BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] This invention relates to a method and apparatus for obtaining samples of formation
fluids at different levels in a bore hole. The characteristics of formation fluids
obtained from various levels within a bore hole are of considerable interest to geologists
as an aid to determining subsurface structure as well as to those engaged in well
completion and production. This invention provides a method and apparatus for lowering
a logging tool into an uncased bore hole on a conventional wireline, positioning the
tool at preselected elevations and obtaining formation fluid samples. The samples
are tested within the tool without withdrawing it from the bore hole and the test
results transmitted to the surface. If it. is determined that the sample should be
recovered it is transferred to one of a plurality of collection chambers within the
tool, and, if not, it is ejected into the bore hole. The logging tool can then be
moved to another level, without withdrawal from the well and the process repeated
until all of the sample collection chambers in the tool are filled.
2. Description of the Prior Art
[0002] Formation fluid sample collection tools have been in use in the industry for a number
of years. See for example the descriptive matter found in the Composite Catalog of
Oil Field Equipment and Services-
-1978-1979, pages 3286-3291 for a description of services and equipment provided by
Halliburton Services. See also in the'1976-1977 edition of the same catalog the description
of the Johnson Inflatable Packer Test Systems at pages 3607-3609. Both the Halliburton
and Johnson systems involve attaching the sampling tool to the drill pipe string and
are not designed for wireline logging. Moreover, they do not have means for isolating
and testing formation fluids at various selected levels within the bore hole to make
a determination as to the desirability of collecting and retaining the sample without
withdrawal of the tool from the well. These two differences are of considerable significance
when the time the well must be out of commission for sampling is taken into consideration.
To run a tool into a well on a wireline requires but a small fraction of the time
required to run in a drill pipe string and the advantage of being able to collect
a number of pretested samples each time the tool is sent down the well further greatly
reduces the time during which the well is out of commission.
[0003] Wireline formation testers have been available since the early 1950's and have been
used to obtain fluids, flow rates and pressures from prospective reservoirs. Because
of limited tool capacity and capabilities, however, recovered fluids often are entirely
or mostly drilling mud filtrate. Moreover, there is no fluid property monitoring capability.
Thus these tools are useful only in the case of reservoirs where adequate flow is
obtained and recovered fluids are relatively free of mud .filtrate. They tend not
to be useful in those cases wherq geological exploration is involved and fluid samples
other than those containing hydrocarbon are desired.
SUMMARY OF THE INVENTION
[0004] According to one aspect of the present invention there is provided a method for obtaining
formation fluid samples from a bore hole which method comprises:
a) lowering a tool into said bore hole to a preselected level;
b) expanding a pair of packers carried by said tool into sealing contact with said
bore hole to isolate an interval of said bore hole;
c) collecting fluid entering said isolated interval and measuring a property thereof;
d) determining on the basis of the measured property whether it is desired to retain
a sample of said collected fluid and, if the determination is positive, transferring
said fluid to a sample collection chamber within said tool;
e) contracting said packers to free said tool for vertical movement; and
f) raising the tool and the collected sample to the surface.
[0005] The invention also provides apparatus for sampling and testing bore hole formation
fluids, said apparatus comprising a downhole tool having:
a) a pair of expandable packers for isolating an interval of the bore hole;
b) means for expanding the packers;
c) means for withdrawing fluid from the space between the packers;
d) a test chamber for receiving fluid withdrawn from said interval;
e) means for measuring a property of fluid located in said test chamber;
f) a sample collection chamber arranged to receive fluid from said test chamber;
g) signal transmission means for transmitting a data signal representative of said
measured property; and
h) means operable in response to said data signal for controlling flow of fluid from
the test chamber to the sample collection chamber.
[0006] The present invention enables a plurality of high quality samples of formation fluids
to be obtained from the wall of a bore - hole on a single passage of a logging tool
into the bore hole by locating the tool at various levels within the bore hole, isolating.an
interval of the bore hole, withdrawing fluid from the isolated interval, testing the
properties of the withdrawn fluid while within the tool, transmitting the test results
to the surface for determination of the suitability of the sample for collection and,
if it is found suitable, transferring the sample to a collection chamber within the
tool for ultimate removal to the surface.
[0007] A second and related feature of this invention is to provide a logging and sample
collecting tool operable in connection with a conventional wireline for carrying out
the method of this invention.
