US2923530A

US2923530A - Apparatus for investigating earth formations

Info

Publication number: US2923530A
Application number: US570764A
Authority: US
Inventors: Roger Q Fields
Original assignee: Schlumberger Well Surveying Corp
Current assignee: Schlumberger Well Surveying Corp
Priority date: 1956-03-12
Filing date: 1956-03-12
Publication date: 1960-02-02
Anticipated expiration: 1977-02-02

Description

Feb. 2, l1960 FIG. l

R. Q. F IELDS APPARATUS FOR INVESTIGATING EARTH FORMATIONS Filed March l2, 1956 @www HIS ATTORNEY United States Patent "O FOR INVESTIGATING EARTH FORMATIONS Application March 12, 1956, Serial No. 570,764V

7 Claims. (Cl. Z55-1.4)

APPARATUS This invention relates to apparatus for investigating earth formations and, more particularly, pertains to a new and improved core-taking device for obtaining a sample of earth formation material.

In present practice, cores or samples of earth formation material may be obtained by projecting a hollow core-taking tube or barrel into a formation by means of a gun. For example, the gun may be lowered through a borehole drilled into the earth to the level of a formation to be investigated and then discharged. The core barrel thus is impelled toward the sidewall of the borehole and is embedded in the formation, its hollow interior thereby being filled with formation material. Usually the core barrel is secured to the gun by one or more flexible connections. Thus, by raising the gun, the core barrel with its sample is drawn from the formation and can be brought to the surface of the earth for examination.

To facilitate recovery of a core, it has been proposed that the core-barrel be provided with a separable forward portion in the form of an annular ring. In particular, this ring may have a slightly greater diameter than the core barrel, as disclosed in U.S. Patent No. 2,288,210 to Marcel Schlumberger. v

It is an object of the present invention to provide new and improved core-taking device of the general type disclosed in the aforementioned Schlumberger patent.

Another object of the present invention is to provide a new and improved core-taking device in which separable forward and body portions may be conveniently maintained in fixed spatial relation to one another, but are immediately separable after the device is embedded in a formation under investigation.

Yet another object of the present invention is to provide a new and improved'core-taking device including separable portions which, prior to embedding in a formation, are in a relatively stable, unitary assembly thereby minimizing the possibility of inadvertent separation.

A further object of the present invention is to provide a new and improved core-taking device which is simple and inexpensive to construct and yet is entirely efficient and reliable in operation.

Apparatus for investigating earth formations according to the present invention comprises core-receiving and formation-penetrating members disposed adjacent one another and adapted to be impelled toward the formation and embedded therein. A hollow retainer of resilient material receives portions of each of the corereceiving and formation-penetrating members to maintain them in essentially fixed spatial relation` to one another. However, `the retainer is releasable from at least one of the members thereby to permit withdrawal of the core-receiving member from the formation' while the formation-penetrating member remains embedded therein. v t r The novel Ifeatures' of the present invention 'aref set Yforth with particularity in the `appended claims. The

barrel 18 and cutting ring 24.

.present invention, both as to its organization and manner of operation, together with further objects and advantages thereof, Vmay best be understood by reference to the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a cross-sectional view of apparatus for in- Vestigating earth formations embodying the presentl invention taken in a plane perpendicular to the axis of a borehole in which the apparatus is disposed, andv illustrating the apparatus in one condition of operation; and

Fig. 2 is a view similar to Fig. 1, but illustrating the apparatus in another condition of operation.

In Fig. 1 of the drawing there is shown a gun block 10 disposed in a borehole 11 Iopposite a formation of interest 12. Usually borehole 11 contains a drilling mud 13, however, the present inventiony may be employed in either dry or mud-filled boreholes.

Into gun block 10 extends a cylindrical bore 14 followed by a powder chamber 15 which terminates short of the rear surface of the gun block. Chamber 15 contains an appropriate propellant 16 and bore 14 receives a generally cylindrical sample-taking projectile 17 constructed in accordance with the present invention. Al-

though not illustrated, gun block 10 may contain additional projectiles in respective bores distributed along a vertical axis for the gun block. 'Y l Projectile 17 is comprised of a substantially cylindrical, hollow, core barrel 18 provided with a rear or bottom closure 19 and adaptedrto be impelled toward the formation 12 along a longitudinal axis 20 of the core barrel. Core barrel 18 has a forward end 21 lying in a plane perpendicularto axis l2l)V and which, together with a portion of anouter cylindrical surface portion 22 defines a seat. Cylindrical surface` 22 is provided with an annular recess 23 disposed in the vicinity of forwardend of the core barrel. I

A substantially cylindrical formation-penetrating member or cutting ring 24 includes a rearward portion25 provided with a cylindrical recess cooperating withand engaging the

seat

21, 22 of the corefbarrel. VIn addition, cutting ring 24 has an external surface 26 'of generally frusto-conical configuration extending Y Aforwardly from the rearward portion 25 and inwardly toward. longitudinal-Yaxis 20. Surface 26 terminatesY at the forward end of a cylindrical inner surface 27 for 'cutting ring Y24 to defineA a cutting edge 28. Inner surface 27 conforms vgenerally Ato a cylindrical innerrsurface 29 of core barrel 18. Y

Preferably, cutting ring 24 has a portionrof a diameter D1 which is larger than the diameter D2 of core barrel 18. Thus, a portion of the cutting ring has a cross-sectional area in a plane perpendicular to axis 20 larger than the cross-sectional area in a similar plane of the core-barrel.

