CHARACTERIZATION OF POLAR SPECIES IN RESERVOIR FLUIDS

Abstract

A workflow and fluid analysis system to determine polar concentration and type of a reservoir fluid sample that is collected and analyzed in a downhole environment. Once collected this data can be fed into an advisory tool which can predict the probability of different types of issues that might be encountered in production of reservoir fluids from the reservoir. The workflow and fluid analysis system can also be employed in a surface-located laboratory tool for analysis of reservoir fluids.

Claims

1. A method of analyzing a reservoir fluid sample comprising: passing the reservoir fluid sample through at least one cartridge, wherein the at least one cartridge is configured to adsorb at least one polar species of the reservoir fluid sample; and using at least one sensor to generate data characterizing the at least one polar species of the reservoir fluid sample.

2. A method according to claim 1, wherein: the sensor is configured to analyze the at least one polar species as absorbed by the at least one cartridge in order to generate the data characterizing the at least one polar species of the reservoir fluid sample.

3. A method according to claim 1, further comprising: using a fluid to flush the at one polar species from the at least one cartridge, wherein the sensor is configured to analyze the fluid flushed from the at least one cartridge in order to generate the data characterizing the at least one polar species of the reservoir fluid sample.

4. A method according to claim 1, wherein: the data characterizes concentration and type of the at least one polar species.

5. A method according to claim 1, further comprising: using the same sensor or an additional sensor to generate additional data characterizing properties of the reservoir fluid sample that is injected into the at least one cartridge.

6. A method according to claim 1, further comprising: using the same sensor or an additional sensor to generate additional data characterizing properties of fluid that has passed through the at least one cartridge.

7. A method according to claims 6, wherein: the additional data characterizes physical properties of the fluid (such as viscosity, density, composition and/or other chemical properties).

8. A method according to claim 1, further comprising: inputting the data to an advisory tool to predict potential production issues.

9. A method according to claim 1, wherein: the reservoir fluid sample is collected at high pressure high temperature downhole conditions and passed through the at least one cartridge at such downhole conditions.

10. The method according to claim 1, wherein: the reservoir fluid sample is passed through the at least one cartridge at ambient conditions.

11. A method according to claim 1, wherein: the at least one sensor comprises an NMR sensor, optical spectrometer, electrochemical sensor or other suitable sensor.

12. A method according to claim 1, wherein: the at least one cartridge is filled with material that is configured to adsorb at least one polar species of the reservoir fluid sample.

13. A method according to claim 1, wherein: the at least one cartridge comprises a plurality of cartridges filled with material that is configured to adsorb different polar species of the reservoir fluid sample.

14. A method according to claim 1, wherein: the at least one cartridge comprises a plurality of cartridges filled with different types of rock material.

15. A method according to claim 1, further comprising: repeating the method for multiple zones in a given well or multiple wells in a given field or multiple fields connected to a reservoir in order to build polarity data which will help in adopting different prevention and/or mitigation strategies for potential production issues.

16. A tool comprising: a cartridge, operatively in communication with a flowline of the downhole tool, wherein a fluid is communicated to the cartridge, and wherein the cartridge is configured to absorb a selected polar species; and a detector operatively configured to detect a material absorbed on the cartridge.

17. The tool of claim 16, wherein the tool is a laboratory tool or a downhole tool.

18. The tool of claim 16, wherein the tool comprises a plurality of cartridges.

19. The tool of claim 18, wherein each cartridge of the plurality of cartridges are configured to absorb a different selected polar species.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present application is further described in the detailed description which follows, and in reference to the noted plurality of drawings by way of non-limiting examples of embodiments of the present application, in which like reference numerals represent similar parts throughout the several views of the drawings.

[0029] FIG. 1 is a schematic diagram of a system for downhole analysis of reservoir fluids;

[0030] FIG. 2 is a schematic diagram of downhole tool that is configured to carry out a workflow that determines polar concentration and type of a reservoir fluid sample;

[0031] FIG. 3 is a schematic diagram of another downhole tool that is configured to carry out a workflow that determines polar concentration and type of a reservoir fluid sample; and

[0032] FIG. 4 depicts plots that show NMR spectra analysis of polar species of a crude oil sample adsorbed onto a cartridge in accordance with the workflows and systems of the present disclosure.