[0008] This invention thus can provide an improved method and apparatus for obtaining formation
fluid samples from a bore hole. The method involves initially lowering a tool suspended
by a wireline into the bore hole to a preselected level; and utilizing a pair of packers
carried by the tool to isolate an interval of the bore hole by inflating the packers
to expand them into sealing contact with said bore hole. Fluid is withdrawn from the
isolated interval between the packers and its electrical resistivity is measured in
a resistivity test chamber located within the tool. The resistivity measurement is
sent to the surface via the wireline and when the resistivity becomes constant, indicating
that formation fluids uncontaminated by drilling mud components are being withdrawn
into the tool, the withdrawn fluids are directed into a second test chamber wherein
the redox potential (Eh), acidity (pH) and temperature of the fluids are measured
and the results are sent to the surface by the wireline. It is then determined from
the thus transmitted results whether it is desired to retain a sample and, if determination
is positive, the fluid is pumped to one of a plurality of sample collection chambers
within said tool. If the determination is negative the fluid is returned to the bore
hole, the packers are deflated to free the tool for vertical movement and the tool
is moved to another preselected location; where the above-referred to steps are repeated.
This procedure is followed until the sample chambers in the tool are filled with desired
samples, and finally the wireline is retracted to return the tool and the contained
samples to the surface.
[0009] A preferred embodiment of the apparatus of this invention comprises a tool adapted
to be introduced into a bore hole on a conventional seven conductor wireline and having
a pair of spaced apart inflatable packers for isolating an interval of the bore hole.
A hydraulic pump is provided within the tool for pumping fluids from the interval
between the packers, initially for inflating the packers, and subsequent to their
inflation for pumping fluids through a resistivity test chamber and a second test
chamber where redox potential (Eh), acidity (pH) and temperature measurements are
obtained, and finally into one or more sample collection chambers located within the
tool. Conventional means are associated with each of the chambers for performing the
above-described measurements and for transmission of the results thereof to the surface
through the wireline. In addition, there are provided suitable valve means electrically
controlled from the surface for sequentially carrying out the method steps of this
invention.
BRIEF DESCRIPTION OF THE DRAWING
[0010]
Figure 1 is a side view of a preferred embodiment of a logging tool of this invention
disposed within a section of a bore hole;
Figure 2 is a schematic view showing the relationship of the various elements of the
tool of this invention during the packer inflation step;
Figure 3 is a similar view showing the relationship of the elements during the testing
step; and
Figure 4 is a similar view showing the relationship during the sample collection step.
DETAILED DESCRIPTION OF THE INVENTION
[0011] In Figure 1 a preferred embodiment of the tool 10 of this invention is shown in a
downhole position in a bore hole 11. In this embodiment the tool is made up in tubular
sections 12 through 16 which are connected in sealed relationship by collars 17. During
movement through the bore hole and when the packers 20 are not set, the tool 10 is
suspended from the cable head section 16 to which the supporting wireline 21 is securely
attached by coupling 22. The use of individual sections 12-16 each containing certain
kinds of components is, of course, optional but it provides a convenient way to manufacture,
assemble and service the tool 10. The maximum diameter of the tool 10 is, of course,
limited by the size of the. bore hole 11 and the effectiveness of the expandable packers
20. A convenient arrangement is to make the sections 13-16 of somewhat smaller diameter
so that these portions of the tool can be utilized in smaller bore holes and to utilize
a packer section 12 appropriately sized to perform adequate sealing in a particular
bore hole to be tested and sampled. The following Table gives preferred packer sizes
for different bore hole diameters:

From the toregoing it will be seen tnat, for a versatile tool, the maximum diameter
of the sections 13-16 is about five inches. The length of a tool of five-inch diameter
will depend upon the degree of miniaturization in hydraulic and electric circuitry
and in the size and number of samples which are to be collected. Usually the length
is between 6 and 12 feet.
[0012] In Figures 2-4 the hydraulic relationship.of the various parts of the tool 10 during
various steps of the preferred method are shown. In each of these Figures the main
fluid flow for the particular step involved is indicated by a heavy line.
[0013] In Figure 2 the step of inflating the packers is illustrated. Fluid from the bore
hole 11 is withdrawn into the tool 10 through an open port 24 in packer section 12
passing through a filter 25 and resistivity test chamber 26. This test chamber which
is preferably conventional can contain a pair of spaced apart electrodes across which
a voltage is impressed. The resulting current flow between the electrodes provides
an indication of resistivity. Suction for withdrawing the fluid is provided by a pump
27 driven by an electric motor 28 powered from the surface by an electric current
delivered through the wireline 21. From pump 27 the withdrawn fluid passes through
conduit 30 to the packers 20 which are inflated thereby to engage the wall of the
wellbore in sealing relationship and isolate an interval thereof. To prevent the development
of a pressure differential in the bore hole 11 above and below the tool 10 when the
packers 20 are inflated, a passage 29 is provided through the packer section 12 as
shown in Figure 1. A pressure relief valve shown at 31 vents fluid to the bore hole
when the packers 20 are filled. A back flow check valve 32 prevents fluid from flowing
back out of the packers 20 when pump 27 is not operating. An electrically controlled
packer deflate valve 33 is provided for venting conduit 30 to the wellbore when it
is desired to deflate the packers 20.
