Abstract:
A wellbore cleanup tool is run on slickline. It has an onboard power supply and circulation pump. Inlet flow is at the lower end into an inlet pipe that keeps up fluid velocity. The inlet pipe opens to a surrounding annular volume for sand containment and the fluid continues through a screen and into the pump for eventual exhaust back into the water in the wellbore. A modular structure is envisioned to add debris carrying capacity. Various ways to energize the device are possible. Other tools run on slickline are described such as a cutter, a scraper and a shifting tool.

Description:
FIELD OF THE INVENTION 
     The field of this invention is tools run downhole preferably on cable and which operate with on board power to perform a downhole function and more particularly wellbore debris cleanup. 
     BACKGROUND OF THE INVENTION 
     It is a common practice to plug wells and to have encroachment of water into the wellbore above the plug.  FIG. 1  illustrates this phenomenon. It shows a wellbore  10  through formations  12 ,  14  and  16  with a plug  18  in zone  16 . Water  20  has infiltrated as indicated by arrows  22  and brought sand  24  with it. There is not enough formation pressure to get the water  20  to the surface. As a result, the sand  24  simply settles on the plug  18 . 
     There are many techniques developed to remove debris from wellbores and a good survey article that reviews many of these procedures is SPE 113267 Published June 2008 by Li, Misselbrook and Seal entitled Sand Cleanout with Coiled Tubing: Choice of Process, Tools or Fluids? There are limits to which techniques can be used with low pressure formations. Techniques that involve pressurized fluid circulation present risk of fluid loss into a low pressure formation from simply the fluid column hydrostatic pressure that is created when the well is filled with fluid and circulated or jetted. The productivity of the formation can be adversely affected should such flow into the formation occur. As an alternative to liquid circulation, systems involving foam have been proposed with the idea being that the density of the foam is so low that fluid losses will not be an issue. Instead, the foam entrains the sand or debris and carries it to the surface without the creation of a hydrostatic head on the low pressure formation in the vicinity of the plug. The downside of this technique is the cost of the specialized foam equipment and the logistics of getting such equipment to the well site in remote locations. 
     Various techniques of capturing debris have been developed. Some involve chambers that have flapper type valves that allow liquid and sand to enter and then use gravity to allow the flapper to close trapping in the sand. The motive force can be a chamber under vacuum that is opened to the collection chamber downhole or the use of a reciprocating pump with a series of flapper type check valves. These systems can have operational issues with sand buildup on the seats for the flappers that keep them from sealing and as a result some of the captured sand simply escapes again. Some of these one shot systems that depend on a vacuum chamber to suck in water and sand into a containment chamber have been run in on wireline. Illustrative of some of these debris cleanup devices are U.S. Pat. No. 6,196,319 (wireline); U.S. Pat. No. 5,327,974 (tubing run); U.S. Pat. No. 5,318,128 (tubing run); U.S. Pat. No. 6,607,607 (coiled tubing); U.S. Pat. No. 4,671,359 (coiled tubing); U.S. Pat. No. 6,464,012 (wireline); U.S. Pat. No. 4,924,940 (rigid tubing) and U.S. Pat. No. 6,059,030 (rigid tubing). 
     The reciprocation debris collection systems also have the issue of a lack of continuous flow which promotes entrained sand to drop when flow is interrupted. Another issue with some tools for debris removal is a minimum diameter for these tools keeps them from being used in very small diameter wells. Proper positioning is also an issue. With tools that trap sand from flow entering at the lower end and run in on coiled tubing there is a possibility of forcing the lower end into the sand where the manner of kicking on the pump involves setting down weight such as in U.S. Pat. No. 6,059,030. On the other hand, especially with the one shot vacuum tools, being too high in the water and well above the sand line will result in minimal capture of sand. 
     What is needed is a debris removal tool that can be quickly deployed such as by slickline and can be made small enough to be useful in small diameter wells while at the same time using a debris removal technique that features effective capture of the sand and preferably a continuous fluid circulation while doing so. A modular design can help with carrying capacity in small wells and save trips to the surface to remove the captured sand. Other features that maintain fluid velocity to keep the sand entrained and further employ centrifugal force in aid of separating the sand from the circulating fluid are also potential features of the present invention. Those skilled in the art will have a better idea of the various aspects of the invention from a review of the detailed description of the preferred embodiment and the associated drawings, while recognizing that the full scope of the invention is determined by the appended claims. 
     One of the issues with introduction of bottom hole assemblies into a wellbore is how to advance the assembly when the well is deviated to the point where the force of gravity is insufficient to assure further progress downhole. Various types of propulsion devices have been devised but are either not suited for slickline application or not adapted to advance a bottom hole assembly through a deviated well. Some examples of such designs are U.S. Pat. Nos. 7,392,859; 7,325,606; 7,152,680; 7,121,343; 6,945,330; 6,189,621 and 6,397,946. US Publication 2009/0045975 shows a tractor that is driven on a slickline where the slickline itself has been advanced into a wellbore by the force of gravity from the weight of the bottom hole assembly. 
