US 3152639 A
Description (OCR text may contain errors)
Oct. 13, J. c. PEARCY 3,152,639
METHODS AND APPARATUS FOR TESTING WELLS Filed April 27. 1960 CIRCULAT/NG VALVE I i 7 i 20 l8 I" ill L s l3 rssrzn VALVE j 16' v INVENIOR. JAMES C. PEARCY A TTORNEY United States This invention relates to methods and apparatus for testing oil wells or the like, and more particularly to the testing of deep wells where the tubing or drill pipe is subjected to high hydraulic pressure.
The testing of earth formations for possible production is now an old and well-developed art, and the combination of tubing or drill pipe with a packer and valve capable of being opened and closed, when desired, by manipulation of the pipe, as disclosed in the US. Patent to Simmons, No. 1,930,987, is in common use.
It has long been the practice in deep wells, where high pressures of the column of drilling mud or other well fluid are exerted upon the string of pipe, to partially fill them with liquid, such as water or drilling fluid, to prevent collapse of the pipe due to the high pressures. (See the US. Patent to T. V. Moore, No. 2,189,919.)
To some extent, such loading liquids in the string of piper interfere with the test. The possibly producing formation may not exert enough pressure to overcome the hydrostatic head of the loading liquid when the packer is set and the tester valve opened. Again, the formation pressure may be suificient, but the connate fluid is contaminated by the loading liquid to such an extent as to be bothersome. The latter of these difiiculties is overcome by the use of a gas, such as nitrogen, under pressure, to load the string of pipe, and this also is currently in use.
In accordance with the present invention, the string of pipe used to run the tester and packer into the well is provided with a downwardly closing check valve above the tester valve. The string is also provided with a reverse circulating valve above the check valve.
With this assembly of apparatus, it is possible to load the string of pipe with a fluid which will balance, or partially balance the drilling mud pressure and still permit the taking of an uncontaminated sample of fluid from a selected formation by exposing the formation to substantially atmospheric pressure in the tester chamber below the check valve. At the same time, should the formation contain fluid under a pressure higher than that exerted by the loading fluid, the check valve will open and a large sample of connate fluid will be obtained.
The objects and advantages of the invention will be apparent from what has been said above, and from the following description of the apparatus and method, taken in connection with the accompanying drawing in which:
The single figure is a somewhat diagrammatic representation of apparatus for carrying out the principles of the invention, the View being a side elevation, partly cut away, of testing equipment located in a well bore in the earth.
Referring to the drawing, it will be seen that a well bore is illustrated at 9. Within the well bore, there is a string of drill pipe or tubing designated 10.
The string of pipe is connected to a circulating valve 11, which is shown only generally, being well-known to those skilled in the art. It may be of the type shown in the US. patent to Savitz, No. 2,327,610, or of any other known type, and functions to open the string of pipe to the exterior whenever desired, so that fluid can be circulated, in either direction, through the pipe without regard to flow through the tester or any other apparatus below the valve 11.
Below the circulating valve 11, there is a special section or sub of pipe 12. This should preferably be made of atent O 3,152,639 Patented Oct. 13, 1964 Kit? heavier stock than the pipe 10 as a portion of it will have to withstand the high hydrostatic head of the well fluid exterior thereof. As illustrated, sub 12 comprises cylindrical body means defining a fluid passage extending between circulating valve 11 and the sample chamber in tester 13. Check valve 17 is supported in this passage.
The sub 12 is then connected at its lower end to any suitable tester valve 13. Here again, any conventional tester may be employed, and since many forms such as that featured in the aforementioned Simmons patent are well known, none need be described in detail.
Below the tester 13, a conventional packer 14 is mounted on the string, and beneath the packer, there may be the usual tail pipe and screen 15.
Within the tail pipe, there may be a pressure recorder, as taught in the US. patent to Moore, No. 2,189,919.
The sub 12 is provided with a suitable valve seat 16, and fitted against this seat is a valve 17, which may be of the poppet type, as shown, and provided with a rubber lip 18.
The valve 17 is provided with a stem 20, sliding through a guiding spider 21, secured in the sub 12, as shown, and be urged downwardly by a coiled compression spring 22 at all times.
With the arrangement shown the string of pipe 10 may be filled, or partially filled with loading fluid, either gas or liquid, the valve 17 supporting such fluid and preventing it from exerting any pressure in the portion of the sub 12 therebeneath. In the drawing, this loading fluid is illustrated as a liquid shown at 23.
