The subject disclosure relates to flowlines or channels used in nuclear magnetic resonance (NMR) apparatus that perform NMR measurements.
NMR apparatus that employ small-sized flowlines are used in a variety of applications in multiple industries. In biomedical research for example, NMR relaxation measurements are performed with microcoils on capillary channels, where the sample volume may be as little as a few microliters (μL). Such small fluid channels pose significant challenges to the measurement, due to the large surface-to-volume ratio for the contained fluid.
In sampling tools for geological formations, flowline measurements are used to interrogate bulk fluid properties in downhole conditions. See U.S. Pat. No. 7,804,296 to Flaum et al. which is hereby incorporated by reference herein in its entirety.
A large body of literature on NMR measurements with small flowlines exists. By way of example, U.S. Pat. No. 6,097,188 to Sweedler et al. is entitled “Microcoil Based Micro-NMR Spectrometer and Method” describes an NMR apparatus having an analyte sample holder having a containment region that holds a volume of less than about 10 microliters. Other documents include, e.g., Haun, Jered B. et al., “Micro-NMR for rapid molecular analysis of human tumor samples,” Science Translational Medicine 3(71), (2011); and Lee, Hahko et al., “chip-NMR biosensor for detection and molecular analysis of cells,” Nature Medicine 14:8, pp 869-874 (2008); Wensink, Henk, et al., “Measuring reaction kinetics in a lab-on-a-chip by microcoil NMR,” Lab on a Chip 5.3, pp. 280-284 (2005).
In all prior art situations utilizing miniature (small-sized) flowlines (e.g., with inner diameter or maximum channel width of less than 0.2 inches), undesirable spectra artefacts in the NMR measurements are present.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
Miniature (small-sized) flowlines are provided for NMR apparatus that do not introduce undesirable spectra artefacts when subjected to NMR measurements. The miniature flowlines may be used for oilfield NMR applications (including both uphole and downhole NMR equipment) over a wide range of temperatures and pressures, and in conjunction with a wide range of fluid samples, including hydrocarbons.
In embodiments, a miniature flowline is provided that has an inner diameter or maximum channel width of less than 0.2 inches.
In embodiments, a miniature flowline is formed from extruded polyether ether ketone (PEEK). The PEEK flowline may be annealed to 200° C. to permit the flowline to be used in high temperature environments, such as for downhole NMR measurements.
In embodiments, a miniature flowline is formed from synthetically-grown sapphire crystal, and the inner diameter or channel of the flowline is ground smooth to remove polygon-like edges.
In embodiments, a miniature flowline is formed from ytrria-stabilized zirconia (YSZ) ceramic.
In embodiments, NMR apparatus and devices and systems, such as uphole and downhole NMR equipment, are provided with a miniature flowline as described herein.
The subject disclosure is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of the subject disclosure, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
The particulars shown herein are by way of example and for purposes of illustrative discussion of the examples 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 details in more detail than is necessary, 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.
According to one aspect, in making NMR measurements to interrogate fluid properties, external factors, such as interactions between fluid molecules and the inner wall of the flowline should be minimized. In particular, since flowline NMR is a measurement of molecular dynamics, it is very sensitive to any abnormalities of magnetic susceptibility and surface defects of the flowline materials. Thus, according to one aspect, at least two primary considerations may be applied to a minatured (small-sized) flowline for NMR measurements.
First, the inner surface of the flowline which is in direct contact with the fluids under study can be configued to be smooth with reduced surface roughness or effective porosity. In this context, “smooth” means that the inner surface of the flowline is a regular or consistent surface that is free from projections, lumps, indentations or other surface defects that result in fast relaxation components in a measured relaxation spectrum. In other words, the surface roughness or effective porosity of the inner surface of the flowline is kept at a minimal level as any surface defect (a scratch, a dent, or a small bump) is a potential site for altering molecular trajectories that result in motion slowdowns and fast relaxation components in a measured relaxation spectrum.
Second, the material of the flowline should be non-magnetic, non-conductive, and ideally of zero magnetic susceptibility. Contamination of paramagnetic/ferromagnetic elements should be avoided. The paramagnetic/ferromagnetic elements, which can introduced either in the raw material of the flowline or during machining of the flowline, can create unwanted local magnetic fields that cause an accelerated decoherence of NMR signals (and therefore a fast relaxation).
When using a minaturized flowline for oilfield applications, such as for downhole NMR measurements of formation fluids or borehole fluids, a primary consideration involves the compatibility of the flowline with the downhole conditions and fluids. Thus, in one aspect, the material of the flowline can be selected such that the relaxation time of protons in the material of the flowline will be well below that of relaxation time of the protons in the formation fluids or borehole fluids. In addition, the flowline material of the flowline should be inert to common formation fluids and borehole fluids.
