US3487890A - Core drilling system - Google Patents

Description

Jan. 6, 1970 L. J. MARTINSEN CORE DRILLING SYSTEM wmr/ /////x/////5V///////-n//////////// INVENTOR LYLE J. MARTINSEN ATTORNEY FIG.

Jan. 6, 1970 L.. .1. MARTINSEN CORE DRILLING SYSTEM 5 Sheets-Sheet Filed April 14, 1967 l .www

lllill l! Aly l, uw w Tw i INVENToR LYLE J, MARTINSEN ATTO NEY Jan. 6, 1970 J. MARTnNsEN CORE DRILLING SYSTEM 5 Sheets-Sheet 3 Filed April 14, 1967 INVENTOR LYLE J. MARTINSEN HG. E0

ATTORNEY Jn. 69 M7@ Filed April 14, 1967 1 /f hl 7/ 4 t%Q,24O

L. J. MARTINSEN CORE DRILLING SYSTEM 5 Sheets-Sheet 4 L YLE J. MARTINSEN ATTORNEY Jam. 6, R97@ n.. J. MARTINSEN 3,48%89@ 4 CORE DRILLING SYSTEM Filed April 14, 1967 5 Sheets-Sheet 5 GRESE OIL Fu. a9 WOR INV L YLE J. MARTINSE United States Patent() U.S. Cl. 184-1 5 Claims ABSTRACT OF THE DISCLOSURE In a core drilling system: (a) a lubricant accumulator system for equalizing pressures within and without a swivel mechanism of a core barrel assembly during drilling and to compensate for lubricant losses by expressing reserve lubricant from the accumulator to forcibly insure the presence of lubricant directly adjacent the moving parts of the swivel mechanism to achieve long life and long periods of protracted use without signicant attention, the presently preferred pressureresponsive accumulators sealing one end of the swivel mechanism and comprising (1) an axially-fixed, cannulated, elastomeric pouch disposed at one end and laterally collapsible by pressure to squeeze and thereby eject lubricant from the pouch, (2) a oating piston disposed in an accumulator barrel near the bottom of the swivel mechanism, (3) a floating piston disposed in an accumulator barrel having a trailing expansible elastomeric skirt, which shields the accumulator barrel from exposure to the uid in the drill hole and generally prevents clogging of the accumulator due to contaminant particles in the uid, (4) an expansible, resilient, cupshaped accumulator of the elastomeric material which accepts fluid from the drill hole into the cup and shields the walls of the accumulator barrel from exposure to the iluid while generally preventing clogging of the accumulator due to contaminant particles in the fluid, (5) a floating body of gelatinous materials; (b) structure for minimizing clogging caused by contaminant particles present in the fluid circulated in the drill hole and for accommodating easy removal of sedimentation and like deposition of the contaminant particles without requiring appreciable disassembly of core barrel components.

This application is a continuation-in-part of application Ser. No. 571,521, filed Aug. l0, 1966, now U.S. Patent No. 3,441,098.

The present invention relates generally to the core drilling art and more particularly to novel core barrel structure which provides for more eflcient core barrel operation, longer expected core barrel life, and longer periods of uninterrupted use of the core barrel and which includes (a) novel accumulator structure for use in a core barrel assembly to equalize external fluid pressure and internal lubricant pressure acting on a sealed housing and to insure adequate lubrication of moving parts within the housing after depletion of the volume of lubricant through use, and (b) novel structure for alleviating clogging heretofore created by sedimentation and/ or other deposits of solid particles carried by the fluid circulated in the drill hole.

In core drilling, it has been customary to employ an annular drilling bit disposed at the distal end of an outer tube comprising the distal end of a drill string. The bit progressively cuts through rock responsive to rotation of the drill string, leaving an uncut upwardly projecting rock core central of the bit. As drilling proceeds, the core incrementally becomes disposed within a core receiving barrel or inner tube of a core barrel assembly, which is ice positioned inside the drill string so as to releasably coupled with the outer tube by a latching assembly of the core barrel assembly. A swivel mechanism is interposed between the core receiving barrel and the core barrel latchmg assembly so that the latching assembly rotates with the drill string and the core receiving barrel is normally stationary during drilling.

As drilling takes place, water is continually pumped along the periphery of the core barrel assembly outward around the drilling bit, and upward along the exterior of the outer tube to the surface, thus cooling the bit. The long column of water exerts very high hydrostatic and hydrodynamic pressures in the drill hole.

When a length of core has become disposed in the core receiving barrel suflicient to fill the barrel (usually several feet long), the drill string and/or the core barrel is displaced a short distance away from the leading end of the hole adequate to break the core from the rock formation. An overshot, carried at the end of a Wire line (cable), is latched to the latching assembly of the core barrel assembly, the core barrel assembly is uncoupled from the outer tube, and the overshot and latched core barrel assembly with the broken core therein are Withdrawn to the surface.

