The invention pertains generally to fracturing oil and gas wells for hydrocarbon production. More specifically, the invention relates to a downhole packer tool that engages with and opens a port sleeve pre-installed in the wellbore for hydraulic fracturing and enhancing the production of subterranean wells thereof.
Wells are drilled to a depth in order to intersect a series of formations or zones in order to produce hydrocarbons from beneath the earth. Some wells are drilled horizontally through a formation and it is desired to section the wellbore in order to achieve a better stimulation along the length of the horizontal wellbore. The drilled wells are cased and cemented to a planned depth or a portion of the well is left open hole.
Producing formations intersect with the wellbore in order to create a flow path to the surface. Stimulation processes, such as fracking or acidizing are used to increase the flow of hydrocarbons through the formations. The formations may have reduced permeability due to mud and drilling damage or other formation characteristics. In order to increase the flow of hydrocarbons through the formations, it is desirable to treat the formations to increase flow area and permeability. This is done most effectively by setting either open-hole packers or cased-hole packers at intervals along the length of the wellbore or cementing in the horizontal liner. When using packers, the packers isolate sections of the formations so that each section can be better treated for productivity. Between the packers is a frac port and in some cases a sliding sleeve or a casing that communicates with the formation. In order to direct a treatment fluid through a frac port and into the formation, a seat or valve may be placed close to a sliding sleeve or below a frac port. A ball may be dropped to land on the seat in order to direct fluid through the frac port and into the formation.
One method involves placing a series of ball seats below the frac ports covered by sliding sleeves with each seat size accepting a different ball size. Smaller diameter seats are at the bottom of the completion and the seat size increases for each zone going up the well. For each seat size, there is a ball size, so the smallest ball is dropped first to clear all the larger seats until it reaches the appropriate seat. In cases where many zones are being treated, as many as twenty zones or more, the seat diameters have to be very close. The balls that are dropped have less surface area to land on as the number of zones increase. With less seat surface to land on, the amount of pressure that can be applied on the ball, especially at elevated temperature, becomes less and less. Because the ball is so weak, with increasing pressure to frac the well, the ball often blows right through the seat. Furthermore, the small ball seats reduce the internal diameter (ID) of the production flow path, which creates other problems. The small ID prevents re-entry of other downhole devices, i.e., plugs, running and pulling tools, shifting tools for sliding sleeves, perforating gun size (smaller guns, less penetration), and of course production rates. In order to remove the seats, coiled tubing is used with a mill to mill out all the seats and any balls that remain in the well.
In another method of completion called “plug and perf”, the liner may be cemented in throughout the length of the horizontal section. Typically, composite plugs are run into the well on electric line and pumped out the horizontal section toward the toe until the composite plug is below the section of the zone to be fractured. Once at the desired location, a setting tool is actuated, and the composite plug sets inside of the liner. Perforating guns are sometimes run in the same electric line trip where once the composite plug is set, the guns and setting tool release away from the composite plug and are moved up to a location where the liner is perforated with the guns. Once perforated, the spent perforating gun and setting tool are returned to the surface. Frac fluid is then pumped into the well in order to frac the zone. After treatment, the next composite plug with setting tool and perforating guns is run to the next upper zone section and the process described above is repeated and obviously this becomes very time consuming. This process can be repeated many times, such as up to forty times. Once all zones have been fractured, a coiled tubing unit runs coiled tubing into the well with a motor and mill attached and all of the composite plugs are milled out. The composite plug mill debris is flowed back to the surface and the well is put on production.
It is an object of some embodiments of the invention to provide apparatuses and methods for oil and gas wells to enhance the production of subterranean wells, either open hole, cased hole, or cemented in place and more particularly to improved multizone stimulation systems.
It is an object of some embodiments of the invention to utilize forces achieved from the frac pump for downward force and manipulation of a downhole packer tool to engage with and move the position of a sleeve port.
It is an object of some embodiments of the invention to provide fracture abilities with full internal diameter (ID) without perforating guns and without drilling out the internal diameter (ID) using coil tubing.
