US2511759A - Oil well formation tester - Google Patents

Description

June 13, 1950 P. S.'WILLIAMS OIL WELL FORMATION TESTER Filed April 23, 1948 MMQSQI 5 m 1 O 2 o .1 M KE/ m M @Q 0 P w 1 ELL phtltj: 6. wflziams (Savant/or" Patented June 13, 1 950 ration of Delaware Standard Oil Development Company, 'a, corpo- Application Am 23, 1948, Serial No. 22,922

6 Claims. 1 (G1. 1.66?!) The present invention relates to an improved type of formation tester to be employed in oil;

wells. In accordance with this invention an apparatus is provided having a, motor operated to work pumping means associated with an inflatable packer and a sample containing chamber, to permit sealing off a desired portion of an oil well and to permit withdrawing fluid from this portion of the well into the sample chamber.

In drilling an oil well, the well is maintained full of a fluid such as drilling mud. This is necessary in order to maintain a sufiiciently high hydrostatic pressure in the well to prevent the uncontrolled escape of natural fluids in the earth. However, the necessity for maintaining the well full of fluid during the drilling complicates the removal of natural fluids from the earth for sampling purposes. Thus, in order to remove a sample of fluid from a particular stratum of the oil well, it is first necessary to reduce the hydrostatic pressure of drilling mud on this stratum sufficiently to allow the escapeof the fluid from the stratum and then in some way .to remove the fluid extracted to the surface of the earth. The technique by which this is done is called formation testing and the apparatus employed for the purpose is called formation testing apparatus. It is this field with which the present invention is concerned.

Formation testing apparatus has been proposed of such a nature that an inflatable elastic packer is used to seal off the well at a desired point so as to permit reducing the hydrostatic pressure at the point sealed off without reducing the hydrostatic pressure throughout the well. However, an apparatus of this type presently known to the art is of rather complicated construction and is not flexible in the sense that it cannot be used under a variety of conditions. For example, it is presently necessary to employ one type of formation tester in combination with a drill string or to employ a difierent type of tester in combination with a coring bit or even to employ a tester necessitating removal of all drilling apparatus from the well. Therefore, it is a principal object of this invention to provide an improved form of elastic packer formation tester which may be used under any of the circumstances indicated above.

In accordance with this invention a compact packing means associated with suitablepumpingv means so as to permit sealing off the well at any desired point and so as to permit pumping samples of fluid through a porous section of the elastic packer to a suitable sample-receiving chamher, The apparatus may be supported by a cable or by the drill. string. As indicated, therefore, the apparatus of this invention is characteriz ed by simplicity of construction, flexibility of: use, and ease of sampling.

A preferredform of the apparatusof the present invention is illustrated in the attached Figs. 1, and 2. These figures are related as Fig. 1 is simply the upper continuation of Fig. 2. In these figures, the numeral l identifies a well hole which has been dug in the earth. It is to be understood that this hole is normally filled with fluid such as drilling mud. For simplicity no fluid has be n shown inthe drawings in the hole I. The apparatus illustrated is suitably supported in the hole by means such as the cable 2. As will become apparent, in place of the cable '2, a drill string or equivalent supporting means may be employed. The cable 2 is of the conventional type suitable for sustaining the weight of the apparatus and at the same time suitable for protecting. electrical conductors contained in the cable. In the drawing, the cable 2 is shown to be terminated by a sample-receiving chamber indicated by the numeral 9. This sample chamber supported by the cable 2 serves in turn to support the remaining components of the apparatus. Thus a connecting member or support is provided to connect the sample chamber 9 with the motor 25. The motor 25 in turn is connected to the pump 1 by the connecting and supporting means indicated as rods 26. Similarly, a second pump I5 is connected to pump I by supporting means 21 and the pump I5 is connected to the elastic packer by the supporting rod 28. As illustrated, the motor 25 is an electric motor suitably supplied with electricity through a conductor leading from the cable 2, either through or around the sample chamber 9. The motor 25, is, directly connected to the pumps 1 and i5 through shaft 29. The elastic packer indicated by the numeral 3, as illustrated in the inflated position, is essentially an oval-shaped bag. It will be noted that a portion of the bag, comprising a narrow. circumference, consists of a double walled space identified by the numeral 5 I. While all portions of the packer except the circumference of the double walled portion of the packer are of non-porous material, the portion of the packer comprising the .circumference bounding the space BI is of porous material. This porous section of the packer is indicated by the numeral 52.- In fabricating a packer such as that illustrated, it is convenient to employ rubber, ali though cloth or wire fabric may be employed if desired. Similarly, the porous section of the packer, that is, section 52 may comprise a porous type of rubber. Suitable porous rubber is now commercially available. In the event that the porous section of the packer 52 and the remainder of the packer is made of rubber, the fabrication of the packer is quite simple. The