Although core drilling beneath the surface of the earth has been practiced for many years, a. number of very onerous problems have persisted in the art. For example, using prior techniques, the core, during drilling, tends to frictonally bind or jam up against the inside cylindrical surface of the inner tube as the inner tube progressively descends over the core as the core is drilled. This frequently dictates that drilling be suspended at points in time when only a fraction of the inner tube is filled with core so that the core barrel assembly can be elevated to the surface and the jammed core removed. Thus, commonly, the amount of time and labor spent to actual drill is small by comparison to the time and labor spent in transporting the core barrel assembly to and from the surface and in removing the core from the inner tube at the surface. From time to time, the core will become so tightly frozen in the inner tube that it becomes more practical to replace the inner tube than to remove the core.

Also, the swivel mechanisms of prior art core barrel assemblies, which accommodate rotation of the latching assembly with the drill string while enabling the inner tube to remain generally stationary during drilling, have almost 4perpetually presented problems involving serious time delays, expensive manpower expenditures and equipment damage. For example, oil seals, which help to envelope lubricant within and keep drilling lluid without the swivel mechanism, are caused to collapse or fail, due to instantaneous or prolonged unbalance between internal and external pressures caused by hydrostatic and surge pressure forces. When the oil seal fails during drilling, lubricant formerly sealed in the swivel mechanism is lost and drilling fluid containing debris, including silica, is admitted into the swivel mechanism, unknown to the operator, who proceeds with drilling causing irreparable harm.

IInevitably, minute losses of lubricant from the swivel mechanism are sustained during use. Cumulatively, such losses can be significant, demanding that drilling be regularly interrupted while the core barrel assembly is retrieved to the surface solely to replenish the supply of lubricant within the swivel mechanism. The down time so incurred is painfully expensive. Even though such retrieval precautions are taken, drilling many times proceeds after lubricant losses have resulted in the bearings within the swivel mechanism being dry of lubricant,

causing permanent equipment damage and necessitating premature replacement of parts.

It has been proposed that axially invertible or flexing diaphragms be used to equalize pressure within and without the swivel mechanism to preserve the oil seal and to force lubricant into the bearings. For example, see U.S. Patent 2,555,580. However, high stress concentrations exist in certain areas of these proposed diaphragms, such as the areas where the diaphragm directly flexes or where the diaphragm sharply turns or rolls upon itself as it is progressively axially inverted, making diaphragm rupture likely, due to surge and other pressure forces imposed upon the diaphragm in the drill hole. When the failure of the diaphragm occurs, not only is drilling fluid containing contaminant particles admitted into the swivel mechanism, but fragments of the ruptured diaphragm frequently find their way into the swivel bearings causing irreparable damage. Deposition of sedimentation around the diaphragm regularly causes sanding up of the diaphragm and surrounding structure, prohibiting the diaphragm from serving its intended purpose. The removal of such sedimentation from detrimental association with the diaphragm has heretofore required substantial disassembly of swivel mechanism components at the surface.

With the foregoing in mind, the present invention has as its primary object the provision of novel core barrel assembly improvements for the' alleviation of the abovementioned problems.

Specifically, the present invention in its presently preferred embodiments relates to a core drilling system which comprises a swivel mechanism. One -end of the swivel mechanism is sealed by novel Huid accumulator structure which is immediately responsive to hydrostatic and hydrodynamic pressures occurring in a drill hole. This substantially equalizes the exterior fluid pressure and the interior lubricant pressure which jointly act on the swivel mechanism. In this way, longer expected life, longer periods of uninterrupted use and more productive use are achieved, and relatively complex costly construction and operation are avoided. Lubricant is expressed from the accumulator, which may consist of any one of several embodiments ranging from a laterally collapsible cannulated pouch or a floating piston to a floating body of confined gelatinous material, into operative relation with mechanically moving parts even though the volume of the lubricant Within the swivel mechanism may vary over a wide range.

Moreover, in some embodiments, the swivel mechanism of the present invention includes novel structure which materially alleviates clogging of accumulator action by contaminant particles present in the drilling fluid and facilitates purging of any sedimentation or like deposits of such particles that may collect around the accumulator structure.

Therefore, it is another important object of the present invention to provide an improved core drilling system, including method and apparatus, to adequately lubricate the sealed swivel mechanism during drilling regardless of fluctuations in lubricant volume within a wide range, and to provide essentially instantaneous pressure equalization within and without the swivel mechanism during drilling.