According to an exemplary embodiment of the invention there is disclosed a downhole tool being a packer run on wireline where the frac fluid force of the frac pump is used for downward manipulation. Advantages include that wireline is much cheaper than coil tubing, wells can be virtually endless in the horizontal leg, full internal diameter (ID) is achieved with no drill out and the avoidance of using explosives for perforating. Other exemplary benefits include enabling a high-pressure rating—for example, 10k psi—in some embodiments can easily achieve 15-20k psi. The tool may include a casing collar locator (CCL) for depth correlation. Other features in various embodiments include a spring running lengthwise within the tool and a bypass valve to provide upward force and overcome differential pressure. Either cups or elements may be used as seals in different embodiments. The ports can be open/closed after fracturing.
According to an exemplary embodiment, a downhole packer tool includes a center mandrel and a packer provided around the center mandrel. The tool further includes sleeve engaging members movable between extended and retracted positions to either engage with a port sleeve or allow the packer tool to pass by the sleeve without engagement. In a run mode of operation, the sleeve engaging members retract toward the center mandrel. In a set mode of operation, a hydraulic force of a fluid flowing through the wellbore in a downhole direction generates an outward force pushing the sleeve engaging members away from the center mandrel such that they engage with an adjacent port sleeve. Once engaged, hydraulic fluid pressure causes the packer to move the sleeve into an open position and expand the elements, creating a plug between previously fractured stages below and the wellbore above. While engaged with the sleeve, uphole force applied to the packer tool may also be used to move the sleeve into a closed position in a similar manner.
These and other advantages and embodiments of the present invention will no doubt become apparent to those of ordinary skill in the art after reading the following detailed description of preferred embodiments illustrated in the various figures and drawings.
The invention will be described in greater detail with reference to the accompanying drawings which represent preferred embodiments thereof:
The port 102 in
During the completion phase, tanks 504 of fracture fluid 126 are prepared at surface and the downhole packer tool 100 is installed on a wireline 124 ready for insertion into the wellbore 500. The toe port 502 is opened at this point and high-pressure fracture fluid 126 is pumped down the casing 112 in order to create a first set of fractures 144a at the toe 502 of the wellbore 500. This first set of fractures 144a is beneficial to allow fluid 126 to flow from surface down the casing 112 and into the formation 144 via the first set of fractures 144a.
The downhole packer tool 100 coupled to the surface via wireline 124 is lowered into the casing 112 and sent down the well 500. Gravity may be used to get the tool 100 to the heal 506 and then fracture fluid 126 pumped in the downhole direction is used to move the tool 100 further downhole along the horizontal section. While moving in the casing 112, the drag body 110 (see
Using the hydraulic force of fracture fluid 126 moving toward the toe port 502, the tool 100 is pumped out to be in the vicinity of a first target port 102a. The location of the tool may be determined from a combination of the amount of wireline 124 that has been spooled out along with casing collar location (CCL) 122 sensor signals received from the tool 100 via the wireline 124. Each time the tool 100 passes by a port 102, the CCL 122 sensor signals indicate this fact by detecting the increased metal thickness of the port 102. When reaching the target port 102a being the port adjacent the toe port 502, the fluid pumps are shut off and the operators pull the tool 100 uphole a small distance using the wireline 124. In this embodiment, the action of pulling up on the tool 100 using the wireline 124 combined with the resisting frictional forces of the drag body 110 against the inner sides of the casing 112 causes the packer tool 100 to switch into a set mode of operation. In the set mode of operation, the profile blocks 114 are biased to radially extend outwards for engaging with the sleeve profile 130.
