PRIORITY DOCUMENTS

[0001 ] The present application claims priority from Australian Provisional Patent Application No. 2014902691 titled "FRAC TANK IMPROVEMENTS" and filed on 1 1 July 2014, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

10002] The present disclosure relates to a bulk fluid storage tank. In a particular form the present disclosure relates to a bulk fluid storage tank of the type known as a frac tank, which, in one form, is portable and/or mobile.

BACKGROUND

[0003] The term "frac tank" is derived from one possible use for a bulk fluid storage tank of this kind, being namely use in hydraulic fracturing operations. Hydraulic fracturing is a method used when drilling for natural gas. After a well is drilled, a fracing fluid (typically water containing a particulate such as sand and/or other proppants) are pumped into the well at high pressure. In areas with dense ground such as shale or sand, this process fractures the ground and allows more gas to escape. In order to carry out the fracturing process, a tank (the frac tank) is needed to transport the liquid used to pump the well.

[0004] Tanks of this kind are not limited to use in hydraulic fracturing processes though; they can also be used for the storage of water and other liquids on construction sites, or for storing drilling fluids used to aid the drilling of boreholes.

[0005] Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

SUMMARY

[0006] According to a first aspect, there is provided a frac tank apparatus comprising at least a first storage tank and at least one further storage tank internally, and an eductor arrangement for mixing a motive fluid and a suction fluid to form a mixed fluid or mixture, and distributing the mixed fluid or mixture to at least one of the storage tanks. [0007 ] In one form, the eductor arrangement is adapted to distribute the mixed fluid or mixture to any or each of the storage tanks.

[0008 ] In one form, the suction fluid is one of a liquid or a particulate.

[0009 ] In one form, the eductor arrangement comprises a hopper for receiving a supply of the suction fluid.

[0010] In one form, the eductor arrangement comprises a converging-diverging nozzle comprising a throat to convert a pressure energy of the motive fluid to velocity energy which creates a low pressure zone that draws in and entrains the suction fluid, after passing through the throat of the nozzle, the mixed fluid expands and the velocity is reduced which results in recompressing the mixed fluids by converting velocity energy back into pressure energy.

[001 1 1 The entrained suction fluid may be a gas, a liquid, a slurry, or a dust-laden gas stream.

[0012 ] In one form, the frac tank comprises a body comprising an external shape which substantially matches that of an ISO (or shipping) container.

[0013 ] In one form, the body comprises external dimensions which substantially match those of an ISO (or shipping) container.

[0014] In one form, the frac tank has an external shape which is generally cuboid, and which comprises a base providing a floor for each storage tank, four walls and a top. In one form, the frac tank comprises at least one internal partition to separate the first and second storage tanks.

[0015] In one form, the frac tank is elongate, and comprises a pair of opposing side walls and a pair of opposing end walls.

[0016] In one form, the frac tank has an in use configuration, and a stowed configuration for transport.

[0017] In one form, the hopper is movable between an in use position, and a stowed position. In one form, the hopper is extended into its in use position, and retracted into its stowed position. In one form, the hopper is movable by way of being swung about a pivot point.

[0018] In one form, each of the storage tanks comprises an outlet. In one form, the floor of each storage tank slopes toward its outlet. [0019 ] In one form, each of the storage tanks comprises a means for agitating the contents thereof. In one form, this means comprises a jet mixer or aeration circuit.

[0020 ] In one form, the frac tank comprises a walkway along its top. In one form this walkway is provided with a guard rail. In one form, this guard rail is movable between an in use position, and a stowed position. In one form, the guard rail is extended into its in use position, and retracted into its stowed position. When it is retracted, this guard rail lays against the frac tank top.

[0021 ] In one form, the frac tank comprises a stairway extending from at or near a ground level to the walkway. In one form this stairway is provided with a guard rail. In one form, this stairway guard rail is movable between an in use position, and a stowed position. In one form, the stairway guard rail is extended into its in use position, and retracted into its stowed position.