It is still another significant object of the present invention to provide an improved core barrel system to alleviate clogging of accumulator action due to sedimentation and like deposits of contaminant particles present in the drilling fluid and to accommodate easy purging of any such deposits without requiring significantly disassembly of components. These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in con- ]unctlon with the accompanying drawings wherein;

FIGURE 1 is a fragmentary vertical elevation, shown partly in cross section, of one presently preferred embodiment of this invention comprising a core barrel swivel mechanism equipped with a laterally collapsible cannulated accumulator pouch;

FIGURE 2 is a view similar to FIGURE 1 of the lower portion of the same core barrel assembly;

FIGURE 3 is a fragmentary vertical cross section of the accumulator pouch of FIGURE l in its at rest position;

FIGURE 4 is a fragmentary vertical cross section of the accumulator pouch of FIGURE 1 in a partially collapsed position;

FIGURE 5 is a horizontal cross section taken along line 5-5 of FIGURE 4;

FIGURE 6 is a fragmentary vertical cross section of the accumulator pouch of FIGURE 1 in its fully collapsed position;

FIGURE 7 is a horizontal cross section taken along line 7-7 of FIGURE 6;

FIGURE 8 is a fragmentary vertical cross section of a second presently preferred accumulator pouch embodiment of this invention having an integral restricting orifice forming the mouth of the accumulator pouch;

FIGURE 9 is another fragmentary cross section of still another presently prefered accumulator pouch embodiment depicting an orifice integral with the housing of the swivel mechanism and disposed next to the mouth of the accumulator;

FIGURE 10 depicts in fragmentary vertical cross section another accumulator embodiment of this invention particularly illustrating a unique fluid control mechanism for accommodating selective fluid communication with the accumulator pouch and more rapid descent of the core barrel assembly, to alleviate problems of sedimentation and to facilitate purging of sedimentation deposits from the immediate vicinity of the accumulator pouch;

FGURE 11 is a fragmentary cross section of an end cap for selectively controlling fluid communication with the accumulator, for alleviating problems of sedimentation and for accommodating easy purging of residual deposits of sedimentation from the immediate vicinity of the accumulator;

FIGURE 12 is a bottom plan view taken along line 12-12 of FIGURE 11;

FIGURES 13 and 14 are fragmentary vertical cross `section views of floating piston accumulator embodiments according to the present invention;

FIGURE 15 depicts in fragmentary vertical cross section a further floating piston accumulator embodiment having an elastomeric expandable cannulated skirt for minimizing problems of sedimentation and for shielding the accumulator barrel from contaminant particles in the drilling fluid;

FIGURE 16 shows in fragmentary vertical cross section still another accumulator embodiment according to this invention;

FIGURE 17 depicts in fragmentary vertical cross section another presently preferred accumulator embodiment of this invention wherein pressure-transmitting gelatinous material is used to equalize internal and external pressure on the swivel mechanism;

FIGURE 18 is a horizontal cross section taken along line 18-18 of FIGURE 17; and

FIGURE 19 illustrates in fragmentary vertical cross section another accumulator embodiment of this invention also using pressure-transmitting gelatinous material.

GENERAL Reference is now made to the drawings wherein like numerals are use throughout to identify like parts. FIG- URES 1 and 2 depict a core drilling system constructed according to the present invention and generally designated 20. The core drilling system 20, as is conventional, comprises a outer tube 22, disposed at the distal end of the drill string, and a depending bit (not shown), both positioned in a :downwardly extending hole 26 in the earth.

During drilling, as is also conventional, the drill string along with the outer tube 22 and the bit are rotated by conventional apparatus (not shown) causing the bit to progressively cut an annular hole in the rock formation, leaving an uncut rock core 30 within the hollow of the bit, which core incrementally increases in length as drilling proceeds.

As the core barrel assembly 32 progressively descends over the rock core 30 as the core is cut, the core is accepted within a core-receiving hollow 34 of an inner tube 36 of the core barrel assembly 32, through a conventional shoe (not shown) and a core spring (not shown).

The core barrel assembly 32 comprises a latching assembly (not shown) which may be the latching assembly disclosed in co-pending patent application Ser. No. 571,521, tiled Aug. 10, 1966, the body 42 of which is fragmentarily depicted in FIGURE 1. Of course, other suitable latching assemblies could be used to couple the core barrel assembly 32 to the outer tube 22.

The core barrel assembly 32 also comprises a swivel mechanism generally designated 44. The swivel mechanism 44 functions during drilling to accommodate rotation lof the upper portion of the core barrel assembly, including the latching assembly, along with the drill string while maintaining the lower portion of the core barrel assembly, including the inner tube 36, generally stationary to receive the core. The swivel mechanism 44 is suspended from the body 42 upon a bearing shaft 46. The bearing shaft 46 is threadedly joined to the body 42 at threaded recess 48 and has opposed flat surfaces 47 adapted to receive a wrench for holding the shaft while assembling the core barrel assembly. The bearing shaft 46 has an enlarged annular bearing spacer 50 centrally disposed within the swivel mechanism 44 and the shaft terminates at distal end 52. The bearing shaft 46 contains an axially disposed lubricant passageway 54 communicating with selected portions of the interior of the swivel mechanism through side ports 56 and 58 and a port 6i) disposed at the distal end 52 of the shaft.

The spacer 50 is integral with and concentric of the shaft 46 and is interposed between an upper bearing assembly 62 and a lower bearing assembly 64. Thus, as the bearing shaft 46 rotates with the drill string, the lower race of bearing assembly 62 and the upper race of bearing assembly 64 will likewise rotate as the upper race of the bearing assembly 62 and the lower race of the bearing assembly 64 remain generally stationary.

The bearing assemblies 62 and 64 are retained in the position illustrated in FIGURE 1 by reason of being tightly interposed between an annular abutment surface 70 (comprising the top surface of an annular ridge 116) and a bearing retainer 72. If desired, one or more neoprene washers 74 may be interposed between the abutment surface 76 of the bearing retainer 72 and the upper surface of the upper race of bearing assembly 62, for the purpose of primarily transferring the load required to break the core 30 through the outer tube 22 rather than through the core barrel assembly.

The bearing retainer 72 is threadedly joined at 78 to the bearing housing 80 and cooperates with a conventional spring-loaded oil seal 82, disposed within an annular recess 84 of the bearing retainer so as to seal the interior of the swivel mechanism 44 against entry of drilling uid. An O-ring 79 disposed immediately above the threaded union 78 similarly seals against entry of drilling iiuid. The bearing retainer 72 is provided with one or more lubricating grooves 86 adjacent and parallel to the bearing shaft 46 and with one or more radial lubricating grooves 88 disposed at the distal abutment face 76. Thus, lubricant may easily reach any moving part within the swivel mechanism 44.

Since lubricant losses are sustained during use, the supply of lubricant interior of the swivel mechanism 44 may be replenished from time to time by using a side port 90 disposed in the bearing housing 80 and normally closed by removable plug 92, which is recessed to avoid interference with normal operation.

With reference to FIGURES 1 and 2, as well as FIG- URES 3-7, the lower end of the swivel mechanism 44 is sealed by accumulator structure generally designated 100. The accumulator structure comprises a laterallycollapsible, cannulated elastomeric pouch 102. The principal advantage of the pouch 102 over prior art proposals resides in the fact that it does not axially ex or axially invert upon itself during use. Therefore, the risk that the accumulator pouch will rupture as it is flexed or inverted, forcing ruptures particles into the bearings, is eliminated. The pouch 102 comprises a closed end 104, an elongated central cannulated portion 106 forming an interior, variable-volume lubricant reservoir 107 and having an axial length greater than its essentially constant diameter, an opening or mouth 108 and a radially projecting annular wedge-shaped lip 110, which accommodates anchoring of the accumulator pouch 102 in a substantially fixed axial position while accommodating general lateral collapse of the pouch for purposes yet to be more fully explained. The upper surface 112 of the lip 110, in the installed position, is rmly contiguous with the abutment face 114 of the annular portion 116 of the bearing housing 80. Thus, the opening or mouth 108 of the accumulator pouch 102 is in direct communication with a cylindrical channel 118 central of the annular portion 116.

The accumulator pouch 102 is anchored in its sealed position as depicted in FIGURE l by a close-tolerance accumulator retainer 120, preferably fabricated of corrosion-resistant metal. The retainer 120 provides annular abutment surfaces 122 and 124 which intersect at an acute angle and correspond to matching surfaces 126 and 128 of the lip 110. The retainer 120 is held in the illustrated position by means of a solid end cap 130 which threadedly joins the bearing housing at 132 and firmly abuts against the lower end of the accumulator retainer. Placement and removal of the end cap 130 are accommodated by Span-a-Wrench recesses 134.

It should be carefully observed that the cannulated central portion 106 of the pouch accumulator 102 is spaced from the inside surface of the retainer 121i. Thus, drilling iiuid communicates directly with the exterior of the cannulated central portion 106 through one or more side ports in the bearing housing, an annular chamber 142 and one or more side ports 144 disposed in the retainer 120. This circuitous path to the accumulator pouch is desirable to damp surge forces which sometimes occur in the drilling fluid.

In this way, the accumulator pouch 102 tends to be laterally collapsed in response to the pressure of the drilling fluid. This tends to express lubricant from the interior reservoir 107 upward through the opening 108 in response to the opposed, generally laterally-exerted pressure forces of the drilling fluid acting radially upon the cannulated central portion 106. This maintains lubricant adjacent all moving parts within the swivel mechanism even though lubricant losses have been sustained, and at the same time exerts an internal lubricant pressure force against the oil seal 82 substantially equal and opposite to the external force exerted on the seal 82 by the drilling tluid to obviate collapse of the oil seal. At the same time, creation of areas of high stress concentration in the pouch 102 appear to be avoided thereby reducing the likelihood of rupture. Inherently, when an elastomeric pouch such as 102 is utilized, one part of the central cannulated portion 106 will be slightly weaker than other areas so that when small lubricant losses have been sustained through use of the swivel mechanism 44, external pressure forces exerted by the drilling iluid will partially collapse the accumulator pouch 102, as depicted in FIGURES 4 and 5, and when the maximum permissible amount of lubricant loss has been sustained through use, the accumulator pouch 102 will be fully collapsed as shown in FIGURES 6 and 7. Of course, if the pouch contacts the retainer 120 as it is collapsed, in whole or in part, the cross-sectional shapes would be other than as depicted in FIGURES and 7. Also, the initial cross section could be elliptical or the like to control the manner in which the pouch is collapsed.