[0014] Following inflation of the packers 20 the pump 27 continues to pump fluid from the
bore hole through the resistivity test chamber venting the fluid to the bore hole
through valve 31. This action is preferably continued until the resistivity measurement,
which is conveyed to the surface through the wireline 21 becomes constant indicating
that formation fluids free of drilling mud components are being withdrawn. At such
time the pump 27 is stopped and the various valves are set to provide the flow pattern
shown in Figure 3.
[0015] To better illustrate the invention the various flow controlling valves have been
schematically indicated. A preferred procedure, as will be appreciated by those familiar
with the art, is to use a pair of rotary solenoid actuated valves (not shown) which
are positioned by pulses sent down from the surface. Preferably, one of these rotary
solenoid valves, as will be described later, is employed to control the pumping of
samples to the sample containers and the other is preferably employed to control all
of the other fluid flows.
[0016] After the packers 20 have been set and the resistivity cell 26 indicates that a uniform
formation fluid is being withdrawn, the flow control valve (not shown) is rotated
to place the schematically indicated valve elements in the positions shown in Figure
3. Thus the filter control valve element 35 is actuated to cause the fluid to flow
through line filter 36 instead of the large coarse filter 25 improving the quality
of the withdrawn sample and the control valve 37 is actuated to divert the fluid flow
through the second test chamber 38 to the bore hole 11.
[0017] The second test chamber 38 preferably contains a three electrode system for measuring
acidity (pH) and redox potential (Eh). A temperature sensor (not shown) is also provided
as the temperature at which potential readings are made affects calibration. The preferred
electrodes are as follows:
pH Reference--silver
Eh Reference--platinum
Reference electrode-antimony
but as will be appreciated any of the well known arrangements can be utilized. Moreover,
in certain cases it may be desirable to adapt the test chamber 38 to perform other
or additional kinds of tests such as retractive index, opacity, density of dissolved
gas content all of which are known to those familiar with the art. Conventional electrical
circuits are utilized to send appropriate signals through the wireline to the surface
where pH, Eh and temperature of the formation fluid can be displayed or read out.
It should be noted in Figure 3 that a portion of the fluid does not pass through test
chamber 38 but passes through sample control valve 40 and back to the bore hole 11
through conduit 41. By this arrangement test chamber 38 is not overloaded and there
is more certainty of obtaining a sample representative of the fluid undergoing test
in chamber 38 with the same fluid also simultaneously flowing to and through the sample
control valve 40.
[0018] When the test results transmitted to the surface indicate that the formation fluids
being withdrawn are suitable for collection, the pump 27 is stopped and the sample
control valve 40 is electrically actuated to a position to discontinue flow of fluid
to the bore hole through conduit 41 and to instead convey fluid to the first sample
chamber indicated at 42. The chambers need not be evacuated or vented to the bore
hole 11 as downhole pressures are so large that any air brought down from the surface
in the tool 10 will be so compressed as to occupy but a small fraction of chamber
volume. When sample chamber 42 has been filled the pump 27 is stopped and the rotary
control valve is actuated to packer deflate position opening the valve port indicated
at 33 to the bore hole and permitting the packers 20 to deflate. Suitable valved connections
(not shown) are provided through the side of tool 10 for withdrawal of the samples
from the chambers 42.
[0019] Following deflation of the packers 20 the tool 10 is again free to be moved to other
preselected levels in the bore hole 11, and the above described steps can be repeated.
Alternatively if it is decided at the surface that the formation fluid passing through
test chamber 38 will not produce a sample desired for retention and transport to the
surface no sample is collected at that level in the bore hole; and the pump 27 can
be stopped, the packers 20 deflated and the tool moved to another level.
[0020] In the preferred embodiment of the logging- sampling tool 10 of this invention, the
capability of determining formation fluid pressure is provided by means of a pressure
sensor 45 connected to the fluid conduit downstream of the pump 27. This sensor 45
which preferably contains a transducer monitors formation fluid pressure during periods
when the pump 27 is not operating and sends appropriate signals through the wireline
21 to the surface.
