1. Field of Invention
The present disclosure relates in general to injecting fluid into a well, and in particular to methods and devices that blend additives to the fluid in an eductor.
2. Description of Prior Art
Fluids are often injected into wells during various wellbore operations, such as during drilling, pump down procedures, or hydraulic fracturing (“fracing”). A blender is typically provided at the well site during the fracing process for mixing chemicals, water, and proppant. The chemicals generally include friction reducers and viscosity enhancers. The blender feeds the mixture to high pressure pumps for pressuring the mixture to pressures that often approach 10,000 psi; the pressurized mixture is then injected into the well to create fractures.
Completion of a well typically involves perforating through casing that lines the wellbore, where perforating generally starts at a lowermost depth in the wellbore, and is sequentially performed at reduced depths up the wellbore. Plugs are generally installed in the wellbore above each set of perforations. It is not uncommon for an operator to create twenty or more sets of perforations, and install twenty or more plugs in a well. The plugs are usually removed with a drilling system. High pressure completion drilling fluid is often circulated through the wellbore while the plugs are being drilled. Typical drilling pressures are in the range of 2500 to 5000 psi, and the flow rates are usually at least 100 gpm (gallons per minute). The fluid flow rate and pressure is controlled so that the drilled plug fragments flow out of the wellbore entrained within the completion drilling fluid. To enhance the flow of the completion drilling fluid, friction reducers, chemicals, or viscosifiers such as liquid gelling agents are added to the well fluid in a blender. The friction reducers and viscosifiers are normally polymers. After a designated viscosity has been reached, the drilling fluid is directed from the blender to the high pressure pumps. Blending can be time consuming, which adds to the total time to drill out the wells containing the temporary frac plugs.
Mixing devices and systems such as low, or zero, pressure surface blending systems, low pressure batch mixing systems, low pressure surface hydration systems and other such systems primarily depend on time. Conventional blenders use atmospheric tanks, static mixers, internal stirring paddles, and/or some form of non-positive suction and/or displacement high pressure jetting. The blending unravels and shear stresses component molecules of the chemicals being introduced. Blending is done in efforts to bring multiple components ultimately into one homogeneous and consistent blend of quality product with enhanced chemical and physical characteristics. Atmospheric blending generally requires at least two hours to achieve hydration rates of around 90%.
Disclosed herein is an example method of wellbore operations that includes providing an eductor unit having a housing, an axial bore in the housing, a jet nozzle in the bore, the jet nozzle having an inlet and an outlet, and an inner diameter that reduces with distance away from the inlet. An annular space is formed between an outer surface of the jet nozzle and inner surface of the axial bore, an eductor port is adjacent the annular space that extends through the housing, and a profile is on an inner surface of the housing adjacent the outlet of the jet nozzle and that defines a venturi. The method includes directing a flow of fluid into the inlet of the jet nozzle, so that the fluid flow exits the outlet of the jet nozzle and generate a low pressure zone in the annular space, and forming a mixture by providing communication between an additive and the port, so that the additive is drawn into the annular space and combines with the fluid. In an example, the method further includes directing the mixture into a wellbore to wash plug cuttings from the wellbore. The method optionally further includes directing the mixture through a drill string, so that the mixture discharges from a drill bit on an end of the drill string. Further in this example, the drill string can be coiled tubing or jointed pipe tubulars. In an alternative, multiple eductor ports are included. In an embodiment, the method further includes directing different additives through different eductor ports. In one alternative, the additive is controllingly dosed through the eductor port. An example exists where some of the fluid is bypassed around the jet nozzle. By monitoring a viscosity of the mixture, an amount of the additive combined with the fluid can be regulated based on a monitored value of the viscosity.
Also disclosed herein is a system for use in wellbore operations that includes an upstream line in communication with a source of a wellbore treatment fluid, a downstream line in communication with the wellbore, and an eductor unit. In this example the eductor unit is made up of a housing, an inlet in communication with the upstream line, an exit in communication with the downstream line, a jet nozzle in the housing that defines an annular space between the jet nozzle and an inner surface of the housing, and a port that extends through a sidewall of the housing adjacent the annular space, and that is in selective communication with a source of additive, so that additive drawn into the annular space mixes with the well treatment fluid in the housing to form a mixture. The system can further include a plurality of ports that are each in communication with different sources of additive. The system can optionally include a control valve for regulating a flow of additive to the eductor unit. A profile can optionally be included in a portion of the housing downstream from the jet nozzle, wherein the profile defines a venturi. Examples exist where the additive and wellbore treatment fluid are combined in the eductor unit to form a mixture. Alternatives exist where a sensor is included that is in contact with the mixture, and where the sensor senses a viscosity of the mixture, or where an external sensor that is not in direct contact with the mixture senses the flow rate of the additive being pulled into the mixture inside the eductor unit. Pumps can optionally be included in the downstream line that pressurize the mixture. In an alternative, a mixing device is in the downstream line that is between the pumps and the wellbore.
Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term “about” includes +/−5% of the cited magnitude. In an embodiment, usage of the term “substantially” includes +/−5% of the cited magnitude.
