US2521332A - Oil well formation tester - Google Patents

Description

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' R. H. BLOOD ETAL OIL WELL FORMATION TESTER Filed April 23, 1948 SPEASZHEAD 5 UNgATCl-UNG LEEVE 5 LATCHING Does DRILLING Plum:

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Patented Sept. 5, 1950 UNI ED:- STAT S PATENT oFFIcs 01L WELL FORMATION TESTER Robert H. Blood and Ben William Sewell, Tulsa, .Okla, assignors .to Standard Oil Development Company, a corporation of Delaware Application April 23, 1948, Serial No. 22,878

The present invention-relates: to a novel formation tester to be used in extracting samples of well fluids encountered in oil well drilling operations. r a

During oil drilling operations, the bore hole is generally filled with a fluid such as drilling mud. The purpose of this mud is in large part to maintain a sufliciently high hydraulic pressure on the formations through which the hole is drilled so that natural fluids contained in the formations will not be uncontrollably released. If drilling mud or an equivalent fluid were not employed, gases or liquids under considerable pressure might be released by the drilling operations to be blown to the surface of the earth; in many cases to be blown to the surface of the earth under sumcient pressure to damage the drilling apparatus employed. The presence of drilling mud in the well hole, therefore, complicates the testing of fluids encountered during drilling. In the first place, the hydraulic pressure of the drilling mud substantially prevents fluids from leaving the strata being drilled and in the second place, any fluids ejected from the strata would be mixed/with the drilling mud. Consequently, it is necessary to employ special testing procedures to suitably extract samples of fluids from formations being drilled. Conventionally this has beendone by swabbing the oil well, that is, by reducing the hydrostatic pressure of the drilling mud sufliciently to allow fluids to be released from formations and to be drawn upwardly in the well hole. This procedure has not been particularly satisfactory however, so that at the present time attempts are being made to develop more suitable well testing procedures.

Methods are now being developed for sealing off a particular portion of the oil well permitting the reduction of pressure on this portion of the well so that the drilling. fluid may be extracted from the particular portion without decreasing the hydraulic pressure on the remaining portions of the well. The apparatus developed for this purpose is generally called formation testing apparatus. A particularly useful form of formation testing apparatus which has been developed is that involving an elastic packer. This type of packer is adapted to be supported in a bore hole at a desired point and to be expanded to seal off the hole at that point. By incorporating means in or adjacent to the wall of the packer for extracting a sample from the strata, a fluid sample may be extracted from the earth at the particular point and may be drawn to the sur- :4. Claims. (01. 166-,1)

2 face of the earth. The present invention is dirooted to an improved form of elastic packer,

formation-testing-apparatus. The particular object of this invention is to enable formation testing to be made with a minimum of effort and a maximum of ease. At the same time'the apparatus of this invention is of simple construction.

The nature and objects of this invention'may= be fully understood from the following description in connection with the accompanying draw-' ings in which Fig. 1 diagrammatically illustrates an embodiment of the invention suspendedin an oil well inthe inflated or sealing position, while Fig. 2 represents the same embodiment of the invention suspended in the well-in a deflated po sition.

Referring to the drawings it will be understood thatthe apparatus illustrated is positioned in an oil well I at any desired depth. Theapparatus is suitably supported in the oil well by attachment to a drill stem identified by the numeral 2. The drill stem 2 is of conventional construction and consists essentially of a string of pipe'suit-' ably connected by threads and couplings. It is only necessary that the drill stem terminate in a suitable threading to accommodate the novel apparatus illustrated in the drawing. It is to be understood that the formation tester of this invention comprises all parts of the drawing below composed of rubber or an equivalent elastic ma-' terial. Around one circumference of the elastic packer, preferably positioned about midway of the ends of the packer, is a permeable section Hi.

elastic packer terminates in'and is supported by an inner rod 5 which extends upwardly into the casing 6. Theupp er part of this red'is prefer,-

ably terminated in a spearhead 3. A chamber 1' extends within the rod 5 from a point opening into the bore hole beneath the lower termination of the packer to connect with the telescoping passage 30, providing a continuous passageway upwardly to the by-pass port l2 which opens to the fluid filled bore hole. Another passageway extends from ports or chambers I in the upper part of rod 5, downwardly through the rod 5, to terminate in the perforated openings [6 which are positioned within the elastic packer. This chamberconnecting the perforations .lat in red .5 and the upper port #5 in the rod 5 is identified by the numeral 53. It will be noted that a check valve I4 is also positioned in the passage l3 to permit the flow of fluids upwardlythrough this chamber, but to prevent the flow of'flu'id downwardly. At the upper part of the rod '5 adjacent. to the spearhead 4| are latching dogs 8. These are adapted to swing outwardly or inwardly to engage or disengage the projections .9 provided on the inner part of the housing 6. The latching dogs are urged outwardly by springs not illustrated in the drawing. The general structure of the apparatus of this invention having now been described :and identified, the operation :of "this apparatus maybe understood.

