Apparatus for obtaining high quality formation fluid samples
A well fluid sampling tool is provided. The sampling tool includes at least one insulated sample chamber mounted in a tool collar. The tool collar may be coupled with a drill string such that, when the tool collar is deployed in a well bore, selected sample chambers may receive a fluid sample from outside the drill string without removing the drill string from the well bore (e.g., during measurement while drilling or logging while drilling operations). A heating module in thermal communication with at least one of the sample chambers is disposed to selectively heat the sample chambers in thermal communication therewith. The sampling tool may be particularly useful for acquiring and preserving substantially pristine formation fluid samples.
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This application claims the benefit of U.S. Provisional Application Ser. No. 60/492,483 entitled Apparatus for Obtaining High Quality Formation Fluid Samples, filed Aug. 4, 2003.
FIELD OF THE INVENTIONThe present invention relates generally to the drilling of oil and gas wells, and more specifically, to a formation fluid sampling tool and method of use for acquiring and preserving substantially pristine formation fluid samples.
BACKGROUND OF THE INVENTIONThe commercial development of hydrocarbon (e.g., oil and natural gas) fields requires significant capital investment. Thus it is generally desirable to have as much information as possible pertaining to the contents of a hydrocarbon reservoir and/or geological formation in order to determine its commercial viability. There have been significant advances in measurement while drilling and logging while drilling technology in recent years (hereafter referred to as MWD and LWD, respectively). These advances have improved the quality of data received from downhole sensors regarding subsurface formations. It is nonetheless still desirable to obtain one or more formation fluid samples during the drilling and completion of an oil and/or gas well. Once retrieved at the surface, these samples typically undergo specialized chemical and physical analysis to determine the type and quality of the hydrocarbons contained therein. In general, it is desirable to collect the samples as early as possible in the life of the well to minimize contamination of the native hydrocarbons by drilling damage.
As is well known to those of ordinary skill in the art, formation fluids (e.g., water, oil, and gas) are found in geological formations at relatively high temperatures and pressures (as compared to ambient conditions at the surface). At these relatively high temperatures and pressures, the formation fluid is typically a single-phase fluid, with the gaseous components being dissolved in the liquid. A reduction in pressure (such as may occur by exposing the formation fluid to ambient conditions at the surface) typically results in the separation of the gaseous and liquid components. Cooling of the formation fluid towards such ambient temperatures typically results in a reduction in volume (and therefore a reduction in pressure if the fluid is housed in a sealed container), which also tends to result in a separation of the gaseous and liquid components. Cooling of the formation fluid may also result in substantially irreversible precipitation and/or separation of other compounds previously dissolved therein. Thus it is generally desirable for a sampling apparatus to be capable of substantially preserving the temperature and/or pressure of the formation fluid in its primitive formation condition.
Berger et al., in U.S. Pat. No. 5,803,186, disclose an apparatus and method for obtaining samples of formation fluid using a work string designed for performing other downhole work such as drilling, workover operations, or re-entry operations. The apparatus includes sensors for sensing downhole conditions while using a work string that permits working fluid properties to be adjusted without withdrawing the work string from the well bore. The apparatus also includes a relatively small integral sample chamber coupled to multiple input and output valves for collecting and housing a formation fluid sample.
Schultz et al., in U.S. Pat. No. 6,236,620, disclose an apparatus and method for drilling, logging, and testing a subsurface formation without removing the drill string from the well bore. The apparatus includes a surge chamber and surge chamber receptacle for use in sampling formation fluids. The surge chamber is lowered through the drill string into engagement with the surge chamber receptacle, receives a sample of formation fluid, and then is retrieved to the surface. Repeated sampling may be accomplished without removing the drill string by removing the surge chamber, evacuating it, and then lowering it back into the well. While the Berger and Schultz apparatuses apparently permit samples to be collected relatively early in the life of a well, without retrieval of the drill string, they include no capability to preserve the temperature of the formation fluid. Further, it is a relatively complex operation to remove the formation fluid sample from the Berger apparatus.
Brown et al., in U.S. Pat. No. 5,901,788 disclose a wire or slick line apparatus in which the sample chamber may be thermally insulated, given a high heat capacity, and/or provided with a heating source such as an electric heater, with the intent of maintaining the sample at a temperature similar to that of the formation. Corrigan et al., in PCT Publication WO 00/34624, disclose a slick line apparatus including a sample chamber contained within an evacuated jacket for maintaining the temperature of a formation fluid sample. The Corrigan apparatus further includes multiple heaters spaced along the sample chamber. One drawback of the Brown and Corrigan apparatuses is that they require the retrieval of the drill string from the well bore prior to being lowered therein, which typically involves significant cost and time, and increases the risk of subsurface damage to the formation of interest.