inner portion of the double walled space indible packer having a portion of thepacker made i as a double walled section. The exterior of the packer comprising the outer surface of the double walled section is porous, while the other parts of the packer are non-porous. It is apparent that fluids may be allowed to enter the double walled section of the packer through the outer porous circumference of the packer. Positioned in the double walled section of the packer are a multitude of pellets indicated by the numeral 5. These pellets may consist of glass, metal, rock or any other desired substance. As will become apparent, the function of these pellets is to fill the double walled section of the packer so that this section cannot be compressed suificiently' to seal it. Thus, the presence of the pellets in the double walled section continuously maintains a porous medium in the packer. It is apparent, of course, that the pellets should be of sufficient size so that they do not pass out of the perforations of the porous area-52 of the packer. A conduit 54, porously sealed to prevent passage of the pellets, is provided to connect the double walled section of the packer with the inlet of pump 7. The outlet of this pump is connected with line 55 which leads to the sample chamber 9. Thus, the operation of pump 1 will tend to cause fluid to be pulled through the perforations of layer 52 of the packer through the double walled section of the packer and conduits 54 and 55 into the sample chamber. A conduit I1, is also provided connecting the innermost part of the elastic packer to the outlet of pump I5. The inlet of pump i is connected to the conduit or port It, which opens into the well. Consequently by operation of pump l5, fluid will be pulled from the well through conduits l6 and I1 into the elastic packer, serving to inflate the packer.

The apparatus heretofore described is complete except for the provision of necessary valves in the various chambers. Thus it is necessary that a valve l0 and a valve H be positioned in the sample chamber. The valve I0 is operative to seal the inlet into the sample chamber served by- Thus, the operation of these valves is controlled by current supplied through the conductors at the surface of the earth.

The apparatus illustrated in Figs. 1 and 2 having now been suitably identified and described,

the operation of this apparatus may be fullyunderstood.

By conventional drilling p f0cedures, a suitable bore hole is drilled in the earth. During the drilling operation by various, conventional types of logging, the nature of strata through which Valvethe hole passes are identified. These logging procedures are generally suitable for indicating possible strata suitable for oil production. One such stratum such as the porous zone 4, is illustrated in the drawing. In order to test the fluids, if any, present in this porous formation, the apparatus of this invention is then employed. In the event that a drill string having a core bit has been used to drill the hole, the apparatus may be lowered through the drill string and through the core bit; the core bit, of course, being pulled up from the bottpm of the well sufficiently to be above the porous formation to be tested. Alternatively, the drill string and drilling apparatus may be completely removed from the hole. In any event, the apparatus illustrated in Figs. 1 and 2 is lowered into the well so that the double walled section of the packer is adjacent to the porous formation to be tested. While the apparatus is being lowered, the elastic packer is in the deflated position making the packer and the associated equipment sufficiently compact to readily pass downwardly through the drill string or down the well. When the apparatus has been lowered suificiently so that the double walled section of the packer is adjacent the porous formation to be tested, the packer is inflated by starting the motor 25. At the same time the motor is started, valves l0 and II are opened by operation of suitable electrical circuits at the surface of the earth. Inactual practice, it is convenient to have the solenoid valves Ill and II connected in either series or parallel with the electrical circuit of the motor 25. In this case, it ispossible to start the motor and to open valves H1 and H by closing a single operating switch at the surface of the earth. For simplicity, these circuits are not shown on the drawings as the circuits themselves do not constitute part of this invention andsince they are conventional, simply comprising a suitable switch, a voltage source, and the necessary electrical connections. While pumps I and I5 maybe either centrifugal pumps or positive displacement pumps, let it be assumed nowthat pump i5 is a centrifugal pump. The operation of motor 25 will cause both pumps to operate. Pump l5 will draw fluid from the Well through port l6 and will pump this fluid through line H into the elastic packer causing the packer tobeinflated. Simultaneously pump T will tend to pull fluid through the perforations of layer 52 of the packer through line 54. This fluid will be pumped through line 55 into the sample chamber through valve l0 and out of the sample chamber through valve H. The pumping action ofpump I5 will continue until sufficient fluid has been pumped into the elastic packer to fully expand it, (i. e. the pump I5 is so chosen that the maximum pressure which it will deliver is such as to properly inflate the packer), thoroughly sealing the well hole adjacent to the packer. This will cause the double walled section of the packer to be tightly forced against the porous formation 4. Therefore, the action of the pump 1 will pull fluid from the porous formation through line 54 and 55 into the sample chamber. The pumping action is continued until the setting of the packer is assured and until sufficient time has been allowed for fluid to have filled the sample chamber 9. If desired, an auxiliary electrical device 40, may be placed in line 55 to check the nature of the fluid passing through this line. Suitable indicating devices, for example, a resistivity indicator, will give electrical indications at the surface of the earth, through conductors which may pass through cable 2, of the conductivity of the fluid in line 55. By this means it is possible to insure that the fiuid passing through line 55 is not simply drilling mud obtained from the well, but is fluid extracted from the porous formation 4. When the pumping operation described has been continued until a suitable sample has been 'received in the sample chamber 9, the motor 25 is stopped and the valves and II are closed. Again, if desired, these operations may be completed by opening a single switch at the surface of the earth. Stopping the motor 25, will permit the fluid contained in the elastic packer to pass through line H, through centrifugal pump "I5, and out through the port 18 to deflate the packer. The entire apparatus may then be drawn to the surface of the earth and the sample in sample chamber l3 can be examined as desired.

