WO2015088682A2

WO2015088682A2 - System and method of injecting a proppant mixture during fracturing

Info

Publication number: WO2015088682A2
Application number: PCT/US2014/064612
Authority: WO
Inventors: David A. Howell; Manh V. Phi; Nancy H. Choi; Abdel Wadood M. EL-RABAA; Stuart R. Keller; Fuping Zhou
Original assignee: Exxonmobil Upstream Research Company
Priority date: 2013-12-13
Filing date: 2014-11-07
Publication date: 2015-06-18
Also published as: US20150167441A1; WO2015088682A3

Abstract

A method of forming an elevated pressure proppant-containing fracturing fluid for direct injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment. The method includes providing a high pressure fluid stream to a nozzle having an inlet and an exit; accelerating the high pressure fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; and mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid. A method for fracturing and a system for forming an elevated pressure proppant-containing fracturing fluid for injection into a wellbore are also provided.

Description

SYSTEM AND METHOD OF INJECTING A PROPPANT MIXTURE DURING

FRACTURING

Cross Reference to Related Application

[0001] This application claims the benefit of U.S. Provisional Patent Application 61/915,671, filed December 13, 2013, entitled SYSTEM AND METHOD OF INJECTING A PROPPANT MIXTURE DURING FRACTURING, the entirety of which is incorporated by reference herein.

Field

[0002] The present disclosure relates to a system and method of injecting or educting a proppant mixture for fracture stimulation of oil and gas wells.

Background

[0003] Hydraulic fracturing is one of the most complex oilfield services employed today, requiring equipment to transport and store water and chemicals, prepare the fracturing fluid, blend the fluid with proppant, pump the fluid down the well and monitor the treatment.

[0004] Hydraulic fracturing is a stimulation technique used to create a fracture network in a reservoir to provide a highly permeable pathway for production fluids and gas moving from the reservoir into a wellbore. The fracture network is created by applying pressure on the formation to split the rock, and pumping a mixture of fracturing fluid and proppant into it.

[0005] In a typical setup, at the surface, fracturing fluid and proppant are mixed on the low pressure side of a positive displacement pump, which is then used to push the mixed fluid into the formation at a high pressure. Prior to horizontal well multi-stage fracturing technology, a conventional fractured well may have required a few fracturing stages at 50 bpm or less, with surface pumping pressure of up to 10,000 psi and in some instances even up to 15,000 psi.

[0006] The maintenance program and its frequency for fracturing pumps have increased significantly with shale oil/gas development where horizontal well multi-stage fracturing technology is applied. Each fracturing stage commonly requires pumping at a combined fluid and proppant rate (slurry rate) of up to 50 bpm, and often at rates greater than 50 BPM, such as up to 100 BPM, although sometimes the slurry rate is as low as 1 BPM. Additionally, there may be numerous distinct fracturing intervals within the wellbores, such as up to or even in excess of 30 "stages" per well. Note that each stage may itself be subdivided into various sub-intervals that may somewhat confusingly also be referred to as stages, such as for each of varying proppant concentrations within the slurry. However, the duplicate usage of this term of art within the industry to describe both sub-intervals (stage) within a fracture job (stage) is well known to those skilled in the art and is understood by the contextual use of this term, thus generally avoiding confusion. However, unless clearly identified otherwise, use of the term "stage" herein shall refer to the fracturing job that is executed on a single range of perforations or intervals within a wellbore that is treated with a substantially uninterrupted or continuous pumping process.

[0007] This demand on fracture treatment equipment at a high rate and high pressure for hours to stimulate a shale oil or gas reservoir imputes substantial operating costs, stress, and wear on hydraulic fracturing equipment and pumps, especially when pumping the abrasive proppant-laden slurry through the pumps, lines, valves, and other surface equipment. The rate of wear on such equipment on such multiple stage stimulation jobs can frequently even necessitate repair and maintenance of pumps and other equipment to be performed on the well location, instead of the preferred locale of a workshop. Consequently, delays, costs, personnel time are compromised and cannot be efficiently and wholly directed only to the objective of fracturing the geologic formations).

[0008] Therefore, what is needed are simple, cost-effective methods, systems and apparatus for forming an elevated pressure proppant-containing fracturing fluid for injection into a wellbore that reduces the exposure of a substantial amount of the pumping equipment to the abrasive effects of the proppant, as compared to conventional pumping equipment.

