DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 is a section view of a prior art junk basket that uses an eductor to capture cuttings within;
FIG. 2 shows how the junk basket of FIG. 1 is modified to sense flow;
FIG. 3 shows how the flow meter is operably connected to a movable sleeve shown in the Figure in its normal fully open position;
FIG. 4 shows that a low flow condition causes the motor to move the sleeve to cover a port to give a pulse signal or a simple pressure spike signal to the surface;
FIG. 5 shows a mud pulser assembly as the signaling to the surface of the flow through the tool measured in real time;
FIG. 6 is an alternative to FIG. 5 where a system of wireless communicators allows surface personnel to know the flow through the tool in real time;
FIG. 7 shows an embedded electrical pathway as the way the flow is communicated to the surface in real time;
FIG. 8 shows a combination of a pulser and an outlet valve to signal flow to the surface and to reverse flow the screen in an effort to resolve the problem;
FIG. 9 is a view of the sleeve 54′ shown in FIG. 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The junk basket 12 of FIG. 1 is modified as shown in FIGS. 2-4. A flow sensor 40 receives flow that has passed through the screen 34 leaving the cuttings outside the screen. After passing through the flow sensor that is designed to sense the flow while creating minimal additional pressure drop the flow goes through a crossover 42 and into annulus 44 within the tool 12. Located above the crossover 42 is a battery pack and motor generally referred to as 46. FIG. 3 shows the entire flow regime. The fluid passes first through screen 34 with the cleaner fluid then passing through the flow sensor. Next the flow goes through the crossover and into annulus 44 inside the tool 12 while bypassing the battery pack and motor 46. Passage 10 is illustrated at the left side of FIG. 3. The eductor 14 comprises aligned and preferably inclined openings 46 and 48. Normally pressurized flow from the surface enters passage 10 and rushes out through aligned ports 48 and 50. That rushing flow reduces the pressure in annulus 44 and draws fluid through the screen 34. In the preferred embodiment, the battery pack and motor are connected to a gear drive 52 that can selectively drive a movable sleeve 54 over ports 48. Modulating sleeve 54 with respect to ports 48 using motor 46 and gear drive 52 sends a real time pressure pulse signal to the surface to indicate flow in real time. Note that another sleeve 54′ can be constructed to block ports 50 as shown in FIGS. 3 and 8. It can reciprocate as shown in FIG. 3 or rotate, as shown in FIG. 8 using a spline or hex drive 69, for example, shown in FIG. 9. In that embodiment with pressure continuing from the surface at ports 48 any pressure buildup will first tend to reverse flow the screen 34 and the flow would go out the lower end 20. The motor 46 can include a downhole processor that upon sensing a low flow will not only signal that condition to the surface through movement of sleeve 54 but will also try closing sleeve 54′ to create the aforementioned reverse flow through the screen 34 by closing valve 54′.
With sleeve 54′ on ports 50, closing of the ports 50 responsive to a sensed low flow will result in a reverse flow measured at sensor 40. An electronic pulse generator mounted above eductor 14 can then be signaled by sensor 40, now measuring a reverse flow, to send pulses to the surface to be interpreted there as an indication of reverse flow. A reverse flow signal indicates to surface personnel that the screen 34 has been cleared in a reverse direction and therefore should be operated again in the normal direction by opening valve 54′ using a surface signal or the processor associated with motor 46. The operator can pick up and cut the pump off to reset the system and then kick the pump back on and set down weight to see if a positive direction flow is established.
