JP4879577B2 - Apparatus and method for geological evaluation - Google Patents

Description

  The present invention relates to a technique for performing an underground layer evaluation using a downhole tool disposed in a well pit penetrating the underground layer. More specifically, but not exclusively, the present invention relates to techniques for determining fluid parameters such as viscosity and density of formation fluids drawn and / or evaluated by downhole tools.

Well wells are drilled to find and produce hydrocarbons. A downhole drilling tool with a bit attached to its tip is advanced into the ground to form a well pit. When the drilling tool is advanced, the drilling mud is sucked up through the drilling tool and discharged from the drilling bit to cool the drilling tool and remove the debris. The drilling mud also forms a mud cake that covers the inside of the well pit.
During excavation work, it is desirable to make various assessments of the formation through which the well mine penetrates. In some cases, the drilling tool can be removed and a wireline tool can be deployed in the wellbore to test and / or sample the formation. In other cases, the drilling tool can be equipped with a device for testing and / or sampling the surrounding formation, and the drilling tool can be used for testing or sampling. For example, these samples or tests can be used to indicate the location of valuable hydrocarbons.

  Formation evaluation often requires drawing fluid from the formation into the downhole tool for testing and / or sampling. Various devices such as probes are extended from the downhole tool to establish fluid communication with the formation surrounding the well and draw fluid into the downhole tool. A typical probe is a circular element that extends from the downhole tool and is placed against the side wall of the wellbore. A rubber packer at the tip of the probe is used to create a seal with the well well wall. Another device used to form a seal with a wellbore is called a double packer. With a double packer, the two elastomeric rings spread radially around the tool and isolate a portion of the wellbore between them. The ring forms a seal with the well wall and draws fluid into the well well isolation and further into the inlet in the downhole tool.

  A mud cake that lines the inside of a well well is often useful in helping probes and / or double packers make a seal against the well wall. With the seal in place, fluid from the formation is drawn into the downhole tool through the inlet by reducing the pressure in the downhole tool. Examples of probes and / or packers used for downhole tools are US Pat. Nos. 6,301,959, 4,860,581, 4,936,139, 6,585,045, Nos. 6,609,568 and 6,719,049, and U.S. Patent Application No. 2004/0000433.

  Formation assessment is generally performed on fluid drawn into the downhole tool. Currently, there are techniques for performing various measurements, pre-examinations, and / or sample collections of fluid entering a downhole tool. However, it has been found that as the formation fluid passes through the downhole tool, various contaminants such as wellbore fluid and / or drilling mud may enter the tool along with the formation fluid. These contaminants can affect measurements and / or the quality of formation fluid samples. Furthermore, contamination can result in costs due to well mine work delays by requiring additional time for more testing and / or sampling. In addition, such problems may produce erroneous results that are error-prone and / or cannot be used.

  Thus, it is desirable that the formation fluid entering the downhole tool be sufficiently “clean” or “unused” to perform an effective test. That is, the formation fluid should have little or no contamination. Attempts have been made to eliminate contaminants entering the downhole tool with the formation fluid. For example, as shown in U.S. Pat. No. 4,951,749, a filter is placed in the probe to prevent contaminants from entering the downhole tool with the formation fluid. Further, as shown in US Pat. No. 6,301,959 to Hrametz, the probe is provided with a guard ring for diverting contaminated fluid from the clean fluid as it enters the probe. . Fluid entering the downhole tool typically passes through the flow path and can be captured in the sample chamber or discarded into the well well. Various valves, gauges, and other components can be incorporated along the flow path to deflect, test, and / or capture fluid as it passes through the downhole tool.

The fluid passing through the downhole tool can be tested to determine various downhole parameters or characteristics. Thermophysical properties of hydrocarbon storage fluids, such as fluid viscosity, density, and phase behavior in the storage state, are used to assess potential reserves, determine flow rates in perforated media, and especially complete Systems, separation systems, processing systems, and metering systems can be designed.
Various techniques for judging fluid viscosity have been developed. For example, viscometers having a bob suspended between fixed points for torsion wires have also been proposed, for example, as described in US Pat. Nos. 5,763,766 and 6,070,457. ing. Viscometers have also been formed with vibrating objects. One such viscometer is used in downhole applications for the purpose of measuring the viscosity, density, and dielectric constant of formation fluids or filtrates in hydrocarbon production wells. For example, International Patent Publication No. WO 02/093126 discloses a tuning fork resonator in a pipe to provide real-time direct measurements and estimates of formation fluid or filtrate viscosity, density, and dielectric constant in a hydrocarbon production well. Has been. Another viscometer with a clamped by wire between the two pillars, for example, "the viscosity of the pressurized He exceeding T _lambda", "Physica 76" (1974), pp. 177-180, and "vibration Wire Viscometer "," The Review of Scientific Instruments ", Vol. 35, No. 10, (October 1694), pages 1435 to 1348.

US Pat. No. 6,301,959 U.S. Pat. No. 4,860,581 US Pat. No. 4,936,139 US Pat. No. 6,585,045 US Pat. No. 6,609,568 US Pat. No. 6,719,049 US Patent Application No. 2004/0000433 US Pat. No. 4,951,749 US Pat. No. 5,763,766 US Pat. No. 6,070,457 International Patent Publication Number WO02 / 093126 "Viscosity of pressurized He exceeding Tλ", "Physica 76" (1974), 177-180 pages “Vibrating Wire Viscometer”, “The Review of Scientific Instruments”, Vol. 35, No. 10, (October 1694), p. Retsina, T .; Richardson, S .; M.M. Wakeham, W .; A. Author "Applied Science Research", 1987, 43, 325-346. Retsina, T .; Richardson, S .; M.M. Wakeham, W .; A. 1986, 43, 127-158

  Despite the existence of techniques for measuring viscosity, there remains a need to provide accurate viscosity measurements in the downhole, preferably regardless of the position of the sensor in the downhole with respect to the gravitational field. Such a system should desirably be able to provide an inspection of accuracy and / or accuracy. It would be further desirable for such a system to have a simple configuration adapted for use in harsh well well environments.

  In one aspect, the present invention relates to a viscometer-density meter for a downhole tool that can be placed in a wellbore that penetrates an underground formation. The downhole tool is adapted to convey at least a portion of the fluid in the formation to the viscometer-density meter. The viscometer-density meter includes a sensor unit that can be placed in a downhole tool. The sensor unit includes at least two spatially arranged connectors, wires, and at least one magnet. The wire is available to interact with the fluid when the viscometer-density meter is placed in the downhole tool and the downhole tool is placed in the underground layer to receive fluid from the underground layer. It is suspended in a stretched state between at least two connectors. The connector and wire are configured to form a frequency oscillator. The at least one magnet described above generates a magnetic field that interacts with the wire.