     SUMMARY OF THE INVENTION 
     A wellbore cleanup tool is run on slickline. It has an onboard power supply and circulation pump. Inlet flow is at the lower end into an inlet pipe that keeps up fluid velocity. The inlet pipe opens to a surrounding annular volume for sand containment and the fluid continues through a screen and into the pump for eventual exhaust back into the water in the wellbore. A modular structure is envisioned to add debris carrying capacity. Various ways to energize the device are possible. Other tools run on slickline are described such as a cutter, a scraper and a shifting tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of a plugged well where the debris collection device will be deployed; 
         FIG. 2  is the view of  FIG. 1  with the device lowered into position adjacent the debris to be removed; 
         FIG. 3  is a detailed view of the debris removal device shown in  FIG. 2 ; 
         FIG. 4  is a lower end view of the device in  FIG. 3  and illustrating the modular capability of the design; 
         FIG. 5  is another application of a tool run on slickline to cut tubulars; 
         FIG. 6  is another application of a tool to scrape tubulars without an anchor that is run on slickline; 
         FIG. 7  is an alternative embodiment of the tool of  FIG. 6  showing an anchoring feature used without the counter-rotating scrapers in  FIG. 6 ; 
         FIG. 8  is a section view showing a slickline run tool used for moving a downhole component; 
         FIG. 9  is an alternative embodiment to the tool in  FIG. 8  using a linear motor to set a packer; 
         FIG. 10  is an alternative to  FIG. 9  that incorporates hydrostatic pressure to set a packer; 
         FIG. 11  illustrates the problem with using slicklines when encountering a wellbore that is deviated; 
         FIG. 12  illustrates how tractors are used to overcome the problem illustrated in  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 2  shows the tool  26  lowered into the water  20  on a slickline or non-conductive cable  28 . The main features of the tool are a disconnect  30  at the lower end of the cable  28  and a control system  32  for turning the tool  26  on and off and for other purposes. A power supply, such as a battery  34 , powers a motor  36 , which in turn runs a pump  38 . The modular debris removal tool  40  is at the bottom of the assembly. 
     While a cable or slickline  28  is preferred because it is a low cost way to rapidly get the tool  26  into the water  20 , a wireline can also be used and surface power through the wireline can replace the onboard battery  34 . The control system can be configured in different ways. In one version it can be a time delay energized at the surface so that the tool  26  will have enough time to be lowered into the water  20  before motor  36  starts running. Another way to actuate the motor  36  is to use a switch that is responsive to being immersed in water to complete the power delivery circuit. This can be a float type switch akin to a commode fill up valve or it can use the presence of water or other well fluids to otherwise complete a circuit. Since it is generally known at what depth the plug  18  has been set, the tool  26  can be quickly lowered to the approximate vicinity and then its speed reduced to avoid getting the lower end buried in the sand  24 . The control system can also incorporate a flow switch to detect plugging in the debris tool  40  and shut the pump  38  to avoid ruining it or burning up the motor  36  if the pump  38  plugs up or stops turning for any reason. Other aspects of the control system  32  can include the ability to transmit electromagnetic or pressure wave signals through the wellbore or the slickline  28  such information such as the weight or volume of collected debris, for example. 
     Referring now to  FIGS. 3 and 4 , the inner details of the debris removal tool  40  are illustrated. There is a tapered inlet  50  leading to a preferably centered lift tube  52  that defines an annular volume  54  around it. Tube  52  can have one or more centrifugal separators  56  inside whose purpose is to get the fluid stream spinning to get the solids to the inner wall using centrifugal force. Alternatively, the tube  52  itself can be a spiral so that flow through it at a high enough velocity to keep the solids entrained will also cause them to migrate to the inner wall until the exit ports  58  are reached. Some of the sand or other debris will fall down in the annular volume  54  where the fluid velocity is low or non-existent. As best shown in  FIG. 3 , the fluid stream ultimately continues to a filter or screen  60  and into the suction of pump  38 . The pump discharge exits at ports  62 . 
     As shown in  FIG. 4  the design can be modular so that tube  52  continues beyond partition  64  at thread  66  which defines a lowermost module. Thereafter, more modules can be added within the limits of the pump  38  to draw the required flow through tube  52 . Each module has exit ports  58  that lead to a discrete annular volume  54  associated with each module. Additional modules increase the debris retention capacity and reduce the number of trips out of the well to remove the desired amount of sand  24 . 