When a low flow is sensed at flow sensor 40 the motor 46 runs and the sleeve 54 is driven over the ports 48 as shown in FIG. 4. These Figures show two types of signals to the surface to warn of a low flow condition within the tool 12. Depending on the speed of the sleeve 54 and whether or not it is programmed to reverse direction, the surface signal can be a rapid pressure buildup or it can be pulses through the well fluids picked up by a surface sensor and converted into a flow reading. If the sleeve simply moves to cover the ports 48 and a positive displacement pump is used at the surface, it will simply build up pressure at the surface. Upon seeing that, surface personnel will turn the pump off with the hope that the cuttings on the screen 34 or in the ports in the mill will simply fall into the annular catch region 38 or further downhole, respectively. At the same time as cutting off the surface pump, the operator can lift the mill to stop the milling process. The string can be rotated with the mill lifted to help cuttings come off the mill or settle down into the catch region 38. After doing that the operator can resume pumping and look for feedback in the sensed flow transmitted to the surface as mud pulses and converted to flow readings by surface equipment. If flows resume normal levels after a system reset that pulls the sleeve 54 off of openings 48, the milling can resume. If normal flow rates are not detected at flow meter 40 and the ports 48 continue to be obstructed, the operator will again see higher pressures than normal at the pump on the surface. This will tell the operator to pull the string out of the hole to see what the problem may be. Ideally, the flow rate through the tool 12 for carrying the cuttings to the screen is preferred to be in the order of about 150 feet per minute and this can realized with a flow from the surface of about 4-8 barrels a minute. At that flow rate from the surface the total flow rate through ports 50 is about twice the pump rate from the surface.
Apart from a pressure surge that can be seen at the surface from sleeve movement covering ports 48, the sleeve 54 can be cycled over and then away from ports 48 to create a pattern of pressure pulses in the string going to the surface. A sensor can be placed on the string near the surface and the pulses can be converted into a visual and/audible signal that there is a flow problem downhole using currently available mud pulse technology.
Referring to FIGS. 3 and 4, the gear drive 52 can be a ball screw or a thread whose rotation results in translation of the sleeve 54 since sleeve 54 is constrained from rotating by pin 56 in groove 58.
Signals of low flow can be communicated to the surface by wire in a variety of known techniques one of which is drill pipe telemetry 55 offered by IntelliServe a joint venture corporation of Grant Prideco and Novatek and shown schematically in FIG. 7. Alternatively electromagnetic signals can be wirelessly sent to the surface to communicate the flow conditions downhole as shown schematically in item 57 in FIG. 6. The flow sensing can be directly coupled to a signaling device. For example if the flow sensor is a prop mounted on a ball screw and acted on by a spring bias. The flow through the prop can push it against the spring bias and hold the ports 48 for the eductor 14 in the open position. If the flow slows or stops, the biasing member can back the prop assembly on the ball screw mount. The sleeve 54 can move in tandem with the prop on the ball screw mount so that a slowdown in flow closes openings 48 to give a surface signal as described above.
FIG. 5 shows a pulser 59 in the form of a reciprocating valve member 61 that is operated to go on and off a seat 63 in response to a sensed flow as discussed before. In this embodiment a sliding sleeve such as 54 is not used because the pulser 59 is there. However, a sleeve 54′ can still be used to create a reverse flow to attempt to clear the screen, as discussed above.
Other indicators of potential problems can be the volume of cuttings being accumulated in the catch annular space 38 or their weight or the rate of change of either variable. A sensor 60 to detect the cuttings level or rate of change per unit time can be mounted near the screen 34 or in the space 38 to sense the level and trigger the same signal mechanism to alert surface personnel to pull out of the hole. Similarly, the annular space 38 can have a receptacle mounted on a weight sensor so that the accumulated weight or its rate of change can be detected. Signals can be sent if the weight increases to a predetermined amount or fails to change a predetermined amount over a predetermined time period. In either case the operator may know that the expected amount of debris has been collected or for some reason no debris is being collected. Signals such as mud pulses can differ depending on the condition sensed. The level or weight indication can be used alone or together with the flow sensing. If both are used one can back up the other because a high collected debris condition can also lead to flow reduction through the tool. In that sense, the reading of one can validate the other. Alternatively the reading of one can be a backup to the other if there is a failure in one of the systems.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
Patent Application
20070272404
