1. Field of the Invention
Embodiments disclosed herein generally relate to a downhole debris retrieval tool for removing debris from a wellbore. Further, embodiments disclosed herein relate to a downhole tool for debris removal with maximum efficiency at a low pump rates.
2. Background Art
A wellbore may be drilled in the earth for various purposes, such as hydrocarbon extraction, geothermal energy, or water. After a wellbore is drilled, the well bore is typically lined with casing. The casing preserves the shape of the well bore as well as provides a sealed conduit for fluid to be transported to the surface.
In general, it is desirable to maintain a clean wellbore to prevent possible complications that may occur from debris in the well bore. For example, accumulation of debris can prevent free movement of tools through the wellbore during operations, as well as possibly interfere with production of hydrocarbons or damage tools. Potential debris includes cuttings produced from the drilling of the wellbore, metallic debris from the various tools and components used in operations, and corrosion of the casing. Smaller debris may be circulated out of the well bore using drilling fluid; however, larger debris is sometimes unable to be circulated out of the well. Also, the well bore geometry may affect the accumulation of debris. In particular, horizontal or otherwise significantly angled portions in a well bore can cause the well bore to be more prone to debris accumulation. Because of this recognized problem, many tools and methods are currently used for cleaning out well bores.
One type of tool known in the art for collecting debris is the junk catcher, sometimes referred to as a junk basket, junk boot, or boot basket, depending on the particular configuration for collecting debris and the particular debris to be collected. The different junk catchers known in the art rely on various mechanisms to capture debris from the well bore. A common link between most junk catchers is that they rely on the movement of fluid in the well bore to capture the sort of debris discussed above. The movement of the fluid may be accomplished by surface pumps or by movement of the string of pipe or tubing to which the junk catcher is connected. Hereinafter, the term “work string” will be used to collectively refer to the string of pipe or tubing and all tools that may be used along with the junk catchers. For describing fluid flow, “uphole” refers to a direction in the well bore that is towards the surface, while “downhole” refers to a direction in the well bore that is towards the distal end of the well bore.
The use of coiled tubing and its ability to circulate fluids is often used to address debris problems once they are recognized. Coiled tubing runs involving cleanout fluids and downhole tools to clean the production tubing are often costly.
Accordingly, there exists a need for a more efficient tool and method for removing debris from a wellbore.
In one aspect, embodiments disclosed herein relate to a downhole debris recovery tool including a ported sub coupled to a debris sub, a suction tube disposed in the debris sub, and an annular jet pump sub disposed in the ported sub and fluidly connected to the suction tube.
In another aspect, embodiments disclosed herein relate to a method of removing debris from a wellbore including the steps of lowering a downhole debris removal tool into the wellbore, the downhole debris removal tool having an annular jet pump sub, a mixing tube, a diffuser, and a suction tube, flowing a fluid through a bore of the annular jet pump sub, jetting the fluid from the annular jet pump sub into the mixing tube, displacing an initially static fluid in the mixing tube through the diffuser, thereby creating a vacuum effect in the suction tube to draw a debris-laden fluid into the downhole debris removal tool, and removing the tool downhole debris removal tool from the wellbore after a predetermined time interval.
In yet another aspect, embodiments disclosed herein relate to an isolation valve including a housing, an inner tube disposed coaxially within the housing, and a gate, wherein the gate is configured to selectively close an annular space between the housing and the inner tube.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
Generally, embodiments of the present disclosure relate to a downhole tool for removing debris from a wellbore. More specifically, embodiments disclosed herein relate to a downhole debris removal tool that includes an annular jet pump. Further, certain embodiments disclosed herein relate to a downhole tool for debris removal with maximum efficiency at a low pump rates.
A downhole debris removal tool, in accordance with embodiments disclosed herein, includes a jet pump device. Generally, a jet pump is a fluid device used to move a volume of fluid. The volume of fluid is moved by means of a suction tube, a high pressure jet, a mixing tube, and a diffuser. The high pressure jet injects fluid into the mixing tube, displacing the fluid that was originally static in the mixing tube. This displacement of fluid due to the high pressure jet imparting momentum to the fluid causes suction at the end of the suction tube. The high pressure jet and the entrained fluid mix in the mixing tube and exit through the diffuser.
Basic principles of jet pump operation may generally be explained by Equation 1 below, with reference to
Jet Pump Efficiency=(HD−HS/HJ−HD)(QS/QJ) (1)
where HD is discharge head, HS is suction head, HJ is jet head, QS is suction volume flow, and QJ is driving volume flow. In accordance with certain embodiments of the present disclosure, for maximum jet pump efficiency, an inlet of the annular jet pump is smooth and convergent, while the diffuser is divergent. Additionally, the ratio of the inner diameter, d, of the jet to the inner diameter, D, of the mixing tube ranges from 0.14 to 0.9. Further, the jet standoff distance or driving nozzle distance, l, ranges from 0.8 to 2.0 inches. The mixing tube length, Lm, is approximately 7 times the inner diameter of the mixing tube, D.