Therefore, there exists a need for improved apparatuses and methods for obtaining samples of formation fluid from a well. In particular, an apparatus that does not require retrieval of the drill string from the well and that has the capability of preserving the sample of formation fluid in substantially pristine conditions is highly desirable.
SUMMARY OF THE INVENTIONThe present invention addresses difficulties in acquiring and preserving samples of pristine formation fluid, including those difficulties described above. Aspects of this invention include a sampling tool for obtaining samples of relatively pristine formation fluid without removing the drill string from the well bore. Sampling tools according to the invention may retrieve samples from both deep and shallow wells. Exemplary sampling tool embodiments of this invention are configured for coupling to the drill string and include one or more sample chambers. The sample chambers are typically insulated and/or provided with a heat source (also referred to as a heating module, e.g., an electric heater) for maintaining the temperature of the formation fluid. Sampling tool embodiments according to this invention typically further include on-board electronics disposed to collect multiple samples of pristine formation fluid at substantially any predetermined moment or time interval.
Exemplary embodiments of the present invention may advantageously provide several technical advantages. For example, sampling tool embodiments according to this invention may advantageously provide for improved sampling of formation fluid from, for example, deep wells. In particular, embodiments of this invention are configured with the intent to try to maintain, for as long as possible, the fluid at about the same temperature and pressure conditions as found in the formation. A tool according to this invention, in combination with a logging while drilling (LWD) tool, is couplable to a drill string, and thus in such a configuration provides for sampling of formation fluid shortly after penetration of the formation of interest. Advantages are thus provided for the acquisition and preservation of relatively high quality formation fluid sample in substantially pristine conditions. These high quality samples may provide for more accurate determination of formation properties and thus may enable a better assessment of the economic viability of an oil and/or gas reservoir.
In one aspect the present invention includes a downhole sampling tool. The downhole sampling tool includes a tool collar having at least one sample chamber deployed therein. Each sample chamber includes an insulating layer deployed thereabout. The tool collar is disposed to be operatively coupled with a drill string deployed in a well bore such that, when the tool collar is coupled to the drill string, sample chambers may be selectively placed in fluid communication with formation fluid drawn from outside the drill string without removing the drill string from the well bore. The sampling tool further includes a heating module in thermal communication with at least one of the sample chambers. The heating module is disposed to selectively heat the sample chambers in thermal communication therewith.
In another aspect this invention includes a logging while drilling (LWD) tool. The logging while drilling tool includes a tool collar having at least one chamber mounted therein. Each sample chamber includes an insulating layer deployed thereabout. The tool collar is disposed to be operatively coupled with a drill string deployed in a well bore such that, when the tool collar is coupled to the drill string, sample chambers may be selectively placed in fluid communication with formation fluid drawn from outside the drill string without removing the drill string from the well bore. The LWD tool further includes a heating module in thermal communication with at least one of the sample chambers. The heating module is disposed to selectively heat the sample chambers in thermal communication therewith. The LWD tool still further includes at least one packer element. Each packer element is disposed to seal the wall of the well bore around the LWD tool. Each packer element is further selectively positionable between sealed and unsealed positions. The LWD yet further includes a sample inlet port connected to the at least one sample chamber via an inlet passageway.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter, which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGSFor a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Referring now to
During a drilling, testing, and sampling operation, drill bit 32 is rotated on drill string 30 to create a well bore 40. Shortly after the drill bit 32 intersects the formation 14 of interest, drilling typically stops to allow formation testing before contamination of the formation occurs, e.g., by invasion of working fluid or filter cake build-up. Expandable packers 220 are inflated to sealing engage the wall of well bore 40. The inflated packers 220 isolate a portion of the well bore 40 adjacent the formation 14 to be tested. Formation fluid is then received at port 216 of formation tester 200 and may be pumped into one or more sample chambers 122 illustrated on
It will be understood by those of ordinary skill in the art that the sampling module 100 and the formation tester 200 of the present invention are not limited to use with a semisubmersible platform 12 as illustrated on
Referring now to
As described hereinabove, sample tanks 120 are configured to maintain the temperature of the formation fluid at a value substantially equal to that of the formation (e.g., formation 14 in
With further reference to the embodiment of
Referring again to
With continued reference to
In alternative embodiments, sampling module 100 may be configured to include a sample chamber insert 150 mountable in the collar 110 as illustrated on
Referring now to
With further reference to
Formation tester 200 typically further includes a control module (not shown) of analogous purpose to that described above with respect to controller 140. The control module, for example controls the function of the various sensors described above and communicates sensor output with operators at the surface, for example, by conventional mud telemetry or electric line communications techniques. The control module may further be communicably coupleable with controller 140.