  The connector and the wire can be made of a material having a similar coefficient of thermal expansion so as to form a frequency oscillator. For example, the connector and the wire are made of a single type of material and can substantially eliminate fluctuations in the resonant frequency of the wire due to thermal and elastic deformation caused by downhole conditions. The viscometer-density meter can also be equipped with a flow tube in which the wire is suspended by a connector, in which the flow tube, the connector, and the wire are of similar thermal expansion to form a frequency oscillator. It is desirable to be composed of a material having a rate.

In another aspect, the sensor unit is further equipped with means for preventing rotation of the wire relative to the connector. The means for preventing rotation of the wire can include a boss connected to the wire, the boss having a non-circular cross section.
In yet another aspect, the viscometer-density meter is further equipped with an analysis circuit that receives feedback from the wire to calculate at least two parameters (eg, viscosity and density) of the fluid interacting with the wire.

  In yet another aspect, the present invention relates to a downhole tool that can be placed in a well pit having a wall and penetrating an underground layer. The formation typically has fluids such as natural gas and oil therein. The downhole tool is equipped with a housing, a fluid communication device, and a viscometer-density meter. The housing encloses at least one evaluation cavity. The fluid communication device is extendable from the housing for sealing engagement with the well wall. The fluid communication device has at least one inlet in communication with the evaluation cavity for receiving fluid from the formation and depositing such fluid in the evaluation cavity. The viscometer-density meter is equipped with a sensor unit arranged in the evaluation cavity. The sensor unit is equipped with at least two spatially arranged connectors, wires, and magnets. The wire is suspended in tension between the at least two connectors described above so that it is available for interaction with the fluid in the evaluation cavity. The connector and wire are configured to form a frequency oscillator. At least one magnet generates a magnetic field that interacts with the wire. The viscometer can be any version described above.

  In yet another aspect, the downhole tool can be equipped with a comparison chamber that contains a fluid having known properties, such as viscosity and density. The downhole conditions in the comparison chamber, such as pressure and temperature, are similar (preferably the same) as the downhole conditions in the evaluation cavity. The downhole tool so that the downhole includes one sensor unit disposed within the unknown parameter fluid in the evaluation cavity and the other sensor unit disposed with the known parameter fluid in the comparison chamber. Is also equipped with a sensor unit in the comparison chamber. A signal indicative of at least two of the unknown parameters of the fluid in the evaluation cavity (eg, viscosity and density) is then calculated.

In yet another aspect, the present invention relates to a method for measuring at least two unknown parameters of a fluid in a well pit that penetrates a formation having an unknown fluid. In this method, the fluid communication device of the downhole tool is provided in a state of being in sealing engagement with the wall of the well hole. The fluid is then drawn from the formation into an evaluation cavity in the downhole tool. The fluid data in the evaluation cavity is sampled with a viscometer-density meter having a wire placed in the evaluation cavity and suspended between the two connectors. The wires and connectors are configured to form a frequency oscillator.
In this aspect, the evaluation cavity can be a flow path or a sample chamber. Using data sampled by the viscometer-density meter, at least two parameters can be calculated utilizing the data sampled in the evaluation cavity. The at least two parameters include viscosity and density.

  In yet another aspect, the method can include sampling data for a known fluid in a comparison chamber having a temperature and pressure related to the temperature and pressure of the fluid in the evaluation cavity. In this example, the method generally uses the data sampled from the comparison chamber and the data sampled from the evaluation cavity to calculate at least two parameters of the unknown fluid in the evaluation cavity. Is further included.

In yet another aspect, the invention relates to a computer readable medium that can be provided to or included in an analysis circuit for calculating at least two fluid parameters, such as fluid viscosity and density. In this example, the computer readable medium (1) receives feedback from at least two sensor units in which one sensor unit is placed in a fluid of unknown parameter and the other sensor unit is placed with a fluid of known parameter. Receiving (2) calculating a signal indicative of at least two of the unknown parameters of the fluid in which this one sensor unit is located, and at the same time substantially changing the well well conditions surrounding the sensor unit in the fluid of unknown parameters Includes logic to eliminate. The logic for calculating the signal can include, for example, logic for performing joint inversion of data received from the sensor unit.
In each of the above-described aspects of the present invention, at least two fluid parameters are preferably calculated simultaneously.

  In order that the above features and advantages of the present invention may be more fully understood, a more detailed description of the invention, briefly summarized above, may be had by reference to the embodiments thereof illustrated in the accompanying drawings. . However, since the present invention is capable of accepting other equally effective embodiments, the accompanying drawings show only typical embodiments of the invention and are therefore not to be construed as limiting the scope thereof. Please note that.

  The presently preferred embodiments of the invention are shown in the drawings and are described in detail below. In describing preferred embodiments, similar or identical reference numerals are used to identify common or similar elements. The drawings are not necessarily drawn to scale, and some features and several figures in the drawings may be exaggerated or shown schematically in scale for clarity and accuracy.

Definitions Some terms are defined throughout this description when they are first used, while some other terms used in this description are defined as follows.
"Annular" means a ring, ring-related, or forming a ring, i.e., a line, band, or configuration in the shape of a closed curve, such as a circle or ellipse.
“Contaminated fluid” means a fluid that is not generally acceptable for hydrocarbon fluid sampling and / or evaluation, for example, because the fluid contains contaminants such as filtrate from the mud used during well digging, such as Means gas or liquid.
A “downhole tool” refers to a wellbore by means such as drill strings, wirelines, and coil piping to perform downhole operations related to the evaluation, generation, and / or management of one or more associated underground formations. Means tools deployed in

“Operatively connected” means connected directly or indirectly to transmit or induce information, force, energy, or substance (including fluid).
“Unused fluid” refers to a sufficiently pure, solid, natural, non-polluting or otherwise sufficient to satisfy a given formation for hydrocarbon sampling and / or evaluation useful in the field of fluid sampling and analysis. Means an underground fluid, for example a gas or a liquid.
“Fluid” means either “unused fluid” or “contaminated fluid”.

“Clamp” means a device designed to couple or clamp or compress two or more parts together to securely hold them.
“Connector” means any device or assembly, such as a clamp, for tightly joining or grasping a portion of a wire.
A “frequency oscillator” is a wellbore condition, for example, changes in temperature and pressure, that do not substantially affect the resonant frequency of the stretched wire, and thus are derived from the stretched wire in various wellwell conditions. The resonant frequency (hereinafter referred to as “f ₀ ”) of the tensioned wire in the vacuum can be predicted so that the measured reading is satisfactory to the properties of the fluid interacting with the tensioned wire. It means that there is.