-A suitablewell hole -:I is drilled in the earth by conventional drilling operations. Generally .during these drilling operations, by means of well logs or other means known to the art, some indications as to possible oil-bearing stratain the earth are obtained. Thus, by suitable well-logging .means it may be established that a porous stratum "H exists at some point of {the oil well. In order "to test thejfluid :whi'chmay be :present in' the porous stratum H the apparatus of this invention is then employed. The drill stem is removed from the well and the conventional drilling tools removed from the end of the drill stem. .The apparatus illustrated tinthe drawing is then connected to the end of the :drill ;stem as shown permitting .the entire apparatus to be lowered into the-well. the latchings dogs are manually-depressedso that rod *5 sliding on guides 20, is allowed to drop downwardly with respect to casing holding the elastic packer in the deflated or extendedposition shownin Figure 2, while the apparatus -.-is lowered. The apparatus is lowered until the porous section of the elastic packer is adjacent to the porous stratum to be tested. 'I-Thus;.- as shown in Fig. l the elastic packer is lowered sufliciently in the well so that the porous section lll'of theelasticpacker is adjacent to the porous stratum H of the earth. As stated, while the apparatus is being lowered into the *well the elastic packer is inthedeflated .positionas shown in FigureZ. "In the deflated or extended -posi;- tion, the rod 5 within the elastic packer; and-the components associated with rod :5 exert asufficient weight on the packer to hold item .the elongated position as illustrated. In this position thelatching dogs 8 on'the upper part of rodi'5tarerbelow the shoulders 9 provided :in the chamber =6; When the apparatus has-been suitablyspositioned in .the well, a wire line equipped with. a suitable latch on it is dropped :down the-;drill string :to engage the spearhead 3 of the apparatus. exerting .a pull on the wire line atzthesurface of the earth, the rod .5 is pulled, upwardly with respect to the chamber 6. The upward movement of rod v5 willbring the latching, dogs upwardly to the portion of chamber 6 provided with the latches or shouldersB. At the-same time the upward movement of rod 5 will shorten the elastic packer, causing it toextend laterally to completely fill-and sealthewell. It .will..be noted that the elastic packer is .filled with a Prior to this operation,

.4 multitude of pellets is which give the elastic packer suflicient body so that the pulling upwardly of rod 5 will cause the packer to press against the walls of the drill hole so as to completely seal the hole. When sufficient force has been exerted on the wire line connected to spearhead 3 so that operators at the surface know that the flexible bag has been fully sealedlagainst the wall of the hole, the wire J-line maybe disengaged by suitable and conventional means. The latching dogs 8, engaging the shoulders 9, will hold the apparatus in the inflated position shown in Figure 1. The apparatus is now in suitable condition for withdrawing a fluid sample from the stratum II.

It is apparent that in the preceding description the terms inflated and deflated position of the packer have been loosely used to describe the sealing and non-sealing positions. :Strictly no inflation or deflation occurs since the only change in the condition of the packer is a change of shape.

With the apparatus .in the positionand condition shown in Figure 1, in order to withdraw fluid from the stratum l I it is only necessary that the hydrostatic headof drilling mud existing in the drill stem 2 be reduced .sufliciently. This may beaccomplished by any desired .means such as employing a pistonpump or other pump to reduce the hydrostatic pressure .of the drilling mud in drill stem 2. Thus by pumping .out .at least a portion of the drillingmud in the .stem the pressure existing on the check valve M is decreased. When the pressure has suitably been diminished .so that the pressure .instratum ,Ll .is greater than the hydrostatic pressure exist n at thebottom of the drill stem 2,-check valve Hl will openand fluid from stratum I I will .be inato permeate the porous section .10 of the elastic packer. This .fluid will gradually pass through the pellets contained in the elastic ,packerand will pass through the perforations [6 of .ro.d ,'5 to enter the chamber I3. The check valve l4-will permit the flow of the fluid upwardly through chamber 13 andoutwardly through the .ports..l.5 to :the inner .portion ofchamber 6 which isassociatecluwith the inside of drill stem 2. Consequently .by suitably decreasing the hydrostatic pressure in the drill string fluid will Ibedrawn through the path indicated, upwardly through the drill stem, to the surface 'of the earth for suitable examination. Itmay be noted thatthe function of passageway 7 and.30 during these operations is to maintain an equal pressure above and below the packer so that no vertical component, of force will be exerted on the packer.