[0021] As will be apparent to those skilled in the art any of the conventional logging techniques,
such as gamma ray, neutron, induction, sonic, etc. adaptable for wireline logging,
can be practiced in conjunction with the method and apparatus of this invention by
incorporating appropriate conventional sensing and transmission apparatus within the
tool 10. Information from such ancillary apparatus can be of considerable aid in initially
placing the tool in the bore hole for the testing and sampling procedure of this invention.
Incidentally the words "bore hole" have been used herein and in the claims in their
generic sense and are meant to include any cased or uncased generally cylindrical
opening, sealable by means of a packer and whether intended for exploration or production
purposes. Thus the expression includes drill hole, well bore and other equivalent
terms.
[0022] In the foregoing detailed description, the circuitry for obtaining signals from the
various sensing devices and transmitting them to the surface and for transmitting
electrical commands from the surface to the tool have not been included as these techniques
are well known to those skilled in the art and a multitude of different arrangements
are available and may be used in the practice of this invention.
[0023] Various changes and/or modifications such as will present themselves to those familiar
with the art may be made in the method and apparatus described herein without departing
from the spirit of this invention whose scope is commensurate with the following claims:
1. A method for obtaining formation fluid samples from a bore hole which method comprises:
a) lowering a tool into said bore hole to a preselected level;
b) expanding a pair of packers carried by said tool into sealing contact with said
bore hole to isolate an interval of said bore hole,;
c) collecting fluid entering said isolated interval and measuring a property thereof;
d) determining on the basis of the measured property whether it is desired to retain
a sample of said collected fluid and, if the determination is positive, transferring
said fluid to a sample collection chamber within said tool;
e) contracting said packers to free said tool for vertical movement; and
f) raising the tool and the collected sample to the surface.
2. A method according to Claim 1 wherein the fluid is collected by withdrawing fluid
from said isolated interval to a first test chamber, a property of the withdrawn fluid
is measured in said test chamber, and when said measured property indicates that formation
fluid is being withdrawn into said tool, the withdrawn fluid is directed to a second
test chamber where the property on the basis of which said determination is made is
measured.
3. A method according to Claim 2, wherein said first test chamber is a resistivity
test chamber, the resistivity of the withdrawn fluid is measured therein and the withdrawn
fluid is directed to the second test chamber when the resistivity of the withdrawn
fluid indicates that formation fluid is being withdrawn into said tool.
4. A method according to any preceding claim wherein is step (d), the fluid is transferred
to one of a plurality of sample collection chambers if said determination is positive
and if the determination is negative the fluid is returned to the bore hole,in step
(e) said tool is moved to another preselected location, and then steps (b) to (e)
are repeated until a desired number of the sample chambers in said tool contain samples.
5. A method according to any preceding claim wherein said packers are expanded by
inflating them with fluid pumped from said isolated interval.
6. A method for obtaining formation fluid samples from a bore hole according to Claim
1 which method comprises:
a) lowering a tool suspended by a wireline into said bore hole to a preselected level;
b) utilizing a pair of packers carried by said tool to isolate an interval of said
bore hole by inflating said packers to expand them into sealing contact with said
bore hole;
c) withdrawing fluid from said isolated interval and measuring its resistivity in
a resistivity test chamber within said tool and sending the resistivity measurement
to the surface via said wireline;
d) when the resistivity becomes constant, indicating that formation fluid uncontaminated
by drilling mud components is being withdrawn into said tool, directing the withdrawn
fluid into a second test chamber and measuring therein the redox potential, acidity
and temperature of said fluid and sending results thereof to the surface by said wireline;
e) determining from the thus transmitted results whether it is desired to retain a
sample and, if the determination is positive, pumping said fluid to one of a plurality
of sample collection chambers within said tool, if the determination is negative returning
said fluid to said bore hole;
f) deflating said packers to free said tool for vertical movement and moving said
tool to another preselected location;
g) repeating steps (b) through (f) until the sample chambers in said tool are filled
with desired samples; and
h) retracting said wireline to return the tool and the collected samples to the surface.
7. A method for obtaining formation fluid samples from a bore hole according to Claim
1 which method comprises:
a) lowering a tool suspended by a wireline into said bore hole to a preselected level;
b) utilizing a pair of packers carried by said tool to isolate an interval of said
bore hole by inflating said packers to expand them into sealing contact with said
bore hole;
c) withdrawing fluid from said isolated interval and measuring its resistivity in
a resistivity test chamber within said tool;
d) when the resistivity becomes constant; indicating that formation fluid uncontaminated
by drilling mud components is being withdrawn into said tool, directing the withdrawn
fluid into a second test chamber and measuring therein properties of said fluid and
sending results thereof to the surface by said wireline;
e) determining from the thus transmitted results whether it is desired to retain a
sample and, if the determination is positive, pumping said fluid to one of a plurality
of sample collection chambers within said tool and if the determination is negative
returning said fluid to said bore hole;
f) deflating said packers to free said tool for vertical movement and moving said
tool to another preselected location;
g) repeating steps (b) through (f) until the sample chambers in said tool are filled
with desired samples; and
h) retracting said wireline to return the tool and the collected samples to the surface.