Detailed Description FIG. 1 shows a downhole tool 10 constructed in accordance with the present invention that is suspended from a rig 12 into a well pit 14. The downhole tool 10 can be any type of tool capable of performing formation evaluation, such as excavation, coil piping, or other downhole tools. The downhole tool 10 of FIG. 1 is a conventional wireline tool that is disposed from the rig 12 through the wireline cable 16 into the well 14 and close to the formation F. The downhole tool 10 is equipped with a probe 18 adapted to seal with the wall 20 of the well pit 14 (hereinafter referred to as “wall 20” or “well pit wall 20”), indicated by an arrow. Thus, the fluid is drawn into the downhole tool 10 from the formation F. The backup pistons 22 and 24 help to press the probe 18 of the downhole tool 10 against the well wall 20.

  FIG. 2 shows another example of a downhole tool 30 constructed in accordance with the present invention. The downhole tool 30 of FIG. 2 may be one or more (or itself) of a measurement during drilling (MWD) drilling tool, a logging during drilling (LWD) drilling tool, or other drilling tools known to those skilled in the art. ) Is an excavating tool that can be transported between. The downhole tool 30 is attached to a drill string 32 driven by the rig 12 to form the well pit 14. The downhole tool 30 includes a probe 18 adapted to seal with the wall 20 of the well pit 14 to draw fluid from the formation F into the downhole tool 30 as indicated by the arrows. The viscometer-density meter or sensor unit described below can be used with the downhole tool 10 or the downhole tool 30.

  FIG. 3A is a schematic view of a portion of the downhole tool 10 of FIG. 1 showing the fluid flow system 34. The probe 18 is preferably extended from the housing 35 of the downhole tool 10 for engagement with the well wall 20. The probe 18 is equipped with a packer 36 for sealing with the well wall 20. The packer 36 is in contact with the well pit wall 20 and forms a seal with a mud cake 40 that covers the inside of the well pit 14. The mud cake 40 melts into the well pit wall 20 and creates an intrusion area 42 around the well pit 14. Intrusion area 42 includes mud and other wellbore fluids that contaminate surrounding formations including formation F and a portion of unused fluid 44 contained within formation F.

The probe 18 is preferably provided with an evaluation flow path 46. Examples of fluid communication devices such as probes and double packers for drawing fluid into the flow path are shown in US Pat. Nos. 4,860,581 and 4,936,139.
The evaluation channel 46 extends into the downhole tool 10 and is used to pass a fluid, such as unused fluid 44, through the downhole tool 10 for testing and / or sampling. The evaluation channel 46 extends to a sample chamber 50 that collects a sample of unused fluid 44. With the pump 52, fluid can be drawn into the flow path 46.

Although FIG. 3A shows a sample configuration of a downhole tool used to draw fluid from the formation, various configurations of probes, flow paths, and downhole tools can be used, limiting the scope of the present invention. Those skilled in the art will appreciate that this is not intended.
For example, FIG. 3B is a schematic view of a portion of another version of downhole tool 10 having a correction probe 18a and a fluid flow system 34a for drawing fluid into separate flow paths. More specifically, the fluid flow system 34a shown in FIG. 3B includes a cleaning flow path 46a in addition to the evaluation flow path 46 and pumps 52a and 52b associated with each flow path 46 and 46a. Except for the fluid flow system 34 shown in FIG. 3A. The probe 18a shown in FIG. 3B is similar to the probe 18 shown in FIG. 3A except that the probe 18a has two separate cavities 56a and 56b in which the cavity 56a communicates with the flow path 46 and the cavity 56b communicates with the flow path 46a. And similar. The cavity 56b extends around the cavity 56a such that the cavity 56b draws "contaminated fluid" from the formation F to allow the cavity 56a to draw "unused fluid" from the formation F. The contaminated fluid is discharged from the cleaning flow path 46 a and enters the well pit 14 through the outlet 57. Examples of fluid communication devices such as probes and dual packers used to draw fluid into separate flow paths are described in US Pat. No. 6,719,049 and US Patent Publication assigned to the assignee of the present invention. Application No. 20040004333 and US Pat. No. 6,301,959 assigned to Halliburton.

In accordance with the present invention, the viscometer-density meter 60 (a, b, c) is a downhole tool such as an evaluation channel 46, a cleaning channel 46a, or a sample chamber 50 that measures the viscosity of the fluid in the evaluation cavity. Associated with the evaluation cavity within 10. In the example shown in FIG. 3B, the viscometer-density meter 60 is described with reference numbers 60a, 60b, and 60c for clarity. The viscometer-density meter 60 is shown in more detail in FIGS. 4, 5, and 6.
Also, the downhole tool 30 includes a housing, a probe, a fluid flow system, a packer, an evaluation channel, a cleaning channel, a sample chamber, a pump in a manner similar to the version of the downhole tool 10 shown in FIGS. 3A and 3B. And a viscometer-density meter.

  The evaluation cavity in the evaluation flow path 46 will be described in detail below with reference to FIGS. However, it should be understood that the following description is equally applicable to an evaluation cavity in the cleaning channel 46a or the sample chamber 50. Also, although the viscometer-density meter 60 will be described with respect to the downhole tool 10, it should be understood that such description is equally applicable to the downhole tool 30. 3A and 3B with viscometer-density meter 60 positioned along evaluation channels 46 and 46a, the viscometer-density meter is located at various locations around downhole tool 10 for measuring downhole parameters. 60 can be arranged.

  Generally, the viscometer-density meter 60 includes a sensor unit 62, one or more magnets 64 (a, b), a signal processor 66, and an analysis circuit 68. In the example shown in FIG. 4, the viscometer-density meter 60 is equipped with two magnets designated by reference numerals 64a and 64b in FIG. The sensor unit 62 includes at least two spatially disposed connectors 72 and a viscometer-density meter 60 sensor unit 62 disposed in the downhole tool 10, and the downhole tool 10 is disposed in the underground layer F. Arranged is a wire 74 (FIG. 5) suspended between at least two connectors 72 so that the wire 74 is available for interaction with the fluid when receiving fluid from the formation F. Magnets 64 a and 64 b generate a magnetic field that interacts with a sinusoidal current flowing in wire 74. Signal processor 66 is in electrical communication with wire 74 through signal paths 75a and 75b. The signal paths 75a and 75b can be wires, cables, or air communication links. The signal processor 66 supplies a drive current that forms a sinusoidal current to the wire 74, which typically causes the wire 74 to vibrate or resonate according to the supplied signal. In general, the signal supplied from the signal processor 66 to the wire 74 can be thought of as a constant sweep frequency current signal whose frequency changes in a predetermined manner.

