Fracturing fluid deflecting and screening insert

Fracturing headers and connected conduits are fit with one or more fluid screening and wear minimizing inserts. Tubular screen inserts are provided to screen a flow of fracturing fluid through manifolds prior to, or at, the fracturing header. Each tubular screen insert has a tubular wall having an insert bore, an endwall and an open inlet. A plurality of openings, about the tubular wall, provide fluid communication between the bore and an annular area outside the wall. Oriented in a flow conduit with the closed endwall upstream, the insert excludes and sheds debris therefrom. Oriented with the closed endwall downstream, the insert receives and stores debris. Pairs of inserts, retained in opposing inlet ports, serve to screen fluid and deflect erosive flow from tools such as coil tubing extending therethrough. A fracturing block fit with opposing inlet ports can also be fit with an outlet port for flowback operations.

FIELD

The present disclosure relates to fracturing operations and the delivery of frac fluid to a wellbore. More particularly, one or more screens are provided in the supply lines and other equipment en-route to the wellhead for removing debris.

BACKGROUND

It is known to conduct fracturing or other stimulation procedures in a wellbore by isolating zones of interest, (or intervals within a zone), in the wellbore, using packers and the like, and subjecting the isolated zone to treatment fluids, including liquids and gases, at treatment pressures. In a typical fracturing procedure for a cased wellbore, for example, the casing of the well is perforated to admit oil and/or gas into the wellbore and fracturing fluid is then pumped into the wellbore and through the perforations into the formation. Such treatment opens and/or enlarges drainage channels in the formation, enhancing the producing ability of the well. For open holes that are not cased, stimulation is carried out directly in the zones or zone intervals.

The fracturing operations include a variety of downhole tools that include relatively fine tolerances for operation including shifting sleeves, ports and ball seats. The fluid arriving downhole should be free of solids or debris which could interfere with the tools.

Normally the fluids are solids free or intentionally contain specific and acceptable solid particulates such as frac sand and proppent. Unfortunately, reality is such that debris can also enter the system at the supply side including equipment breakdown or introduced during assembly. Equipment can include pumps and blenders with moving components subject to component wear and castoffs which can enter the fluid stream. Examples of some of the components that can enter the fluid stream include parts of turbine wheels, seals, seat retainers, check valve flappers, and union seals. Further, in the on-site coupling of frac fluid supply lines, debris such as mud and gravel, can be inadvertently introduced.

SUMMARY

Debris and undesirables are screened out of frac fluids en-route downhole to fracturing tools in a wellbore. Debris might include pumper or frac line pieces, seals and/or road gravel. At times the debris is pumped into the well and it interferes with downhole equipment such as packers as part of Mongoose™ Jet Frac System (by NCS Energy Services, Inc.) The downhole equipment has all types of sliding sleeves, activating and deactivating gadgets and their performance can be compromised by debris jamming and getting stuck in the mechanism. A coil header, or frac head adapted to accept coil tubing, is used to protect the coil during the pumping operation down the annulus. A zone or stage in zone is stimulated, the packer jaws are deactivated and the packer tool is raised or lowered to the next desired stage and the jaws are activated and another stimulating is performed. This continues until all the desired stages are completed. A screening device is required to prevent undesirable debris from being pumped into the well that can compromise the mechanics of the tool and or plug the jetted port into the formation.

Herein, several screening embodiments are employed alone or in combination, such as to screen a flow of fracturing fluid in a manifold or equalization header prior to the fracturing header, screening fluid immediately at the fracturing header, or at the exit of the header to the wellbore.

Generally a tubular screen insert is provided having a tubular wall having an insert bore, an endwall and an open end or inlet. A plurality of openings about the tubular wall provide fluid communication between the bore and an annular area outside the wall.

The screen insert can be oriented in a flow conduit with the closed endwall upstream, for shedding debris and passing screened fluid. The screen insert can be oriented with the closed endwall downstream, in a basket orientation, for receiving and storing debris and passing screened fluid.

The basket form of screen insert is particularly amenable for securing in the inlet ports of a fracturing block in a fracturing header, each insert fit to opposing inlet ports in the block. The inserts are retained in the block, such as by sandwiching an insert flange between the block and connecting conduits, such as a connecting flange of an isolation valve or piping.

