . The multiple mixing block zipper manifold  9  depicts three flow paths,  72 ,  73 , and  74  exiting from the multiple mixing block zipper manifold assembly  9  where each flow path allows fluid to flow from a mixing block, such as mixing blocks  28 ,  29 , and  30  in  FIG. 4 , to the respective wellheads  69 ,  70 , and  71  in  FIG. 7 . Flow path  72  includes exit lines  60 ,  61 , and  62  and directs fluid to wellhead  69 . Exit lines  63 ,  64 , and  65  direct fluid to wellhead  70 . Exit lines  66 ,  67 , and  68  direct fluid to wellhead  71 . The combined cross-sectional area of the exit lines of each flowpath must be at least equal to or greater than the combined cross-sectional area of the cross-sectional area of the inlet lines  56 ,  57 ,  58 , and  59 . For example, exit lines  60 ,  61 , and/or  62  must have a combined cross-sectional area equal to or greater than the combined square area of any combination of injection lines  56 ,  57 ,  58  and/or  59  used to pumped sufficient fluid volume into the multiple mixing block zipper manifold  9  to prevent the increase of fluid velocity and pressure increase, which minimizes damage to zipper manifold  9 . 
         [0033]    In  FIG. 4 , each exit lines  10 - 18  typically has at least two valves, barriers, or any combination thereof such as valves  19  and  20  which provide a barrier between mixing block  30  and exit line  18 . Depending on which wellhead  69 ,  70 , or  71  the fluid needs to be directed to, the exit lines on each mixing block  28 ,  29 , or  30  will allow fluid to flow through or be isolated with valves or other barrier. For example, if the desired fluid path is directed to wellhead  69 , the valves  19 ,  20 ,  221 ,  222 ,  223 , and  224  are open or barriers are removed between mixing block  30  and exit lines  16 ,  17 , and  18  allowing fluid to flow from mixing block  30  through exit lines  60 ,  61 , and  62  and into the subterranean formation that wellhead  69  provides access to. If the fluid is being directed into wellhead  69 , then wellheads  70  and  71  are isolated from receiving fluid flow or pressure by closing the valves or adding barriers to exit lines  10 - 15  to prevent fluid from flowing through flow path  73  and/or  74 . 
         [0034]    When the desired fluid flow path is directed to wellhead  70 , the valves/barriers on exit lines  13 ,  14 , and  15  are opened/removed to allow the flow path to exit the multiple mixing block zipper manifold  9 , through exit flow lines  63 ,  64 , and/or  65  and flow into the subterranean formation through access provided by wellhead  70 . When fluid is directed to wellhead  70 , wellheads  69  and/or  71  are isolated from receiving fluid flow or pressure by closing the valves or adding barriers to exit lines  10 ,  11 ,  12 ,  16 ,  17 , and/or  18  in the multiple mixing block zipper manifold  9  to prevent flow and pressure on wellheads  69  and  71 . 
