This invention relates to downhole tools and more specifically relates to downhole tools used in well fracturing and stimulation processes.
Wellbores drilled for the production of hydrocarbons therefrom may be drilled in generally vertical, deviated or lateral/horizontal orientations. Such wellbores may penetrate one or more formations or zones from which hydrocarbons may be produced. It is a regular practice once a well is drilled to stimulate the zones to be produced from to increase production therefrom. One common form of stimulation is called fracturing or fracking. Fracturing a well involves pumping a fracturing or frac fluid into the zone. The frac fluid will generally include proppants. When the fracturing fluid along with the proppant is pumped into the zone and pump rates are thereafter reduced, the crack or fracture cannot close because the proppant keeps the cracks open. The cracks or fractures provide a permeable path to connect the producing wellbore with the zone. While there are a number of methods and systems devised for fracturing multiple zones and for producing hydrocarbons therefrom, there continues to be a need for improved systems and methods from stimulating and producing from multiple zones intersected by a wellbore.
In one aspect there is provided a system for fracturing multiple zones in a wellbore. The system comprises a plurality of spaced-apart sleeve assemblies, each of which defines a central passage therethrough, the sleeve assemblies being selectively switchable between open and closed positions. In the open position a fluid may be communicated through the sleeve assembly to the exterior of the sleeve assembly. In some embodiments, the system further comprises a controller associated with each of the sleeve assemblies for completing and breaking a hydraulic circuit. When the hydraulic circuit is complete, the sleeve assembly is movable between open and closed positions and, when the hydraulic circuit is broken, the sleeve is not movable between open and closed positions.
In another aspect, there is provided an apparatus for fracturing multiple zones in a well. The apparatus comprises a plurality of tubing-deployed fracturing devices, a first control unit, and a second control unit. The fracturing devices are selectively switchable between open and closed positions. Each fracturing device has a unique address. The first control unit can send a unique signal corresponding to the unique address to move the fracturing device between operable and non-operable states. The second control unit can move the fracturing device between the open and closed positions. When the fracturing device is in the open position a zone intersected by the well may be fractured therethrough.
In yet another aspect, a method of fracturing a plurality of zones in a wellbore is provided, the method comprising:
As will be used herein, directional terms, such as “above,” “below,” “upper,” “lower,” etc., are used for convenience in referring to the accompanying drawings and descriptions thereof. In general, the terms “above,” “upper,” “upward,” and other similar terms refer to a direction toward the earth's surface relative to a wellbore, and the term “below,” “lower,” “downward” and other similar terms refer to a direction away from the earth's surface relative to a wellbore.
Referring now to the figures,
Control box 32 may be for example a general purpose computer system having software thereon for communicating with instruments downhole, such as fracturing device 28, and any sensors or gauges that may be included and for computing and storing information based on sent and received communications. For example, control box 32 will recognize and store the current state of each fracturing device, the amount of time each is in the operable state, the amount of time needed and used for fracturing and other information, and will record and store the activities conducted. Control box 32 may also be used to gather downhole parameters and other information from downhole sensors and gauges to aid in determining the production from one or more of the zones 24.
When fracturing device 28 is in the operable state, it is movable between open and closed positions. As will be explained in more detail hereinbelow, when in the open position fracturing device 28 will communicate with the wellbore 14 and with a desired zone 24. Thus, a zone 24 may be fractured or otherwise treated through fracturing device 28 and fluid from the selected zone 24 may flow into the central flow passage 20 of the apparatus 18 from formation 24. When fracturing device 28 is in the non-operable state, it will be held in the open or closed position, whichever position it was in prior to moving fracturing device 28 to the non-operable state.
With reference to
Returning now to
With reference now to both
An input or opening line 46 is communicated with a fluid source 45. Opening line 46 defines a flow path to provide hydraulic fluid to each of fracturing devices 28. Likewise, a closing line 48 is shown as connected to fluid source 47, but may be connected to fluid source 45 if desired. Thus, a single input line 46 and single closing line 48 are utilized to provide fluid to all of fracturing devices 28.
With reference to
Turning now to
Sleeve assembly 36 may comprise outer case 64 with upper end or first end 66, and lower or second end 68. An outer or exterior surface 70 of outer case 64 is the same as outer surface 60 of sliding sleeve assembly 36. Ports 62 are defined in outer case 64.