Accordingly, in one aspect, apparatus is disposable in a fluid conduit between a source of a flow of fracturing fluid and a wellbore for excluding debris, the apparatus having a tubular wall defining a screen bore extending longitudinally therethrough and a plurality of openings spaced about a circumference of the tubular wall excluding debris entrained within the flow of fluid while permitting the fracturing fluid to pass therethrough between the screen bore and an annular flow area about the tubular wall. The bore has a closed endwall for blocking the screen bore and directing fluid through the plurality of openings substantially free of the debris. The bore also has an open end for flow of fluid between screen bore and the fluid conduit.

The apparatus is useful in the context of a fracturing block for a fracturing header for delivering fracturing fluid to a wellbore. The block as a main bore contiguous with the wellbore; and at least two opposing inlet ports in fluid communication with a main bore in communication with the wellbore. Each inlet port receives a flow of fluid from a connecting conduit and discharges the fluid to the main bore for delivery to the wellbore. Each inlet port has a screen insert fit thereto.

In another aspect, a fracturing header is provided using the above fracturing and further comprising a flowback outlet port wherein the fracturing block comprises two opposing inlet ports for receiving the flow of fluid from the connecting conduit; and the flowback outlet port is in communication with the main bore for discharging flowback fluid from the main bore.

In another aspect a system is provided for delivering fracturing fluid, substantially free of debris to a wellbore, comprising providing a fracturing block having a main bore connected to the wellbore and two or more fluid inlet ports for receiving fracturing fluid therein; and a screen insert fit to each of the two or more inlet ports. The system can further comprise an equalization header or manifold for supplying fracturing fluid to the two or more inlet ports. The equalization header can further comprise two or more screen inserts fit to each of two or more discharge outlets to the fracturing header.

In another aspect, a multipurpose block for a fracturing header is provided including inlet ports for a flow of fracturing fluids and at least one outlet port for flowback. The flowback block is fit with a wear sleeve across the interface between the block and connecting conduit. More particularly a fracturing header for a wellbore is provided comprising a multipurpose block having a main bore in communication with the wellbore, the multipurpose block further comprising two or more inlet ports disposable in opposing pairs and in communication with the main bore; and flowback outlet ports in communication with the main bore for receiving a flow of fluid from the main bore.

DESCRIPTION

As shown inFIG. 1, a fracturing operation can include various connections for delivering fracturing fluid to a coil head, buffalo head, frac head or fracturing header as termed herein. The fracturing head distributes fracturing fluid, including proppent for transport down a wellbore. A fracturing header typically includes a fracturing block that has multiple inlet ports for distributing a high rate of flow and erosive fracturing fluid thereto. A flow block can be included for discharging flowback after a fracturing operation. As shown, one or more connecting piping, frac iron or conduits can be routed to the fracturing header. Further, flow of fluid to two or more of the inlet ports of the fracturing header can be equalized between various fracturing fluid sources using an equalization header.

All of the above components provide opportunities to introduce means for excluding debris. Herein, various inserts can be provided, depending on the environment, to screen fracturing fluids delivered down a wellbore and further to reduce the energy of the erosive flow before contacting tools and coil tubing, tool-conveyance strings.

As shown inFIGS. 1 to 4, one or more of these connections can include a screen insert according to embodiments disclosed herein. Due to the erosive nature of the fluid, it is a general objective to minimize or avoid local increases in the fluid velocity. Hence, screen inlet and outlets are maximized with the constraints of the particular environment. In some embodiments, the screen insert have flow passages generally equal or greater in cross sectional flow area than are the flow areas of supply and discharge equipment or components themselves.

Further, the components, such as fracturing headers, equalization headers and the like, can be manufactured to complement the screen inserts and best screen and distribute the flow of fracturing fluid. As shown, the equalization header is upstream of the fracturing header and distributes flow to each of the two or more inlet ports of the fracturing header. InFIG. 2, the equalization header is formed with a bore and the inserts oriented and mounted for blocking yet shedding debris and enabling periodic removal. In the case of a fracturing header, the screen inserts are oriented for capturing debris, the screen inserts and header block working together to deflect flow from any tool passing therethrough and even reduce flow velocity. In fracturing headers with main bore deflector sleeves, so as to protect coil tubing passing therethrough, the inclusion of screen inserts in the fluid inlet ports enhances the sleeve's protection. In other embodiments, use of the screen inserts can obviate the need for a deflector screen at all.