8. A method for obtaining formation fluid samples from a bore hole according to Claim
1-which method comprises:
a) lowering a tool suspended by a wireline into said bore hole to a preselected level;
b) utilizing a pair of packers carried by said tool to isolate an interval of said
bore hole by inflating said packers to expand them into sealing contact with said
bore hole;
c) withdrawing fluid from said isolated interval and measuring its resistivity in
a resistivity test chamber within said tool and sending the resistivity measurement
to the surface via said wireline;
d) when the resistivity measurement indicates that formation fluid is being withdrawn
into said tool, directing the withdrawn fluids into a second test chamber and measuring
therein the redox potential, acidity and temperature of said fluids, sending results
thereof to the surface by said wireline;
e) determining from the thus transmitted results whether it is desired to retain a
sample and, if the determination is positive, pumping said fluid to one of a plurality
of sample collection chambers within said tool, if the determination is negative returning
said fluid to said bore hole;
f) deflating said packers to free said tool for vertical movement and moving said
tool to another preselected location;
g) repeating steps (b) through (f) until the sample chambers in said tool are filled
with desired samples; and
h) retracting said wireline to return the tool and the collected samples to the surface.
9. A method for obtaining formation fluid samples from a bore hole according to Claim
1 which method comprises:
a) lowering a tool suspended by a wireline into said bore hole to a preselected level;
b) utilizing a pair of packers carried by said tool to isolate an interval of said
bore hole by inflating said packers to expand them into sealing contact with said
bore hole;
c) withdrawing fluid from said isolated interval and measuring its resistivity in
a resistivity test chamber within said tool and sending the resistivity measurement
to the surface via said wireaine;
d) when the resistivity becomes constant, indicating that formation fluid uncontaminated
by drilling mud components is being withdrawn into said tool, directing the withdrawn
fluid into a second test chamber and measuring therein selected physical properties
of said fluid and sending results thereof to the surface by said wireline;
e) determining from the thus transmitted results whether it is desired to retain a
sample and, if the determination is positive, pumping said fluid to a sample collection
chamber- associated with said tool;
f) deflating said packers to free said tool for vertical movement; and
g) retracting said wireline to return the tool and the collected sample to the surface.
10. Apparatus for sampling and testing bore hole formation fluids, said apparatus
comprising a downhole tool having:
a) a pair of expandable packers for isolating an interval of the bore hole;
b) means for expanding the packers;
c) means for withdrawing fluid from the space between the packers;
d) a.test chamber for receiving fluid withdrawn from said interval;
e) means for measuring a property of fluid located in said test chamber;
f) a sample collection chamber arranged to receive fluid from said test chamber;
g) signal transmission means for transmitting a data signal representative of said
measured property; and
h) means operable in response to said data signal for controlling flow of fluid from
the test chamber to the sample collection chamber.
11. An apparatus operable on a wireline logging cable for sampling and testing bore
hole formation fluids said apparatus comprising a downhole tool adapted to be connected
to said wireline, said tool having:
a) a pair of inflatable packers for isolating an interval of the bore hole when inflated;
b) an electrically driven hydraulic pump for withdrawing fluids from the space between
said packers and conduit means interconnecting the outlet of said pump to said packers
whereby inflation thereof may be accomplished to isolate said interval of said bore
hole;
c) a resistivity test chamber through which said withdrawn fluids are conducted;
d) a second test chamber in communication with the outlet of said pump and adapted
to measure properties of said withdrawn fluids;
e) a sample collection chamber adapted to be in communication with the outlet of said
pump;
f) signal transmission means for transmitting to the surface the results of resistivity
and other properties measured in said second test chamber; and
g) valve means controlled from the surface through said wireline for controlling the
flow of said withdrawn fluids, initially to inflate - said packers and subsequently
to direct said fluids to said second test chamber and said sample collection chamber.
12. Apparatus according to Claim 11 in which the second test chamber is suitable to
test acidity, redox potential and temperature.
13. Apparatus according to any one of Claims 10 to 12 in which a plurality of sample
collection chambers are 'provided.