A first or upper coupling 72 is connected, and preferably threadedly connected at upper end 66 to outer case 64. A lower or second coupling 74 is connected and preferably threadedly connected to outer case 64 at the lower end 68 thereof. Both of couplings 72 and 74 are adapted to connect to tubulars 26 in apparatus 18. It is understood that apparatus 18 may be cemented or not cemented in the well as described herein. If apparatus 18 is used in an open, uncemented well, packers or other means known in the art may be used to hold apparatus 18 in wellbore 14.
Sliding sleeve assembly 36 further comprises a mandrel 76 with upper and lower ends 78 and 80, respectively. The upper and lower ends 78 and 80 are connected to couplings 72 and 74, respectively. Mandrel 76 has an inner diameter that defines axial flow passage 82 which defines a part of flow passage 58. Mandrel 76 defines at least one and preferably a plurality of ports 84 therethrough. Ports 84 are in alignment with ports 62. When fracturing device 28 is in the closed position communication between ports 84 and 62 is blocked. Mandrel 76 has an undercut or recess 86 defined in an outer surface 87 thereof, which may provide for ease of manufacture and assembly. Mandrel 76 and outer case 64 define annular space 88 therebetween. Annular space 88 has first or upper end 89 and second or lower end 91. A piston or sliding sleeve 90 with upper end 92 and lower end 94 is disposed and movable in annular space 88. In the closed position of fracturing device 28, upper end 92 abuts upper coupling 72 at upper end 89 of annular space 88. Piston 90 defines a plurality of ports 96 therethrough. A set screw 93 extends from piston 90 into recess 86. Recess 86 has a width sufficient to receive set screw 93 and will prevent rotation of piston 90 as it moves longitudinally in annular space 88. Set screw 93 thus moves with piston 90 and is slidably movable in recess 86.
Piston 90 is slidably disposed in annular space 88. O-rings 100 and 102 on mandrel 76 sealingly engage piston 90. O-rings 100 and 102 are located above and below ports 84 in mandrel 76, respectively. Additional O-rings 104 may be placed at the upper and lower ends of mandrel 76 to seal against upper and lower couplings 72 and 74, respectively. Piston 90 has an O-ring 106 positioned above port 96. Outer case 64 may have O-ring 108 that sealingly engages piston 90. O-rings 110 may be utilized to sealingly engage upper and lower couplings 72 and 74 and may be placed in grooves defined in outer case 64.
With reference to
As can best be seen from
Passageways 142 can be seen in
As can best be seen from
An annular or ring-shaped space 152 is defined by a recess 154 in the inner surface of second ported fitting 146 and an aligned recess 156 in the lower coupling 74. A flow passage 157 communicates fluid from port 147 to annular space 152. A passageway 158, and preferably a plurality of passageways 158 communicate fluid between annular space 152 and annular space 88. In one embodiment six passageways 158 are included. A flow path for each fracturing device 28 may therefore be defined by opening line 46, inlet branch 50, inlet tube 52, port 132, passages 141 and 142, annular space 88, passages 157 and 158, port 147 and closing line 48. Fluid may be supplied by a single source to each of opening and closing lines 46 and 48, such as for example source 45, or may be supplied by separate sources 45 and 47. In either case, the flow path may be referred to as a hydraulic circuit which can be opened/completed or closed/broken by solenoid valve 44 upon receipt of the unique signal that matches the address of the fracturing device 28 to be operated. Passages 141, 142, 157 and 158 are represented by lines in the drawings but it is understood that the lines represent passageways for the communication of fluid therethrough. As can be seen from
In operation, apparatus 18 is lowered into wellbore 14 until fracturing devices 28 are positioned at desired locations in the well. Generally, fracturing devices 28 will be located adjacent zones 24 to be fractured. As described, there may be more or less than the number of fracturing devices 28 and zones 24 than shown in the drawings. Once apparatus 18 is in place, it may be cemented in the wellbore 14 in a manner known in the art although it is understood that apparatus 18 may be used in an open wellbore in which no cementing occurs.