Returning toFIG. 1, in the case of an equalization header10, one can provide a screening embodiment comprising a protruding screen insert12, rejecting debris from entering the protruding screen insert12, such debris being recovered in at a cleanout14for periodic removal of excluded debris.

As shown, the cleanout14is a blind flange, but embodiments can also include a fluid lock section sandwiched between a first valve and a second block valve, forming a recovery chamber therebetween, for on-the-fly access and cleanout. The recovery chamber would have a bleed port for reducing pressure therein before servicing.

In detail, the equalization header10includes a block having two or more supply inlets16a,16b, from two or more fluid sources, two or more discharge outlets17a,17bto a fracturing header20, and a cross passage22for fluid flow equalization between the supply inlets16a,16b. A protruding screen insert12is fit to one or more of the discharge outlets17a,17b. Each protruding screen12comprises a screen body or insert having a bore24in communication with its respective discharge outlet17a,17b. The screen bore24has a transverse endwall25, which is substantially a closed endwall, forcing the majority of the fracturing fluid to pass through one or more openings26,26. . . generally formed along a tubular wall28of the screen insert. Openings can be optionally formed in the closed endwall25. The openings26fluidly connect the insert bore24, and open end27, and outlets17a,17bwith the supply inlet or inlets16a,16b. For maximizing the cross-sectional flow area into the inserts12, the one or more openings26are circumferentially spaced about the tubular wall28. The openings, provided about the circumference, can each be sized to maximize flow therethrough yet to exclude pre-determined characteristics of known debris, and yet remain sufficiently supported structurally in the insert12overall. In this projecting form of screen insert12, the circumferentially arranged openings26also conduct fluid to collide in the bore24, absorbing the energy in turning the fluid from a generally radial, incoming vector to an axial vector along the bore24to the outlet17aor17brespectively.

The openings24are formed through the wall28of the insert12. Each opening26, from the wall's exterior, inward to the openings interior, can be profiled to minimize flow disruption. A screen insert12is fit to each of the two or more discharge outlets17a,17b, each insert12comprising the tubular wall28and the insert bore34extending longitudinally therethrough, the insert bore24having the upstream endwall25thereacross and an open downstream fluid outlet or open end27in fluid communication with a respective inlet port of the fracturing header20, the plurality of slot-like openings26spaced circumferentially about and extending through the tubular wall28for screening the flow of fluid to the fracturing header20.

For a block structure like the equalizing header10, an internal flow bore30is sized to provide generally unrestricted fluid access to the screen insert, and as shown, an annular flow area32is provided about each screen insert12as the bore30narrows thereabout. Thus, fluid flow in the annulus32can be determined to be at a velocity about equal to or at a lower than that in the supply line16a, further entering the insert's openings at sub-supply velocities, and also can flows through the insert's bore24at sub-supply velocities.

Each insert12can be provided with an upset at the downstream end for fitting with a corresponding annular recess in the header at the interface with downstream connectors, such as flanged outlets17a,17b. In other words, the insert12is inserted into the header discharge outlet17a,17b, the upset fitting and seating into the annular recess, and downstream valves, blocks, or adapters sandwich the screen securely into the equalization header10.

As suggested above, additional flow area through a closed endwall25of screen insert12can be provided by one or more additional openings26, admitting fluid through the substantially closed endwall to comingle with the fluid admitted through the circumferentially-arranged openings.

The protruding screen12in the equalization header environment can be located at any other suitable point of connection along the fracturing fluid supply conduit.

As shown inFIGS. 2 through 4, in the environment of the fracturing header20, the screen inserts12are fit to inlet ports of a main block38of the header20and can be oriented in the form of a basket for collecting debris and for dispersing fluid in a radially outward pattern. Typically, for low profile blocks, each inlet port is located as a side port, arranged substantially perpendicular to the main bore. As a fracturing header basket screen insert12is not readily self-cleaning, it is advantageous, for maximizing time between servicing, to have a pre-screen in an equalization header10or other upstream location.

The fracturing header might also be equipped with a supplemental deflector sleeve for protecting coil tubing inserted therethrough. A discussion of an angled form of deflector sleeve is set forth in Applicant's U.S. Pat. No. 8,122,949, issued Feb. 28, 2012. Further the screen insert12can have a blank or closed endwall which deflects the flow of fluid generally radially, thereby minimizing direct erosive contact with components in the bore such as coil tubing. In other instances, depending on screen configuration and flow rates, and particularly at low pumping rates, one can avoid the use of a deflector sleeve, and rely on the inserts alone for protecting such components.