Once in the set mode of operation, the fluid pumps are turned back on and the packer tool 100 is pushed downhole again by the hydraulic fluid 126 force toward the desired port 102a. Because the profile blocks 114 are now extended and pushing outwards against the casing 112, when the packer tool 100 reaches adjacent the sleeve 130 of the target port 102a, the profile blocks 114 enter and engage with the sleeve profile 138 and the packer tool 100 is held captive against the sleeve 130. At this point, the packer tool 100 stops moving downhole and the operators at surface no longer observe wireline 124 spooling out. In response to observing this condition, the fluid 126 rate and pressure may be increased by the surface operators to any desired level to apply more downhole pressure on the packer tool 100. As pressure increases, the packer elements 118 compress causing them to bulge outwards and seal off the casing 122 and fluid 126 flow. As previously mentioned, the seal block 120 also moves the center mandrel 104 forward and blocks off the bypass window 106. The production flow path is thereby sealed by the packer tool 100. Since there is no longer anywhere for the fracture fluid 126 to go, pressure builds and hydraulic forces in the downhole direction are transferred from the packer tool 100 via the profile blocks 114 to the sleeve 130. The sleeve 130 includes shear pins 140 that snap at a predetermined force thereby allowing the sleeve 130 to move from the closed position to the open position as pushed by the packer tool 100.
The center mandrel 104 in this embodiment also includes a mandrel sleeve 710 upon which the seal block 120 along with the bypass window 106 are mounted. As the seal block 120 is pushed in the downhole direction D, the mandrel sleeve 710 moves in the downhole direction D as well thereby moving the bypass window 106 under the packer elements 118. This movement of the mandrel sleeve 710 in the downhole direction D is resisted by the differential spring 708 which tends to push the mandrel sleeve 710 in the uphole direction opposite D by the forces of the drag assembly 110.
The mode switch is actuated in some embodiments by a J-track 706 adjacent the profile blocks 114. The J-track 706 is a known mechanism used in the setting and unsetting of downhole tools and equipment such as packers. The downhole packer tool 100 of this embodiment is switched modes by an upward and then downward movement. The J-slot profile 706 creates the track for an actuating cam 712 or pin 714 that alternatingly moves the tool 100 into 1) a set mode configuration where the first cone 700 and the second cone 702 are enabled to come closer together, and 2) a run mode configuration where the first cone 700 and the second cone 702 are prevented from coming close together. In the set mode, the cones 700, 702 can come closer together therefore pushing the profile blocks 114 outward in the R direction. In the run mode, the cones 700, 702 are prevented from coming together and therefore do not push the profile blocks 114 outward in the R direction; instead, springs 1700 (see
The differential spring 708 helps overcome the differential pressure that may be apparent between the downhole side of the packer elements 118 and the uphole side of the packer elements 118 even after the fluid 126 pumps are shut off After the pumps are shut off, there is no longer any downhole force applied against the seal block 120 and the differential spring 708 therefore pushes the center mandrel sleeve 710 in the uphole direction. The bypass window 106 is thereby exposed and pressure differences on either side of the packer elements 118 is equalized via fluid 126 flowing between the bypass window 106 and bypass opening 108. Without a pressure difference, the packer elements 118 decompress (i.e., unseal from the sleeve 130 inner surface) and the packer tool 100 can be removed from the port 102 by surface operators activating motors to pull up on the wireline 124.
In some embodiments, the cone extending member 1400 is omitted; however, without the cone extending member 1400, the downhole side 1004 of the profile block 114 may have little outward force in the R direction because the second cone 702 is only pushed in the R direction by forces resulting from the drag assembly 110, which typically has very little friction and therefore little force compared to the forces exerted against the profile block 114 by the first cone 700 when the profile block 114 is engaged in the sleeve profile 138.