  Analysis circuit 68 receives feedback from wire 74. A sinusoidal current flows through the wire 74 and generates a detectable electromotive force (emf) when the frequency is generally in the lowest order mode close to the resonant frequency. It is the drive voltage and the motion emf that are measured as a function of the frequency at resonance. In general, the analysis circuit 68 receives feedback from the wire 74 indicating the resonant frequency of the wire 74. Depending on the viscosity of the fluid, the resonant frequency of the wire 74 changes in a predetermined manner, which allows a determination of the viscosity of the fluid. A method for determining the viscosity from the feedback from the wire 74 will be described in detail below. The analysis circuit 68 can be any type of circuit that can receive feedback from the wire 74 and calculate the viscosity of the fluid. In general, the analysis circuit 68 will include a computer processor that executes a software program stored on a computer-readable medium, such as a memory or disk, that allows the analysis circuit 68 to calculate viscosity. However, it should be understood that in particular embodiments, the analysis circuit 68 may be implemented using analog or other types of devices. For example, the analysis circuit 68 may include an analog / digital converter and then a decoder that calculates the viscosity of the fluid. Although the analysis circuit 68 and the signal processor 66 are shown separately in FIG. 4, it should be understood that the analysis circuit 68 and the signal processor 66 can be implemented in a single circuit or in separate circuits. Further, although the analysis circuit 68 and the signal processor 66 are shown in FIG. 4 as being in the downhole tool 10, the signal processor 66 and / or the analysis circuit 68 may be located outside the downhole tool 10. You should understand what you can do. For example, the signal processor 66 that generates the sweep signal can be located in the downhole tool 10, while the analysis circuit 68 is located in the monitoring center located near the well well 14 or far away from the well well 14. It is located outside the well pit 14 within.

  The sensor unit 62 of the viscometer-density meter 60 is provided with a housing 76. The housing 76 forms a channel 78 (FIGS. 5 and 6), an inlet 80 that communicates with the channel 78, and an outlet 82 that communicates with the channel 78. In the example shown in FIG. 4, the fluid flows in the direction 84 within the evaluation flow path 46. Thus, when fluid encounters sensor unit 62, fluid exits housing 76 through outlet 82 as it enters channel 78 through inlet 80. In addition, when the housing 76 is provided with an outer dimension smaller than the inner dimension of the evaluation channel 46, a certain amount of fluid is also formed between the outer surface 88 of the housing 76 and the inner surface 89 of the evaluation channel 46. It will pass through the housing 76 in the channel 87 (FIG. 4).

  The wire 74 is disposed in the channel 78 such that the fluid contacts substantially the entire wire 74 between the connectors 72 as the fluid passes through the housing 76. This ensures that the fluid flows over the entire length of the wire 74 between the connectors 72 and facilitates cleaning of the wire 74 between the fluids. The wire 74 is made of a conductive material that can vibrate at a plurality of fundamental mode resonance frequencies (or its harmonics) due to the tension of the wire 74 and the viscosity of the fluid surrounding the wire 74. The wire 74 is preferably made of a material having a large density because the sensitivity increases as the difference between the fluid density and the wire 74 density increases. Also, while the density provides sensitivity to fluid around the wire through the ratio of fluid density to wire density, the wire 74 needs to have a high Young's modulus to provide stable resonance. Various materials can be used for the wire 74. For example, the wire 74 can be composed of tungsten or chromel. When the wire 74 is used to sense a gas such as natural gas, the wire 74 preferably has a relatively smooth outer surface. In this example, chromel is the preferred material for constructing the wire 74.

As shown in FIG. 4, the magnet 64 is preferably disposed outside the evaluation flow path 46 and attached to the outer surface of the evaluation flow path 46. Further, the magnet 64 can be incorporated in the housing 76. Alternatively, the housing 76 can be constructed of a magnetic material.
As shown in FIGS. 5 and 6, the housing 76 can be equipped with a first housing member 90 and a second housing member 92. The first housing member 90 and the second housing member 92 cooperate to form a channel 78. The first housing member 90 and the second housing member 92 are made of a conductive non-magnetic material so that the magnetic field generated by the magnet 64 can interact with the wire 74 without substantial interference from the housing 76. Preferably, it is configured. For example, the first housing member 90 and the second housing member 92 may be composed of a downhole compatible material such as K500 monel, tungsten, or another type of non-magnetic material, such as stainless steel.

  Also, the housing 76 has an insulating layer 96 (see FIG. 5) disposed between the first housing member 90 and the second housing member 92 in order to insulate the first housing member 90 from the second housing member 92. 5) is equipped. Wires 74 extend between opposite sides of the insulating layer 96 to electrically connect the first housing member 90 to the second housing member 92. The insulating layer 96 can be composed of a first insulating layer 98 and a second insulating layer 100. The wire 74 is equipped with a first end 102 and a second end 104. The first insulating layer 98 is disposed near the first end 102 of the wire 74, and the second insulating layer 100 is disposed near the first second end 104 of the wire 74. The wire 74 hooks into the channel 78 and serves to electrically connect the first housing member 90 to the second housing member 92.

  In the example of the sensor unit 62 shown in FIG. 4, each of the first housing member 90 and the second housing member 92 includes a first end portion 108, a second end portion 110, and a first end portion 108. And an intermediate portion 112 between the second end 110 and the second end 110. The first end 108 and the second end 110 are provided with a cross-sectional area or diameter that is smaller than the cross-sectional area or diameter of the intermediate portion 112. Accordingly, each of the first housing member 90 and the second housing member 92 has a shoulder 114 that separates the first end 108 and the second end 110 from the intermediate portion 112. An inlet 80 and outlet 82 are formed in the first housing member 90 and the second housing member 92 near the shoulder 114 so that the channel 78 passes through the intermediate portion 112 of the housing 76. The shoulder 114 is shaped to guide fluid to the inlet 80.

  In order to connect the signal paths 75 a and 75 b to the sensor unit 62, the viscometer-density meter 60 further includes a first terminal 116 coupled to the first housing member 90 and a second housing member 92. A coupled second terminal 118 is provided. Accordingly, signal processor 66 and analysis circuit 68 are in communication with first and second terminals 116 and 118 through signal paths 75a and 75b. It should be noted that signal paths 75a and 75b generally extend through evaluation channel 46 through one or more feedthroughs 120. The feedthrough 120 prevents fluid from passing through the opening formed in the evaluation flow path 46 while at the same time providing a fluid tight seal to allow the signal paths 75a and 75b to extend through the evaluation flow path 46. provide.