The fracturing header basket screen insert12is also a tubular screen. As described in detail later, the insert12has a bore in communication with a supply of fracturing fluid, such as an equalizing header10, and again has one or more openings formed along the tubular wall for fluidly connecting the insert bore with the fracturing header bore for conducting fluid downhole to the downhole tools.

The screens inserts12distribute fluid flow radially for preventing direct impingement of the fracturing fluid with tools passing therethrough such as coiled tubing40. As shown inFIG. 2, a deflector sleeve42can also be fit coaxially to the main block38and is used to protect the coil tubing40.

As shown inFIG. 3A, the screens inserts12distribute fluid flow radially for preventing direct impingement of the fracturing fluid with the coil tubing40and a deflector sleeve is not even used, maximizing the size of fracturing header bore for passing tools therethrough. A separate flowback block43can be provided adding about 30 inches to the height of the fracturing header20. As shown inFIG. 3B, the main block38of the fracturing header20can comprise four inlets44,44,44,44

As shown inFIG. 4A, the fracturing header20comprises a main block38having a plurality of inlet ports46, four shown, a plurality of inlets44each connected to an inlet46and a screen insert12for each inlet port46.

With reference toFIG. 4B, the main block38ofFIG. 4Ais illustrated free from all connecting equipment. The block38is fit with a deflector sleeve42, and two pairs of screen inserts12. A first pair of inserts12a,12aare fit to opposing first inlet ports46a,46a, and a second pair of inserts12b,12bare fit to opposing second inlet ports46b,46b.

InFIGS. 5A to 9Ba fracturing header20is shown fit with a deflector sleeve42and two or more screen inserts12,12. . . .

Turning toFIGS. 5A and 5B, a fracturing header20is shown fit with a first pair of screen inserts12a,12ato a first pair of inlet ports46a,46a.

In more detail, and as shown inFIG. 6A, the main block38is coupled at inlet ports46a,4ato isolation valves50,50. Coil tubing38passes through a deflector sleeve42fit to a main bore52in the block38. The inlet ports46,46are arranged in the block38opposing one another and fluidly connected with the main bore52. Each inlet port46forms a trajectory of fluid F which is generally towards a centerline of the main bore52, through which the coil tubing38passes. In this instance the coil tubing38is primarily protected from fracturing fluid by the deflector sleeve42, intercepting fluid before impinging upon the coil tubing38. The screen inserts12,12further deflect the incoming fluid.

Better shown in the embodiment illustrated inFIG. 6B, fluid F flows radially from the inserts12,12, about the deflector sleeve42, and down the main bore52to the wellbore, generally parallel to the coil tubing38.

Often the connecting interfaces, such as block valves50,50, have bore diameters which are larger than that of the fracturing block38. In such cases, there is a vulnerability of the inlet ports46and valve interface to flow disruption and elevated erosion. With reference toFIGS. 6Babs7A, the insert12can be fit with a sleeve extension48for extending into the bore of the fluid inlet connecting conduit such as a valve50. The sleeve extension48forms a tapered inlet49for a more orderly fluid flow from the generally larger bore of the valve to the smaller bore of the inlet port46. The upstream inlet end of the insert has an inlet size substantially that of the connecting conduit Therefore, the screen bore24is tapered intermediate the larger diameter upstream inlet end and the smaller diameter adjacent the openings.

In another embodiment illustrated inFIG. 7A, the flow of fluid exiting the inserts is manipulated and the insert itself is fit with a circumferential flange, intermediate along its length, for mounting in the block. As shown, the downstream endwall of the inserts12are shaped, in this instance conical, with the apex projecting upstream, directing a generally axial flow through the sleeve bore24to an angularly outward flow into the annular flow area32. The conical endwall directs the flow F generally radially as before, but with improved flow dynamics and reduced wear on the insert. However, the flow dynamics in the main bore52may be less favorable for impingement on the coil tubing. Further empirical response will ascertain the various combinations of insert and main bore flow dynamics.