[0022] In one form, the frac tank is supported on wheels at or towards one end, and is adapted to be towed at or near the opposing end.

[0023 ] In one form, the frac tank further comprises a rear tow attachment point via which a road train can be formed.

[0024 ] In one form, a first frac tank is connected to a prime mover, a road train dolly is connected to the rear tow position of the first frac tank, and a further frac tank (or trailer) is connected to the road train dolly.

[0025 ] In a further aspect, there is provided a frac tank apparatus comprising a body comprising an external shape which substantially matches that of an ISO (or shipping) container with opposing ends, the frac tank apparatus further comprising wheels at or toward a first end, means by which the frac tank is adapted to be towed at or toward a second end, at least a first storage tank and at least one further storage tank internally, and an eductor arrangement for mixing a motive fluid and a suction fluid to form a mixed fluid or mixture, and distributing the mixed fluid or mixture to at least one of the storage tanks.

[0026] In a further aspect, there is provided a bulk fluid storage tank comprising a body comprising an external shape and dimensions which substantially match those of an ISO (or shipping) container, the body further comprising at least a first internal storage compartment and at least one further internal storage compartment, and an eductor arrangement for mixing a motive fluid and a suction fluid to form a mixed fluid or mixture, and distributing the mixed fluid or mixture to at least one of the storage tanks. [0027 ] A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention.

[0028] The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured.

BRIEF DESCRIPTION OF DRAWINGS

[0029] Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein:

[0030] Figure 1 is an isometric view of a bulk fluid storage tank (frac tank) according to an embodiment, in an in use configuration;

[0031 ] Figure 2 is a side view of the frac tank of Figure 1 ;

[0032] Figure 3 is an end view of the frac tank of Figure 1 ;

[00331 Figure 4 is a top view of the frac tank of Figure 1 ;

[0034] Figure 5 is an isometric view of the frac tank of Figure 1 , in a transport configuration;

[0035] Figure 6 is a side view of the frac tank of Figure 5;

[0036] Figure 7 is a view of an opposing end of the frac tank to that illustrated in Figure 3;

[0037] Figure 8 is a detail view of an eductor arrangement from the frank tank of Figure 1 ;

[0038] Figure 9 is a cross-sectional view taken along plane 9-9 (shown in Figure 10) of Figure 3;

[ 0039] Figure 10 is a cross-sectional view taken along plane 10-10 of Figure 2; [0040 ] Figure 1 1 is a cross-sectional view taken along plane 1 1-1 1 of Figure 2;

[0041 1 Figure 12 is a side view of the frac tank of Figure 5 jacked ready for coupling to a prime mover;

[0042 ] Figure 13 is a side view of a pair of frac tanks arranged as a road train towed behind a semitrailer prime mover; and

[0043] Figure 14 is a side view of a pair of frac tanks arranged as a road train towed behind a semitrailer prime mover.

[0044] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS

[0045] Referring now to Figure 1 , there is shown a bulk fluid storage tank apparatus 1 (hereinafter referred to as a frac tank 1) comprising a body 2 having an external shape which substantially matches that of an ISO (or intermodal/shipping) container, and external dimensions which substantially match those of an ISO (or shipping) container. This enables handling, stacking, storage and international shipping of the frac tank 1 as if it were a conventional shipping container, and provides for ease of transport and delivery to a job site virtually anywhere in the world, as well as convenient stacking and storage of both filled and empty tanks.

[0046 ] Accordingly, it follows that the body 2 of the frac tank apparatus 1 has an external shape which is generally cuboid and elongate. The body 2 comprises a base 6 comprising a floor for each storage tank, a pair of opposing side walls 8, a pair of opposing end walls 10, and an open top 12.