A substantially cylindrical hollow retainer 30 of resilient material, such as rubber, receives portions of core inner surface 31 provided with. a ridge 32 extending inwardly into recess 23 of the core barrel. VIn addition, the retainer has an inner surface portion 33 conforming toand engaging at least a portion of the external surface 26 of generally frusta-conical configuration of the cutting ring. Accordingly, the core barrel and the cutting ring are maintained in essentially xed spatial relation to one another. The retainer further includesv a forward surface 34, disposed in a plane substantially perpendicular to the longitudinal axis 20, adapted to engage formation material.v

Appropriately connected Yto opposite sides'of core'barrel 18, are a pair of flexible retrieving wires 35 and 35'. These wires are formed into

coils

36 and 37 which are dis Patenti-.d rgb. 2,1960

Retainer 30 includes an posed in

respective openings

38 and 39 in gun block 10U and their remaining ends are appropriately connected to' the gun block.

From an inspection of Fig. -1-, it may beseen that to assemble a core-takingl projectile embodying the present invention, cutting ring 24 is merely placed` so that recess 25 engages seat 21,` 22 of core barrel 18 and the retainer 30 simply may be stretched to receive the `cutting ring and-the lcore barrel. The retainer may then be released so,` that it fallsY into the position illustrated in Fig. 1. lf desired, a suitable lubricant may be used to facilitate the positioning of the retainer. Obviously, for a secure spatial association of the elements, the diameter of retainer 30, prior to the assembly of the elements, should be somewhat smaller than illustrated in lFig. 1. i

ln operation gun block` including a sample-taking projectile 17 embodying the presentinvention is lowered into borehole 11 to a position opposite` the formation of interest 12 as illustrated in Fig. l. Retainer 30 holds the cutting ring24 in a xed position with respect to core barrel 18 during descent. l

, At the desired depth, propellant 16 is ignited, and the projectile 17 is impelled toward the sidewall of the borehole 1-1. During this portion of an operating cycle, cutting ring 24 remains in a fixed position relativeto core barrel 18 with recess 25 on

seat

21, 22. A

As the projectile enters the formation, .forward face .34 of retainer 30 engages formation material so that continued movement of the projectile effects relative displacement of the retainer; The retainer thus is displaced to a position illustrated in Fig. 2 during the phase of operation in which core barrel 18 receives a core sample 40. In some instances, the passage of the projectile 17 through mud 13 `causes relative displacement of the retainer 30. v Y Since cutting ring 24 cuts an oversize hole 41 inearth formations 1,2, and' no` longer is attached to core barrel 18 because of the movement of retainerti, the core barrel together with the core sample 40 may be withdrawn from the formation while cutting ring 24 remains embedded therein. This is done by drawing upwardly on `gun block 10, motion being imparted to the core barrel V18 by means of retrieving wires 35 and 35.". Thus, the core barrel may be brought to the surface and the sample 4t).A can be examined. Y 4 Y It is obvious from the foregoing discussionthatvin a formation-sampling projectile embodying the present invention, the possibility of premature, inadvertent separation between the retaining ring and the `core barrel .is minimized., However, after a core sample is obtained,

, the core barrel and cutting ring are easily separated.

Furthermore, it is evident that a projectile embodying `the present invention is simple and inexpensive to construct. Therefore, a projectile embodying the present invention aifords an important advance over prior devices of this type.

While a particular embodlment of the presentinvention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spiritand scope of this invention. i

I claim: v

l. Apparatus for investigating earth formations comprising' core-receiving and formation-penetrating members disposed adjacent one another in end-to-end relation Vand adapted to be impelled toward ,a formation and `embedded therein, ,th'e outer diameter of said formationpenetrating member being greater than the outer diameter of said core-receiving member and the end or" said formation-penetrating member that extends `away from said core-receiving member being in the shape of a cutting edge, and a hollow retainer of resilient material including means for receiving adjacent portions of each of said core-receiving `and said formation-penetrating members to maintain said members essentially iixed in relation to one another, but releasable from at least said formation penetrating member thereby to permit Withdrawal of said core-receiving member .from the formation while said formation-penetrating member remains embedded therein.