     Various options are contemplated. The tool  40  can be triggered to start when sensing the top of the layer of debris, or by depth in the well from known markers, or simply on a time delay basis. Movement uphole of a predetermined distance can shut the pump  38  off. This still allows the slickline operator to move up and down when reaching the debris so that he knows he&#39;s not stuck. The tool can include a vibrator to help fluidize the debris as an aid to getting it to move into the inlet  50 . The pump  38  can be employed to also create vibration by eccentric mounting of its impeller. The pump can also be a turbine style or a progressive cavity type pump. 
     The tool  40  has the ability to provide continuous circulation which not only improves its debris removal capabilities but can also assist when running in or pulling out of the hole to reduce chances of getting the tool stuck. 
     While the preferred tool is a debris catcher, other tools can be run in on cable or slickline and have an on board power source for accomplishing other downhole operations.  FIG. 2  is intended to schematically illustrate other tools  40  that can accomplish other tasks downhole such as honing or light milling. To the extent a torque is applied by the tool to accomplish the task, a part of the tool can also include an anchor portion to engage a well tubular to resist the torque applied by the tool  40 . The slips or anchors that are used can be actuated with the on board power supply using a control system that for example can be responsive to a pattern of uphole and downhole movements of predetermined length to trigger the slips and start the tool. 
       FIG. 5  illustrates a tubular cutter  100  run in on slickline  102 . On top is a control package  104  that is equipped to selectively start the cutter  100  at a given location that can be based on a stored well profile in a processor that is part of package  104 . There can also be sensors that detect depth from markers in the well or there can more simply be a time delay with a surface estimation as to the depth needed for the cut. Sensors could be tactile feelers, spring loaded wheel counters or ultrasonic proximity sensors. A battery pack  106  supplies a motor  108  that turns a ball shaft  110  which in turn moves the hub  112  axially in opposed directions. Movement of hub  112  rotates arms  114  that have a grip assembly  116  at an outer end for contact with the tubular  118  that is to be cut. A second motor  120  also driven by the battery pack  106  powers a gearbox  122  to slow its output speed. The gearbox  122  is connected to rotatably mounted housing  124  using gear  126 . The gearbox  122  also turns ball screw  128  which drives housing  130  axially in opposed directions. Arms  132  and  134  link the housing  130  to the cutters  136 . As arms  132  and  134  get closer to each other the cutters  136  extend radially. Reversing the rotational direction of cutter motor  120  retracts the cutters  136 . 
     When the proper depth is reached and the anchor assemblies  116  get a firm grip on the tubular  118  to resist torque from cutting, the motor  120  is started to slowly extend the cutters  136  while the housing  124  is being driven by gear  126 . When the cutters  136  engage the tubular  118  the cutting action begins. As the housing  124  rotates to cut the blades are slowly advanced radially into the tubular  118  to increase the depth of the cut. Controls can be added to regulate the cutting action. They controls can be as simple as providing fixed speeds for the housing  124  rotation and the cutter  136  extension so that the radial force on the cutter  136  will not stall the motor  120 . Knowing the thickness of the tubular  118  the control package  104  can trigger the motor  120  to reverse when the cutters  136  have radially extended enough to cut through the tubular wall  118 . Alternatively, the amount of axial movement of the housing  130  can be measured or the number of turns of the ball screw  128  can be measured by the control package  104  to detect when the tubular  118  should be cut all the way through. Other options can involve a sensor on the cutter  136  that can optically determine that the tubular  118  has been cut clean through. Reversing rotation on motors  108  and  120  will allow the cutters  136  to retract and the anchors  116  to retract for a fast trip out of the well using the slickline  102 . 
       FIG. 6  illustrates a scraper tool  200  run on slickline  202  connected to a control package  204  that can in the same way as the package  104  discussed with regard to the  FIG. 5  embodiment, selectively turn on the scraper  200  when the proper depth is reached. A battery pack  206  selectively powers the motor  208 . Motor shaft  210  is linked to drum  212  for tandem rotation. A gear assembly  214  drives drum  216  in the opposite direction as drum  212 . Each of the drums  212  and  216  have an array of flexible connectors  218  that each preferably have a ball  220  made of a hardened material such as carbide. There is a clearance around the extended balls  220  to the inner wall of the tubular  222  so that rotation can take place with side to side motion of the scraper  200  resulting in wall impacts on tubular  222  for the scraping action. There will be a minimal net torque force on the tool and it will not need to be anchored because the drums  212  and  216  rotate in opposite directions. In the alternative, there can be but a single drum  212  as shown in  FIG. 7 . In that case the tool  200  needs to be stabilized against the torque from the scraping action. One way to anchor the tool is to use selectively extendable bow springs  224  that are preferably retracted for run in with slickline  202  so that the tool can progress rapidly to the location that needs to be scraped. Other types of driven extendable anchors could also be used and powered to extend and retract with the battery pack  206 . The scraper devices  220  can be made in a variety of shapes and include diamonds or other materials for the scraping action. 