As shown in more detail in the close up ofFIG. 7B, the inlet ports46of the main block38are fit with an annular inlet recess53and the insert12includes a circumferential flange54sized to correspond with the annular inlet recess53. The insert12is retained in the block38and flow F to avoid being lost downhole. Basically, the insert12is provided with an upset or flange54intermediate its length for fitting with a corresponding annular recess53formed in the block at the interface with an upstream isolation valve50or other intermediate connectors, spool or piping. The insert12is inserted into the inlet port46until the flange54seats in the recess53. The valve50is connected to the block38, sandwiching the screen inset12securely to the block38.

The valve50is fit with a flange55for connecting to the main block. The insert's flange54fits to the block's annular inlet recess53and the valve flange55sandwiches the circumferential flange to the main block, the screen insert being retained therein and the sleeve extension extending onto the valve50. As is typical, the valve flange55is sealed to the main block using a ring seal56.

Turning toFIGS. 8A and 8B, the main block38can be fit with two or four inlet ports46. The inlet ports46are typically arranged in opposing pairs, such as that shown inFIG. 4B, a first pair46a,46aand46b,46b. While all ports can be of the same diameter and flow capacity (SeeFIG. 11), the ports46can be of different sizes—generally having pairs of opposing ports having the same sizes for balancing inlet flow dynamics. As shown in the plan view ofFIG. 8A, a first pair of opposing ports46a,46acan be larger than a second pair of ports46b,46b. InFIG. 8B, sectioned through the larger inlet ports46a,46a, one inlet port46bof the smaller, second pair of ports46b,46bis shown in the background.

Note that the overall height of the block38is maintained as consistent as possible for ready substitution in a fracturing header without dimensional changes. For example, a block having 4 1/16″ diameter first ports46a,46awould have an overall height equivalent to that for a block having 3 1/16″ first ports46a,46a. As shown, a block38can be fit with both 4 1/16″ and 3 1/16″ ports.

Referring toFIGS. 9A and 9B, another form of insert mounting is illustrated in which the connecting valve50is larger than that of the inlet port46. The block38is also fit with an annular inlet recess and the insert12is also fit with circumferential flange, however the flange retains a full diameter and extends to an upstream end for fitting to the valve50.

With reference toFIGS. 11 through 12B, the use of screen inserts12is equally applicable for use in a fracturing block38absent a deflection sleeve.

Turning toFIGS. 10A,10B, andFIG. 11the inlets46of the block38are enlarged about the insert12to form annular flow areas32about each screen insert12. Thus, firstly flow is permitted to exit the periphery of the insert12and secondly, one can optionally reduce the velocity of the flow as it transitions from the screen insert12to the main bore52. Further, and as discussed below for the screen inserts themselves, the form of openings26can vary for a variety of objectives including manipulating flow velocity and wear behavior at the insert12or block38. As shown, the screen bore24is closed or substantially closed or closed at a closed endwall25for forcing fracturing fluid through one or more openings26,26. . . . In the case of a basket screen for a fracturing header, the closed endwall is located at a downstream end. The openings26are formed along the tubular wall28, and optionally also in the in the closed endwall (SeeFIG. 1). The openings26fluidly connect the insert bore24and the connecting piping including valves50. The one or more openings26are circumferentially spaced about the tubular wall28. The openings can be sized to maximize flow therethrough yet to capture pre-determined characteristics of known debris. The remaining portion of the tubular wall28, between openings26,26, remains sufficiently supported structurally.

As discussed, the annular flow area32is provided for receiving fluid flow and can further aid in velocity management. Again, the insert ports46, the annular flow area and the insert are sized and configured to minimize the introduction of erosion markers. If there is structure or are tools present in the main bore52, such as coil tubing or deflector sleeve or both, one can further minimize the tendency for erosion using inserts12. As shown, with a deflector sleeve in place, the insert12or inserts12,12may or may not be fit with additional axial porting as was the case with the protruding screen insert for the more generic supply flow cases such as the equalization header. Axial porting discharges a flow stream generally directed at the centreline of the bore52, such flow behavior being favorably dissipated against an opposing and incoming flow of fluid, but less desirable if directed at an obstructing component. However, in such embodiments a blank or closed endwall deflects fluid from such components, particularly if there is no deflector sleeve in place.