According to embodiments, the material of the flowline can be easily machinable. According to other embodiments, the material of the flowline can have good mechanical properties. Recommended material properties for a minaturized flowline for downhole NMR measurements are summarized in Table 1:
An example of a flowline for NMR measurements that does not satisfy the recommended material properties of Table 1 is a flowline machined from PEEK (polyether ether keton) stock and provided with a 1/16″ inner diameter. The machined PEEK flowline was used to perform the NMR measurements of
According to embodiments, four different materials meeting the criteria of Table 1 were tested for suitability for a minaturized flowline for NMR measurements.
In a first embodiment, alumina was used as the material for the flowline. For example, an alumina ceramic is made by firing amorphous Al2O3 in a furnace. A first tube is formed from the alumina ceramic and has a 0.125 inch (round) outer diameter and 0.063 inch (round) inner diameter, and a second tube is formed from the alumina ceramic and has a 0.25 inch (round) outer diameter and 0.125 inch (round) inner diameter. Both the first and second tubes were filled with water and tested at 21° C. with the same miniaturized NMR sensor fixture described above with reference to the machined PEEK tube and the same NMR pulse sequence. The T2 relaxation spectra and corresponding CPMG data for the water in the two tubes are shown in
In a second embodiment, sapphire was used as the material for the flowline. Sapphire is widely deployed in downhole sampling tools and is also routinely used to make NMR sample-holders. A flowline formed from sapphire and having a 0.069 inch (round) inner diameter and 0.125 inch (round) outer diameter was filled with water and tested at room temperature and a pressure of 10 psi with the same miniaturized NMR sensor fixture described above with reference to the machined PEEK tube and the same NMR pulse sequence. The T2 relaxation spectrum and corresponding CPMG data for the water in the sapphire flowline are shown in
In a third embodiment, yttria-stabilized zirconia (YSZ) was used as the material for the flowline. A salient feature of YSZ is its capability to withstand 40,000 psi differential pressure across the wall of ther flowline without any pressure compensation. This material capability has the potential of greatly simplifying the design of the NMR sensor. A flowline formed from YSZ sapphire and having an approximately 0.118 inch (round) inner diameter and 0.197 inch (round) outer diameter was filled with water at tested at room temperature using different NMR echo spacings; i.e., TE=150 μs, 500 μs, and 1000 μs. The T2 relaxation spectra and corresponding CPMG data for the water in the YSZ flowline are shown in
In a fourth embodiment, PEEK was used as the material for the flowline, and the flowline was formed by extrusion to construct an extruded thick-wall tube comprising PEEK. As part of the extrusion process, the PEEK material is pushed through a die of the desired cross-section.
According to one aspect, when making the extruded PEEK flowline, the inner diameter of the extruded PEEK flowline can be supported by a through-hole gauge pin and thus can be preserved in its post-extrusion condition. When a tube of extruded PEEK was subjected to temperature cycles of up to 150° C., a small (2%) shortening of the tube length was observed. At such elevated temperatures, the PEEK polymer began to melt and released strains inside the tube body. To avoid the probe deformation, other extruded PEEK flowlines were subjected to annealing using temperatures of 200° C. following the procedure in Table 2.
Using the annealed extruded PEEK flowlines or tubes, NMR relaxation measurements were performed on water and dodecane samples from room temperature to 150° C. and from 10 psi to 13,000 psi pressure.
Similarly,
It will be appreciated from
According to one aspect, NMR measurements were conducted to generate T1-T2 spectra of the water samples in the annealed extruded PEEK flowlines at a few selected temperature points.
NMR relaxation measurements were performed with a few different echo spacings at 125° C. As the echo spacing decreased from 700 to 200 μs, the measured T2 values monotonically increased from 7 to 8 seconds. This is a near 15% rise, despite that 8 seconds is still 3 seconds short of the measured T1 of 11 seconds. Some small components of fast relaxation and broadened fluid peaks at short echo spacings were also observed, which may originate from the increased RF duty cycle and from the fact that the pulse and echo spacing are not a multiple of the B1 pulse period.
In an embodiment, a large portion of a probe can be made of nonmagnetic alloys (including both probe head and pressure vessel housing) that can withstand HTHP operations. The sample fluids are introduced into the probe head as depicted in
The piston can be configured to equalize pressures across the wall of the extruded PEEK flowline. In this case, the pressure-compensated chamber outside the flowline can be filled with fluid of equal pressure to the fluid in the flowline. The annular space between pressure vessel housing and the flowline can be partitioned into two chambers (left and right) by the piston. To avoid interference with signals from the sampled fluids, the fluid in the left chamber (pressure-compensation chamber) does not include protons. In contrast, the fluid in the right chamber is the same as the flowline fluid, which enters the space through the compensation port. When the operating condition varies, the piston moves so as to maintain pressure equilibrium across the wall of the flowline in the measurement section.
