Abstract:
An improved downhole fluid pressure powered reciprocating rotary drilling motor includes an automatic fluid valve means and a fluid controller that in combination provide a fluid driven periodic forcing function to excite a drill bit both axially and rotationally for enhanced drill bit penetration in oil well work-over and oil well open hole earth borings on both rotating and non-rotating drill strings.

Description:
TECHNICAL FIELD 
     The present invention relates to an improved downhole reciprocating rotary fluid powered drilling motor for use on rotating and non-rotating drill strings in oil well work-over servicing and open hole oil well earth boring to improve drilling effectiveness and increase drill bit penetration rates. 
     BACKGROUND OF THE INVENTION 
     This application is for an invention previously described in my Disclosure Document No. 449,617 entitled “RECIPROCATING DRILLING MOTOR” filed Jan. 11, 1999 in the United States Patent and Trademark Office under the Disclosure Document Program (MPEP 1706). 
     Because of various oil well conditions, variable drilling applications, diverse drilling mediums, various drilling rig configurations, and rig operator preferences considerable research, development, time, effort and cost have been applied to perfect a reciprocating rotary drilling motor of the nature described herein. Certain levels of success have been achieved over the ensuing years and progress is continuing to this day as all factors concerned, tried, tested and incorporated contributed to the present invention. 
     SUMMARY OF THE INVENTION 
     Because of the aforementioned variables a broad range of tool operations is needed to accommodate most well service and open hole drilling conditions, and great improvements in drill penetration rates have been achieved in all drillable media. 
     The present invention provides for faster drilling in oilfield applications but can also be used in drilling water wells, geophysical bore holes, environmental test holes, quarry blast holes, construction pier holes and the like. In order to increase the drill bit penetration rate, this invention provides a rotary automatic pressure fluid driven periodic fast cycling forcing function motor wherein the drill bit is alternately thrust forward by pressure fluid impulse and then hammered forward by percussive impact with sustained high frequency energy delivery to the medium being drilled. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustration of a coiled tubing oil well work-over service rig A with a non-rotating drill string B in an old production well with well head components D showing the application of the fluid powered reciprocating rotary drilling motor E drilling out mineral deposits that have accumulated in the production tubing C; 
     FIG. 2 is an elevational view in central section of the drilling motor with means for attachment to the distal end of a coiled tubing drill string on its upper end and a drill bit on its lower end; 
     FIG. 3 is a cross-sectional view taken at section line  3 — 3  of FIG. 2 showing a motor cam and cam follower reciprocal mandrel rotational means; 
     FIG. 4 is a side elevational view of a tubular cam with helical slots for the followers and a single direction rotational clutch face on its lower end; 
     FIG. 5 is a end view of the lower end of the cam showing the circled radial teeth of the clutch face; 
     FIG. 6 is an illustration of a land open hole rotary drilling rig with rotating drill string and application of the drilling motor having a splined extension joint for bit rotation; 
     FIG. 7 is an elevational view through the central section of the drilling motor of FIG. 6 with means for attachment to a rotating drill string on its upper end, a splined extension joint near is lower end for transferring rotary torque while allowing motor mandrel extension and retraction and means for attaching a bit on its lower end; and, 
     FIG. 8 is a cross-sectional view taken at section line  8 — 8  of FIG. 7 further showing the splined torque transmitting slip joint. 
    
    
     DETAILED DESCRIPTION 
     The preferred embodiment of the reciprocating drilling motor E in FIG. 2 consists of a housing  2 , mandrel-bit  3 , fluid control means  4 , automatic valve means  5 , variable pressure and volume fluid chamber  6 , and mandrel-bit rotation means  7 . Housing  2  is made up of top sub  10 , barrel  11  and bearing sub  12  and all are sealed and threadably connected. Housing top sub  10  has threaded connection means  13  to the non-rotatable coiled tubing drill string and the pressure fitted supply therein. Housing  2  further has internal fluid containment walls to conduct fluid from the fluid control means  4  past and outside the automatic valve means  5  and forms part of the variable chamber  6  as well as mounting for mandrel-bit  3 . On its lower end is an impact receiving surface  28  that coacts with the bit  16  of the mandrel-bit  3  for transferring impact blows thereto. Mandrel-bit  3  is made up of mandrel  15  and threadably connected bit  16  and has a fluid flow passageway  17  through the mandrel and bit with a valve seat  18  around the upper end. 
     The mandrel  15  has an enlarged upper end  35  in close fitting sealed relation with the inside bore  8  of barrel  11 , a reduced diameter shank  19  in close fitting relation with the inside diameter of bearing sub  12  and is adapted for axial limited movement with the housing  2 . The bit  16  may be of any style and cutting structure on its lower end and has an impact receiving surface  20  on its upper end. Seals  34  are provided on the mandrel upper enlarged end to prevent fluid passage between the upper end  35  of the mandrel  15  and barrel  11  of housing  2 . 
     The fluid control means  4  is an orifice type fluid metering flow restrictor having an inside passageway  14  therethrough and is fixed inside top sub  10 . This control means  4  determines how fast the variable chamber  6  expands and contracts and thereby determines the motor cycling frequency. Fluid control means  4  may also have a fluid diffuser to prevent fluid steam from impacting on the automatic valving means  5  and altering operation of it. 