For example, a typical fracturing header, having coil tubing extending through a 4″ main bore downhole may only have an 8 to 9 square inch annular flow area about the coil tubing. Typically fracturing fluid is provided through 2.25″ diameter supply piping, each having a cross section of 4 sq in for two inlets being 8 sq ins or about equal to the net area about the coil tubing. Entering the fracturing block having a 4″ diameter fracturing head inlet port, the inlet area of each of two or more inlets is about 12.5 square inches, however the screen inlet only has a 3″ internal diameter or about 7 square inches each and thus for two inlets the useable area is 14 square inches, about half that being supplied, but necessarily doubling by the time it flows down the fracturing header to about the coil tubing. About the screen insert, the annular flow area at a 6″ diameter is 28 square inches for a net annular flow area of about 15.5 sq in, maintaining a lower velocity as the flow traverses the change in direction from the opposing inlet ports46to the main bore52. Accordingly the fluid flow velocity is reduced as it flows from each inlet as it enters the fracturing header bore about the coil tubing of deflector sleeve. Thus the fluids velocity is at its lowest as it turns to commence its downhole run to the tools down below.

Turning toFIGS. 13A through 18B, the inserts12themselves are described in more detail.

With reference toFIGS. 13A and 13B, a tubular insert12is shown having closed endwall25and open end27. In this embodiment, the open end in an open inlet. One form of manufacture includes taking a tubular section and adding a closed endwall, such as a circular plate secured at an end of the tubular section for forming the structure of the insert. The screen insert is then machined in a computer numerical control (CNC) unit for dimensional sizing and tapers and then slotted in a milling machine such as by using a slot drill. The tubular material can start as a high tensile strength alloy which is also treated such as by spraying with a tungsten or similar hardened material to resist erosion. The screens can be manufactured of wear resistant materials, such as EN30B, a nickel air/oil hardened steel having high strength and toughness, or other materials with a wear coating, surfacing or both.

As shown, a nominal 4 1/16″ diameter would have an internal diameter of bore24of about 3″. A plurality of slots-like openings26are formed through the tubular wall28each of having a length of 4″×0.375″ in width. Fifteen openings26can be formed for a total of 22.5 sq in. A different number and size of slots could be used. A nominal 3 1/16″ diameter screen insert12, can have a 2 1/16″ bore24and the tubular wall28being fit with 4″ long×0.375″ slot-like openings26. Ten openings provide about 15 sq in of flow area. The circumferential flange54can be in the order of about 1/16- 3/32″.

Further, as shown, the openings26can be profiled on an angle to generally correspond with a fluid flow path from the insert bore24to the annular flow areas32when in use within the fracturing block38. An angle of 45 degrees is shown. The openings in the tubular wall28from the insert's interior or bore24, to the insert's exterior or annular flow area32can be square cut or profiled to minimize flow disruption. An example of profiling in the openings includes angled opening ends60shown inFIGS. 13B and 14B. Having reference toFIGS. 7A and 7Bas the flow of fluid exits the openings26, angled ends60can also be aligned with an angled inlet end62of the annular flow area32, avoiding eddies and erosive flow disruptions. Further,FIG. 17Aillustrates the profiled openings corresponding to a transition in the inlet port to the annular flow area32. Further, inFIG. 17Bthe openings are extended downstream to the closed endwall. InFIG. 17A, the openings26include upstanding square cut slot ends at a downstream end of the insert12or flush cut slot ends as shown inFIG. 17B. Other profiles can be configured if one wishes to control the egress of fluids and corresponding effects or impact on components extending through the main bore52.

Comparing the inserts ofFIG. 13B, a flat end wall25F, andFIG. 14B, a conical end wall25C, one can see two embodiment or variations in the style of the closed endwall25. As shown inFIG. 14B, the conical end wall25C also directs fluid outwardly through the openings26. A flat end wall25F ofFIG. 13Bcould further diffuse the energy of the fluid flow prior to passing through the slot-like openings into the annular flow areas32and then onward toward the main bore52.

The openings26are spaced circumferentially and each is sized to maximize flow therethrough yet trap debris within. The openings can be equally spaced, more so dictated by manufacturing convenience.

Turning toFIGS. 15A and 15B, a fracturing block38is shown in two different embodiments here being a 15 inch high, 18.9 inch square block fit with nominal 4 1/16″ inserts12a,12a(FIG. 15A) and 3 1/16″ inserts12b,12b(FIG. 15B). The main bore52has a 7″ diameter at top and bottom with an internal taper resulting in a localized diametral increase at about the inlet ports46.