       FIG. 9  shows using a slickline  400  conveyed motor to set a mechanical packer  403 . The tool  400  includes a disconnect  30 , a battery  34 , a control unit  401  and a motor unit  402 . The motor unit can be a linear motor, a motor with a power screw or any other similar arrangements. When motor is actuated, the center piston or power screw  408  which is connected to the packer mandrel  410  moves respectively to the housing  409  against which it is braced to set the packer  403 . 
     In another arrangement, as illustrated in  FIG. 10 , a tool such as a packer or a bridge plug is set by a slickline conveyed setting tool  430 . The tool  430  also includes a disconnect  30 , a battery  34 , a control unit  401  and a motor unit  402 . The motor unit  402  also can be a linear motor, a motor with a power screw or other similar arrangements. The center piston or power screw  411  is connected to a piston  404  which seals off using seals  405  a series of ports  412  at run in position. When the motor is actuated, the center piston or power screw  411  moves and allow the ports  412  to be connected to chamber  413 . Hydrostatic pressure enters the chamber  413 , working against atmosphere chamber  414 , pushing down the setting piston  413  and moving an actuating rod  406 . A tool  407  thus is set. 
       FIG. 11  illustrates a deviated wellbore  500  and a slickline  502  supporting a bottom hole assembly that can include logging tools or other tools  504 . When the assembly  504  hits the deviation  506 , forward progress stops and the cable goes slack as a signal on the surface that there is a problem downhole. When this happens, different steps have been taken to reduce friction such as adding external rollers or other bearings or adding viscosity reducers into the well. These systems have had limited success especially when the deviation is severe limiting the usefulness of the weight of the bottom hole assembly to further advance downhole. 
       FIG. 12  schematically illustrates the slickline  502  and the bottom hole assembly  504  but this time there is a tractor  508  that is connected to the bottom hole assembly (BHA) by a hinge or swivel joint or another connection  510 . The tractor assembly  508  has onboard power that can drive wheels or tracks  512  selectively when the slickline  502  has a detected slack condition. Although the preferred location of the tractor assembly is ahead or downhole from the BHA  504  and on an end opposite from the slickline  502  placement of the tractor assembly  508  can also be on the uphole side of the BHA  504 . At that time the drive system schematically represented by the tracks  512  starts up and drives the BHA  504  to the desired destination or until the deviation becomes slight enough to allow the slack to leave the slickline  502 . If that happens the drive system  512  will shut down to conserve the power supply, which in the preferred embodiment will be onboard batteries. The connection  510  is articulated and is short enough to avoid binding in sharp turns but at the same time is flexible enough to allow the BHA  504  and the tractor  508  to go into different planes and to go over internal irregularities in the wellbore. It can be a plurality of ball and socket joints that can exhibit column strength in compression, which can occur when driving the BHA out of the wellbore as an assist to tension in the slickline. When coming out of the hole in the deviated section, the assembly  508  can be triggered to start so as to reduce the stress in the slickline  502  but to maintain a predetermined stress level to avoid overrunning the surface equipment and creating slack in the cable that can cause the cable  502  to ball up around the BHA  504 . Ideally, a slight tension in the slickline  502  is desired when coming out of the hole. The mechanism that actually does the driving can be retractable to give the assembly  508  a smooth exterior profile where the well is not substantially deviated so that maximum advantage of the available gravitational force can be taken when tripping in the hole and to minimize the chances to getting stuck when tripping out. Apart from wheels  512  or a track system other driving alternatives are envisioned such a spiral on the exterior of a drum whose center axis is aligned with the assembly  508 . Alternatively the tractor assembly can have a surrounding seal with an onboard pump that can pump fluid from one side of the seal to the opposite side of the seal and in so doing propel the assembly  508  in the desired direction. The drum can be solid or it can have articulated components to allow it to have a smaller diameter than the outer housing of the BHA  504  for when the driving is not required and a larger diameter to extend beyond the BHA  504  housing when it is required to drive the assembly  508 . The drum can be driven in opposed direction depending on whether the BHA  504  is being tripped into and out of the well. The assembly  510  could have some column strength so that when tripping out of the well it can be in compression to provide a push force to the BHA  504  uphole such as to try to break it free if it gets stuck on the trip out of the hole. This objective can be addressed with a series of articulated links with limited degree of freedom to allow for some column strength and yet enough flexibility to flex to allow the assembly  508  to be in a different plane than the BHA  504 . Such planes can intersect at up to 90 degrees. Different devices can be a part of the BHA  504  as discussed above. It should also be noted that relative rotation can be permitted between the assembly  508  and the BHA  504  which is permitted by the connector  510 . This feature allows the assembly to negotiate a change of plane with a change in the deviation in the wellbore more easily in a deviated portion where the assembly  508  is operational. 
     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: