US2313806A - Coring apparatus - Google Patents

Description

March 16, 1943.

w. J. CRITEI'S conme APPARATUS Fil'ed llarch 24, 1941 Z SheetS-ShQBt 2 FIG. 3

INVENTOR V w. J. canes 71min Patented Mar. 16, 1943 CORING APPARATUS Wilbur J. Crites, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Application March 24, 1941, Serial No. 385,016

Claims.

This invention relates to coring and more particularly to apparatus for obtainingrepresentative cores from subsurface formations.

It is common practice in the petroleum industry to obtain cores from hydrocarbon-bearin formations for the purpose of determining certain reservoir characteristics which are useful in predicting reservoir fluid performance. ,Vir-

gin reservoirsmay be bored usually with a relatively high percentage of core recovery. Depleted formations at shallow depths may be,

cored with equal success. on the other hand. coring depleted reservoirs at greater depths yields a relatively low percentage of core recovcry. in the present practice of coring, a drilling fluid is usually circulated downwardly throug the drill pipe and thence upwardly through the annular space between the bore hole and the unconsolidated formation is cored, drilling fluid un'der considerable pressure will wash away certain portions of the core so that that which remains is non-representative of the formation cored. If a consolidated formation is cored, the drilling fluid will penetrate the core, contaminating the formation fluid therein. Nonrepresentative or contaminated cores have little or no value for analytical interpretation.

By the practice of my invention 1 am able to obtain representative formation cores, which are not contaminated by drilling fluid. The inven-, tion is especially useful in coring low pressure and non-consolidated formations, as the pressure of the drilling fluid on the face of the formation is approximately that of the formation. When a constant load is carried on the core bit,

' therotational speed of the bit is inversely'proportional and the developed torque is directly proportional to the hardness of the formation being cored.

It is the primary object of my, invention to obtain representative cores from subsurface formations.

Another object of my invention is the provision of apparatus for obtaining representative cores from low pressure and non-consolidated formations.

A further object ofmy invention is the provision of apparatus forobtaining subsurface formation cores which are not contaminated with drilling fluid.

These and additional objects and advantages will be apparent to persons skilled in the art by reference to the following description and annexed drawings, wherein-- Figure 1 is an elevation view. of one embodiment of my invention, partly in cross section;

. Figure 2 is an elevation view of a second em.- bodiment ofmy invention, partly in'cross section; Y

Figure 3 is an enlarged horizontal cross section view of the driving mechanism, taken along the line 3-3 of Figure l, and;

Figure 4 is a sectional view of the driving mechanism, taken along the line 4-4 of Figure 3.

Referring to Figure 1, I have shown a casing III which extends downwardly in a bore hole II from the surface of the ground (not shown). A drill stem I2 is suspended and rotated within casing I0 in a well known manner from the surface of the ground. It will be noted from the a fluid supply chamber I5, a differential drive --mechanism I6, an annular space I1, an inner core barrel I8, and a core bit I9. The upper part of bit I9 is grooved to receive the lower portion of drill stem I2 in such a manner that the drill stem is free to rotate irrespective of the rotation of the bit. A fluid, such as an oil,

which is used in operating my device, cools and lubricates the bit and carries away the formation cuttings made thereby.

Chamber I 4 is formed by a cylindrical wall 20, whichis a portion of the drill stem, intermediate a plug 2| and a filtering element 22 which are positioned within the drill stem and ,provide the top and bottom, respectively, of the chamber.

The upper part of wall 20 has openings 23 which" v of the core barrel.

valve and perforations provides a means for disrotary pump 25 which'serves .as' a fluid transmission or driving means. Any type of positive displacement rotary pump may be employed in the practice of my invention. It is to be noted that the rotary ump 25 is positioned in and secured to drill pipe l2 by means of an outer housing 26. An inner partition 21, which allows communication between the rotary pump 'and i supply-chamber l through an inlet 28 and with annular space I! through a restricted outlet 29,

of smaller diameter than inlet 28, contains an idler gear 30 which rotates on a fixed idler pin 3| and meshes with a rotor 32. The rotor, which is secured to a shaft 33, also rotates within the inner partition, and cooperates with the idler to' pump fluid from inlet 28 through outlet 29. A fixed crescent-shaped member 34 is positioned between the rotor and the idler. Fluid from within the pump is prevented from leaking out around shaft 33 by a packing gland 35 which is placed in the'lower portion of housing 26.

Referring again to Figure 1, it will be noted that shaft 33 is secured to inner core barrel I8. The inner core barrel is threadedly attached to bit l9 and contains a check valve 36, which is positioned near the upper end of the core barrel, and one or more perforations 31, which are provided between the valve and the upper end This arrangement of the ing means or core catcher 38 which allows the core, which is cutfrom a formation by the bit, to enter core barrel I8 through a passage 39 therein during the coring operation. When the coring assembly is being removed from the well bore, the retaining means holds the core in the core barrel. In addition to a central core 'passage 39, bit I!) is provided with a plurality of fluid passages 40 which allow fluid from annular space I! to lubricate and cool the bit and to carry away formation cuttings which are chipped from the formation during the coring operation by a plurality of cutters 4|. It is to be noted that the bit contains a packing element 42 at the base of drill stem |2, which prevents. leakage of the fluid around the base of the drill stem.

In the operation of this embodiment of my invention, the assembly shown in Figure 1 is lowered into bore hole II in the usual manner from he surface -of the ground. A predetermined amount of circulating oil is injected into annular space 24 until the hydrostatic head of the oil is substantially equal to the formation pressure. In reservoirs where my invention may be practiced, the formation pressure is generally suflicient to .allow the oil to fill chambers l4 and I5, annular space [1, and annular space 24 to a point above openings 23 in the receiving chamber. The normal circulation of the oil through the apparatus may be thought of asstarting in supply chamber l5-from which it enters inlet 28 of pump 25 and is pumped through outlet 29 into annular space II. The oil leaves the annular space flowing through passages 40 in hit l9 to lubricate and cool the. bit. The oil entrains cuttings made by the bit and travels upwardly in annular space 24 entering receiving chamber I4 through openings 23. Filtering element 22 separates the circulating oil from the cuttings, retaining the cuttings above the filter and allowing the oil to pass downwardly into supply chamber 15 from which it may be recirculated.

. 'It will be noted the circulation is maintained 4 pumped and a torque will be developed in the pump which is sufficient to overcome the load on the bit and cause it to turn in the same direction as the drill pipe, but at a slower speed. As long as the weight on .the bitremains constant, the

differential speed between the bit and the drill pipe and a constant rate of circulation will be maintained. Further, unless there is a resistance to turning of bit l9, it will rotate at substantially the same speed as drill pipe 12, however, under this condition, no fluid will be transmitted through pump 2-5. This is the case when the drill pipe is held off the bottom of bore hole II. On the other hand, if bit 19 is prevented from turning while drill pipe l2 rotates at a constant speed, a maximum torque is developed and a maximum rate of circulation is obtained. This is analogous to setting full weight on the bit While coring an extremely hard. formation and thus preventing rotation of the bit. The available torque for rotating the bit actually is the torque developed in pumping oil through pump 25, as bit I9 is directly connected to the pump rotor by core barrel [8 and shaft 33. A torque is developed in pumping oil, as the pump receives fluid through inlet 28 and discharges it through restricted outlet 29. All parts of the pump are responsive to the rotation of the drill pipe except rotor 32, which is responsive to the torque developed in pumping oil through the pump. If there is a difl'erential speed of rotation between hit F9 and drill pipe l2, oil will be pumped. In the practice of my invention, the rotational speed of bit l9 and the volume of oil circulated by the pump are functions of the weight which is placed upon the bit. Furthermore, the speed of the bit varies inversely as the hardness of the formation,

whereas the volume of oil circulated varies di-- rectly as the hardness of the formation. In coring a soft formation, bit I9 will rotate more rapidly than it will in coring a hard formation, while the rate of fluid circulation in coring a soft formation will be less than in coring a hard formation. This feature of my invention climinates washing away the 'soft portions of a formation core by high velocity fluid.

In describing a second embodiment of my invention, I have designated like parts by the same reference numerals. By referring to Figure 2, it will be noted that in this embodiment bit i9 is bored to receive andsupport core barrel I9 and is threadedly attached to an outer member 43 which bears at the top against drill pipe l2. The top of the outer member is provided with a spider 44 by which the member is secured to shaft 33. A plurality of spacing members 45 are positioned'in annular space I! to align core barrel I8, which may remain stationary or rotate independently of bitl9. In addition to core retical to the first embodiment.

"tational speed ofthe bit and the volume of oil taining means 38, a second pair of core catchers 46 may be provided in core 'barrel l8 to aid in retrieving the core. The top ofthe core barrel has a conduit 41 which establishes communication between the top of the core barrel and annular space 24 and through which the pressures" within the core barrel and the annular space'are equalized. It will be noted that a packing gland 48 is placed'around conduit 41 in the top of the core barrel. The packing permits rotation of the cor'e'barrel and prevents the circulating oil from entering the corebarrel from space H.

sage in said means; a fluid passage in said means communicatingwith the pump outlet; arecepy tacle communicating with the core passage for The operation of this second embodiment is very similar to the operation of ,the first. The

' .torque developed in pump 25 turns outer member 43 and bit IS. The fluid circulation is iden- Similarly, the rocirculated are functions of the weight placed on the bit,

It is to be understood that the forms of my invention, herewith shown and described, are to be taken as preferred examples. of the same, and

that various changes in shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention, or the scope of the subjoined claims.

I claim:

I. In coring apparatus, the combination comprising a conduit adapted to be rotated in a well bore; a pump including a casing secured to and rotatable with the conduit and a rotor in the casing; core cutting and retaining means con--- nected to the rotor and adapted to engage the bottom of the well bore; and liquid supplied to the pump, whereby, upon rotation of the conduit and the pump casing, the said means will be rotated against the resistance of its contact with the bottom of the well bore.

2. In coring apparatus, the combination comprising a drill stem adapted to be'rotated in a bore hole; a pump including a casing secured to the drill stem and rotatable therewith, an inlet, an outlet, and a rotor inthe casing; a coring tool connected to the rotor and adapted to engage against the receiving and retaining core material, and liquid supplied to the pump through the inlet thereof,

whereby upon rotation of the drill stem and the pump casing, the core drill means will be rotated tom of the bore hole.

' 5. In coring apparatus, the combination comprising a drill stem adapted to be rotated in 'a borehole; a positive, displacement rotary pump I including a casing within the drill stem and secured thereto so as to rotate therewith, said casing forming a partition across the interior of the drill stem, an inlet establishing communication between the casing and the portion of the drill stem above the casing, anoutletestablishing communication between thecasing and the portion of the drill stem below the casing, and a rotor in the casing; acoring tool rotatably coupled to the lower. end ,of the drill stem and connected to the pump rotor so as to rotate therewith, said coring tool being adapted to engage the bottom of 1 the bore hole; and liquid supplied to the pump casing through the inlet thereof,

whereby, upon rotation of the drill stem and .the pump casing, the coring tool will be rotated against the resistance of its contact with the bottom of the bore hole.

6. In coring apparatus, the combination com-1 prising a conduit adapted to be rotated in a bore hole, a positive displacement rotary pump in- 'cluding a casing secured to the conduit and rotatable therewith, said casing forming a partition across the interior of the conduit, an inlet I communicating with thecasing and the portion the bottom of the bore hole; a passage in the coring tool communicating with the pump outlet; and liquid supplied to the pump through the inlet thereof, whereby, upon rotation of the drill stem and the pump casing, the coring tool will be rotated against the resistance ofits contact with the bottom of the bore hole.

3. In coring apparatus, the combination comprising a' drill stem adapted to be rotated in a bore hole; a pump includinga casing secured to the drill stem and rotatable therewith, an inlet,

an outlet, and a rotor in the casing; a coring tool connected to the rotor and adapted to' en gage the bottom of'the bore hole;.said coring tool including rotary core cutting means, core receiving means, and a passage communicating with the pump outlet; and liquid supplied to the pump through the inlet thereof, whereby, upon rotation of the drill stem and the pump casing, 6 the coring tool will be rotated against the,re-,

sistance of it's contact with the bottom of the bore hole.