  The first terminal 116 and the second terminal 118 can have the same configuration and function. In order to implement the first terminal 116 and the second terminal 118, the first housing member 90 and the second housing member 92 include the first housing member 90 and the first housing member 92. A screw hole 124 formed in either the end 108 or the second end 110 can be provided. In the example shown in FIG. 5, the first housing member 90 and the second housing member 92 are provided with screw holes 124 formed in both the first end portion 108 and the second end portion 110. Yes. 4 to 6, the signal paths 75a and 75b are connected to the first housing member 90 and the second housing member 92 in the first terminal 116 and the second terminal 118, respectively. For this purpose, a threaded fastener 126 is provided.

  The first housing member 90 and the second housing member 92 are connected to each other by any suitable mechanical or chemical type assembly. As shown in FIG. 6, the viscometer-density meter 60 is provided with a plurality of threaded fasteners 130 (FIG. 6) that fix the first housing member 90 to the second housing member 92. It should be noted that the threaded fastener 130 is generally constructed of a conductive material such as steel or aluminum. Also, to prevent the threaded fastener 130 from forming an electrical path between the first housing member 90 and the second housing member 92, the viscometer-density meter 60 includes a threaded fastener 130. A plurality of insulated feedthroughs 132 are provided to insulate each of the first and second housing members 90 and 92 from each other.

  The sensor unit 62 of the viscometer-density meter 60 can be secured in the evaluation flow path 46 by any suitable assembly. It should be understood that the sensor unit 62 can be fixed to prevent longitudinal movement within the evaluation channel 46 and rotational movement within the evaluation channel 46. The signal paths 75a and 75b are preferably provided with sufficient rigidity to prevent the sensor unit 62 from moving in the longitudinal direction and / or rotating in the evaluation flow path 46. Moreover, the movement of the sensor unit 62 in the evaluation flow path 46 can be prevented by using an additional fixing means. For example, the diameter can be shortened on the downstream side of the sensor unit 62 in order to prevent movement of the sensor unit 62 in the evaluation flow path 46 in the length direction.

  As will be appreciated by those skilled in the art, the first housing member 90 and the second housing member 92 cooperate to form a connector 72 when secured together by a threaded fastener 130. The wire 74 is connected and tensioned as follows. The wire 74 is connected at one end. The other end is fed through the second connector 72 but is not tensioned. A mass (not shown) is attached from the end protruding from the loose connector 72. The tension to the wire diameter, and hence the resonance frequency, is determined by the magnitude of the mass suspended from the wire 74 in the earth's gravitational field, and the resonance frequency of about 1 kHz is a 500 g mass suspended by a 0.1 mm diameter wire. Obtainable. Changing the diameter of the wire 74 can change the viscosity range of the measurement object. After about 24 hours, wire 74 clamps the second end to remove mass. This procedure reduces twist in the wire 74. The wire 74 is then heated and cooled to provide a wire with a fairly stable resonance frequency between each thermal cycle, and in the case of the viscometer-density meter 60, the wire 74 resonance frequency is a resonance on the order of 60s. It needs to be stable during the time required to determine the complex voltage as a function of frequency over the range.

  To calculate viscosity, a sinusoidal current is passed through wire 74 in the presence of a magnetic field. The magnetic field is perpendicular to the wire 74, and when a sinusoidal current is present, the wire 74 moves due to the magnetic field. The resulting induced electromotive force (motion emf) or complex voltage is added to the drive voltage. The motion emf can be detected through an analysis circuit 68 having a signal processor including a lock-in amplifier or spectrum analyzer where the drive voltage is offset or zeroed. The wire 74 resonates when the current frequency is near or at the fundamental resonance frequency. The complex voltage is usually measured at frequencies across resonance, and the observations are combined with the solution, wire density, and radius to determine the viscosity for a fluid of known density. The magnitude of the current depends on the viscosity of the fluid and is modified so that an acceptable signal-to-noise ratio is obtained in the detection circuit, a value smaller than 35 mA is commonly used, and the resulting complex motion emf is several microvolts It is. In addition to current magnitude, the diameter of the wire 74 also determines the upper working viscosity, and increasing the wire diameter increases the upper working viscosity. There are other ways to excite and detect wire motion, but none are as convenient as lock-in amplifiers.

  In order to calculate the viscosity and density of the fluid from the feedback received from the wire 74, the analysis circuit 68 operates as follows. The wire 74 is placed in a magnetic field and driven into steady state transverse vibration by passing alternating current through the wire 74. The resulting voltage V generated between the wires consists of two components.

The first term V ₁ results solely from the electrical impedance of the stationary wire, while the second V ₂ results from the motion of the wire when a magnetic field is present. V ₁ is shown below.

In equation (2), f is the frequency at which the wire 74 is driven when a magnetic field is present, while a, b, and c are adjustable parameters determined by regression using experimental results. The parameters a, b, c account for the electrical impedance of the wire and absorb the offset used in the lock-in amplifier to ensure that the voltage signal is detected in the most sensitive range possible. It is also a thing. The second component of V ₂ is given by the instrument solution by:

In Equation (3), Λ is the amplitude, f ₀ is the wire resonance frequency in the vacuum state, Δ ₀ is the internal damping of the wire, β is the additional mass generated from the fluid displaced by the wire, and β ′ is the damping due to the fluid viscosity It is.
The fluid mechanism of the oscillating wire that reveals the additional mass β of the fluid and the viscous resistance β ′ can be represented by:

as well as

  Where k and k 'are given below.

as well as

  In equations (6) and (7), A is a complex quantity shown below.

  here,

In equation (8), K ₀ and K ₁ are modified Bessel functions, and Ω is related to the Reynolds number that characterizes the flow around a cylindrical wire of radius R. In equation (9), fluid viscosity and density are indicated by η and ρ, respectively. Thus, fluid viscosity and density are determined by adjusting the values so that the in-phase and quadrature voltages predicted by equations (1) through (9) match the experimentally determined values over a function of frequency. can do. The frequency range over which data is collected is typically about f _r ± 5 g, where g is the half width of the resonance curve and f _r is the fundamental transverse resonance frequency. Bandwidth selection is not important in electrically perfect devices with high signal-to-noise ratio and zero electrical crosstalk that increases with increasing frequency. However, this is very important when Q {= f / (2g)} becomes 1, which occurs when the bandwidth is increased, which corresponds to an increase in viscosity and the corresponding SN unless the drive voltage is increased. The importance of determining the bandwidth that occurs with the ratio reduction and the measurement is made will become clear below.