There is some evidence that use of neoprene or like washers 74 may under some conditions cause a jarring effect due to the give of the Washer, while breaking the core. This jarring effect may cause pinhole puncture of the accumulator pouch 102. Therefore, the neoprene washers may be eliminated so that the retainer directly abuts the upper bearing. This also holds the oil seal 82 in xed position relative to the bearing shaft 46 and thereby avoids damage to the oil seal caused by axial displacement of the shaft relative to the oil seal, especially after the Wearing of a groove upon the shaft by the oil seal.

Under some conditions, it is desirable to provide a constriction at or immediately adjacent the opening of the accumulator pouch for the purposes of prohibiting inadvertent inversion of the pouch through the opening due to phenomenally high surge forces which sometimes occur, and to restrict entry of elastomeric fragments into the bearings in the event that unusually high pressures in the drill hole rupture the accumulator pouch. To this end, the accumulator pouch could initially be fabricated to provide an integral elastomeric orifice 150 at the opening of the pouch communicating with the interior of the swivel mechanism (FIGURE 8) or the bearing housing 80 could be fabricated to provide an orice opening 152 (FIGURE 9).

Referring again to FIGURE 2, a flow control mechanism, generally designated 160, is shown as being interposed between the bearing housing Sti and the inner tube 36 and so secured by respective threaded connections 162 and 40.

The flow control mechanism 160 comprises a housing 166 provided with a plurality of radially disposed side ports 168 providing open communication between the exterior of the housing and an interior hollow cylindrical chamber 170. The housing 160 terminates downwardly in an integral orifice plate 172 which has a centrally disposed orifice 174. The interior surface 176 is dish-shaped so as to converge toward the orifice 174. Thus, during drilling, a ball valve 178, due to force of gravity, will center over the orifice 174, closing the orice to fluid communication. However, when the core barrel assemably 32 is lowered from the surface to the drilling site through the drilling fluid, force of the fluid will dislodge the ball valve 178 from its normally closed position (shown in solid lines in FIGURE 2) to an elevated position such as that shown in dotted lines in FIGURE 2. Thus, displacement of drilling fluid through the orifice 174 and out the side ports 168 will take place to accommodate more rapid descent of the core barrel assembly to the drilling site.

The accumulator structure and the flow control mechanism can be modified as depicted in FIGURE to achieve several purposes. The accumulator structure of FIGURE 10, generally designated 19t), comprises the previously described accumulator pouch 102, an accumulator retainer 192 substantially identical to the retainer 120 except the lower edge at 194 is contoured as depicted to tightly and contiguously abut the adjacent top dish-shaped surface 195 of a threadedly retained (at 196) orifice plate 198. The orice plate 198 has a centrally disposed orice 200 of predetermined diameter to restrict communication of drilling fluid with the pouch 102 during drilling operation. The upper surface 195 of the oriice plate 198 is more sharply convergent immediately adjacent the orifice 200 so that contaminant particles present in the drilling fluid will not tend to accumulate in significant quantities along the top surface 195 but will rather descend or drain out along the surface and through the orifice by force of gravity.

The orifice plate 198 may be provided with wrenchreceivng recesses 202 for threading and unthreading of the orifice plate from the bearing housing.

The flow control mechanism of FIGURE l0, generally designated 210, comprises a housing 212 substantially identical to the previously described housing 166. The housing 212 has a hollow interior chamber 214, a plurality of side ports 16, and an integral orice plate 218. The orifice plate 218 has a centrally disposed orifice 220 and an upper dish-shaped surface 222 forming part of the interior chamber 214. Thus, during drilling, a ball 224 will rest as shown in phantom lines in FIGURE 10 to prohibit iiui-d communication through the orifice 220 from the inner tube 36, which is joined by a threaded connection at 226 to the flow control housing 212. However, when the core barrel assembly comprising ow control mechanism 210 is lowered from the surface toward the drilling site, fluid as indicated by the arrows in FIGURE l() will elevate the ball 224 from the position shown in dotted lines to the position shown in solid lines thereby prohibiting communication of fluid pressure through the orifice 200 against the accumulator pouch 102. At the same time, a relatively large volume of iiuid displacement out the side port 216 is accommodated to facilitate more rapid descent of the core barrel assembly.