         [0035]    When the desired fluid flow path is directed to wellhead  71 , the valves/barriers on exit lines  10 ,  11 , and/or  12  are opened/removed to allow the flow path to exit the multiple mixing block zipper manifold  9 , flow through the flow path lines  74  that couple the fluid path from the multiple mixing block zipper manifold  9  to the subterranean formation provided by wellhead  71 . When fluid is directed to wellhead  71 , wellheads  69  and/or  70  are isolated from receiving fluid flow or pressure by closing the valves or adding barriers to exit lines  13 - 18  in the multiple mixing block zipper manifold  9  to prevent flow and pressure on wellheads  69  and/or  70   
         [0036]    An example in accordance with the mounting system  44  is presented in  FIG. 5 . The entire multiple mixing block zipper manifold  9  is mounted to a skid or trailer  45  to allow for transportation to and from the job site, and is used to support the multiple mixing block zipper manifold  9  during operations. In certain instances, the barriers or valves  19 ,  20 ,  221 ,  222 ,  223 ,  224 ,  225 ,  226 ,  227 ,  228 ,  229 ,  230 ,  231 ,  232 ,  233 , and  234  connected between the mixing blocks  28 ,  29 , and  30  to the exit lines  10 ,  11 ,  12 ,  13 ,  14 ,  15 ,  16 ,  17 , and/or  18  can be operated manually, electrically, pneumatically, hydraulically, or any other known means. Preferably the valves  19 ,  20 ,  221 ,  222 ,  223 ,  224 ,  225 ,  226 ,  227 ,  228 ,  229 ,  230 ,  231 ,  232 ,  233 , and  234  are powered by hydraulic closing unit  29  that is used to open or closed the hydraulic valves. The power unit  29  can be left on the trailer  31  during operations or might be removed from the trailer  31  depending on customer preference. The mounting system  31  has integrated plumbing that runs between the hydraulic closing unit  46  to the valves/barriers  19 ,  20 ,  221 ,  222 ,  223 ,  224 ,  225 ,  226 ,  227 ,  228 ,  229 ,  230 ,  231 ,  232 ,  233 , and  234  of each exit line  10 ,  11 ,  12 ,  13 ,  14 ,  15 ,  16 ,  17 , and/or  18 . The plumbing system of the mounting system  44  is designed to eliminate the plumbing from being a trip or fall hazards, while also position in way that provides access to the plumbing. 
         [0037]    The mounting system is built with a mezzanine working deck  47  that allows a clear walking space to access the valves and associated equipment on the multiple mixing block zipper manifold  9 . The panels of the mezzanine working deck  47  are removable to provide access to equipment and coupling points of the multiple mixing block zipper manifold  9  position under or around the mezzanine working deck  47 . The mezzanine working deck is accessible by a stairway  48  that runs from the ground level up to the mezzanine working deck  47  level. Both the stairway  48  and mezzanine working deck  47  have safety support railings  49  that allow for safe operations on the mounting system  44 . 
         [0038]    The mounting system  45  in  FIG. 5  is structurally engineered to support the multiple mixing block zipper manifold  9  and the associated equipment during transit and operations. 
         [0039]    The mounting system has a series of support legs or stands  50 ,  51 ,  52 , and  53  that can be deployed to add stability to the mounting system  44  during operations and retracted when the mounting system  44  is in transit. As seen in an example of a job site in  FIG. 7 , the mounting system of the manifold  44  is transported to location and set on the job site in accordance to customer instructions. The support legs  50  -  53  on the mounting system  45  are deployed after the unit  44  is set in its desired location. Incoming fluid conduits  56 ,  57 ,  58 , and/or  59  are coupled to the appropriate injection points  23 ,  24 ,  25 , and/or  26  shown in  FIG. 4  to make a flow path for fluid and pressure to enter the buffer chambers  28 ,  29 , and  30  in  FIG. 2 . The fluid flow and pressure are generated upstream of the mounting system  44  by pump trucks  54  that pump the fluid(s) to the frac missile  55  and then through the incoming fluid conduits  56 ,  57 ,  58 , and/or  59  to connect to the multiple mixing block zipper manifold. 
         [0040]    Next, the exiting flow conduits  60 ,  61 ,  62 ,  63 ,  64 ,  65 ,  66 ,  67  and/or  68  are coupled to the exit lines  10 ,  11 ,  12 ,  13 ,  14 ,  15 ,  16 ,  17 , and/or  18  of the multiple mixing block zipper manifold  9 , which provides the flow path for fluid and pressure to flow to wellheads  69 ,  70 , and or  71 . Once the flow conduits paths  72 ,  73 , and/or  74  are coupled to wellheads  69 ,  70 , and/or  71  via the exit flow lines  60 ,  61 ,  62 ,  63 ,  64 ,  65 ,  66 ,  67  and/or  68  to the multiple mixing block zipper manifold  9 , in turn fluidly connected to the frac missile  55  and thereby to the pump trucks  54 , fluid access is provided, as desired, to the formations. Once operations commence, a series of valves/barriers will be opened/closed to direct fluid to the appropriate wellhead and isolate fluid and pressure from the adjacent wellhead(s) as described previously. 
         [0041]    While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible. 
         [0042]    Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.