  Equations (4) through (9) are obtained by assuming: (1) The radius of the wire 74 is small compared to the length of the wire 74, (2) the compressibility of the fluid is negligible, and (3) the radius of the housing 76 containing the fluid is In comparison, it is large, and (4) the amplitude of vibration is small. In vibrating wire viscometers reported in the literature, the resonant frequency is sensitive to both the wire tension and the density of the fluid surrounding the wire, and this sensitivity to density is often clamped at the top. The mass is then increased by attaching the mass to the lower end and utilizing Archimedes' principle. However, when the density is determined from an alternative source, for example from the equation of state, only the resonant line width need be stable.

In general, a vibrating wire viscometer, such as the viscometer-density meter 60, is an absolute device that theoretically does not need to determine a calibration constant. In practice, however, the physical properties of a portion of the wire 74, such as density and radius, cannot be determined with sufficient accuracy by independent methods. Therefore, these characteristics are usually determined by calibration. To do this, measurements are made both in vacuum and fluids with known viscosities and densities. Δ ₀ is obtained by the former. The wire radius R is the only other unknown variable needed to make a viscosity measurement. Given the viscosity and density of the calibration fluid, a single measurement can determine the wire radius.

1. Solution Correction The complex voltage V generated across the wire 74 consists of V ₁ resulting from the electrical impedance of the wire 74 and V ₂ resulting from the motion of the wire 74 in the presence of a magnetic field (Equation 1). In addition to the contribution due to electrical impedance, V ₁ also contributes to background noise such as electrical crosstalk or other forms of coupling. These interferences create a relatively smooth background over the frequency interval near the resonant frequency of the vibrating wire 74. In order to properly reproduce the measured complex voltage as a function of frequency, an additional frequency dependent parameter is included in equation (2). That is,

  Without taking into account the additional frequency dependent term in equation (10), the measured complex voltage is often not well suited to the solution, resulting in large errors in fluid density and viscosity. . This is especially true for highly viscous fluids.

2. Determination of Fluid Density and Viscosity from Vibrating Wire In order to determine fluid density and viscosity, it is necessary to fit data by solving the vibrating wire 74. The least squares fit method is based on the idea that the optimal characterization of a set of data is to minimize the sum of the squares of the data deviations from the fit model (or solution). The sum of squared deviations is closely related to the goodness-of-fit statistics called chi-square (or χ ² ) below.

Where f _i is the frequency index, D (f _i ) and V (f _i ) are the recorded complex voltage and solution, respectively, and ν is the number of degrees of freedom to fit the N data points. is there. In order to minimize the chi-square measure defined in (11) when finding unknown parameters including fluid density and viscosity, the least square criterion is formulated as follows:

However, “ρ”, “η”, “f ₀ ”, “Λ”, “a”, “b”, “c”, and “d” are unknown parameters. A “Levenberg-Marquardt” algorithm [14] provides a non-linear regression procedure to solve this minimization problem.

Among all unknown parameters, vibration amplitude (ie, Λ) and constants related to stationary wire electrical impedance and other background interferences (ie, a, b, c, and d) are determined by the minimization procedure. Demanded well. However, the fundamental uncertainty between density, viscosity, and f ₀ prevents the correct value of density and viscosity from being sorted by its own fit. To eliminate this basic uncertainty, additional relationships between density, viscosity, and f ₀ are used as constraints in the fitting procedure. Mathematically, the relationship between these variables can be written in the form of a general function.

Alternatively, this relationship can also include additional measurements such as the resonance half width (g) and the resonance frequency (f _r ) that can be derived from the data.

Equations (13)-(14) can be established experimentally through calibration procedures or based on field data. The preferred embodiment of the present invention is a special case of equations (13)-(14), specifically a hyperplane defined by a fixed f ₀ . Retsina et al. (Retsina, T .; Richardson, SM; Wakeham, WA, Applied Science Research, 1987, 43, 325-346, and Retsina, T .; Richardson, SM. As discussed in Wakeham, WA, 1986, 43, 127-158), f ₀ is the wire 74 in a vacuum state that is directly related to the tension acting on the wire 74. It can be designated as the resonant frequency. If f ₀ is known or given, the minimum value search for the hyperplane defined by the fixed f ₀ can be limited.

FIG. 7a shows a flowchart 134 for calculating viscosity and density simultaneously as described above. Initially, as indicated by blocks 134a, b, and c, constants for wire diameter, wire density, and internal damping coefficient, initial estimates for fluid density, viscosity, and resonant frequency f ₀ , as well as constraint G ( The density, viscosity, and resonance frequency f ₀ ) are input to the calculation block 134d. The initial wire response is then calculated as represented by block 134d. The initial wire response can be calculated at in-phase and quadrature voltages.

  Input data as a function of frequency, such as in-phase and quadrature voltages, is received as shown at block 134e, and then is chi-squared based on the difference between the data and the calculated response, as shown at block 134f. calculate. Next, updates of fluid density, viscosity, resonance frequency, and lambda estimates a, b, c, and d are received. Using any of the non-linear regression analysis, updated data can be obtained, as indicated by block 134g. The analysis circuit 68 then applies a convergence test based on the chi-square and update of the estimate (as indicated by block 134h). If the convergence test indicates that the convergence is within a predetermined or acceptable amount, the process branches to stage 134i where the fluid density and viscosity are output. However, if the convergence test indicates that the convergence is outside a predetermined amount, the process returns to step 134d where the wire response is recalculated based on the updated fluid density, viscosity, and resonance frequency, and the convergence test Steps 134d, 134e, 134f, 134g, and 134h are repeated until convergence is within a predetermined amount.

FIG. 7b shows a flow diagram for simultaneously calculating viscosity and density in the same manner as described above with respect to FIG. 7a, except as follows. It should be noted that the steps of FIG. 7b that are identical to FIG. 7a are labeled with the same reference numbers for the sake of clarity.
In the process of calculating the viscosity and density shown in FIG. 7, the sensor unit 62 is tested to determine the resonance frequency f ₀ . To calibrate the sensor unit 62, the sensor unit 62 is placed in an environmental chamber with a known fluid, and then the temperature and pressure are changed so that calibration data is obtained. Thereafter, calibration data is input to the analysis circuit 68, as indicated by block 136b, and the resonance frequency f ₀ is calculated using such calibration data, as indicated by block 136c.

FIG. 8 is a graph showing a chi-square performance surface cut by a fixed f ₀ hyperplane where an overall minimum exists. The graph includes axes F, D, and V. The F axis represents the frequency of f ₀ in Hz. The D axis represents the density of the fluid surrounding the wire 74 in kg / m ³ . The V axis represents the viscosity of the fluid surrounding the wire 74 by cp. The meaning of the shaded portion is a chi-square value, and the dark color is a low chi-square value. The position of the minimum value 137 provides a density and viscosity estimate.

