APPARATUS AND METHOD FOR COLLECTING A DOWNHOLE FLUID
A method and apparatus for collecting a downhole fluid are disclosed. A method includes receiving a downhole fluid into a downhole sub from a first borehole wall portion adjacent a formation of interest and expelling at least a portion of the received downhole fluid from the downhole sub to a second borehole wall portion, wherein substantially all of the expelled downhole fluid enters the second borehole wall portion. An apparatus includes a downhole sub, a formation sampling member coupled to the downhole sub for collecting the downhole fluid from a first borehole wall portion adjacent a formation of interest, a sample expulsion member coupled to the downhole sub for expelling at least a portion of the collected downhole fluid from the downhole sub to a second borehole wall portion, wherein substantially all of the expelled downhole fluid enters the second borehole wall portion.
Latest Patents:
The present disclosure generally relates to apparatuses and methods for evaluating formations traversed by a well borehole and in particular to formation sampling and testing.
Background InformationFormation sampling and testing tools have been used in the oil and gas industry for collecting formation samples, for monitoring formation parameters such as pressure along a well borehole, and for predicting performance of reservoirs around the borehole. Such formation sampling and testing tools typically include an elastomer packer or pad that is pressed against a borehole wall portion to form an isolated zone from which formation samples are collected. Information that helps in determining the viability of the formation for producing hydrocarbons and in determining drilling operation parameters may then be acquired by evaluating the formation samples.
Information about the subterranean formations traversed by the borehole may be obtained by any number of techniques. Techniques used to obtain formation information include obtaining one or more downhole fluid samples produced from the subterranean formations. Downhole fluids, as used herein include any one or any combination of drilling fluids, return fluids, connate formation fluids, and formation fluids that may be contaminated by materials and fluids such as mud filtrates, drilling fluids and return fluids. Downhole fluid samples are often retrieved from the borehole and tested in a rig-site or remote laboratory to determine properties of the fluid samples, which properties are used to estimate formation properties. Modern fluid sampling also includes various downhole tests to estimate fluid properties while the fluid sample is downhole.
Some formations produce hazardous fluids, and local governmental regulations may greatly control and restrict the amount of formation fluids that are introduced into the well borehole to reduce the risk of exposing the surface environment and personnel to these hazardous fluids. This is the case even when it is necessary to retrieve connate formation samples from formations that produce hazardous downhole fluids. It is difficult to retrieve connate formation samples from these hazardous fluid producing formations, because borehole fluids and filtrates often contaminate the formation samples. One obstacle is that cleanup processes used to remove borehole contaminants from a fluid sample to obtain a connate fluid sample substantially free of borehole contaminants usually results in ejecting large amounts of formation fluid into the borehole. Thus, the hazardous formation fluids are produced into the return fluid posing environmental threats and hazards to personnel at the surface.
SUMMARYThe following presents a general summary of several aspects of the disclosure in order to provide a basic understanding of at least some aspects of the disclosure. This summary is not an extensive overview of the disclosure. It is not intended to identify key or critical elements of the disclosure or to delineate the scope of the claims. The following summary merely presents some concepts of the disclosure in a general form as a prelude to the more detailed description that follows.
A method for collecting a downhole fluid includes receiving a downhole fluid into a downhole sub from a first borehole wall portion adjacent a formation of interest and expelling at least a portion of the received downhole fluid from the downhole sub to a second borehole wall portion, wherein substantially all of the expelled downhole fluid enters the second borehole wall portion.
Another method aspect for collecting a downhole fluid includes conveying a downhole sub in a borehole, the downhole sub including a fluid sampling tool. A first borehole wall portion adjacent a formation of interest is sealed using a first seal coupled to the fluid sampling tool and a second borehole wall portion is sealed using a second seal coupled to the fluid sampling tool. A first fluid path is established with the first borehole wall portion and the tool. A second fluid path is established with the second borehole wall portion and the tool. The method further includes receiving the downhole fluid into the fluid sampling tool using the first fluid path, flowing the received downhole fluid through the tool during a cleanup process, estimating a fluid contamination level during the cleanup process, and expelling at least a portion of the received downhole fluid from the tool using the second fluid path during the cleanup process to remove some or all borehole contaminants from the received downhole fluid until fluid flowing through the tool is a substantially contamination free connate formation fluid. The substantially contamination free connate formation fluid may be stored in a fluid sample chamber.
An apparatus includes a downhole sub, a formation sampling member coupled to the downhole sub for collecting the downhole fluid from a first borehole wall portion adjacent a formation of interest, a sample expulsion member coupled to the downhole sub for expelling at least a portion of the collected downhole fluid from the downhole sub to a second borehole wall portion, wherein substantially all of the expelled downhole fluid enters the second borehole wall portion.