Embodiments of the present disclosure provide a downhole debris removal tool for removing debris from a completed wellbore with a low rig pump rate. An operator may circulate fluid conventionally down a drillstring at a low flow rate when desirable, e.g., in wellbores with open perforations or where a pressure sensitive formation isolation valve (FIV) is used. The downhole debris removal tool, in accordance with embodiments disclosed herein, lifts (through a vacuum effect) a column of fluid from the bottom of the tool at a velocity high enough to capture heavy debris, such as perforating debris or milling debris, with a low rig pump rate. In contrast, in conventional debris removal tools, high pump flow rates are required to remove such heavy debris. In certain embodiments, the downhole debris removal tool has sufficient capacity to store the collected debris in-situ, thereby providing easy removal and disposal of the debris when the tool is returned to the surface.
Referring now to
The ported sub 203 is disposed below the top sub 201 and houses a mixing tube 208, a diffuser 210, and an annular jet pump sub 206. The ported sub 203 is a generally cylindrical component and includes a plurality of ports configured to align with the diffuser 210 proximate the upper end of the ported sub 203, thereby allowing fluids to exit the downhole debris removal tool 200. The ported sub 203 may be connected to the top sub 201 by any mechanism known in the art, for example, threaded connection, welding, etc.
As shown in more detail in
Referring to
A spacer ring 224 may be disposed around the lower end 230 of the annular jet pump sub 206 and proximate a shoulder 234 formed on an outer surface of the lower end 230. The spacer ring 224 is assembled to the annular jet pump sub 206 and the annular jet cup 232 is disposed over the lower end 230 and the spacer ring 224. Thus, the spacer ring 224 limits the movement of the annular jet cup 232. One or more spacer rings 224 with varying thickness may be used to selectively choose the location of the assembled annular jet cup 232, and provide a pre-selected gap between the annular jet cup 232 and the annular jet pump sub 206. That is, the thickness of the spacer ring 224 may be selected so as to provide a desired d/D ratio. Varying the gap between the annular jet cup 232 and the annular jet pump sub 206 also provides for adjustment of the distance of the at least one jet 209 from the mixing tube 208 entrance. Thus, the jet standoff distance (l) of the tool 200 may be increased, thereby promoting jet pump efficiency.
Referring back to
In one embodiment, the screen 214 may be a cylindrical component with a small perforations disposed on an outside surface, as shown in
In certain embodiments, at least one extension piece may be added to the downhole debris removal tool to increase the capacity of the debris sub 202 such that more debris may be stored/collected therein.
At least one isolation valve 2106 may be integrated into the at least one extension piece 2100, as shown in
Referring to
Referring to
During operation, the at least one isolation valve remains open so that the suction action of the tool is maintained. It may be advantageous to close the at least one isolation valve when the downhole debris removal tool is pulled from the well so that an extension piece may be installed. While the isolation valve is in the closed position, components may be added, removed, and/or replaced therebelow without fluid and debris that may have accumulated above the isolation valve spilling out into the wellbore or onto the deck. Additionally, after the debris removal tool is removed from the well, components therebelow may be removed and the isolation valve may be opened so that accumulated debris may be removed from the tool.
Referring back to
As shown in
Referring back to
After completion of the debris recovery job, the drill string is pulled from the wellbore and the downhole debris recovery tool 200 is returned to the surface. As shown in
In certain embodiments, a drain pin may be disposed in bottom sub 205 and may be opened before removing debris removal cap 207 so that fluid may be emptied from the bottom sub 205 and/or the debris sub 202. Referring to
Referring now to
The two stages 313, 315 of the annular jet pump sub 306 may provide a more efficient pumping tool. In particular, the two staged annular jet pump 360 may reduce the pumping flow rate of the tool and double the overall efficiency of the downhole debris removal tool 300. In the embodiment shown in
Referring to
As discussed above, a spacer ring (not shown) may be disposed around the lower end 330 of the annular jet pump sub 306 and proximate a shoulder (not shown) formed on an outer surface of the lower end 330. The spacer ring (not shown) may limit the movement of the annular jet cup 323, 325. One or more spacer rings with varying thickness may be used to selectively choose the location of the assembled annular jet cup 323, 325, and provide a pre-selected gap between the annular jet cup 323, 325 and the annular jet pump sub 306. That is, the thickness of the spacer ring may be selected so as to provide a desired d/D ratio. Varying the gap between the annular jet cup 323, 325 and the annular jet pump sub 306 also provides for adjustment of the distance of the at least one jet 309, 311 from the mixing tube 308 entrance. Thus, the jet standoff distance (l) of the tool 300 may be increased, thereby promoting jet pump efficiency
Tests
Tests were run on various embodiments of the present disclosure. A summary of these tests and the results determined are described below.