With reference to FIGURES ll and l2, an end cap 230 may be used in substitution for the previously described end cap 130 (FIGURE l). End cap 230 may be provided with wrench-receiving recesses 232 and with a plurality of through passageways 234 for accommodating selective uid pressure communication with the accumulator. A disc-shaped, pressure-responsive flap 236 is bonded along only a portion of its peripheral edge to the underside of the end cap 230, say from location 238 to location 240 (FIGURE 12). Thus, when the core barrel assembly is descending from the surface to the drilling site, tiuid pressure will deflect the ap from the dotted line position to the solid line position of FIGURE ll to prohibit imposition of sharp iluid pressure variations through the ports 34 and against the accumulator. However, during drilling, the flap 236 will, due to force of gravity, hang downwardly as shown in dotted lines in FIGURE ll so that pressure of the drilling fluid may be transmitted to the accumulator and in turn to the lubricant within the swivel mechanism substantially equalizing internal and external pressure imposed on the swivel mechanism and urging lubricant against moving parts.

Under some conditions, a oating piston accumulator, such as those shown in FIGURES 13 and 14, may be used in place of the previously described accumulator 102. In FIGURE 13, the swivel mechanism housing is fashioned to provide a close-tolerance accumulator barrel 240 of suitable diameter and length in which a comparatively large volume of lubricant is adapted to be stored above the top surface 242 of a floating piston 244. The floating piston 244 is provided with an annular groove 246 in which an O-ring 248 is situated to seal lubricant within and drilling lluid without the accumulator barrel 240. Both the barrel 240 and the piston 244 should be 'fabricated from corrosion-resistant material, such as brass or stainless steel, to adequately resist attack by the drilling iluid.

The floating piston 244 is pressure-responsive, being provided with a cone-shaped lower surface 250 which is in fluid communication with the drilling iluid through a port 252 in an end cap 254, which end cap is of a construction substantially similar to the construction of the previously described end cap 130.

Thus, changes in the pressure of the external drilling fluid will be substantially instantly transferred to the lubricant inside of the swivel mechanism by reason of displacement of the piston 244 within the accumulator barrel 249. T he maximum volume of the lubricant reservoir of the accumulator barrel 240 is normally chosen so that the core barrel assembly may be used for a prolonged period of time without interruption of drilling for the purpose of replenishing lubricant Within the swivel mechanism. Obviously, as lubricant losses are progressively sustained by the swivel mechanism due to use, the floating piston 244 will be upwardly displaced by pressure during drilling so that the volume of the lubricant reservoir within the accumulator barrel 240 will be reduced an amount substantially identical to the volume of lubricant losses accumulatively sustained up to any point in time.

Reference is now made to FIGURE 14 where another floating piston accumulator embodiment of this invention is illustrated. This embodiment differs in structure only slightly from the embodiment of FIGURE 13 and operates in essentially the same way. Specifically, a closetolerance sleeve 260 is concentrically disposed in tighttting relation within the swivel mechanism housing 80 at 262. The juncture between the housing and the sleeve is sealed by an O-ring 264 disposed witin a recess fashioned in the sleeve 260 near the top thereof. Except possibly for dimensions, the floating piston of FIGURE 14 is substantially identical with the floating piston of FIG- URE 13 and is correspondingly numbered. Thus, a reservoir for lubricant is provided within the accumulator barrel 263 above the top surface 242 of the floating piston 244. A circuitous path is provided between the exterior of the swivel mechanism and the bottom surface 250 of the floating piston 244 through a side port 265 in the housing 80, an annular chamber 266 provided at the lower end of the sleeve 260 and one or more side ports 268 near or at the bottom edge of the sleeve 260. This circuitous path damps surge forces.

The sleeve 260 is composed of a corrosive-resistant material, such as brass or stainless steel, so that those portions of the sleeve which come in contact with drilling fluid will not be subject to attack.

Where it is desired to totally shield the accumulator barrel from the influence of the corrosive drilling fluid and at the same time materially alleviate any tendency to build up accumulations of sedimentation and like deposits of solid particles present in the drilling fluid, the embodiments shown in FIGURES 15 and 16 may be resorted to. The accumulator embodiment of FIGURE 15 comprises a floating piston 270, equipped with or without an O-ring (not shown). The volume bounded by the top surface 272 of the piston 270 and the cylindrical Wall of an accumulator barrel 240 of the housing 80 comprises a variable-volume lubricant reservoir of the type and for the purposes previously mentioned.

A corrugated, cup-shaped skirt 274 is interposed between the bottom surface 276 of the piston 270 and the bottom end 278 of the Wall 240. The corrugated skirt 274 comprises a flat closed end 280, the outside of which is bonded or otherwise suitably secured to the bottom surface 276 of the piston 270. The corrugated skirt 276 also comprises a central corrugated and cannulated portion 282 and terminates in a radial, outwardly divergent wedge-shaped annular lip 284. The annular lip is held in the fixed position illustrated by contiguous surface engagement with the housing 286 and housing 80 adjacent their threaded connection at 288. Preferably an end cap 290, having a plurality of axially disposed ports 292, is used so that fluid communication with the inside of the skirt 274 is readily provided and at the same time detrimental deposits of sedimentation consisting of solid particles contained within the drilling fluid, do not occur.