4. In coring apparatus, the combination comprising a drill stem adapted to be rotated in a bore hole; a pump including'a casing secured to an outlet, and a rotor in the casing; core drill means connected to the rotorand adapted to engage the bottom of the bore hole; a core pasthe drill stem and rotatable therewith, an inlet,

of the conduit thereabove, an outlet communicating with the casing and the portion of the conduit therebelow, and a rotor in the casing, a coring too1 rotatably'coupled to the 7 lower end oi the conduit and including a core drill connected to the pump rotor so 'asto rotate therewith and adapted to engage the bottom of the bore hole,

a fluid passage extending through the core drill and communicating with the pump outlet, a core receiving receptacle, and a core passage in the core drill communicating with said receptacle;- and liquid supplied to the pump casing through the inlet thereof, whereby, upon rotation of the conduit and the pump casing, the core drill will be rotated against the resistance of its contact with the bottom of the bore hole.

'7. In coring apparatus, the combination comprising a conduit adapted to be rotated in abor'e hole, a positive displacement rotarypump including a casing secured to the conduit and rotatable therewith, said casing forming a partition across the interior of the conduit, an inlet communicating with the casing and the portion r of the conduit thereabove,an outlet communicata core receiving receptacle disposed within the conduit and spaced therefrom to form an annular passage therewith communicating with the pump outlet and the fluid passageand positioned intermediate the pump casing and the core drill, and acore passage in the core drill communicating with said receptacle: aridliquid supplied to the sistarice of its contact with the bot-' pump casing through the inlet thereof, whereby, upon rotation of the conduit and the pump casing, the core drill will be rotated-against the resistance of its contact with the bottom ofthe bore hole.

8. In coring apparatus, the combination comprising a first conduit adapted to be rotated in a well bore; a second conduit extending below the nected to the second conduit; a coring tool connected to the second conduit and adapted to engage the bottom of the bore hole; and liquid supplied to the pump casing through the inlet, whereby, upon rotation of the first conduit and the pump casing, the second conduit and the coring tool will be rotated against the resistance of its contact with the bottom of the well bore.

9. In coring apparatus, the combination comprising a first conduit adapted to be rotated in a well bore; a second conduit extending below the first conduit and rotatable with respect thereto, said conduits being in communication;' a pump including a casing forming a partition across'the first conduit and secured thereto so as to rotate therewith, an inlet'establishing communication between the casing and the portion of the first conduit thereabove, an outlet establishing com- '.munication between the casing and the second duit and adapted-to engage the bottom of the bore hole, a fluid passage extending through the core drill and communicating with the pump outlet,

a core receiving receptacle, and a core passage in the core drill communicating with said receptacle; and liquid supplied to the pump casing through the inlet thereof, whereby, upon rotation of the first conduit and the pumpcasing, thesecond conduit and the core drill will be rotated against the resistance of its contact with the bottom of the well bore. 5

10. In coring apparatus, the combination comprising a first conduit adapted to be rotated in a well bore; a second conduit extending below the first conduit and rotatable with respect thereto, said conduits being in communication; a pump including a casing forming a partition across the first conduit and secured thereto so as to rotate therewith, an inlet establishing communication between the casing and the portion of the first conduit thereabove, an outlet establishing communication betweenthe casing and the second conduit, and a rotor in the casing fixedly connected to the sec-ondconduit; a coring tool includ- 'ing a core drill connected to the second conduit and adapted to engage the bottom of the bore hole, a fluid passage extending through the core drill, a core receiving receptacle within the second conduit and spaced therefrom to form an annular passage therewith communicating with the pump outlet and the fluid. passage and positioned intermediate the pump casing and the core drill, and a core passage in the core drill communicating with said receptacle; and liquid supplied to the pump casing through the inlet thereof, whereby, upon rotation of the first conduit and the pump casing, the second conduit and the core drill will be rotated against the resistance of its contact with the bottom of the well bore.

WILBUR J. CRITES.

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