The inlet ports46as sized to accept the outer diameter of the screen inserts. Each inlet port46is enlarged within the block38for form the annular flow areas32which are contiguous with the main bore52. In the case of the 4 1/16″ insert, the annular flow area32can be about 6″ in diameter for about a 1″ annular flow area about the insert. In the case of the 3 1/16″ insert, the annular flow area32can be about 5″ in diameter, also for about a 1″ annular flow area about the insert.

The insert extends inwardly from the inlet port46sufficiently so that the openings26discharge into the annular flow area32. The mounting of the insert is also coordinated so that the closed endwall25terminates before the through bore portion of the main bore52. For example, for a block 18.9″ across, about 9.45″ to the centerline, the circumferential flange of the insert can be set back about 4.8″ so as to terminate at about 4.65″ from the centreline. This leaves a clear through bore of 9.3″. In this case the main bore for passage of tools therethrough is about 7″, providing more than enough clearance to avoid tool or interference of a deflector sleeve42with the inserts12. In an embodiment, the flow exiting the insert's openings26can be at a velocity less than about that of the supply of fracturing fluid to the fracturing header20.

With reference toFIGS. 16A,16B andFIGS. 18A and 18B, various alternate methods for securing the inserts12in the inlet ports46are shown.

InFIG. 16A, the insert is secured in a main block inlet port46having an annular recess53in the block38about the inlet port46forming a seat against which a shoulder of flange54of the insert rests or bears. InFIG. 16Bthe block is not provided with a recess53so the insert flange54bears directly on the block itself at the inlet port46. InFIG. 18Aillustrates a main block inlet port46without a recess and an insert12without a flange. The insert is secured against movement using a retainer66such as a radially extending set screw. The insert is fit with one or more pockets or a circumferential groove68for receiving the retainer66. The retainer can be arranged in the block38, or as shown through the connecting piping or flange55.FIG. 18Billustrates the insert12according to FIGS.7A,7B and FIGS.13B and14Ba having a flange54for engagement with an annular inlet recess53.

EXAMPLE

Screen Inserts

A wellbore fracturing operation was conducted. As the tool used was large in diameter, no deflector sleeve was used in the fracturing header. The operation was conducted at 3 M3/min of fracturing fluid from each of four inlet ports for a total of 12 M3/min combined flow. The fracturing header was fit with four 4 1/16″ screen inlets. A total of about 300 tonnes of proppent was delivered downhole. Upon inspection, the coil tubing was in superb condition and the screen inserts showed only slight erosion. Note that a 4 1/16″ diameter screen is rated at about a max rate of 3 M3/min of fracturing fluid and a 3 1/16″ diameter screen is rated at about a max rate of 2 M3/min.

Relative velocities were as follows. Each 2.25″ supply conduit, at 3 M3/min was flowing at about 64 ft/sec and once the flow exited the screen insert into the 6″ diameter annular flow area about the 4″ screen insert (net annular area of about 15.7 sq in), the velocity has slowed to about 16 ft/sec before the coil tubing was exposed to the flow of fluid and proppent.

In one aspect, the screen inserts are provided to contain debris but another aspect includes the ability of the design and use thereof to diffuse and deflect the sand and proppent-laden fluid prior to contacting the susceptible coil tubing. Further, use of the screen intakes allows the operator to eliminate the use of the main deflector sleeve, enabling the running of larger downhole tools.

As found, it is desirable to avoid the need for a main deflector sleeve as the resulting main bore is left wide open, avoiding restrictions and hang-ups when passing large diameter downhole tools. Optionally, a screen insert can also be provided below the deflector sleeve, at the bottom of the fracturing header, sized with an opening to pass the coiled tubing.

Following fracturing, fluids are returned to the surface, such returns known as flowback. Flowback is comprised of a portion of the fluid and contained debris, sand and proppent used to fracture the wellbore. The flowback material is also a management and erosive wear challenge. Further, it is conventional in the prior art to provide a separate flow block for redirection of returning fluids. This extra block is firstly another component at additional expense, and also further increases the height of the fracturing header by both the height of the block and that of a connecting spool (SeeFIG. 3A).

Herein, for fracturing operations conducted at lower rates that do not require the maximum capacity of a fracturing block, one of the former inlets can be configured as a flowback port. For example, a four inlet block, fit with 4″ inlet ports, normally capable of flows of 12 M3/min could be used for a fracturing job programmed for a maximum rate of 6 M3/min. Accordingly, only two inlet ports are used for fracturing operations and one port is used for flowback. The fourth port is blocked off.