Although the invention has been described in connection with preferred embodiments, it should be understood that various modifications, additions and alterations may be made to the invention by one skilled in the art without departing from the spirit and scope of the invention. For example, although the above description has focused on a downhole packer tool 100 with profile blocks 114 that engage with a corresponding profile 138 in a port sleeve 130, other types of sleeve engaging members instead of or in addition to profile blocks 114 can be used in a similar manner. For instance, in other embodiments, the downhole packer tool 100 may instead include slips that are either extended in a set mode or retracted in a run mode. The slips may engage with the inner surface of a slidable sleeve 130 of a port with or without any corresponding profile 138. In this way, the same feature of engaging the packer tool 100 to a sleeve 130 and then pushing the sleeve 130 open via hydraulic forces applied against the packer 100 can advantageously be used in other embodiments without the profile 138 and profile blocks 114. Likewise, the slips may engage with a chamber wall 1904 without the profile 2100. Thus, the hydraulic pressure caused by the packer tool 100 sealing off production flow can be used in other embodiments with the profile 2100 and profile blocks 114. Different modes of locating the packer tool 100 to the correct position without profile blocks 114 and corresponding profile 138, 2100 to help guide the position include using the sensor signals from the CCL 122. However, that said, utilizing the profile blocks 114 to engage and be held captive within a sleeve profile 130 or a chamber wall profile 2100 as described above has an advantage that the downhole packer tool 100 is ensured to be positioned at a safe distance from the port holes 136. This is particularly beneficial when sand passes by the port holes 126 under extreme pressures and speed during fracturing operations. Damage to the packer 100 is prevented by positioning the packer tool 100 a safe distance away from the port holes 136.
In another example modification, instead of using one or more packer elements 118 as described above to seal off the product flow line, the packer tool 100 in other embodiments may use cups. The principle of operation remains the same and the cups may extend outward and seal off the flow after the packer tool 100 is held captive adjacent the sleeve 130 and/or chamber wall 1904.
In yet another example modification, the wireline 124 described herein to pull the packer tool 100 up-hole may be replaced in other embodiments with slickline. Slickline may prevent the use of the CCL 122 sensor because the signals may have no wired path to surface; however, costs may be beneficially reduced in some applications by the omission of both the CCL 122 sensors in the packer tool 100 and from using slickline instead of wireline 124 to retract the tool back to surface and switch modes of operation. Of course, although both slickline and wireline 124 are beneficial because they are cheaper than coiled tubing, in other embodiments, the packer tool 100 may also be controlled from surface using coiled tubing.
In yet other example embodiments, the open ports 102 after fracturing is complete may be closed by the downhole packer tool 100. For instance, after the frac fluid 126 pumps are stopped, the surface operators may pull upward on the wireline 124 in order to remove the packer tool 100 from the sleeve 130. In some embodiments, springs may be included in the port sleeves 130 that are biased to keep the port sleeve 130 closed absent packer tool 100 applied forces. As such, upon removal of the packer tool 100 from the sleeve 130, the sleeves 130 will automatically close. In yet other embodiments, the action of removing the packer 100 from the sleeve 130 may close the port sleeve 130 such as by sliding the sleeve 130 to the closed position before the profile blocks 114 disengage from the sleeve profile 138.
According to an exemplary embodiment, a downhole packer tool 100 used in a wellbore 500 includes a center mandrel 104 and a packer 118 provided around the center mandrel 104. The tool 100 further includes sleeve engaging members 114 movable between extended and retracted positions to either engage with a port sleeve 130 or allow the packer tool 100 to pass by the sleeve 130 without engagement. In a run mode of operation, an inward force retracts the sleeve engaging members 114 toward the center mandrel 104. In a set mode of operation, a hydraulic force of a fluid 126 flowing through the wellbore 500 in a downhole direction generates an outward force that pushes the sleeve engaging members 114 away from the center mandrel 104 such that they engage with an adjacent port sleeve 130. Once engaged, hydraulic fluid 126 pressure causes the packer tool 100 to move the sleeve 130 into an open position. While engaged with the sleeve 130, uphole force applied to the packer tool 100 may also be used to move the sleeve 130 into a closed position in a similar manner.
The steps of utilizing the downhole packer tool 100 to engage with and open sleeves 130 on ports 102 as described and illustrated herein are not restricted to the exact order described, and, in other embodiments, described steps may be omitted or other intermediate steps added. Functions of single modules may be separated into multiple units, or the functions of multiple modules may be combined into a single unit. All combinations and permutations of the above described features and embodiments may be utilized in conjunction with the invention.
This application claims the benefit of priority of U.S. Provisional Application No. 62/750,289 filed Oct. 25, 2018, which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
62750289 | Oct 2018 | US |