All of the fracturing devices 28 will be in the closed position as apparatus 18 is lowered into the well such that piston 90 will be located as shown in
The method for opening and closing fracturing devices 28 includes sending a signal from control box 32 to the fracturing device 28 to be operated. After apparatus 18 is lowered into the well a signal that matches the unique address on the fracturing device 28 to be communicated with is sent to move the fracturing device 28 into the operable state. The signal will energize solenoid valve 44, which opens or completes the hydraulic circuit. An increase in current will be recognized at control box 32, which indicates that solenoid valve 44 is energized and fracturing device 28 is in the operable state. Fluid can be pumped through opening line 46 and inlet branch 50. Fluid will be pumped through inlet tube 52, port 132 and passages 141 and 142 and will engage upper end 92 of piston 90 to urge piston 90 downwardly until ports 62, 84 and 96 are aligned. As piston 90 moves downwardly fluid will be pushed through passages 158 and 157 and into port 147 in second ported fitting 146. Fluid will be pushed upwardly through closing line 48 to the fluid source 47 at the surface or other location. All of the other fracturing devices 28 will be in the non-operable position so that no flow therethrough will be permitted. Once the sliding sleeve assembly 36 is moved to the open position as shown in
Piston 90 will be held by fluid in the position shown in
Fluid will prevent piston 90 from moving and will hold piston 90 in the closed position. The same process can be followed with each or selected ones of the plurality of fracturing devices 28 to fracture or otherwise treat all of the selected zones 24. Once the process is complete, the unique signal associated with each can be sent to each fracturing device 28 to move all, or selected ones of the fracturing devices 28 to the open position to allow fluid to flow through the ports 62, 84 and 96 into the central flow passage 20 and upward to the surface. In this manner all of the zones 24 may be produced simultaneously. If desired, only certain of the fracturing devices 28 may be moved to the open position to allow production only from desired zones. The composition of the fluid coming from a particular zone, for example the gas, oil/water composition, can be determined in a manner known in the art such as by taking samples. Flow rates can be determined also. Decisions regarding which of the fracturing devices are to be open or closed may be made based on this information.
The operation described herein may be carried out manually, or software may be programmed to perform all steps. For example, once the apparatus 18 is in place, an operator can cause a signal to be sent to energize solenoid valve 44 for the first fracturing device 28. Fluid will be pumped through opening line 46 to move the fracturing device to the open position. After a predetermined period of time solenoid valve 44 will be de-energized and the fracturing device 28 will be locked in the open position. Fracturing or other treatment processes can then occur. Once the fracturing is complete, which may take several hours, the operator will again cause a signal to be sent to energize solenoid valve 44, and fluid will be pumped through closing line 48 to move fracturing device 28 to the closed position. Solenoid valve 44 is then de-energized to break the hydraulic circuit; thus placing fracturing device 28 in the non-operating state and locking the fracturing device 28 in the closed position.
If desired, control box 32 can be programmed to carry out the steps. In addition, the wellbore operator is provided the opportunity to re-fracture or retreat formations or to treat formations that have not previously been treated during the life of a well. For example, if a well is underproducing or can be produced more efficiently all of the sleeve assemblies can be returned to the closed position. Selected ones of the fracturing devices 28 can be moved to the open position and selected zones can be refractured or retreated. In this manner, production can be increased. In addition, it may be that the apparatus 18 included fracturing devices at locations that were not initially treated, which if conditions change can be opened and additional zones treated as described herein after initial production.
As is clear herein, the fracturing and production will occur through central flow passage 20 which is an open bore with no plugs, balls or packers or any sort of flow restriction therein. Because there is no other opening to a particular zone except for a single fracturing device 28, the need for any isolation devices such as flows, frac balls and packers is eliminated. While the apparatus 18 described herein has a controller 34 associated with each fracturing device 28, a single controller can be used to operate more than one sliding sleeve assembly 36 if desired.
Thus, it is seen that the apparatus and methods of the present invention readily achieve the ends and advantages mentioned as well as those inherent therein. While certain preferred embodiments of the invention have been illustrated and described for purposes of the present disclosure, numerous changes in the arrangement and construction of parts and steps may be made by those skilled in the art, which changes are encompassed within the scope and spirit of the present invention as defined by the appended claims.
This application claims the benefit of U.S. Provisional Application No. 61/922,523 filed Dec. 31, 2013, which is hereby incorporated by reference.
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