Naturally, when pressure displaces the piston 270 upward, as for example so as to displace the bottom piston surface 276 from the solid position to the dotted position (FIGURE 15), the corrugated skirt 274 will readily extend or expand with the movement of the piston, and when the piston retracts toward the solid line position shown in FIGURE 15, the corrugated skirt 274 will likewise contract. At all times, the skirt. 274 shields the cylindrical surface 240 of the swivel mechanism housing from contact with the corrosive drilling fluid. Thus, using this embodiment, it is not necessary to compose the surface 240 of expensive corrosive-resistant materials. It should be observed that at no point in time does the corrugated skirt 274 axially flex or axially invert upon itself during use.

If desired, the piston 270 shown in FIGURE 15 may be eliminated and the corrugated skirt 274 function as a corrugated cup-shaped accumulator, as shown in FIG- URE 16. The normal at-rest position of the corrugated cup-shaped accumulator 274 is shown in solid lines in FIGURE 16, while an expanded position of the accumulator 27-4 is shown in dotted lines in the same figure.

A number of experiments have been conducted to date for the purposes of (a) providing one or more economical, simplified ways of increasing the expected life of a core barrel assembly, (b) providing for longer uninterrupted periods of drilling, providing for less down time (Le. periods when drilling is not occurring), and (c) more productive use of the core barrel assembly. The embodiments shown in FIGURES 17 through 19 have been surprisingly effective.

Much of the core barrel structure generally designated 300 in FIGURES 17 and 18 is identical or substantially identical to structural components shown in FIGURE 1 and earlier described. Only the salient `differences between the core barrel assembly 300 and the core barrel assembly 20 will hereafter be described.

The housing 301 of the swivel mechanism 302 is provided with a solid end at 304 and an axial blind bore 306, the interior of which comprises a lubricant chamber 308. Lubricant is introduced into the chamber 308 through a zerk fitting 310 and a passage 312. The zerk fitting 310, when not in use, is preferably capped by a plastic or similar closure 314, contoured to contiguously conform to the exposed portion of the zerk tting 310. A radially disposed bore 316 is provided in the exposed side of the housing 310 to accommodate easy placement of the zerk fitting during assembly, easy placement and removal of the cap 314, and easy access to the zerk fitting for replenishing the supply of lubricant in the reservoir 308.

The bearing assemblies 62 and 64 are held in position by a bearing retainer 320 which differs from the previously ydescribed bearing retainer 72 in that axially disposed lubricant groove 322 terminates at an annular portion 324 so as to directly feed the side port 326 of a radial passage 328 disposed within the bearing shaft 46. An Oring seal 330, disposed within a suitably configurated recess 332, functions to seal drilling fluid Without and lubricant within the swivel mechanism 302. The lower surface 333 of the retainer 320 is shown as directly abutting the top surface of the top race of the bearing assembly 62.

The radial passage 328 communicates with an axial bore 334 in the shaft 46, which bore extends from the passage 328 to the upper shaft end 336 at port 338 of the shaft 46. Port 338 opens upwardly into the conical hollow 339 adjacent the shaft end 336.

Direct pressure communication is provided between the interior of the swivel mechanism 302 and the drilling fluid by means of serially disposed passageways 340 and 342, the latter terminating in side port 344, and all of which is contained internal of the latching body 42.

Thus, the length of passageways serially provided between the port 326 and the port 344 comprises a hollow depository or elongated channel, the length of which may be regarded as essentially infinity when compared with the diameter of the port 344.

Preparatory to use, grease, a fluid-resistant gelatinous material, is forced through the zerk fitting 310 to fill the lubricant reservoir 308, all lubricant passageways within the swivel mechanism 304 as well as the serially disposed 1 1 passageways 328, 334, 339, 340 and 342, so that the gelatinous grease is directly exposed to the drilling fluid at port 344.

In use, the grease disposed within the passages 342, 340, 334 and 328, functions as an accumulator or floating piston of gelatinous material so that variations in the pressure of the drilling fluid are almost instantaneously transmitted to the interior of the swivel mechanism. Also, as lubricant losses are sustained through use, the floating grease piston within the passages 342, 343, 334 and 328 will progressively descend in response to the pressure of the drilling fluid so that a volume of gelatinous grease previously comprising part of the floating grease piston will become disposed within the swivel mechanism 302 in a quantity substantially equal to the lubricant losses at any point in time.

It has been found through the mentioned experimentation that a relatively short length of the oating piston of gelatinous material initially disposed within the passage 342 adjacent the port 344 will become contaminated by the drilling liuin. Thus, each time a drilling cycle has been completed so that the inner tube is suitably filled with core and the core barrel assembly with the broken core is elevated to the surface, a grease gun may be impressed against the zerk fitting 310 and a quantity of grease inserted into the interior of the swivel mechanism 302 so as to discharge a quantity of grease from the port 344 until it is evident that all contaminated grease has been so discharged. This procedure is not time consuming and does not require termination of drilling operations solely for the purpose of replenishing the lubricant. It may be easily attended to While the core barrel assembly is at the surface between normal drilling cycles. Examination of the interior of the swivel mechanism following use has proved that contaminating drilling tluid was completely excluded from the interior of the swivel mechanism using this economical and highly simplified floating grease piston technique.