DETAILED DESCRIPTION

[0033] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the subject disclosure only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the subject disclosure. In this regard, no attempt is made to show structural details in more detail than is necessary for the fundamental understanding of the subject disclosure, the description taken with the drawings making apparent to those skilled in the art how the several forms of the subject disclosure may be embodied in practice. Furthermore, like reference numbers and designations in the various drawings indicate like elements.

[0034] In accordance with the present disclosure, a workflow and fluid analysis system is provided to determine polar concentration and type of a reservoir fluid sample (e.g., crude oil or a mixture of oil and connate water or connate water alone or crude oil, connate water, and other previously introduced chemicals or material, or mixtures thereof). In embodiments, the determination of the polar concentration of the sample is performed in two steps. In the first step, the polar species of the sample is removed by passing the sample through one or more cartridges. In embodiments, the cartridge(s) can be a tube that is filled with tailored particle material or materials viz., ion exchange resin (cationic or anionic), rock materials such as silica, sandstone, carbonate or any other rock material or adsorbent to remove selective species (such as acids or amines) from the sample as the sample passes through the tube. Also, multiple cartridges can be prepared by packing with more than one type of material in series. Such particles can be further coated with materials to selectively adsorb certain polar species. The size of the adsorbent particles loaded into the cartridge(s) can be tuned from nano- to millimeter sizes and/or the length of the cartridge(s) can be tuned within a wide range of lengths, with a preferred length between 1 cm to 10 cm. The packing density of the cartridge(s) can also be varied either by particle size or pressure or any other means.

[0035] Once the sample is passed through the cartridge(s), the cartridge(s) can be washed with other fluid (e.g., liquid and/or gas), such as compressed air or a gas phase solvent, to clear those molecules that are not tightly bound to the particle surfaces, for example, trapped oils.

[0036] Then, the polar species of the sample can be detected on the surface of the cartridge packing material. For example, the cartridge may be directly used in an NMR measurement to determine the amount of polar species on the particle surfaces without removing them. The polar species can also be detected by releasing the adsorbed material from the particle surface. This can be achieved by flushing with liquid or gaseous solvents and the resulting samples can be analyzed with a sensor (such as NMR, optical spectroscopy or electrochemical sensors or other suitable fluid sensor).

[0037] Additionally, the part of the sample that has passed through the cartridge (with the polar species removed), namely the non-polar part of the sample, can be analyzed with a sensor and compared with analytical results of the sample (before extraction of the polar species of the sample) to provide an estimate of the polar species. The analysis can be performed using one or more sensors (such as an NMR sensor, optical spectrometer or electrochemical sensor or other suitable sensor).

[0038] Note that by varying the packing type in the cartridge(s), the workflow and fluid analysis system can selectively separate different types of polar and non-polar species (such as acids, amines, resins, aromatics, saturates, and in some cases asphaltenes) from the sample.

[0039] Furthermore, the cartridges can be prepared with different reservoir rock materials to better understand how the sample behaves when it is exposed to different rock material in a given formation or reservoir.

[0040] The workflow can be carried out under high pressure/high temperature conditions in a downhole environment as part of a downhole tool that is located in a wellbore that traverses a subterranean reservoir. Alternatively or additionally, the workflow can be performed under high pressure/high temperature conditions in the surfaced-located laboratory set up. For example, high temperature high pressure NMR systems can be used to perform such measurement in a downhole tool or in a lab.

[0041] The workflow can be performed in multiple zones in a given oil well or multiple wells in a given field or multiple fields connected to a reservoir in order to build polarity data (referred to as a ‘Polarity Scale’) which will help in adopting different prevention and/or mitigation strategies for potential issues. This polarity scale readings can also be used as an input in Eqn. 1 instead of actual concentration of polar species.

[0042] FIG. 1 is a schematic diagram that illustrate an embodiment of a system 14 for downhole analysis of reservoir fluids according to the present disclosure. The system 14 includes a tool string 20, which may be used for testing earth formations and analyzing the composition of fluids from a formation. The tool string 20 typically is suspended in a borehole 12 from the lower end of a multiconductor logging cable or wireline 22 spooled on a winch 16 at the formation surface. The wireline 22 is typically electrically coupled to a surface electrical control system 24 having appropriate electronics and processing systems for the tool string 20.

[0043] The tool string 20 includes an elongated body 26 encasing a variety of electronic components and modules. A fluid admitting assembly probe 28 and tool-anchoring member 30 are respectively arranged on opposite sides of the elongated body 26. The fluid admitting assembly 28 is operable for selectively sealing off or isolating selected portions of a borehole wall 12 such that pressure or fluid communication with adjacent earth formation is established. One or more fluid analysis modules 32 are provided in the tool body 26. Fluids obtained from a formation and/or borehole flow through a flowline 33, via the fluid analysis module or modules 32, and then may be discharged through a port of a pump out module. Alternatively, formation fluids in the flowline 33 may be directed to one or more fluid collecting chambers 34 and 36 for receiving and retaining the fluids obtained from the formation for transportation to the surface.

[0044] The fluid admitting assembly, fluid analysis module(s), the flow path and the collecting chambers, and other operational elements of the tool string 20 can be controlled by electrical control systems, such as the surface electrical control system 24 (note FIG. 2). Preferably, the electrical control system 24, and other control systems situated in the tool body 26, for example, include processor capability for characterization of formation fluids as described in more detail below.

[0045] The system 14 preferably includes a control processor 40 operatively coupled to the tool string 20. The control processor 40 is depicted in FIG. 1 as an element of the electrical control system 24. Preferably, certain parts of the workflow as described herein can be embodied in a computer program that runs in the processor 40 located, for example, in the control system 24. In operation, the program is coupled to receive data, for example, from the fluid analysis module 32, via the wireline cable 22, and to transmit control signals to operative elements of the tool string 20.

[0046] The computer program may be stored on a computer usable storage medium 42 associated with the processor 40 or may be stored on an external computer usable storage medium 44 and electronically coupled to processor 40 for use as needed. The storage medium 44 may be any one or more of presently known storage media, such as a magnetic disk fitting into a disk drive, or an optically readable CD-ROM, or a readable device of any other kind, including a remote storage device coupled over a switched telecommunication link, or future storage media suitable for the purposes and objectives described herein.

[0047] In other embodiments, the tool string 20 can be conveyed by drill pipe or tubing or other conveyance mechanism as part of a logging-while drilling tool or other downhole tool.

[0048] FIG. 2 is a schematic diagram of a downhole tool (e.g., part of the tool string 20 of FIG. 1) that is configured to carry out operations of the workflow as described herein. In this embodiment, the downhole tool is configured to inject a reservoir fluid sample (e.g., crude oil) at high pressure high temperature conditions of the downhole environment (labeled “sample in”) into a sample cartridge. While the sample flows through the cartridge, selected polar species will be adsorbed onto it and the treated sample (effluent) will be sent to the reservoir at the end of the line. Excess reservoir fluid can be sneezed out from the column using the pump.

[0049] The material adsorbed by the cartridge will be detected by a sensor (such as NMR, optical spectroscopy or electrochemical sensors or other suitable sensor).

[0050] While the sample is flowing into the system prior to entering the cartridge and after leaving the cartridge, the same sensor (or some other sensor) can be used to measure physical properties of the fluid, such as viscosity and density as well as chemical properties which is not limited to composition of the sample and change after the treatment.

[0051] Data generated by the sensor(s) can be incorporated into cloud database or local database. Such data will be supplied to an advisory tool which can provide probability of various issues with that sample and potential strategies to increase the longevity of the producing well.

[0052] This analysis can be performed in multiple zones in the well or multiple wells in a field or multiple fields in a given reservoir to understand potential challenges and develop right strategies for production.

[0053] FIG. 3 is a schematic diagram of a downhole tool (e.g., part of the tool string 20 of FIG. 1) which houses different types of cartridges that are configured to perform selective separation of the sample and perform multiple analysis at the same time. There can be multiple units configured to perform similar analysis in multiple zones in a given well, etc.

[0054] The cartridges presented in FIG. 3 can also be connected in series in order to extract from the same crude oil or any other sample.

[0055] In alternate embodiments, similar measurements can be carried out at high pressure high temperature conditions or ambient conditions as part of a surface-located laboratory tool, such as a laboratory NMR tool, optical spectrometer or other suitable tool.

[0056] The following presents a specific example with NMR, where polar species are separated from a crude oil sample onto a special cartridge material and then analyzed with NMR spectroscopy.

[0057] An FID experiment was performed on two ion exchange resin (IER) cartridges and the frequency spectra are shown in FIG. 4. The frequency spectrum is obtained by Fourier transform of the time domain data acquired by the FID experiment. One cartridge employs activated IER particles before being exposed to the crude oil. The second cartridge employs IER particles with adsorbed acid molecules. This second cartridge is prepared by stirring a crude oil sample for 12 hours with the IER material. After 12 hours, the IER with acid sample was cleaned to remove the excess oil so that only the strongly adsorbed molecules are on the surface of the particles. Here the IER is representative of the cartridge packing material, which will perform similar activity of separating different chemical species selectively.

[0058] FIG. 4 depicts plots that show NMR spectra analysis of polar species of a crude oil sample adsorbed onto a cartridge. The blue line (IER activated) is the NMR spectrum signal from the first cartridge before exposure to the crude oil sample. The red line (IER with acid) is the NMR spectrum signal from the second cartridge exposed to the crude oil. The spectra are normalized by the weight of the sample. The additional amplitude in the Red line signal is indicative of the adsorbed molecules on the particles in the second cartridge. This additional signal can be obtained by subtracting IER active signal from the IEA acid signal. This difference signal can be calibrated to determine the amount of the adsorbed molecules.

[0059] In addition to the FID experiment, other NMR experimental techniques can be used too. For example, CPMG, solid echo, magic echo experimental techniques can be used to determine the relaxation time of the adsorbed molecules. Multi-dimensional NMR spectroscopy can also be used to determine the molecular species of the sample.

[0060] Some of the methods and processes described above, can be performed by a processor. The term “processor” should not be construed to limit the embodiments disclosed herein to any particular device type or system. The processor may include a computer system. The computer system may also include a computer processor (e.g., a microprocessor, microcontroller, digital signal processor, or general purpose computer) for executing any of the methods and processes described above.

[0061] The computer system may further include a memory such as a semiconductor memory device (e.g., a RAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM), a PC card (e.g., PCMCIA card), or other memory device.

[0062] Some of the methods and processes described above, can be implemented as computer program logic for use with the computer processor. The computer program logic may be embodied in various forms, including a source code form or a computer executable form. Source code may include a series of computer program instructions in a variety of programming languages (e.g., an object code, an assembly language, or a high-level language such as C, C++, or JAVA). Such computer instructions can be stored in a non-transitory computer readable medium (e.g., memory) and executed by the computer processor. The computer instructions may be distributed in any form as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over a communication system (e.g., the Internet or World Wide Web).

[0063] Alternatively, or additionally, the processor may include discrete electronic components coupled to a printed circuit board, integrated circuitry (e.g., Application Specific Integrated Circuits (ASIC)), and/or programmable logic devices (e.g., a Field Programmable Gate Arrays (FPGA)). Any of the methods and processes described above can be implemented using such logic devices.

[0064] The components, steps, features, objects, benefits and advantages that have been disclosed are merely illustrative. None of them, nor the discussions relating to them, are intended to limit the scope of protection in any way. Numerous other embodiments are also contemplated, including embodiments that have fewer, additional, and/or different components, steps, features, objects, benefits and advantages.

[0065] Nothing that has been stated or illustrated is intended to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public. While the specification describes particular embodiments of the present disclosure, those of ordinary skill can devise variations of the present disclosure without departing from the inventive concepts disclosed in the disclosure.

[0066] In the present application, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure, known or later come to be known to those of ordinary skill in the art, are expressly incorporated herein by reference.

[0067] Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.