For detailed understanding of the present disclosure, references should be made to the following detailed description of the several embodiments, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals and wherein:
The exemplary wireline
In the non-limiting embodiment of
The exemplary formation sampling tool 134 shown in
Referring to
One or more flush-through fluid sample containers 142 may be included below the fluid pump 140 and above the sample expulsion member 138. In several examples, the fluid sample containers 142 are individually or collectively detachable from the downhole evaluation tool formation sampling tool 134. Further details of several exemplary flush-through fluid sample containers will be provided below with reference to
The exemplary fluid sample containe 400 shown in
Additional fluid control devices 416 are shown in the exemplary embodiment of
The exemplary embodiment shown in
The fluid sample container 400 may be detachable from the downhole sub 102 using detachable flow line connectors 418 and one or more detachable mounting members 424 that couple the fluid sample container body 402 to the downhole sub 102. The downhole sub 102 may include a pump 140 for conveying fluid through a fluid flow control device 416, which may be a valve controllable downhole using command signals. The fluid flow control device 416 is in communication with the internal cavity 404.
The exemplary fluid sample container 400 may further include a check value 426 as shown coupled to the input flow line connector 418 and a similar check valve 426 coupled to the output flow line connector 418 to help ensure fluid flows through the fluid sample container 400 in one direction during a downhole sample cleanup process.
The non-limiting embodiment of
The fluid evaluation module 428 may include any number of fluid measurement devices for estimating fluid characteristics of the fluid 406 entering or leaving the internal cavity 404. The fluid evaluation module 428 may be arranged to estimate optical characteristics, electrical characteristics, physical characteristics and any combination of characteristics of the fluid 406. For example, some test devices may be in fluid contact with fluid flowing in the fluid evaluation module, some devices may be in optical communication, some devices may be in acoustic communication, some devices may be in physical contact with the fluid, and still others may be in pressure and/or thermal communication with the fluid.
Optical characteristics may be estimated using a downhole fluorescence test device, a reflectometer, a spectrometer, or any combination thereof. Physical characteristics of the fluid may be estimated using a viscometer, a pressure sensor, a temperature sensor, fluid density transducer, or any combination thereof. Electrical characteristics of the fluid 406 may be estimated using resistivity measurement devices, capacitance and dielectric constant measurement devices, or combinations thereof. Other devices may be included with the fluid evaluation module 428 for estimating fluid chemical properties and compositional properties. Exemplary devices include, but are not limited to, a gas chromatograph, a pH test device, a salinity test device, a CO2 test device, an H2S test device, a device for determining wax and asphaltene components, a device for determining metal content, (mercury or other metal), a device for determining acidity of the fluid, or any combination thereof.
In one or more embodiments, the internal cavity 404 is defined by a smooth curvilinear surface 430 within the body 402. The surface 430 may be selected based on the desired cavity volume, overall size of the body and on fluid flow characteristics. In the exemplary embodiment of
Turning now to
The exemplary fluid sample container 500 includes and elongated body 502 having an internal cavity 504 for receiving fluid samples 506. The elongated body 502 portion of the exemplary fluid sample container 500 includes a first end 508 and a second end 510 axially displaced from the first end. The elongated body 502 has a first opening 512 in the first end 508 for receiving the fluid into the internal cavity 504 from the formation sampling member 136. A second opening 514 in the second end 510 may be used for expelling at least a portion of the fluid 506 from the internal cavity 504 through the fluid expulsion member 138. The fluid sample container 500 of this non-limiting embodiment includes a pressure control device 516 for controlling pressure of the fluid sample 506. The pressure control device 516 provides a flow path via a check valve 522 for fluid 506 flowing through the internal cavity 504 and allows for substantially unrestricted flow during the cleanup process and expulsion of fluid from the internal cavity 504 via the expulsion member 138. The pressure control device 516 in one or more non-limiting embodiments includes a piston 526 that is movably disposed within the cavity 504. One or more O-rings 518 provide a fluid and pressure seal between the piston 526 and cavity wall 530. The check valve 522 is positioned within the piston 526 to provide a flow path through the piston 526 to the opening 514 in the second end 510.
The piston 526 is shown positioned toward the second end 510 with the sample 506 shown with an arrow to indicate the direction of flow through the container 500. The check valve 522 prevents flow in the opposite direction. In this manner, the fluid flow through the internal cavity is substantially free flowing during sample cleanup.