In testing a well, the apparatus is assembled as shown and run into the well with sufiicient loading fluid 23 being added from time to time, as desired. When the formation selected for the test is reached, the packer 14 is set and the tester valve 13 opened. The pressure recorder (not shown) in the tail pipe 15, if used, will record substantially the formation pressure at this time, because the chamber in the lower portion of the sub 12 between the check valve 17 and the tester valve 13 will be maintained at atmospheric pressure all during the time the string is being run into the well.
If desired, the tester valve 13 may now be closed, the packer 14 unseated, and the string removed from the well. A sample of the connate fluid in the chamber of the sub may then be examined. The circulating valve 11 may be opened to permit the loading fluid to drain out of the pipe 10 as it is being removed from the well if desired. This will not interfere with the retention of the connate fluid trapped in the sub 12 between the check valve 17 and the tester valve 13.
On the other hand, if the formation is exhibiting sufficient pressure to overcome the hydrostatic head of the loading fluid, plus the force exerted by the spring 22 on the valve 17, a much larger sample of connate fluid may be obtained, as the connate fluid flows on up into the pipe 10. This action is entirely automatic once the tester valve 13 is opened. That is, it is not necessary to manipulate the string in any way to insure the taking of a large sample of formation fluid, if the well is capable of producing it against the pressures mentioned.
In summary, it will be seen that when the check valve 17 is seated, the upper end of the sample-receiving chamber is sealed so as to effectively prevent commingling of the loading fluid and connate, i.e. well fluid. If the pressure of the well fluid should reach a certain value, exceeding the combined force of the spring 22 and the hydrostatic head of the loading fluid, the upper end of the sample chamber will become unsealed as the valve 17 opens so as to permit an outflow of well fluid from the sample chamber. As will be appreciated, the pressure value at which valve 17 will open will vary, depending upon the specific gravity of the loading fluid.
The arrangement illustrated is thus capable of obtaining either a small sample of fluid from a formation of low pressure and a large sample of fluid from a formation of high pressure in a deep well without subjecting the pipe used to run the tester into the well to the danger of collapse.
While only one embodiment of the invention has been shown and described, it is obvious that various changes may be made without departing from the spirit of the invention or the scope of the annexed claim.
1. A method of testing the productivity of a formation in a well bore with a sample-receiving chamber supported at the lower end of a conduit string, said method comprising: lowering a sample-receiving chamber supported by a conduit string into a well bore while maintaining the interior of said sample-receiving chamber substantially at atmospheric pressure; placing loading fluid into the interior of said conduit string to support the wall of said conduit string and to provide a body of loading fluid above said sample-receiving chamber; opening said chamber to allow well fluid from said well bore to flow into the lower end thereof; sealing the upper end of said chamber to prevent commingling of said fluids when the pressure of the well fluid is below a certain value; unsealing the upper end of said chamber to permit flow of well fluid therefrom when the pressure of the well fluid exceeds said certain value; and closing the lower end of said chamber to prevent chamber-contained well fluid from flowing out of the lower end thereof.
2. Apparatus for testing the productivity of a formation encountered in drilling a deep oil well or the like comprising in combination: a string of pipe, a circulating valve for placing the interior and exterior of said string of pipe in fluid communication, means for selectively opening said valve in response to manipulation of said string of pipe and independently of fluid pressure within said string of pipe, a downwardly seating check valve positioned beneath said circulating valve and having a chamber therebenath, body means defining fluid passage means within said apparatus extending between said circulating valve and said chamber, with said check valve being supported by said body means within said fluid passage means, a tester valve beneath said chamber in association with a well bore packer, said check valve providing means whereby loading fluid introduced into the string of pipe to prevent pipe collapse is segregated from connate fluid which passes through said tester valve to enter said chamber and said circulating valve providing means whereby said loading fluid may be circulated between the interior and exterior of said pipe string, spring means positively urging said check valve downwardly into chamber segregating position, and guide means engaging said check valve for insuring constant alignment of said check valve for aligned movement into said position.
References Cited in the file of this patent UNITED STATES PATENTS 2,073,107 Johnson Mar. 9, 1937 2,214,550 Edwards Sept. 10, 1940 2,227,192 Losey Dec. 31, 1940 2,327,610 Savitz Aug. 24, 1943 2,850,097 Bloom Sept. 2, 1958