Summary

[0009] In one aspect, provided is a method of forming an elevated pressure proppant- containing fracturing fluid for direct injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment. The method includes providing a high pressure fluid stream to a nozzle having an inlet and an exit; accelerating the high pressure fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; providing a low pressure stream including a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; and mixing the low pressure fluid stream including a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid.

[0010] In some embodiments, the high pressure fluid stream is provided from a source of substantially proppant-free fluid.

[0011] In some embodiments, the substantially proppant-free high pressure fluid stream is provided by a high pressure pump.

[0012] In some embodiments, the high pressure pump is a centrifugal pump.

[0013] In some embodiments, the centrifugal pump is a multi-stage centrifugal pump.

[0014] In some embodiments, the multi-stage centrifugal pump is powered by a jet turbine.

[0015] In some embodiments, the high pressure pump is a positive displacement pump.

[0016] In some embodiments, the nozzle and suction chamber form an eductor.

[0017] In some embodiments, the eductor further comprises an outlet end in fluid communication with a well.

[0018] In another aspect, provided is a method of fracturing a formation penetrated by a well. The method includes the steps of: providing a substantially proppant-free fluid stream to an inlet of a high pressure pump; pressurizing the substantially proppant-free fluid stream to form a high pressure substantially proppant-free fluid stream; feeding the substantially proppant-free high pressure fluid stream to a nozzle having an inlet and an exit; accelerating the high pressure substantially proppant-free fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid; and injecting the elevated pressure proppant-containing fracturing fluid into the well.

[0019] In some embodiments, the substantially proppant-free high pressure fluid stream is provided by a high pressure pump.

[0020] In some embodiments, the high pressure pump is a centrifugal pump.

[0021] In some embodiments, the centrifugal pump is a multi-stage centrifugal pump. [0022] In some embodiments, the multi-stage centrifugal pump is powered by a jet turbine.

[0023] In some embodiments, the nozzle and suction chamber form an eductor.

[0024] In some embodiments, the eductor further comprises an outlet end in fluid communication with a well.

[0025] In some embodiments, the method further includes the step of passing elevated pressure proppant-containing fracturing fluid through one or more mixing baffles.

[0026] In some embodiments, the method further includes the step of adding a viscosity reducing additive to the low pressure stream comprising a proppant.

[0027] In yet another aspect, provided is a system for forming an elevated pressure proppant-containing fracturing fluid for injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment. The system includes at least one high pressure pump having an inlet and an outlet, for pressurizing a substantially proppant-free fluid; at least one low pressure pump having an inlet and an outlet, for pressurizing a proppant-containing fluid; and at least one eductor, the at least one eductor comprising a nozzle having an inlet and an outlet, a suction chamber and an eductor outlet, the nozzle inlet in fluid communication with the outlet of the at least one high pressure pump, the suction chamber in fluid communication with the outlet of the at least one low pressure pump and the eductor outlet in fluid communication with the well.

[0028] In some embodiments, the high pressure pump is a centrifugal pump.

[0029] In some embodiments, the centrifugal pump is a multi-stage centrifugal pump.

[0030] In some embodiments, the multi-stage centrifugal pump is powered by a jet turbine.

[0031] In some embodiments, the system further includes one or more mixing baffles positioned downstream of the eductor outlet.

[0032] In some embodiments, the system further includes a blast joint positioned upstream or downstream of the eductor nozzle inlet.

[0033] In some embodiments, a plurality of high pressure pumps for pressurizing a substantially proppant-free fluid, a low pressure pump for pressurizing a proppant-containing fluid, and an eductor are structured and arranged to provide elevated pressure proppant- containing fracturing fluid for injection into a well.

[0034] In yet another aspect, provided is a method of increasing the service life of a high pressure pump used in a system for forming an elevated pressure proppant-containing fracturing fluid for direct injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment; the method comprising the steps of: providing a substantially proppant-free fluid stream to an inlet of a high pressure pump; pressurizing the substantially proppant-free fluid stream to form a high pressure substantially proppant-free fluid stream; feeding the substantially proppant-free high pressure fluid stream to a nozzle having an inlet and an exit; accelerating the high pressure fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; and mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid.