A 7⅞″ downhole debris recovery tool, in accordance with embodiments disclosed herein, was tested to evaluate the suction flow (flow at the pin end of the tool) for a given driving flow (pump flow rate through the tool). The flow rates at each location were determined using flow meters. To evaluate the suction flow, fluid was pumped through the tool at 20-425 gpm for 2-3 minutes at each pump rate. Pump pressure, pump flow rate, and in-line flow meter rate were recorded. The tool was tested with various spacer rings to provide 0.16 d/D, 0.25 d/D, and 0.39 d/D ratio rings. The results of this part of the test are summarized below in Tables 1-3.
Plots of suction flow rate versus the pump flow rate are shown in
Additionally, the 7⅞″ downhole debris recovery tool was tested to determine if the tool could lift heaving casing debris along with sand. The debris used in each test varied and included sand, metal debris, set screws, gravel, and o-rings. In one test, a packer plug retrieval/perforating debris cleaning trip after firing perforating guns was replicated.
During these tests, a conventional debris removal tool was also tested and compared with the tool of the present invention. Generally, the downhole debris removal tool of the present disclosure had a lower overall operating pressure. It was also observed that the tool can be reciprocated to TD several times before pulling the string out of the hole to reduce the number of trips. The flow rates recorded during the tests were based on a 1.5 inch inlet on the bottom of the tool. It was also determined that the overall jet pump size could be increased to boost performance by reducing the O.D. of the jet pump sub.
From the results of the test performed, it was determined that the smaller the d or inner diameter of the jet, the stronger the suction at the suction tube and the higher the efficiency of the jet pump. However, it was observed that an inner diameter of the jet of 0.051″ or greater may result in lower suction flow velocity. In one test with a large d of 0.156″ (equivalent jet diameter) (d/D=0.39), the tool almost lost the ‘pump’ function. It was further noted that the larger the d/D ratio, that is, the ratio of the equivalent diameter of the jet to the inner diameter of the mixing tube, the weaker the sucking force. At low flow rates, conventional and the annular jet pump had higher efficiencies (20 GPM pumping flow rate). It was observed that if the overall size of the jet pump can be increased, the efficiency of the jet pump at higher rig pump rates can be increased due to lower turbulence values and friction losses in the jet pump itself. An advantage of the annular jet pump arrangement is that it will allow for the largest possible jet pump size for a given tool outer diameter due to its unique geometry.
Advantageously, embodiments of the present disclosure provide a downhole debris removal tool that includes a jet pump device to create a vacuum to suction fluid and debris from a wellbore. Further, the downhole debris removal tool of the present disclosure produces a venturi effect with maximum efficiency at low pump rates for removing debris from, for example, FIV valves and completion equipment. Additionally, the downhole debris removal tool of the present disclosure may be used in wellbores of varying sizes. That is, the annular size, or annulus space between the casing and the tool, may be insignificant. Embodiments of the present invention provide a downhole debris removal tool that can easily be field redressed and that allows verification of removed debris on the surface. Advantageously, special chemicals do not need to be pumped with the tool and high rig flow rates are not required for optimal clean up.
Further, embodiments disclosed herein advantageously provide an isolation valve for a downhole debris removal tool. In particular, an isolation valve in accordance with embodiments disclosed herein provides selective isolation of a debris sub to allow for connections between multiple segments of a debris sub and/or connections between the debris sub and other tools or components to be broken and made up with minimal spillage or leakage of debris and fluids contained within the debris sub. An isolation valve formed in accordance with the present disclosure may provide a safer and cleaner downhole debris removal tool.
Furthermore, embodiments disclosed herein advantageously provide a downhole debris removal tool having a drain pin. The drain pin formed in accordance with the present disclosure provides selective fluid communication between the debris sub and the suction tube to allow for fluid contained in the debris sub to be selectively disposed of through the suction tube. Selective disposal of the fluids contained within the debris sub may be performed on a rig floor after the downhole debris removal tool has been removed from the wellbore. Draining fluid from the tool may provide a safer working environment by reducing the risk of fluid spillage when disassembling components of the downhole debris removal tool.
Advantageously, embodiments disclosed herein provide a downhole debris removal tool including magnets disclosed on or proximate a screen disposed in the debris sub. Magnets disposed on or proximate the screen may attract metallic debris to the magnet or magnetic surface. Collection of the metallic debris on the magnets may prevent or reduce clogging the screen. Thus, embodiments disclosed herein may provide a more efficient downhole debris removal tool.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2009/038552 | 3/27/2009 | WO | 00 | 9/27/2010 |
Publishing Document | Publishing Date | Country | Kind |
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WO2009/120957 | 10/1/2009 | WO | A |
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