The pressure control device 516 may be actuated using a device controller 520. In one or more embodiments, the device controller 520 may be a pump substantially similar to the pump 140 described above and shown in
Several non-limiting operational embodiments for formation sampling will now be described with reference to
Fluid flow into the downhole sub may be maintained in a substantially continuous manner to perform a cleanup process for removing borehole contaminants from the downhole fluid entering the downhole sub. The sample cleanup process may include initially expelling fluid from the downhole sub while the pump or formation pressure urges fluid through the downhole sub. In one or more embodiments, the fluid is monitored for content properties during the cleanup process to estimate a cleanliness level of the fluid flowing within the tool. In one or more embodiments, fluid expulsion is accomplished by reinjecting the expelled fluid into the formation proximate the downhole sub to limit or prevent the fluid from entering the borehole annulus. In one or more embodiments, the fluid is injected into the formation using an extendable expulsion member that is extended to establish fluid communication with the formation. The fluid expulsion may be halted when the fluid within the tool is estimated to be substantially free of contaminants.
In one or more embodiments, fluid samples may be contained within the tool using an internal fluid sample container 400, 500. In one or more embodiments, the fluid cleanup process may include urging the fluid received in the tool through a first end of the fluid sample container and expelling the fluid from a second end of the fluid sample container. Once the estimations show that the fluid within the fluid sample container are substantially free of contaminants, the second container end flow path may be closed using a sub-carried valve 416 that is in fluid communication with the output flow line 422.
The pump 140 may be used to increase the pressure in the container internal cavity 404, 504 to a desired pressure. Once the pressure within the internal cavity reaches the desired pressure, then the pump may be halted and a second sub-carried valve 416 that is in fluid communication with the input flow line 420 may be actuated to close the flow path into the internal cavity 404, 504. In this manner, the fluid sample 406, 506 is sealed within a volume defined between the two sub-carried valves 416.
Pressure within the internal cavity may be controlled after sample collection and during transport using a pressure control device. Fluid may flow through the pressure control device during the cleanup process and a check valve may be used to allow fluid flow in only one direction through the pressure control device. An inert gas may be used to move a piston within the internal cavity to control pressure.
In one or more embodiments, the fluid sample container 400, 500 may be transported to a surface location and removed from the downhole sub without losing fluid containment within the internal cavity 404, 504. Surface operations may include actuating the first end and second end fluid control devices 416 within the container body 402, 502 to seal the respective first end and second end portions of the internal cavity 404, 504. The fluid sample 20 container 400, 500 may then be disconnected from the downhole sub 102 by disconnecting the detachable couplings 424 and the flow line connectors 418.
The sample container internal cavity 404, 504 may be flushed of contaminants and/or connate fluids without leaving substantial residue within the internal cavity. The pump 140 may generate a fluid flow through the cavity. In some embodiments, the cavity 404, 504 includes a curvilinear wall 430, 530 that reduces fluid sticking within the cavity. The wall 430, 530 may further include a surface treatment that further reduces fluid resistance and may be used to reduce sample sticking along the wall 430, 530.
Fluid initially urged into the downhole sub 102 may include one or more contaminants such as borehole fluid and filtrates. Undesirable fluid sample components such as the above-noted contaminants may be cleaned from the fluid entering the downhole evaluation tool 126 by pumping the fluid into the tool and then expelling the fluid through the sample expulsion member 138 until the fluid entering the tool is substantially free of the undesirable contaminants.
In one or more embodiments, pumping and expulsion is performed for a period of time without separate content monitoring with the period of time selected to establish substantially contaminant-free connate fluid flow in the tool. The fluid sample expulsion may be halted on or after completion of the time-based pumping. In one or more embodiments, fluid flowing in the tool is monitored using a downhole tester to estimate fluid content in substantially real-time. The fluid sample expulsion may be halted on or after the content estimate establishes that the fluid flowing in the tool is substantially contaminant-free connate fluid.
One or more operational embodiments address fluid expulsion where environmental regulations, safety concerns or other factors make it desirable to reduce or avoid introducing produced formation fluid to the well borehole. Fluid communication may be established between the sample expulsion member 138 and the formation proximate the sample expulsion member. In this manner, fluid expelled from the tool may be directly injected into the formation with leakage into the well borehole being reduced to levels in compliance with the applicable regulations or to levels that mitigate the safety hazards or that otherwise meet the selected leakage standards set for the particular sampling operation. Formation fluid samples that are substantially free of contaminants may be brought to the surface for testing on-site or in a laboratory environment using the flush through sample container 142.