After a suitable fluid sample has. been obtained as described, it. is necessary to deflate the elastic packerjn, order to permit removal from the .well or .tohpermit testing .atapother .portion lof the well. Deflation of thepacker .is accomplished .by dropping. a suitable unlatching. sleeve throughthe drill stemtofall over thespearheadi of-the ap paratus and .over' the latching dogs 8. This unlatching sleeve is .diagrammatical l indicated in the .drawingland is identified .by the numeralJiE. It .will be noted that the ,unlatching ,sleeve consists essentially .of .a cylindrical member which will suitably fit over thespearheadhavingdownwardly extending ends which will =engiage the latching .dogs -8. The .ends of the .unlatching sleeve are indicated .by the numeral 42 m are preferably beveled as to suitably depress the latching dogs -8 so .as to permit disengagement of these latching dogs from the shouldered.

While the upper part of the unlatchin-g sleeve is not shown, the design oi this portion of the sleeve is not critical. It is preferred, however, that the upper portion of the sleeve be equipped with a spearhead to permit withdrawal of the sleeve as desired. On withdrawing the sleeve a further fluid sampling operation may be conducted at a different portion of the well. It will be noted that when the unlatching sleeve is dropped down through the drill string the latching dogs will be depressed by the ends 42 of the unlatching sleeve. Depressing the latching dogs will permit the weight of the rod 5 and the associated parts to extend the elastic packer downwardly to the deflated position as indicated in Fig. 2.

As described, the novel formation testing apparatus of this invention consists of a packed elastic sealing means which may be suitably sealed against the wall of the drill hole by shortening its inner support. The sealing of the packer against the wall permits the hydrostatic pressure on the inner [part of the packer to be reduced and at the same time brings a porous portion of the packer in contact with strata adjacent the bore hole. By this means it is possible to readily and simply remove fluid from the strata, bringing the fluid to the surface through the drill stem on which the apparatus is supported. The novelty of this apparatus will be made clear from the appended claims.

1. Improved formation tester apparatus for well bores comprising a first hollow elongated supporting member, a second elongated supporting member at least a portion of which is slidably fitted within said first supporting member, an elastic packer fixed at one end to said first supporting member and at its other end to said second supporting member whereby lengthwise movement of said second supporting member relative to said first supporting member causes lateral changes in the shape of said packer, said packer being constructed of impermeable flexible material and provided with a porous wall portion intermediate its ends, said packer and said supporting members defining between them an annular space, pelleted packing material maintained within said annular space, and conduit means connecting said annular space with the interior of said first supporting member.

2. Apparatus according to claim 1 including latching means pivotally attached to the portion of said second supporting member which is slidably fitted within said first supporting member and latching means attached within said first supporting member adapted to engage said first named latching means and thereby control the slidable movement of said second supporting member relative to said first supporting member.

3. Apparatus according to claim 1 including a passageway extending through said elastic packer and provided with exterior openings above and below said packer.

4. Improved formation tester apparatus for well bores comprising a pair of tubular supporting members adapted for longitudinal movement with respect to each other, at least one of said members having a chamber adapted to receive fluid, an elastic packer attached at one end to one of the said supporting members and at the other end to the other supporting member in a manner adapted to effect lateral changes in said packer upon said movement of said supporting members with respect to each other and defining with said supporting members an enclosed space, said packer being constructed of impermeable flexible material and provided with a porous wall portion intermediate its ends, pelleted packing material within said enclosed space, and conduit means connecting said enclosed space with said chamber in said supporting member.

ROBERT H. BLOOD. BEN WILLIAM SEWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 49,544 Noe Aug. 22, 1865 602,547 Titus Apr, 19, 1898 2,404,825 Brown et a1. July 30, 1946 2,441,894 Mennecier May 18, 1948

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