With reference toFIG. 19, a fracturing block38can be adapted for both fracturing and post-fracturing flowback operations. Such a multipurpose block38M is equipped with a pair of opposing inlet ports46,46for fracturing. A third port is configured as an outlet port70for the discharge flow of flowback FB. A forth port, not shown, and if available is blocked. The outlet port70is also fit with a flowback sleeve insert72. The flowback sleeve insert72is provided as a wear sleeve for protecting the vulnerable interfaces between block38M and connecting piping or valving against the abrasive flowback FB. As with the screen inserts above, the tubular sleeve material can start as a high tensile strength alloy which is also treated such as by spraying with a tungsten or similar hardened material to resist erosion, manufactured of wear resistant materials, such as EN30B, or other materials with a wear coating or surfacing or both.

As discussed above, the erosive effect of the flow of fracturing fluids on downhole tools is effectively managed using either a deflector sleeve42, screen inserts12,12or both a deflector sleeve and screen inserts.FIG. 19illustrates an embodiment using a deflector screen42, however the inlet ports46,46could also be fit with screen inserts (not shown).

Connecting discharge piping80and connections such as a valve80V (FIG. 20A) or piping80P (FIG. 21A) connects to the outlet port70for receiving the flowback FB.

As shown inFIG. 20A, a flowback sleeve insert72is fit to the outlet port70for bridging the interface between the block and connecting discharge piping80. The sleeve72is retained to the block38M. As shown inFIG. 20B, one form of retainer is a circumferential flange54about the sleeve72and located intermediate along its length, such as that used in the case of the screen inlet12as shown inFIGS. 7A and 7B. A flange85of the connecting piping80sandwiches the circumferential flange54between the flange85and block38M. As shown inFIG. 22, a fourth port86is fit with a blind flange87

The sleeve72has an outer diameter fit to the diameter of the outlet port70. A sleeve inlet88receives flowback FB. An optional bellmouth form of inlet88aids in flow dynamics. A sleeve outlet discharges flowback FB at a sleeve outlet90to the connecting piping80. As shown inFIG. 20B, in the case of a valve80V, the valve diameter is similar to that of the outlet port70, accordingly, the sleeve72has an inside diameter or bore that is tapered to the sleeve outlet90to enlarge to substantially match that of the valve80V.

With reference toFIGS. 21A and 21B, when the flowback outlet port70is connected to piping80P, the inside diameter of the piping is typically smaller than that of the block ports. Accordingly, considering the wall thickness of the sleeve insert72, the outer diameter of the sleeve outlet90is tapered to accommodate the smaller sleeve outlet90. This can also be accomplished in whole or in part with modification of an adapter flange85to incorporate a tapered bore. Accordingly, the change in diameter can be managed by a more gradual taper upon both the outer diameter of the sleeve72and the inside diameter of the adapter flange85. As shown, the sleeve insert72can have an inside diameter about the same diameter as the piping80P. While examples are presented herein of a valve80V having a same inside diameter as the outlet port, and a connecting pipe having a smaller inside diameter, the principles of tapered inside and taper outside diameters are employed to minimize flow disruption. As shown inFIG. 21C, both the outer diameter of the sleeve outlet90and the inside diameter can be varied to match the diameter of the block outlet port70and the diameter of the connecting piping80.

Deflector Screen

With reference toFIGS. 23A and 23B, in another embodiment, the deflector sleeve42can be a deflector screen42sfit with the slot-like openings26. In this case, the deflector screen is a tubular sleeve that fits to the main bore52top and bottom of the block38. A plurality of openings26are formed and spaced about the circumference of the deflector screen permitting flow F to pass through the deflector screen and continue downhole to the wellbore. The form and method of forming and spacing the openings is as discussed above for the screen inserts.

InFIG. 23A, the deflector screen42sis a tapered tubular having a solid profile opposing the inlet ports46for protecting coil tubing and other tool components passing therethrough. The plurality of openings26are vertically spaced or offset downhole so as to only receive the flow of fluid once the energy has been dissipated. The deflector screen has a lower flange100that slidable engages the main bore52and can seal thereto with an O-ring101or the like.

InFIG. 23B, the plurality of openings26are slotted through the flange100for an additional axial flow through component.