In operation, formation tester 200 is advantageously positioned adjacent a formation of interest in the well bore. The packer elements 220 are inflated, thereby isolating a substantially annular portion of the well bore adjacent the formation. One or more pumps 250 are utilized to pump formation fluid into the tool at port 216. The pump 250 may include, for example, a bi-directional piston pump, such as that disclosed in U.S. Pat. Nos. 5,303,775 and 5,377,755 to Michaels et al., or substantially any other suitable pump in view of the service temperatures and pressures, exposure to corrosive formation fluids, and other downhole conditions. Fluid is typically pumped into the tool (rather than flowing by the force of the reservoir pressure) in order to maintain it above its bubble pressure (i.e., the pressure below which a single phase fluid becomes a two phase fluid). Sampled formation fluid then passes through the fluid identification module 210 where it is tested using one or more of the various sensors described above. Fluid is typically pumped in and then discharged from the tool via passageway 212 and output port 213 until it is sensed to have predetermined properties (e.g., a resistivity in a certain range) identifying it as likely to be a substantially pristine formation fluid. Typically, upon first pumping, the formation fluid is contaminated with drilling fluid. After some time, however, substantially pristine formation fluid may be drawn into the tool and routed to sampling module 100 via passageway 214. Samples may be obtained using substantially any protocol (e.g., at a various time intervals or matching certain predetermined fluid properties measured by identification module 210).
Referring now to
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims
1. A downhole sampling tool, comprising:
- a tool collar, the tool collar including at least one sample chamber deployed therein, each sample chamber including an insulating layer deployed thereabout;
- the tool collar disposed to be operatively coupled with a drill string deployed in a well bore such that, when the tool collar is coupled to the drill string, sample chambers may be selectively placed in fluid communication with formation fluid drawn from outside the drill string without removing the drill string from the well bore; and
- a heating module in thermal communication with at least one of the sample chambers, the heating module disposed to selectively heat said sample chambers in thermal communication therewith.
2. The sampling tool of claim 1, further comprising a sample inlet port on an outer surface of the tool collar, the sample inlet port connected to the sample chamber via a fluid passageway.
3. The sampling tool of claim 2, further comprising a pump in fluid communication with the sample inlet port.
4. The sampling tool of claim 3, wherein the pump comprises a bi-directional piston pump.
5. The sampling tool of claim 1, wherein the tool collar comprises a plurality of sample chambers deployed therein.
6. The sampling tool of claim 1, wherein the at least one sample chamber is deployed substantially coaxially with the tool collar.
7. The sampling tool of claim 1, wherein the insulating layer comprises an r-value of greater than or equal to 12.
8. The sampling tool of claim 1, wherein the insulating layer comprises an insulating material selected from the group consisting of a polyurethane coating and an aerogel foam.
9. The sampling tool of claim 1, wherein the insulating layer comprises an evacuated region.
10. The sampling tool of claim 1, wherein the heating module comprises an electrical resistance heater.
11. The sampling tool of claim 10, wherein a portion of the heating module is wound about the sample chamber.
12. The sampling tool of claim 10, wherein the heating module comprises an electrically resistive coating deployed about the sample chamber.
13. The sampling tool of claim 1, further comprising an electronic controller in control communication with the heating module.
14. The sampling tool of claim 13, wherein the electronic controller is further in control communication with at least one temperature sensor deployed in the sample chamber.
15. The sampling tool of claim 14, wherein the electronic controller is configured to maintain a temperature of the sample chamber above a predetermined minimum temperature.
16. The sampling tool of claim 1, being coupled to a logging while drilling tool.
17. The sampling tool of claim 1, wherein the sample chamber and the heating module are deployed in a sample chamber insert, the sample chamber insert sized and shaped for removable receipt within the tool collar.
18. A downhole sampling tool, comprising:
- a tool collar, the tool collar including a sample chamber insert deployed therein, the sample chamber insert sized and shaped for removable receipt within the tool collar;
- at least one sample chamber deployed in the sample chamber insert, each sample chamber including an insulating layer deployed thereabout;
- a heating module deployed in the sample chamber insert in thermal communication with at least one of the sample chambers, the heating module disposed to selectively heat said sample chambers in thermal communication therewith; and
- the tool collar disposed to be operatively coupled with a drill string deployed in a well bore such that, when the tool collar is coupled to the drill string, sample chambers may be selectively placed in fluid communication with formation fluid drawn from outside the drill string without removing the drill string from the well bore.
19. The sampling tool of claim 18 wherein the insulating layer comprises an insulating material selected from the group consisting of a polyurethane coating and an aerogel foam.
20. The sampling tool of claim 19, wherein the insulating layer comprises an evacuated region.
21. The sampling tool of claim 18, wherein the heating module comprises an electrical resistance heater, a portion of the electrical resistance heater wound about at least one of the sample chambers.