2. Apparatus Ifor investigating` earth formations comprising core-receiving and formation-penetrating members disposed adjacent one another in end-to-end relation andadapted to be impelled along a longitudinal axis of said members toward a formation and embedded therein, the outer diameter of said formation-penetrating.member being greater than the outer diameter of said corereceiving member and the end of said formation-penetrating member that extends away from said core-receiving member being of a generally frusto-conical configuration converging away from said core-receiving member to provide a cutting edge, and a Ahollow retainer of resilient material includingmeansfor receiving adjacentportions ofk each of said core-receiving and said formation-penetrating members to ,maintain said members essentially 'fixed in relation to one another,V but releasable `from at least said Aformation penetrating member, said retainer t including a forward surface near the forward end of said formation penetrating member disposed in a plane substantially transverse to said longitudinal axis and extending laterally outwardly from said members, saidsurface being adapted to engage formation material and effect release of said retainer from 4said one member Vthereby to permit withdrawal of saidcore-receiving member from the 4formation while said formation-penetrating member remains embedded therein.

3. Apparatus for investigating earth formations comprising a hollow'core-receivingmember adapted to be impelled toward a 4formation and having .al forward end, a formation-penetrating member having a cutting edge disposedadjacentsaid forward end of said core-receiving member and in end-,to-cnd relationship tl1erewith,'means adapted to impelsad core-receiving member in the direction of said forward end into aformation, and a hollow retainer of resilient material including means for receiving adjacent portionsfofjeach of said core-receiving and said formation-penetrating rnembersqto` maintain `said members in essentially lixed relation to one another, but releasable from at least said formation penetrating member thereby to permit withdrawal ofV said core-receiving memberfrom the formation while.saidformation-penetrating` member remain's embedded therein.

4.V Apparatus forV investigating wearth formations icomprising a hollow core-receiving member adapted to be impelledtoward a formation and'having a forward end and an annular recess in `the `vicinity of said forward end, a formationepenetratirig member having a cutting edge disposed adjacent said forward end of said core-receiving Ymember in end-to-end relation therewith, means adapted Ycore-receiving member from the formationwhilesaid formation-penetrating member remains embeddedv therein.

5. Apparatus for investigating earth formations comprlsing' a-hollow` core-receiving member adapted `to be .impelled toward `a formation and having forward end, `an `annular formation-penetrating member having a cut-` ting edge disposed adjacent'sai'd'- forward `end of said core-receiving member in end-to-end` relation therewith and-having an external ,surface Vof `generally frusto-coni- .-calconguration converging forwardly from said forward end of said core-receiving member, and an annular retainer of resilient material including means for receiving adjacent portions of each of said core-receiving and said formation-penetrating members and having an internal surface substantially conforming to the configuration of said generally frusto-conical surface of said formationpenetrating member, said retainer further including means for maintaining said members in essentially fixed relation to one another, but releasable from at least said formation penetrating member thereby to permit withdrawal of said core-receiving member from the formation while said formation-penetrating member remains embedded therein.

6. Apparatus for investigating earth formations comprising a hollow core-receiving member having a forward end, including a forward portion of a given area in a plane transverse to a longitudinal axis for said member, and being adapted to be impelled toward a formation, a formation-penetrating member having a cutting edge disposed adjacent said forward end of said core-receiving member in end-to-end relation therewith and having a rearward portion in a plane transverse to said longitudinal axis of an area larger than and overlying said given area, and a hollow retainer of resilient material including means for receiving adjacent portions of each of said core-receiving and said formation-penetrating members to maintain said members in essentially fixed relation to one another, but releasable from at least said formation penetrating member thereby to permit withdrawal of said core-receiving member from the formation while said formation-penetrating member remains embedded therein.

7. Apparatus for investigating earth formations comprising a substantially cylindrical, hollow core barrel adapted to be impelled toward a formation along a longi- 6 tudnal axis of said core barrel and including a forward end defining a seat and an outer cylindrical surface portion having an annular recess disposed in the vicinity of said forward end, a substantially cylindrical cutting ring including a rearward end cooperating with and engaging Said seat of said core barrel and an external surface of generally frusto-conical configuration extending forwardly from said rearward end and inwardly toward said longitudinal axis and forming a cutting edge, and a substantially cylindrical hollow retainer of resilient material 'eceiving portions of said core barrel and said cutting ring, including an inner surface having a ridge extending inwardly into said recess of said core barrel and having a portion conforming to and engaging at least a portion of said external surface of generally frusto-conical configuration of said cutting ring to maintain said core barrel and said cutting ring in essentially fixed relationship to one another, and said retainer further including a forward surface near the forward surface of said formation penetrating means disposed in a plane substantially transverse to said longitudinal axis extending laterally outwardly from said members, said surface being adapted to engage formation material so that continued movement of said cutting ring in a forward direction effects relative displacement between said cutting ring and said retainer thereby to permit withdrawal of said core barrel from the formation while said cutting ring remains embedded therein.

eferences Qited in the file of this patent UNITED STATES PATENTS Leone Dec. 25, 1956