[0035] In some embodiments, the high pressure fluid stream is provided from a source of substantially proppant-free fluid.

[0036] In some embodiments, the substantially proppant-free high pressure fluid stream is provided by a high pressure pump.

[0037] In some embodiments, the high pressure pump is a centrifugal pump.

[0038] In some embodiments, the centrifugal pump is a multi-stage centrifugal pump.

[0039] In some embodiments, the high pressure pump is a positive displacement pump.

[0040] In some embodiments, the nozzle and suction chamber form an eductor.

[0041] In some embodiments, the eductor further comprises an outlet end in fluid communication with a well.

[0042] In some embodiments, the method further includes the step of passing elevated pressure proppant-containing fracturing fluid through one or more mixing baffles.

Brief Description of the Drawings

[0043] FIG. 1 presents a diagrammatic view of an illustrative example of a system for hydraulic fracturing, in accordance with prior practice. [0044] FIG. 2 presents a diagrammatic view of an illustrative, non-exclusive example, of a system for hydraulic fracturing, according to the present disclosure.

[0045] FIG. 3 presents a diagrammatic view of an illustrative, non-exclusive example of a system for forming an elevated pressure proppant-containing fracturing fluid for injection into a wellbore, according to the present disclosure.

[0046] FIG. 4 presents a cutaway view of an illustrative, non-exclusive example of an apparatus for the induction of high concentration slurry into a high pressure main stream, according to the present disclosure.

[0047] FIG. 5 presents a cutaway view of another illustrative, non-exclusive example of a system for the induction of high concentration slurry to a high pressure main stream, according to the present disclosure.

Detailed Description

[0048] FIGS. 2-5 provide illustrative, non-exclusive examples of system for forming an elevated pressure proppant-containing fracturing fluid for injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, methods and systems, according to the present disclosure and/or of systems, apparatus, and/or assemblies that may include, be associated with, be operatively attached to, and/or utilize such systems. In FIGS. 2-5, like numerals denote like, or similar, structures and/or features; and each of the illustrated structures and/or features may not be discussed in detail herein with reference to each of FIGS. 2-5. Similarly, each structure and/or feature may not be explicitly labeled in each of FIGS. 2-5; and any structure and/or feature that is discussed herein with reference to any one of FIGS. 2-5 may be utilized with any other of FIGS. 2-5 without departing from the scope of the present disclosure.

[0049] In general, structures and/or features that are, or are likely to be, included in a given embodiment are indicated in solid lines in FIGS. 1-5, while optional structures and/or features are indicated in broken lines. However, a given embodiment is not required to include all structures and/or features that are illustrated in solid lines therein, and any suitable number of such structures and/or features may be omitted from a given embodiment without departing from the scope of the present disclosure. [0050] FIG. 1 presents a schematic view of an illustrative example of a system for hydraulic fracturing 10, in accordance with prior practice. In a conventional setup, system 10 includes a plurality of water tanks 12, each typically in the form of a conventional portable tank. The water from the plurality of portable water tanks 12 passes through gel tank 14 for thickening. Delayed crosslinkers may be added, as desired. The mixture passes on to the hydration tank 16 then onto a blender unit 18, where proppant from proppant tank 20 is mixed.

[0051] The proppant mixture is sent to a manifold 22 and sent via one or more low pressure lines 24 to one or more high pressure pumps 26, where the proppant mixture is pressurized and returned to manifold 22 via one or more high pressure lines 28. The high pressure proppant mixture is then transferred via line 30 to well 32. Annular pump 34 may be used to add additional fluid to the wellbore, or the annulus, to support operations.

[0052] As may be appreciated from FIG. 1, water and proppant are mixed on the low pressure side of system 10 and high pressure pumps, which may be positive displacement pumps, are used to push the mixed fluid into the formation at high pressure. Prior to horizontal well, multi-frac stage technology, a conventional fractured well may have required a few stages at 50 bpm or less, with surface pumping pressure of 10,000 psi or less. The maintenance program and its frequency for the high pressure pumps have increased significantly with shale oil/gas development, where horizontal well, multi frac stage technology is applied. Each frac stage requires pumping at greater than about 50 bpm at pressures that may be higher than 10,000 psi. Additionally, there may be 30 or more frac stages employed per well. This demand on fracture treatments, conducted at a high rate and high pressure for hours to stimulate a shale oil or gas reservoir, has put great stress on the high pressure frac pumps, which increases maintenance and downtime. The system and methods disclosed herein address one or more of these issues.