The present disclosure is to be taken as illustrative rather than as limiting the scope or nature of the claims below. Numerous modifications and variations will become apparent to those skilled in the art after studying the disclosure, including use of equivalent functional and/or structural substitutes for elements described herein, use of equivalent functional couplings for couplings described herein, and/or use of equivalent functional actions for actions described herein. Such insubstantial variations are to be considered within the scope of the claims below.
Claims
1. A method for collecting a downhole fluid, the method comprising:
- receiving the downhole fluid into a downhole sub from a first borehole wall portion adjacent a formation of interest; and
- expelling at least a portion of the received downhole fluid from the downhole sub to a second borehole wall portion, wherein substantially all of the expelled downhole fluid enters the second borehole wall portion.
2. A method according to claim 1, wherein the first borehole wall portion includes an isolated zone sealed using one or more of expanding a packer to contact the borehole wall and extending a probe having a sealing pad to contact the borehole wall.
3. A method according to claim 1, wherein the second borehole wall portion includes an isolated zone sealed using one or more of expanding a packer to contact the borehole wall and extending a probe having a sealing pad to contact the borehole wall.
4. A method according to claim 1, wherein receiving the downhole fluid into a downhole sub includes using a pump to lower fluid pressure within the first flow path.
5. A method according to claim 1, wherein expelling at least a portion of the received downhole fluid includes injecting the expelled downhole fluid into the formation of interest.
6. A method according to claim 1, wherein expelling at least a portion of the received downhole fluid includes injecting the expelled downhole fluid into a formation that is proximate the formation of interest.
7. A method according to claim 1 further comprising estimating a property of the downhole fluid as the downhole fluid flows through the downhole sub.
8. A method according to claim 7, wherein estimating a property of the downhole fluid includes estimating a contamination level.
9. A method according to claim 8, wherein expelling at least a portion of the received downhole fluid includes expelling the received downhole fluid until the estimated contamination level reached a predetermined level of contamination.
10. A method according to claim 1 further comprising storing at least a portion of the received downhole fluid in a fluid sample container.
11. A method for collecting a downhole fluid, the method comprising:
- conveying a downhole sub in a borehole, the downhole sub including a fluid sampling tool;
- sealing a first borehole wall portion adjacent a formation of interest using a first seal coupled to the fluid sampling tool;
- sealing a second borehole wall portion using a second seal coupled to the fluid sampling tool;
- establishing a first fluid path with the first borehole wall portion and the tool;
- establishing a second fluid path with the second borehole wall portion and the tool;
- receiving the downhole fluid into the fluid sampling tool using the first fluid path;
- flowing the received downhole fluid through the tool during a cleanup process;
- estimating a fluid contamination level during the cleanup process;
- expelling at least a portion of the received downhole fluid from the tool using the second fluid path during the cleanup process to remove some or all borehole contaminants from the received downhole fluid until fluid flowing through the tool is a substantially contamination free connate formation fluid; and
- storing the substantially contamination free connate formation fluid in a fluid sample chamber.
12. An apparatus for collecting a downhole fluid, the apparatus comprising:
- a downhole sub;
- a formation sampling member coupled to the downhole sub for collecting the downhole fluid from a first borehole wall portion adjacent a formation of interest; and
- a sample expulsion member coupled to the downhole sub for expelling at least a portion of the collected downhole fluid from the downhole sub to a second borehole wall portion, wherein substantially all of the expelled downhole fluid enters the second borehole wall portion.
13. An apparatus according to claim 12 further comprising one or more of a packer and a probe having a sealing pad to contact the borehole wall for isolating the first borehole wall portion.
14. An apparatus according to claim 12 further comprising one or more of a packer and a probe having a sealing pad to contact the borehole wall for isolating the second borehole wall portion.
15. An apparatus according to claim 12 further comprising a pump for flowing the downhole fluid through the downhole sub.
16. An apparatus according to claim 12, wherein the sample expulsion member includes a port positioned for injecting the expelled downhole fluid into the formation of interest.
17. An apparatus according to claim 12, wherein the sample expulsion member includes a port positioned for injecting the expelled downhole fluid into a formation that is proximate the formation of interest.
18. An apparatus according to claim 12 further comprising a fluid evaluation module for estimating a property of the downhole fluid as the downhole fluid flows through the downhole sub.
19. An apparatus according to claim 18, wherein the fluid evaluation module is operable for estimating a contamination level of the downhole fluid.
20. An apparatus according to claim 12 further comprising a fluid sample container for storing at least a portion of the received downhole fluid.
Type: Application
Filed: Apr 2, 2008
Publication Date: Oct 8, 2009
Applicant:
Inventor: Angus J. Simpson (Cypress, TX)
Application Number: 12/061,411
International Classification: E21B 49/08 (20060101);