Where it is desired to use an oil lubricant within the swivel mechanism 302, the embodiment of FIGURE 19 may be resorted to. The only structural difference of the embodiment of FIGURE 19 as contrasted with that described in conjunction with FIGURES 17 and 18 is that the latching mechanism body 42 is shown as being equipped with a sinuous passage 350 which opens to the exterior at port 352. The body 42 is also recessed at 354 to satisfactorily receive a zerk fitting 356. The fitting 356, when not in use, is preferably capped by a closure 358 fabricated of plastic. The cap 358 may be of the type manufactured by Clover Industries of Tonowanda, N.Y. The zerk fitting 356 communicates through passage 360 to the conical end 339 of the threaded bore 48.

Preparatory to use, lubricant fluid is introduced through zerk fitting 310 into the bore 308 and throughout the interior of the swivel mechanism 302. Also, a sufiicient quantity of lubricant fluid is so introduced to bring the level of the lubricant oil within the passage 334 to a location such as 362. Thereafter, using zerk fitting 356, grease or other suitable gelatinous material is introduced through the passage 360 and the conical bore portion 339 into the top of passage 334 and throughout the sinuous passage 350, the gelatinous material being then disposed to the exteriorat port 352.

Thus, during use, the gelatinous material disposed within the passage 350. the conical portion 339, and the top of the passage 334, functions as an accumulator ram or floating grease piston in the manner and for the purposes previously mentioned.

From the foregoing, it should be appreciated that the novel improvements of the present invention provide a number of accumulator embodiments provided for the purpose of achieving longer life, longer peri-ods of continuous uninterrupted use, and more productive operation. These accumulators are adapted to be disposed between the swivel mechanism and the drilling fluid during drilling and serve to not only equalize internal and external pressure acting on the swivel mechanism, but also compensate for lubricant losses sustained during use. Certain embodiments of the present invention shield the accumulator structure from the corrosive and abrasive influence of the drilling uid and others minimize likelihood of sedimentation and other deposits of solid particles and allow lfor easy purging of any residual deposits of such particles.

This invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a device for substantially equalizing external and internal pressures imposed on a sealed housing of a core barrel assembly comprising a swivel mechanism containing moving parts including anti-friction means, lubricant, and lubricant passage'ways, the improvement comprising a pressure-responsive floating body of gelatin-ous material disposed in a hollow depository having first port means of the core barrel assembly in open communication with lubricant inside of the sealed core barrel housing and sec-ond port means of the core barrel assembly in open communication with said external pressure such that (a) the magnitude of external pressure exerted through the second port means on the floating body of gelatinous material will be substantially transferred serially through the geia'inous material and the lubricant to the interior of the sealed housing thereby substantially equalizing external and internal pressure and (b) the gelatinous material will tend to be displaced inwardly to press lubricant into the moving parts and thus compensate for any loss in lubricant volume occasio-ned by use.

2. In a device as defined in claim l further comprisingan intake port for selectively injecting additional gelatinous material such that any gelatinous material contaminated by the substance exerting said external pressure may be ejected from the hollow depository from the second port means.

3. In a device as defined iu claim 2 wherein said 1ubricant and the gelatinous material are grease and wherein said intake port is disposed adjacent and in communication with a lubricant passage remote from the hollow depository.

4. In a device as defined in claim 1, wherein said lubricant is oil and said gelatinous material is grease, and 4wherein said intake port is disposed adjacent and in communication with the hollow depository intermediate the first and second port means for selectively expelling contaminated grease from the hollow depository out the second port means, and further comprising an oil intake port for selectively replenishing the oil in the sealed housing.

5. In a method of substantially equalizing internal lubricant pressure and external uid pressure within and without a sealed housing comprising part of a core barrel assembly adapted to be used in a drilling liuid Within a hole comprising; confining an elongated body of ygelatinous material between the external drilling fluid and the internal lubricant, exposing one end of the gelatinous material to the pressure o-f the drilling fluid at a relatively small opening, placing the other end of the gelatinous material in generally incompressible pressurebearing relation with the internal lubricant whereby during use the external fluid pressure will be substantially transferred interior of the sealed housing through the gelatinous material and the lubricant.

(References on following page) l l@ References Cited HOUSTON S. BELL, IR., Primary Examiner UNITED STATES PATENTS Us' CL XR.

2,555,800 6/1951 Deely 175-228 184-29, 39,- 175-228; 308134-1, 168, 17o, 187

2,751,196 6/1956 Smith 175-228

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