If f ₀ is stable and known within ± 1 Hz, the fluid density can be determined within 3-4% for a wide range of fluids. The error is smaller for dense fluids (1% to 2%). If known within ± 0.5 Hz, the density error will be about 1-2% for a wide range of fluids. The viscosity error is generally smaller than the density error (about 3%) when f ₀ is ± 1 Hz. Similarly, the viscosity error is smaller for dense fluids. To estimate fluid density and viscosity simultaneously, a preferred embodiment requires a sensor unit that forms a frequency oscillator that provides a stable and predictable f ₀ at a variety of different temperatures and pressures. Typical temperature and pressure ranges in the downhole environment are in the range of 50 to 200 ° C. and 2.07 to 172.4 MPa (300 to 25000 psi).

  Another version of the sensor unit 150 used with the viscometer-density meter 60 is shown in FIG. As will be described in more detail below, the sensor unit 150 does not have a conductive first housing member 90 and second housing member 92 separated by an insulating layer 96 in which the sensor unit 150 extends in parallel. The sensor unit 62 is similar in structure and function except that a pair of conductive connectors 152 separated by an insulated flow tube 154 surrounding the wire 156 is provided. The sensor unit 150 will be described in more detail below.

The sensor unit 150 is stable and predictable so that at least two different parameters such as the density and viscosity of the fluid in which the sensor unit 150 is immersed can be calculated simultaneously from the data generated by the sensor unit 150. Form a frequency oscillator that yields f ₀ .
The connector 152 is designated in FIG. 9 by reference numbers 152a and 152b for purposes of clarity. These connectors 152 have the same configuration and function. Accordingly, only the connector 152a will be described below. The connector 152a is equipped with a clamp member 158, a clamp plate 160, and at least one fastener 162 for connecting the clamp plate 160 to the clamp member 158. Clamp member 158 is coupled to flow tube 154 through any suitable mating assembly. For example, as shown in FIG. 9, the clamp member 158 is provided with an end support 166 that fits a predetermined part of the flow tube 154 so that the end support 166 is supported by the flow tube 154. ing. In the version shown in FIG. 9, the flow tube 154 is provided with a neck-down portion 168, and the end support 166 forms a collar arranged to cover the neck-down portion 168. Also, the clamp member 158 is provided with a flange 170 connected to and extending from the end support 166. At least one registration pin 174 is provided on the flange 170 to center the wire 156 on the flange 170. The clamp member 158 is preferably provided with at least two spaced registration pins 174 so that the wire 156 can be threaded between the registration pins 174 as shown in FIG.

The fastener 162 connects the clamp plate 160 to the clamp member 158 in order to fix the wire 156. The fastener 162 can be any type of device that can couple the clamp member 158 to the clamp plate 160. For example, the fastener 162 can be a screw.
The flow tube 154 is preferably composed of a material having a similar coefficient of thermal expansion as the wire 156. When the wire 156 is composed of tungsten, the flow tube 154 can be composed of a ceramic such as “Shapal-M”.

At least one opening 180 is formed in the clamp member 158 to allow fluid to enter and exit the flow tube 154 through the opening 180. As shown in FIG. 9, the clamp member 158 can be provided with at least two openings 108 each having a semicircular shape. However, it should be understood that the shape of the opening 180 may vary depending on the wishes of the designer. More particularly, it should be understood that the opening 180 may have an asymmetrical shape, a symmetric shape, or an unusual shape.
Wire 156 is configured in a similar manner to wire 74 described above. Wire 156 is supported and tensioned in flow tube 154 in a manner similar to that wire 74 is supported and tensioned in housing 76. Signal paths 75a and 75b from signal processor 66 and analysis circuit 68 are coupled to their respective connectors in any suitable manner, such as screws, bolts, or terminals.

As described above, if f _{0 of} sensor unit 150, ie, the resonance in vacuum of equation (1), is stable, both density and viscosity are determined from the complex voltage measured as a function of frequency over the resonance. It is possible. Sensor unit 150 includes two metal connectors 152 separated by a flow tube 154 formed from an insulated material. These materials also have different elastic properties and in some cases thermal properties. The connector 152 and flow tube 154 are preferably held together by the tension of the wire 156 alone.

The sensor unit 150 preferably has f ₀ that is not affected by fluid properties and pressure. The latter may have a small but computable contribution from the compressibility of the wire material. Furthermore, the response of wire 156 to temperature variations, including different coefficients of thermal expansion resulting from the use of different materials in the resonator configuration, should be measurable or calculable. Wire 156 is tensioned by passing a current through it in the presence of a vertical magnetic field and begins lateral movement. These elements suggest that the sensor unit 150 can be improved by eliminating the rotational movement of the wire 156 that would result from the wire 156 having an elliptical cross section, and the sensor unit 150 also allows current to flow through the wire. Each end of the wire 156 should be insulated to allow it to flow.

Although tungsten has a rough surface, Young's modulus E (≈411 GPa) and density ρ _s (≈19,300 kg · m ⁻³ ) are higher than other materials. Preferred material. When the wire 156 is tensioned, the former helps provide a stable resonance, while the latter provides sensitivity to the fluid around the wire 156 through the ratio ρ / ρ _{s of} equations (4) and (5). Is. The influence of the surface roughness can be ignored on condition that the vibration amplitude is small and the Reynolds number is smaller than 100. With respect to density measurement, it is desirable that the wire density tends to the density of the fluid, as derived from the concept of added mass. Thus, tungsten can be used, but other materials having a density lower than tungsten are acceptable depending on the expected density of the fluid being measured.

In order to minimize the effects of different thermal expansions, this choice of wire material determines the materials used for the connector 152, flow tube 154, and tensioning mechanism. Desirably, the mechanical properties of the insulating material forming the flow tube 154 are as close as possible to the materials used for both the wire 156 and the connector 152. For example, the effect of different thermal expansions on wire tension can be reduced by selecting a material that has a linear thermal expansion coefficient comparable to that of tungsten, since the temperature is out of the ambient environment. I will. “Shapal-M”, which is a machinable ceramic having a high thermal expansion coefficient with a compressive strength of 1 GPa, has a linear thermal expansion coefficient α = (1 / L) dL / dT = 5.2 when T = 298K. It has 10 ⁻⁶ K ⁻¹ while α (W, 298 K) ≈4.5 · 10 ⁻⁶ k ⁻¹ . Alternative materials for the insulating material could include either aluminum nitride or “Macor”, although α of these materials is not equivalent to W.