22. The sampling tool of claim 18, further comprising an electronic controller communicably coupled with (i) the heating module and (ii) at least one temperature sensor deployed in the sample chamber.
23. The sampling tool of claim 22, wherein the electronic controller is configured to maintain a temperature of the sample chamber above a predetermined minimum temperature.
24. The sampling tool of claim 18, further comprising a bi-directional piston pump connected to a sample inlet port, the sample inlet port connected to the sample chamber via a fluid passageway.
25. A logging while drilling tool comprising:
- a tool collar, the tool collar including at least one sample chamber mounted therein, each sample chamber including an insulating layer deployed thereabout;
- the tool collar disposed to be operatively coupled with a drill string deployed in a well bore such that, when the tool collar is coupled to the drill string, sample chambers may be selectively placed in fluid communication with formation fluid drawn from outside the drill string without removing the drill string from the well bore;
- a heating module in thermal communication with at least one of the sample chambers, the heating module disposed to selectively heat said sample chambers in thermal communication therewith;
- at least one packer element, each packer element disposed to seal the wall of the well bore around the logging while drilling tool, each packer element being selectively positionable between sealed and unsealed positions; and
- a sample inlet port connected to the at least one sample chamber via an inlet passageway.
26. The logging while drilling tool of claim 25, comprising first and second packer elements, the sample inlet port being disposed between the first and second packer elements.
27. The logging while drilling tool of claim 25, further comprising a fluid identification module in fluid communication with the inlet passageway, the fluid identification module including at least one sensor disposed to sense a property of a formation fluid.
28. The logging while drilling tool of claim 27, wherein at least one of the sensors in the fluid identification module is selected from the group consisting of a resistivity sensor, a dielectric sensor, a pressure sensor, a temperature sensor, an optical sensor, an acoustic sensor, a nuclear magnetic resonance sensor, a density sensor, a viscosity sensor, and a pH sensor.
29. The logging while drilling tool of claim 27, further comprising:
- a first fluid passageway connecting the fluid identification module to the at least one sample chamber; and
- a second fluid passageway connecting the fluid identification module to an output port through which fluid may be expelled from the tool.
30. The logging while drilling tool of claim 25, wherein the tool collar comprises a plurality of sample chambers mounted therein.
31. The logging while drilling tool of claim 25, wherein the insulating layer comprises an r-value of greater than or equal to 12.
32. The logging while drilling tool of claim 25, wherein the heating module comprises an electrical resistance heater wound about the sample chamber.
33. The logging while drilling tool of claim 25, further comprising an electronic controller in control communication with the heating module.
34. The logging while drilling tool of claim 25, further comprising a bi-directional piston pump in fluid communication with the sample inlet port.
35. The logging while drilling tool of claim 25, wherein the sample chamber and the heating module are deployed in a sample chamber insert, the sample chamber insert sized and shaped for removable receipt within the tool collar.
36. An integrated apparatus for retrieving a fluid sample from a well bore, the apparatus comprising:
- a drill string having a drill bit disposed on one end thereof;
- a formation evaluation tool disposed on the drill string proximate to the drill bit; and
- a formation fluid sampling apparatus also disposed on the drill string proximate to the drill bit, the formation fluid sampling apparatus including: a tool collar, the tool collar including at least one sample chamber deployed therein, each sample chamber including an insulating layer deployed thereabout; the tool collar disposed to be operatively coupled with the drill string such that sample chambers may be selectively placed in fluid communication with formation fluid drawn from outside the drill string without removing the drill string from the well bore; and a heating module in thermal communication with at least one of the sample chambers, the heating module disposed to selectively heat said sample chambers in thermal communication therewith.
37. A method for acquiring a formation fluid sample from a formation of interest in a well bore, the method comprising:
- (a) deploying a formation fluid sampling tool at a location of a formation of interest in a well bore, the sampling tool being operative coupled with a drill string proximate to a drill bit, the sampling tool comprising: a tool collar, the tool collar including at least one sample chamber deployed therein, each sample chamber including an insulating layer deployed thereabout; the tool collar disposed such that the at least one sample chamber may be selectively placed in fluid communication with formation fluid drawn from outside the drill string without removing the drill string from the well bore; and a heating module in thermal communication with at least one of the sample chambers, the heating module disposed to selectively heat said sample chambers in thermal communication therewith;
- (b) pumping formation fluid into selected ones of the sample chambers; and
- (c) heating the formation fluid received in (b) in the selected sample chambers using the heating module.
Type: Application
Filed: Aug 4, 2004
Publication Date: Feb 10, 2005
Applicant: PathFinder Energy Services, Inc. (Houston, TX)
Inventor: Michael Moody (Katy, TX)
Application Number: 10/911,357