[0047] The frac tank 1 comprises a trailer-axle suspension system and wheels 4, which are recessed into the body 2 at or towards one end, so that the frac tank 1 can be rested on its base 6 (as illustrated in Figures 1 through 1 1), or tilted into a towing position (as illustrated in Figures 12 and 13) wherein the wheels 4 are brought into contact with the ground as the base 6 is lifted clear of the ground.

[0048] With reference to Figures 12 and 13, it can be seen that to aid tilting and thereby coupling of the frac tank 1 to a prime mover, the frac tank 1 comprises a pair of what are commonly referred to as 'landing legs' 14. In the case of the illustrated embodiment, each of these landing legs 14 comprises a hydraulic linear actuator (or cylinder), each cylinder comprising a cylinder barrel 15 which is secured with respect to the body 2, and a downwardly directed piston 16 which carries a foot 17 at its lowermost end. This piston 16 extends from the cylinder barrel 15 to tilt the frac tank 1, and retracts to lower the body 2 to the ground.

[0049 ] For each landing leg 14 there is a housing 18 recessed into a side wall of the body 2 at or toward a towed end of the frac tank 1 (i.e. an end opposing the end which comprises wheels 4). Each side wall comprises an opening for its respective housing, which is covered with a panel 19 unless access to the landing leg 14 is required.

[0050 ] The suspension system and wheels 4 are configured for over-the-road or highway speed travel, to enable the frac tank apparatus 1 to be transported with a semi-tractor or other suitable vehicle.

[0051 ] With reference to Figures 13, it can be seen how a frac tank 1 towed by a prime mover 100 may be equipped with a rear tow 102 position in the form of (but not necessarily limited to) a pintle hitch, to which a road train dolly 104 is attached. This road train dolly 104 supports a forward end of a further (or second) frac tank 1 , thereby forming a road train. That is to say, the second frac tank 1 is connected to the rear end of the first frac tank 1 by a road train dolly 104 comprising a fifth wheel connected to a king pin on the second frac tank 1 , and further comprising a drawbar having a tongue connected to the pintle hitch 102 on the rear of the first frac tank 1.

[0052] With reference to Figure 14, it can be seen how a dual axle frac tank 120 towed by a prime mover 100 may be equipped with a rear tow 102 position in the form of a pintle hitch, to which a road train dolly 104 is attached. This road train dolly 104 supports a forward end of a further frac tank 1 , thereby forming a road train.

[0053 ] With reference to Figure 9, it can be seen that the frac tank 1 comprises an internal partition 20 to separate this into first and second storage tanks (or compartments) A and B, where each of the storage tanks (or compartments) A and B comprises an outlet (or drain) 24, and the floor 22 of each storage tank slopes toward its outlet 24 to aid drainage.

[0054] The frac tank 1 further comprises an eductor arrangement 30 for mixing a motive fluid (commonly water) and a suction fluid (such as a proppant or 'frac sand') to fonn a fluid mixture which can be distributed to one or both of the storage tanks A and/or B. With reference to Figure 1 1, it can be seen that the eductor arrangement 30 comprises a motive fluid inlet 32, a suction fluid inlet 34, a hopper 40 for receiving a supply of the suction fluid and feeding this to suction fluid inlet 34, a mixed fluid outlet 38, and a converging-diverging nozzle 36 between the suction fluid inlet 32 and the mixed fluid outlet 38. [0055] With reference to Figure 9, it can be seen that the mixed fluid outlet 38 branches via a T-piece into a first eductor outlet 42 and a second eductor outlet 44, where the first eductor outlet 42 outlets into the first storage tank A, and the second eductor outlet 44 outlets into the second storage tank B. Valves 46 can be incorporated in one or both of the eductor outlets 42 and/or 44 to open, close or throttle these as required.

[0056] The converging-diverging nozzle 36 comprises a throat to convert a pressure energy of the motive fluid to velocity energy which creates a low pressure zone that draws in and entrains the suction fluid, after passing through the throat of the nozzle 36, the mixed fluid expands and the velocity is reduced which results in recompressing the mixed fluids by converting velocity energy back into pressure energy.