In this example, the fluid pressure is increased from 600 bar to 900 bar. Accordingly, the signal amplitude increases by about 1.6%. By scaling the signal amplitude with a constant, the acquired NMR signal data agrees well with reported numbers in the literature. See Caudwell, D. R., et al. “The viscosity and density of n-dodecane and n-octadecane at pressures up to 200 MPa and temperatures up to 473 K”, International Journal of Thermophysics 25.5 (2004): 1339-1352. In practice, the constant can be determined from calibration by measuring the NMR signals with a fluid of known density or by comparing to reported numbers on the fluids of study in previous work.
It should be appreciated that the extruded PEEK, sapphire and YSZ flowlines as described herein are useful in oilfield applications where high temperatures and high pressures may be present. Thus, formation fluids may be more accurately analyzed downhole by locating a downhole nuclear magnetic resonance (NMR) tool in a borehole, with the NMR tool including a small-sized flowline or HPHT probe as described herein. For example, the flowline of the NMR tool can have an inner diameter of less than 0.2 inch and be formed from either extruded polyether ether ketone (PEEK), sapphire, or yttria-stabilized zirconia (YSZ) as described herein. The formation fluid may be flowed into the flowline. Then, the NMR tool may conduct NMR measurements on the fluid in the flowline to analyze the fluid. In alternate embodiments, a small-sized flowline or HPHT probe as described herein can be part of some other downhole NMR equipment or uphole NMR equipment where formation fluid (or produced fluid) are flowed into the flowline. Then, the NMR equipment may conduct NMR measurements on the fluid in the flowline to analyze the fluid.
Referring to
While
The intake section 25 includes a probe 28 mounted on an extendable base 30 having an outer and inner concentric seals or packers 31, 36 for sealingly engaging the borehole wall 17 around the probe 28. The intake section 25 is selectively extendable from the downhole tool 10 via extension pistons 33. The probe 28 is provided with an interior channel 32 and an exterior channel 34 separated by the wall of the inner seal 36.
The flow section 27 includes a sample line 38 and a guard line 40 driven by one or more pumps 35. The sample line 38 is in fluid communication with the interior channel 32, and the guard line 40 is in fluid communication with the exterior channel 34. The illustrated flow section 27 may include one or more flow control devices, such as the pump 35 and valves 44, 45, 47 and 49 depicted in
Initially, an invaded zone 19 surrounds the mudcake 15 and the borehole wall 17. Formation fluid 22 with a sufficiently low level of contamination is located in the formation 20 behind the invaded zone 19. Preferably, contaminated fluid from the invaded zone 19 is drawn through the exterior channel 34 into the guard line 40 and discharged into the borehole 14. Preferably, fluid is drawn into the interior channel 32 through the sample line 38 and either is discharged into the borehole 14 or diverted into one or more sample chambers 42. Once it is determined that the fluid drawn into the interior channel 32 and through the sample line 38 has a sufficiently low level of contamination (and thus is representative of the formation fluid 22), valve 44 and/or valve 49 may be activated using known control techniques to divert the formation fluid from the sample line 38 into the sample chamber(s) 42.
The system 26 is also preferably provided with one or more fluid monitoring systems 53 for analyzing the fluid that enters the probe 28 and flows through the sample line 38 and possibly the guard line 40. The fluid monitoring system 53 may be provided with various monitoring devices or sensors, such as one or more optical spectroscopic analyzers, one or more fluid densiometers, one or more fluid viscometers, and possibly others.
In embodiments, the one or more fluid monitoring systems 53 can include an HPHT probe with small-sized flowline such as described herein with respect to
The details of the various arrangements and components of the system 26 described above as well as alternate arrangements and components for the system 26 would be known to persons skilled in the art and found in various other patents and printed publications, such as those discussed herein. Moreover, the particular arrangement and components of the system 26 may vary depending upon factors in each particular design, use or situation. Thus, neither the system 26 nor the present disclosure are limited to the above described arrangements and components and may include any suitable components and arrangement. For example, various geometries for the seals or packers of the probe 28 and corresponding channels can be used and various flow lines, pump placement and valving may be provided for a variety of configurations. Similarly, the arrangement and components of the downhole tool 10 may vary depending upon factors in each particular design, or use, situation. The above description of exemplary components and environments of the tool 10 with which the fluid sampling device 26 of the present disclosure may be used is provided for illustrative purposes only and is not limiting upon the present disclosure.
Although only a few examples have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the examples without materially departing from this subject disclosure. 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.
The subject disclosure claims priority from U.S. Provisional Patent Appl. No. 62/821,172, filed on Mar. 20, 2019, entitled “SMALL FLOWLINES FOR NUCLEAR MAGNETIC RESONANCE MEASUREMENTS,” herein incorporated by reference in its entirety.
Number | Date | Country | |
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62821172 | Mar 2019 | US |