     The automatic valving means  5  consists of valve support means  21  having a fixed mounting inside top sub  10  with a fluid flow passageway  24  through it, valve  22  made up of valve head  23  and valve stem  9  which has valve stroke adjustment means  25  on its upper end, valve shift spring  26  that is nested on both ends and allows the valve  22  to easily shift downward but will position the valve upward and valve lift-off spring  27  around valve stem  9  that accelerates the valve upward very fast when the valve head  23  separates from the valve seat  18 . 
     At the start of the valve means  5  operational cycle, the valve head  23  is spaced from valve seat  18  of the mandrel-bit  3  and mandrel  15  so that a pressure differential force exits across the valve head  23  and valve seat  18  when the pressure fluid supply through the flow control means  4  reaches a certain volume. The pressure differential force causes valve head  23  to rapidly shift to seat  18 , thereby stopping fluid flow through passageway  17  and causing the pressure and volume to build up in the variable pressure fluid chamber  6 . The pressure and volume expand with equal and opposite force against the housing  2  upwardly and the upper end surface of mandrel  15  forcing it downwardly overcoming the down force of the drill string or the forward resistance of the bit  16  or a combination of each resistance depending on which has the least resistance. 
     The bit  16  then may be driven forward or the housing may be raised by the stroke distance of the valve  22 . During the valve  22  stroke, spring  26  is compressed and spring  27  is compressed each storing energy to perform a certain function when the stroke limit is reached and valve liftoff occurs. As the mandrel  15  moves down relative to the housing  2  and the valve  22  stroke limit is reached, further movement causes the valve head  23  to leave valve seat  18  relieving pressure in chamber  6 . Valve liftoff spring  27  then rapidly accelerates the valve  22  upwardly since there is no longer a pressure differential across valve head  23  and valve seat  18  and valve shift spring  26  repositions the valve  22  to its original cycle start position. 
     At this time in the motor operational cycle with the pressure forcing function of chamber  6  dissipated, the down force of the drill string and resistance of the bit become the dominant motor forces, chamber  6  reduces to its original size and the mandrel-bit  3  and the housing collide at the impact receiving surface  20  of the mandrel-bit  3  and impact receiving surface  28  of the housing  2 . The valve head  23  is now originally spaced with valve seat  18  and a new motor cycle is ready to begin. 
     Motor cycling frequency can occur very many times a minute providing alternate bit force pressure thrusts with stored energy percussive blows to bit  16 . The motor described herein can be effective in removing tubing mineral deposits without rotary rotational producing means  7  if fitted with a suitable full circle cutting bit structure. For drilling solid well material such as cement or bridge plugs, rotary bit action combined with dual vertical thrust and percussive forces, the motor effectivity is greatly enhanced. 
     The mandrel bit rotation means  7  of FIG. 2 consists of a cam follower  29  fixed with the shank  19  of mandrel  15 , a slotted helical cam  30  in working engagement with the cam follower  29 , a one-way directional clutch  31  half of which is clutch face  32  and is part of the cam and half of which is clutch face  33  and is part of bearing sub  12  of housing  2  and a spring  39  for biasing the cam downward and keeping the clutch faces in engagement. FIGS. 2,  3 ,  4  and  5  show the above relationships. 
     In operation of the mandrel-bit  3  and rotational means  7 , the mandrel strokes up and down as before described but now also rotates the cam  30  in one direction but cannot rotate the cam  30  in the opposite direction because of the one-way directional clutch  31 . The operation of the mechanism is such that the cam on one directional stroke in combination with the cam follower and clutch will rotate the mandrel bit some angled amount and on the opposite directional stroke will reset the clutch  31  to another position and fast stroke repetition will provide intermittent stepped periodic mandrel-bit  3  rotation relative to the housing  2 . 
     FIGS. 6,  7  and  8  show the pressure fluid powered rotary drilling motor used with conventional type open hole drilling rig G having the usual surface rotated drill string H. Since the drill string is rotated there is no requirement for bit rotational means within the drilling motor so a variation of the motor is specified herein with a mandrel-bit splined extension means  50  for transferring the drill string H provided torque from the motor J housing  51  to the motor mandrel  52  and bit L. In the application the mechanical structure of the motor must be somewhat heavier since the motor down force is provided by weighted drill collars and the mandrel  52  has been modified to take the percussion blow involved. 
     Since use with a more conventional bit L is desirable but most of the principles of the motor operation involved are the same as before described such as the fluid control means  4 , the automatic valving means  5 , the variable fluid chamber  6 , and the reciprocating mandrel-bit  54  are now made up of mandrel  52  and bit L and have the impact receiving surface  55  on an enlarged portion upward facing surface of the mandrel  52  and the impact receiving surface  63  on the downward facing surface of the spline sub  59 . Internal splines  56  of motor housing  51  as a portion of bearing and spline sub  59  are mated with external longitudinal splines  60  on the mandrel shank  52  and adapted for sliding coaction while transferring rotary motion to the mandrel  52  and bit L. 
     The chamber  6  (FIG. 7) formed by components of housing  51  and the motor mandrel  52  may be sealed and contain a lubricant for increased service life and the lubricant can pass through splined extension means  50  with very little motion damping. Also better bearings may be added between the bearing sub  59  and the mandrel  52  without deviating from the spirit of the invention. In FIGS. 2,  3 ,  4  and  5  wherein the mandrel-bit  3  rotational means  7  is shown and described, a different configured cam may be used and the whole mechanism may be sealed and lubricated. 
     The foregoing specification is exemplary of certain preferred embodiments and explains how to make and use the invention. The appended claims are intended to cover the embodiments disclosed as well as improvements which may be added within the scope of the invention.