[0053] Referring now to FIG. 2, a schematic view of an illustrative, non-exclusive example, of a system for hydraulic fracturing 100, according to the present disclosure, is presented. System 100 includes a plurality of water tanks 1 12, each typically in the form of a conventional portable tank. The water from the plurality of portable water tanks 1 12 passes through gel tank 114 for thickening. Delayed crosslinkers may be added, as desired. The mixture passes on to the hydration tank 116 and is sent to a manifold 122 via line 1 18. From manifold 122, the thickened water is sent via one or more low pressure lines 124 to one or more high pressure pumps 126, where it is pressurized and returned to manifold 122 via one or more high pressure lines 128. The high pressure thickened water main stream is then transferred via line 130 to an apparatus 140 for forming an elevated pressure proppant- containing fracturing fluid, wherein a high concentration proppant slurry is provided under low pressure from a proppant tank 120 via line 136 for induction into the high pressure main stream and sent to well 132. Annular pump 134 may be used to add additional fluid to the wellbore, or the annulus, to support operations.

[0054] As those skilled in the art will plainly recognize, the system for hydraulic fracturing 100 of FIG. 2 functions without the need for exposure of the high cost, high pressure pumps 126 to the abrasive effects of proppant, as compared to conventional pumping equipment and systems for hydraulic fracturing, such as the system 10 of FIG. 1.

[0055] Referring now to FIG. 3, presented is a schematic view of an illustrative, nonexclusive example of a system 200 for forming an elevated pressure proppant-containing fracturing fluid for injection into a wellbore 232. As was the case for system 100 depicted in FIG. 2, system 200 reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional systems, such as system 10 depicted in FIG. 1.

[0056] System 200 includes apparatus 240 for forming an elevated pressure proppant- containing fracturing fluid. In some forms, apparatus 240 may include at least eductor 242 that includes a nozzle 244 having an inlet 246 and an outlet 248, a suction chamber 250 and an eductor outlet 252. As shown, the nozzle inlet 246 is in fluid communication with the outlet 254 of at least one high pressure pump 256. The at least one high pressure pump 256 has an inlet 258 that is in fluid communication with a source of fracturing fluid 260. As shown, the suction chamber 250 of the at least eductor 242 is in fluid communication with the outlet 262 of at least one low pressure pump 264. The at least one low pressure pump 264 has an inlet 266 that is in fluid communication with a source of high concentration proppant slurry 270. Eductor outlet 252 may be placed in fluid communication with a well 232. An enlarged cutaway view of apparatus 240 is presented in FIG. 4.

[0057] High pressure pump 256 may be selected from a wide variety of commercially available pumps. In some embodiments, high pressure pump 256 is a centrifugal pump. In some embodiments, the centrifugal pump is a multi-stage centrifugal pump. In some embodiments, the multi-stage centrifugal pump is powered by a jet turbine.

[0058] In some embodiments, a plurality (not shown) of high pressure pumps 256 are used to pressurize a substantially proppant-free fluid. The plurality high pressure pumps 256, together with low pressure pump 264 for pressurizing a proppant-containing fluid and at least one eductor 242 are structured and arranged to provide elevated pressure proppant-containing fracturing fluid for injection into a well 232.

[0059] FIG. 5 presents an enlarged cutaway view of an apparatus 340 for forming an elevated pressure proppant-containing fracturing fluid. Apparatus 340 may include at least eductor 342 that includes a nozzle 344 having an inlet 346 and an outlet 348, a suction chamber 350 and an eductor outlet 352. In some embodiments, apparatus 340 may include two or more eductors 342 in parallel to increase throughput. As in the embodiment of FIG. 2, the nozzle inlet 346 may be placed in fluid communication with an outlet of at least one high pressure pump (not shown), which in turn is in fluid communication with a source of fracturing fluid (not shown). Suction chamber 350 of the at least one eductor 342 may be placed in fluid communication with an outlet of at least one low pressure pump (not shown), which in turn is in fluid communication with a source of high concentration proppant slurry (not shown). Eductor outlet 352 may be placed in fluid communication with a well (not shown). As shown, eductor 342 is provided with one or more mixing baffles 374 positioned downstream of the nozzle outlet 348. In the embodiment of FIG. 5, eductor 342 is provided with one or a pair or more of blast joints 372 may be positioned upstream of inlet 346, within educator 342, and/or downstream of the eductor nozzle 348. Nozzle 344 may also comprise a blast joint and/or other wear resistant material. As those skilled in the art will recognize, blast joints 372 are heavy wall and/or hard, abrasion-resistant materials and connectors designed to minimize the abrasive or erosive effects of the energized, high velocity erosive action caused by fluids.

[0060] As those skilled in the art will recognize, eductors operate on basic fluid dynamic principles. The fundamental principles are Bernoulli's law^ and momentum transfer*^ and are as follows:

_Pl + l/2 (p₁7₁ ²) = p₂ + l/2(pv₂ ² (1) mv— m₁v₁—m₂v₂ = Ap * A (2)

[0061] As mentioned, eductors take a high pressure motive stream and accelerate it through a tapered nozzle to increase the velocity of the fluid (gas or liquid) that is put through the nozzle. This fluid is then carried on through a secondary chamber where the friction between the molecules of it and a secondary fluid, generally referred to as the suction fluid, causes this fluid to be pumped. These fluids are intimately mixed together and discharged from the eductor.

[0062] There are three connections common to all eductors. The motive connection is where the power for the eductor is generated, by increasing the velocity of the motive fluid. The nozzle in this section takes advantage of the physical properties of the motive fluid. Eductors with liquid motives use a converging nozzle as liquids are not generally compressible. Eductors with gas motives utilize converging-diverging nozzles to achieve maximum benefit from the compressibility of the gas. In one form, the nozzle is provided with a smooth flow path. Flow paths with roughness on high velocity surfaces cause eductors to operate less efficiently.

[0063] The suction connection of the eductor produces the pumping action of the eductor. The motive fluid passes through the suction chamber entraining the suction fluid as it passes. The friction between the fluids causes the chamber to be evacuated. This allows pressure in the suction vessel to push additional fluid into the suction connection of the eductor. The high velocity of the motive stream in this section of the eductor directs the combined fluids toward the outlet section of the eductor.

[0064] As the motive fluid entrains the suction fluid, part of the kinetic energy of the motive fluid is imparted to the suction fluid. This allows the resulting mixture to discharge at an intermediate pressure. The percentage of the motive pressure that can be recovered is dependent upon the ratio of motive flow to suction flow and the amount of suction pressure pulled on the suction port. The mixture then passes through the diverging taper converts the kinetic energy back to pressure. The combined fluid then leaves the outlet of the eductor.

[0065] By use of the term "elevated pressure" in connection with the output stream of an eductor is meant to acknowledge the fact that mixing a higher pressure stream with a lower pressure stream in an eductor will result in the output stream being at an intermediate pressure with respect to the higher pressure stream and the lower pressure stream, but nevertheless, elevated in pressure over the lower pressure stream.

[0066] In some embodiments, provided is a method of forming an elevated pressure proppant-containing fracturing fluid for direct injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment. The method includes providing a high pressure fluid stream to a nozzle having an inlet and an exit; accelerating the high pressure fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; and mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid.

[0067] In some embodiments, provided is a method of fracturing a formation penetrated by a well. The method includes the steps of: providing a substantially proppant-free fluid stream to an inlet of a high pressure pump; pressurizing the substantially proppant-free fluid stream to form a high pressure substantially proppant-free fluid stream; feeding the substantially proppant-free high pressure fluid stream to a nozzle having an inlet and an exit; accelerating the high pressure substantially proppant-free fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid; and injecting the elevated pressure proppant-containing fracturing fluid into the well.

[0068] In some embodiments, provided is a method of increasing the service life of a high pressure pump used in a system for forming an elevated pressure proppant-containing fracturing fluid for direct injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment; the method comprising the steps of: providing a substantially proppant-free fluid stream to an inlet of a high pressure pump; pressurizing the substantially proppant-free fluid stream to form a high pressure substantially proppant-free fluid stream; feeding the substantially proppant-free high pressure fluid stream to a nozzle having an inlet and an exit; accelerating the high pressure fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; and mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid.

[0069] Benefits of the systems and methods disclosed herein include less erosion of current positive displacement pumps, reduced cost by decreasing working horsepower and required standby pumping equipment, reduced generation of proppant fines during pumping, since the induction system decreases damage to the proppant, itself. As may be appreciated, fines are notorious and reduce the conductivity of fracture network. Other benefits include the fact that lower maintenance centrifugal pumps could replace the currently employed positive displacement pumps. Centrifugal pumps could be used to handle only clear fluid, reducing maintenance cost. Multi-stage centrifugal pumps may be powered by jet turbines. Also, decreased location size may be realized due to a reduced requirement for standby horsepower. Finally, unintentional, high concentration proppant slugs that cause screen out may be eliminated.

[0070] In the present disclosure, several of the illustrative, non-exclusive examples have been discussed and/or presented in the context of flow diagrams, or flow charts, in which the methods are shown and described as a series of blocks, or steps. Unless specifically set forth in the accompanying description, it is within the scope of the present disclosure that the order of the blocks may vary from the illustrated order in the flow diagram, including with two or more of the blocks (or steps) occurring in a different order and/or concurrently. It is also within the scope of the present disclosure that the blocks, or steps, may be implemented as logic, which also may be described as implementing the blocks, or steps, as logics. In some applications, the blocks, or steps, may represent expressions and/or actions to be performed by functionally equivalent circuits or other logic devices. The illustrated blocks may, but are not required to, represent executable instructions that cause a computer, processor, and/or other logic device to respond, to perform an action, to change states, to generate an output or display, and/or to make decisions.

[0071] As used herein, the term "and/or" placed between a first entity and a second entity means one of (1) the first entity, (2) the second entity, and (3) the first entity and the second entity. Multiple entities listed with "and/or" should be construed in the same manner, i.e., "one or more" of the entities so conjoined. Other entities may optionally be present other than the entities specifically identified by the "and/or" clause, whether related or unrelated to those entities specifically identified. Thus, as a non-limiting example, a reference to "A and/or B," when used in conjunction with open-ended language such as "comprising" may refer, in one embodiment, to A only (optionally including entities other than B); in another embodiment, to B only (optionally including entities other than A); in yet another embodiment, to both A and B (optionally including other entities). These entities may refer to elements, actions, structures, steps, operations, values, and the like.

[0072] As used herein, the phrase "at least one," in reference to a list of one or more entities should be understood to mean at least one entity selected from any one or more of the entity in the list of entities, but not necessarily including at least one of each and every entity specifically listed within the list of entities and not excluding any combinations of entities in the list of entities. This definition also allows that entities may optionally be present other than the entities specifically identified within the list of entities to which the phrase "at least one" refers, whether related or unrelated to those entities specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and/or B") may refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including entities other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including entities other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other entities). In other words, the phrases "at least one," "one or more," and "and/or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B and C," "at least one of A, B, or C," "one or more of A, B, and C," "one or more of A, B, or C" and "A, B, and/or C" may mean A alone, B alone, C alone, A and B together, A and C together, B and C together, A, B and C together, and optionally any of the above in combination with at least one other entity.

[0073] In the event that any patents, patent applications, or other references are incorporated by reference herein and define a term in a manner or are otherwise inconsistent with either the non-incorporated portion of the present disclosure or with any of the other incorporated references, the non-incorporated portion of the present disclosure shall control, and the term or incorporated disclosure therein shall only control with respect to the reference in which the term is defined and/or the incorporated disclosure was originally present.

[0074] As used herein the terms "adapted" and "configured" mean that the element, component, or other subject matter is designed and/or intended to perform a given function. Thus, the use of the terms "adapted" and "configured" should not be construed to mean that a given element, component, or other subject matter is simply "capable of performing a given function but that the element, component, and/or other subject matter is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the function. It is also within the scope of the present disclosure that elements, components, and/or other recited subject matter that is recited as being adapted to perform a particular function may additionally or alternatively be described as being configured to perform that function, and vice versa.

Industrial Applicability

[0075] The systems and methods disclosed herein are applicable to the oil and gas industry.

[0076] It is believed that the disclosure set forth above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the inventions includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions and/or properties disclosed herein. Similarly, where the claims recite "a" or "a first" element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.

[0077] It is believed that the following claims particularly point out certain combinations and subcombinations that are directed to one of the disclosed inventions and are novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower, or equal in scope to the original claims, are also regarded as included within the subject matter of the inventions of the present disclosure.

Claims

1. A method of forming an elevated pressure proppant-containing fracturing fluid for direct injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment; the method comprising the steps of: a) providing a high pressure fluid stream to a nozzle having an inlet and an exit; b) accelerating the high pressure fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; c) providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; and d) mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid.

2. The method of claim 1, wherein the high pressure fluid stream is provided from a source of substantially proppant- free fluid.

3. The method of claim 2, wherein the substantially proppant- free high pressure fluid stream is provided by a high pressure pump.

4. The method of claims 1-3, wherein the nozzle and suction chamber form an eductor.

5. The method of claim 4, wherein the eductor further comprises an outlet end in fluid communication with a well.

6. A method of fracturing a formation penetrated by a well, the method comprising the steps of: a) providing a substantially proppant- free fluid stream to an inlet of a high pressure pump; b) pressurizing the substantially proppant-free fluid stream to form a high pressure substantially proppant-free fluid stream; c) feeding the substantially proppant-free high pressure fluid stream to a nozzle having an inlet and an exit; d) accelerating the high pressure substantially proppant-free fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; e) providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; f) mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid; and g) injecting the elevated pressure proppant-containing fracturing fluid into the well.

7. The method of claim 6, wherein the substantially proppant-free high pressure fluid stream is provided by a high pressure pump.

8. The method of claim 6 or 7, wherein the high pressure pump is a centrifugal pump..

9. The method of claims 6-8, further comprising the step of passing elevated pressure proppant-containing fracturing fluid through one or more mixing baffles.

10 The method of claims 6-9, wherein the high pressure fluid stream is provided from a source of substantially proppant-free fluid.

11. The method of claims 6-10, wherein the eductor further comprises an outlet end in fluid communication with a well.

12. The method of claims 6-1 1, wherein the nozzle and suction chamber form an eductor.

13. A system for forming an elevated pressure proppant-containing fracturing fluid for injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment, comprising: a) at least one high pressure pump having an inlet and an outlet, for pressurizing a substantially proppant-free fluid; b) at least one low pressure pump having an inlet and an outlet, for pressurizing a proppant-containing fluid; and c) at least one eductor, the at least one eductor comprising a nozzle having an inlet and an outlet, a suction chamber and an eductor outlet, the nozzle inlet in fluid communication with the outlet of the at least one high pressure pump, the suction chamber in fluid communication with the outlet of the at least one low pressure pump and the eductor outlet in fluid communication with the well.

14. The system of claim 13, wherein the high pressure pump is a centrifugal pump.

15. The system of claim 13-14, further comprising one or more mixing baffles positioned downstream of the eductor outlet.

16. The system of claims 13-15, wherein a plurality of high pressure pumps for pressurizing a substantially proppant-free fluid, a low pressure pump for pressurizing a proppant-containing fluid, and an eductor are structured and arranged to provide elevated pressure proppant-containing fracturing fluid for injection into a well

17. A method of increasing the service life of a high pressure pump used in a system for forming an elevated pressure proppant-containing fracturing fluid for direct injection into a wellbore that reduces exposure of a substantial amount of the pumping equipment to the abrasive effects of proppant, as compared to conventional pumping equipment; the method comprising the steps of: a) providing a substantially proppant-free fluid stream to an inlet of a high pressure pump; b) pressurizing the substantially proppant-free fluid stream to form a high pressure substantially proppant-free fluid stream; c) feeding the substantially proppant- free high pressure fluid stream to a nozzle having an inlet and an exit; d) accelerating the high pressure fluid stream through the nozzle from the inlet to the exit to increase the velocity thereof; e) providing a low pressure stream comprising a proppant to a suction chamber, the suction chamber positioned adjacent the nozzle exit; and f) mixing the low pressure fluid stream comprising a proppant with the high pressure fluid stream to form an elevated pressure proppant-containing fracturing fluid.

18. The method of claim 17, wherein the high pressure fluid stream is provided from a source of substantially proppant-free fluid.

19. The method of claims 17-18, wherein the nozzle and suction chamber form an eductor.

20. The method of claim 19, wherein the eductor further comprises an outlet end in fluid communication with a well.