[0057] The hopper 40 is movable between an in use position (as illustrated in Figure 8), and a stowed position (as illustrated in Figure 5) for transportation of the frac tank 1. The hopper 40 is extended into its in use position by swinging it upward about a pivot point, and retracted into its stowed position by swinging it downward. When stowed, the hopper 40 passes through a hatch 48 to a position below a level of the top 12 of the frac tank 1.

[0058 ] The frac tank apparatus 1 comprises a pump P, which is located at the towed end of the tank body. Located adjacent to the pump P are a number of fluid fittings to which either of the pump inlet PI or pump outlet P2 can be functionally connected as required, to supply fluid to or extract fluid from, the storage tanks A and B. Fitting Nl is a connector for the motive fluid inlet 32, fitting N3 is a suction line for tank A, fitting N4 is a filler for tank B, and N6 is a suction line for tank B.

[0059] In order to provide access to the hopper 40, the frac tank 1 comprises, at the pump P end of the body 2, a stairway 50 which extends from ground level to the top of the body 2.

[0060] There is also provided a walkway 60 which extends along the top of the body 2 from the stairway 50 to the hopper 40, and which surrounds a platform 62 which surrounds the hopper 40. Hatch 48 forms part of this walkway 60 when closed over the retracted hopper 40.

[0061 ] This walkway 60 and platform 62 are provided with a guard rail 70, which is movable between an in use position, and a stowed position for transport of the frac tank 1. Similarly, the stairway 50 is provided with a stairway guard rail 80, which is also movable between an in use position, and a stowed position for transport of the frac tank 1. [0062 ] The walkway 60 and platform 62 guard rail 70 comprises a plurality of gates 72 which are pivotally connected with respect to the body 2 so that these can be either laid down (ie stowed), or stood upright (ie in use).

[0063 ] The stairway guard rail 80 comprises a plurality of balusters 82 which are pivotally secured at one end with respect to the stairway 50, and pivotally secured at a further end with respect to a handrail 84. When the stairway guard rail 80 is stowed, the balusters 82 lay against the stairway 50, and the hand rail 80 lays against the balusters 82. When the stairway guard rail 80 is to be moved from its stowed position to its in use position, the balusters 82 are swung upwardly until they are substantially normal to the stairway 50.

[0064] Movement of both the guard rail 70 and stairway guard rail 80 can be automated by way of a system comprising electrical or fluid powered actuators and controls for these, or manually effected. Where they are manually erected, a releasable locking means can be used to hold them in their in use (ie erected) positions.

[0065 ] Each of the storage tanks A and B comprises a means 90 for agitating the contents thereof. An agitation means 90 is a useful inclusion because it can be used to prevent a mixed fluid from separating in the tank A or B, or to remix contents in cases where these may have been allowed to sit for a period of time. In the case of the illustrated embodiment, this mixing means 90 comprises a jet mixer system, although alternatively, it could comprise an aeration circuit.

[0066] With reference to Figure 10, it can be seen that for each of the storage tanks A and B, the agitation means 90 comprises an inlet fitting 92 to which the outlet P2 of the pump P is to be functionally connected. The inlet fitting 92 is attached to a fluid supply conduit 94 which extends in an approximate U-shape about the floor of the tank A or B. The fluid supply conduit 94 comprises a plurality of jet nozzles 96 spaced apart along the length thereof, which receive fluid from the supply conduit 94 and outlet this into the tank A or B as a jet of the supply fluid which then agitates the contents of the tank A or B.

[0067] In one possible application, water may be drawn from tank A, mixed with a proppant using the eductor arrangement 30, and the resultant mixture (the fracing fluid) stored in tank B until required.

[0068] The frac tank disclosed herein will find application in storing, transporting and mixing fluids in remote locations.

[0069] Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0070] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0071 ] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.