It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation.
In one embodiment, the bit 20 includes nozzles that discharge a mixture M of completion drilling fluid. After the mixture M is discharged from bit 20, fragments of the drilled plugs 121-123 become entrained in the mixture M. The pressure of the mixture M exiting the bit 20 is sufficient to circulate the completion drilling fluid up the wellbore 14, through BOP 30, and into a return line 32. In the return line 32, the mixture M with fragments is directed to a solids removal system 34 for processing to remove particulate matter and solids within the mixture M, such as the cuttings from drilling though the plugs 121-123. A pressure control valve 36 is shown installed in return line 32 for maintaining a back pressure against pressure in wellbore 14, formation 16, and in return line 32. Removing the solids and particulate matter from the completion drill fluid forms a conditioned well fluid defined as fluid F. A storage tank 38, via line 40, receives fluid F discharged from solid removal system 34.
Still referring to
In the example of
Referring now to
A profile 75 is shown that extends axially along a portion of the sidewalls of bore 70 and proximate the outlet 74 of jet nozzle 71. An inner surface of profile 75 follows a path that is generally oblique to an axis AX of bore 70 and radially inward from sidewalls of bore 70. At an axial distance downstream from outlet 74, the inner surface of profile 75 transitions radially outward towards sidewalls of bore 70 and along a path oblique to axis AX. At the transition the profile 75 has a maximum radial thickness, which forms a minimum diameter Dmin within bore 70. An angle between the surface of profile 70 and axis AX downstream of transition is greater than an angle between surface of profile 70 and axis AX upstream of transition. The profile 75 thus reduces flow path diameter in the bore 70 from a maximum diameter DB to minimum diameter Dmin, and back to maximum diameter DB. The changes in diameter of the bore 70 define a venturi 76 within bore 70. As such, the restricted diameter of the venturi 76 causes a localized increase in velocity of the fluid F flowing within bore 70, which in turn generates a localized reduced pressure. An annular space 77 shown between the sidewalls of bore 70 and outer radius of jet nozzle 71 also experiences a localized reduced pressure. Reducing the pressure in the annular space 77 creates a pressure differential between the annular space 77 and line 46, which induces a flow of additive A through ports 671-676 into annular space 77.
Shown in
The feedback for determining the flow through lines 46, 48 (
One of the advantages of the mixing of the additive A and fluid F within the eductor unit 44 is that particular additives can be controllingly dosed into the stream of fluid F flowing within the eductor unit 44. In certain embodiments when used in conjunction with the high pressure mixing device 58, completion drilling fluid additives are homogenously mixed, blended and the polymers hydrated near instantaneously. An example of near instantaneously is from about 10 seconds to about 15 seconds or less. One non-limiting example of hydration is defined by the absorption of water into the polymeric molecule, or cleavage of water into the polymeric molecule; thus embodiments exist where the greater the absorption, the higher the yield of the polymer. In contrast, traditional ways of hydrating particular polymers may require multiple hours of blending, mixing, and shear stressing. The additive A is added to the fluid F over a period of time when forming the mixture M in the eductor unit 44; thus the flowrate of additive A into the eductor unit 44 is less than that of the known method of dumping all of the additive into a mixing vat. The reduced flow rate of the additive of the present disclosure is believed to be due to efficiency of hydration percentage when used in conjunction with the high pressure inline mixer 58. Accordingly, as described above and illustrated in the figures, combining the additive A with fluid F in the confines of the eductor unit 44, and used in conjunction with the high pressure inline mixer 58, increases initial contact surface area between the additive A and fluid F, thereby significantly and unexpectedly increasing the rate of hydration over previously known methods.
In one alternative, the percent hydration of the additives A in the fluid F is estimated by measuring viscosity of the mixture M, and correlating the measured viscosity with a value of hydration. Example methods of measuring hydration rates of additive A verses percentage of polymer by volume of mixture M include using field hand held devices, one of which is a marsh funnel viscosity measurement devices or viscometers, such as the Viscolite 700, manufactured by Hydramotion, which measures the dynamic viscosity in centipoise. Information on the Viscolite 700 can be obtained from Nelson Systems, sys.nelsontech.com. A non-limiting example of hydration rates achieved within the high pressure inline mixer 58 when utilizing the eductor unit 44 include up to about 98% hydration, 96% hydration, 92% hydration, 90% hydration, 88% hydration, 86% hydration, and all values between these listed values. In one embodiment, 100% hydration occurs when the molecules making up the additive being hydrated have become fully associated, or cleaved, with an amount of water molecules such that the molecules making up the additive being hydrated cannot become associated with any more or any additional water molecules. Not only is there a tremendous time savings with the eductor unit 44, but capital costs can be significantly reduced as blender units are significantly more expensive than the piping and hardware of an example of the eductor unit 44.
The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, the embodiments of
This application is a continuation of, and claims priority to and the benefit of U.S. Provisional application Ser. No. 62/294,708 filed Feb. 12, 2016, the full disclosure of which is hereby incorporated by reference herein in its entirety and for all purposes.
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