As indicated, if desired, pump is as well as pump 1 may consist of a positive displacement instead of a centrifugal pump. In the event Pump i5 is a positive displacement pump, it is necessary to include two further valves in the system. These are valves I8 and 20, located in line 11. Valve 18 is a simple check valve, spring loaded to be opened at a given pressure. The valve is adjusted so that this pressure is suflicient to insure full inflation of the elastic packer, but is insufiicient to permit rupture of the elastic packer. Thus on operation of the pump l5, fluid will be pumped into the elastic packer until the packer is fully inflated, at which time the pressure in the system will be suificient to open the relief valve [8. This will permit fluid pumped by pump 15 to bleed oil into the well without permitting the packer to deflate. After the sampling operation has been completed, in order to deflate the packer, it is then necessary to open valve 20 in line 11. Valve 20 may again comprise a solenoid operated valve which may" be suitably controlled at the surface of the earth by means of conductors passing through the cable '2. For the purpose of simplicity, these conductors have not been illustrated in the drawing. Again, if desired the valve 20 may be connected in an electrical circuit with valves in and II and the motor 25 so that on closure of a single switch, the motor 25 will be started and valves l0 and II will be opened and valve 20 will be closed. Alternatively, when the single switch is opened, the motor 25 is stopped and valves 10 and II are closed and valve 20 is opened.

As indicated above, the apparatus illustrated is subject to many refinements and many-modifications. An important refinement which may be, or should be, used is the provision of a channel 22 which passes downwardly through the elastic packer to provide a fluid chamber from the space above the packer to the space below the packer. The function of this passageway is to permit equalization of pressure above and below the packer so that no vertical component of pressure is exerted on the elastic packer.

A further modification of importance is to substitute for the cable 2 and the sample chamber 9, a drill string. In this event, the drill string will serve as both a supporting means for the apparatus and as a sample receiving chamber. The line will then pass directly into the drill string without necessity for valves III or I I. The support 50 holding the motor may be connected to the drill string by means of a simple pipe cap which may be threaded on to the drill string.

On operation of the pump 25, therefore, fluid will be withdrawn from the porous formation 4 and will be pumped into the drill string toward;

the surface of the earth. In this event it will be string.

It should also be noted, that the apparatus 1 illustrated in the drawing is diagrammaticjanjd is presented solely to illustrate the nature of this invention. sample chamber or a drill string is closely? coupled to the motor, the pumps, and the elastic packer, so as to provide an integral apparatus extremely compact and comparatively light in In actual construction,- the weight.

In view of the many modifications of the present invention, the appended claims are to be interpreted broadly, limited only by the true contribution to the art:

What is claimed is:

1. A well testing apparatus for use in a fluidfllled borehole comprising in combination a suppotring means provided with a sample-receiving chamber, an inflatable elastic bag fixed to said supporting means, the walls of said elasticbag being constructed of non-porous flexible ma- 7 terial, a porous wall attached circumferentially to the exterior of said elastic bag about a middle portion thereof and defining an annular chamber with a portion of the wall of said has. a first pumping means and a second pumping means carried by said supporting means, a first conduit connecting said annular chamber through said first pumping means to said sample-receiving chamber, and a second conduit connecting the interior of said elastic bag to said second pumping means. said last-named pumping means having an inlet port communicating with said fluid in the borehole.

2. Apparatus as defined in claim 1 in which said supporting means comprises a section of drill pipe whose interior constitutes said samplereceiving chamber.

3. Apparatus as defined by claim 1 in which said sample-receiving chamber is provided with an inlet valve associated with said first conduit and an outlet valve having a port communicating with said fluid in the borehole.

4. Apparatus as defined by claim 1 in which said annular chamber contains pelleted packing material.

5. Apparatus as defined by claim 1 including a channel passing through said elastic bag and communicating with said fluid in the borehole above and below said bag.

6. Apparatus as defined by claim 1 in which said second conduit is provided with a pressure relief valve adapted to vent fluid into said borehole upon attainment of a predetermined pressure within said conduit.

PHILIP S. WE-LIAMB.

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

UNITED STATES PATENTS Number Name Date 602,547 vTitus Apr. 19, 1898 2,404,825 Brown July 30. 1946 2,441,894 Mennecier May 18, 1948

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