The above criteria make another version of the sensor unit 200 of the vibrating wire viscometer-density meter 60 shown in FIGS. 11 and 12 to reduce f ₀ variations resulting from temperature, pressure, and fluid properties. It was used to do. Sensor unit 200 comprises sensor unit 200 with nearly the same material, such as tungsten, having the same thermal expansion and elasticity characteristics, while at the same time minimizing the rotation of wire 156 and influencing f ₀ resulting from variations in fluid properties. The configuration and the function are similar to those of the sensor unit 150 except that the influence of temperature and pressure is reduced by reducing. A sensor unit 200 shown in FIG. 11 includes a flow tube 208 disposed between two connectors 204 and 206 both made of tungsten and the connectors 204 and 206 on which the wire 202 is held. Wire 202 is rigidly connected to each connector 204 and 206. For example, in the example shown in FIGS. 11 and 12, the wire 202 is electron beam welded (EBW) to each connector 204 and 206.

  Connector 204 includes a boss 212 and a distal portion 214. The boss 212 is coupled to the wire 202 and is designed to prevent the wire 202 from rotating. For example, the boss 212 can be provided with a non-circular cross section, such as a quadrangle, to prevent the wire 202 from rotating. The boss 212 is disposed in a cavity formed in the end portion 214. The boss 212 has a shape that facilitates alignment with the connector 206. The boss 212 can be formed in any suitable shape to facilitate alignment with the connector 206. For example, the boss 212 can include a tapered or conical end to facilitate alignment with the connector 206. The wire 202 can be attached to the boss 212 through any suitable method that secures the wire 202 to the boss 212. For example, the wire 202 can be placed in a slot (not shown) formed in the boss 212 and electron beam welded as described above so that the boss 212 forms a clamp around the wire 202.

  Connector 206 includes end mount 216, boss 218, insulator 220, and adjustment assembly 222 that adjusts the relative position of boss 218 and end mount 216. Boss 218 is coupled to wire 202 in the same manner that boss 212 is coupled to wire 202. Boss 218 is designed to prevent wire rotation. For example, the boss 218 can be provided with a non-circular cross section, eg, a square, to prevent the wire 202 from rotating. The boss 218 is disposed in a cavity 224 formed in the end mount 216.

  Insulator 220 provides electrical isolation between end mount 216 and boss 218. In the embodiment shown in FIGS. 11 and 12, the insulator 220 is formed as a sleeve that lines the cavity 224 in the end mount 216 and extends across the face 226 of the end mount 216. Insulator 220 can be formed of any insulating material that can withstand a downhole environment. For example, it can be made of a ceramic material such as “Shapal-M”.

  The adjustment assembly 222 can be any device that can adjust the relative position between the boss 212 and the end mount 216 to allow adjustment of the tension of the wire 202. For example, the adjustment assembly 222 can include a wire tension nut 230 that is threadedly engaged with the boss 212. Of course, there are many other configurations that can be used to clamp the wire 202 to the housing to allow tensioning of the wire 202. For example, as shown, between two clamps or connectors or the use of a spring.

  As described above, it is desirable that the tensioned vibrating wire 74, 156, or 202 has a resonant frequency that is stable with respect to temperature, pressure, and fluid. A stable resonant frequency essentially meets the requirement of constant wire tension. Although it is plausible to construct a stable oscillator solely from mechanical considerations, the concept of relative measurement provides another solution. One of the viscometer-density meter 60 (designated 60a) is placed in a fluid of unknown viscosity and density, and another of the viscometer-density meter 60 (designated 60b) is a fluid of known viscosity and density. FIG. 13 shows a fragmentary view of another version of the downhole 10a that is similar in construction and function to the downhole 10 described above, except that it has two or more viscometer-density meters 60 disposed therein. Viscometer-density meters 60a and 60b are equipped with magnets 64a and 64b. In this approach, two similar sensor units 250a and 250b are used, one immersed in a fluid with unknown properties, such as density and viscosity, and the other immersed in a fluid with known properties. The sensor units 250a and 250b can be configured in the manner described above for the sensor units 62, 150, or 200 described above.

  The sensor unit 250 a is disposed in the evaluation flow path 252, and the evaluation flow path 252 can be the evaluation flow path 46, the cleaning flow path 46 a, or the sample chamber 50 described above. In the downhole tool 10a, an elbow or joint 254 that is in fluid communication with the flow path 252 is provided. The joint 254 forms a comparison chamber 255 in which a known fluid and sensor unit 250b is placed. The downhole tool 10 a is equipped with a pressure equalizing assembly 256 that equalizes the pressure in the flow path 252. In general, the pressure equalization assembly 256 can be any device that can equalize the pressure between the evaluation channel 252 and the comparison chamber 255. For example, as shown in FIG. 13, the pressure equalization assembly 256 can include a reciprocating piston 258 that moves relative to the comparison chamber 255 to equalize the pressure.

Sensor units 250a and 250b are connected to one or more signal processors 260 and analysis circuitry 262 for supplying drive voltages and for determining one or more fluid parameters such as viscosity and density as described above. The signal processor 260 and analysis circuit 262 are similar in configuration and function to the signal processor 66 and analysis circuit 68 described above.
The ratio of resonance between the sensor units 250a and 250b is determined, for example, as illustrated in FIGS. 14a and 14b. FIG. 14a shows a process 170 for calculating the density and viscosity of the fluid utilizing the two viscometer-density meters 60a and 60b shown in FIG. Process 170 has steps similar to those utilized in FIG. 7a above. For purposes of clarity, similar steps are labeled with the same reference numbers 134a, 134b, 134d, 134e, 134f, 134g, 134h, and 134i and will not be described in detail again.

  In general, the fluid density and viscosity that will enter the comparison chamber 255 are determined by known methods, such as using a “NIST” table, as shown in steps 172 and 174. . The analysis circuit 262 receives the signal from the sensor unit 250b, as shown at step 176, and then calculates the resonant frequency based on the known density and viscosity of the fluid in the comparison chamber 255, as shown at step 178. The analysis circuit 262 then calculates the viscosity and density in the manner described above for FIG. 7A.

Another process for calculating the fluid density and viscosity of the unknown fluid in flow path 252 is shown in FIG. 14b. In process 180, fluid density, viscosity, and lambda initial estimates a, b, c, and d are input to analysis circuit 262, as indicated by blocks 182 and 183. As indicated by block 184, constants such as wire diameter, wire density, and internal attenuation coefficient are input to analysis circuit 262. As indicated by block 186, other inputs such as temperature and pressure at which the sensor unit 250a in the flow path 252 is exposed are input to the analysis circuit 262. Thereafter, input data such as in-phase and quadrature voltages are read from sensor units 250a and 250b, as represented by blocks 188 and 190, and the joint inversion of the data from sensors 250a and 250b is represented as indicated by block 183. calculate. The analysis circuit 262 then outputs the fluid density and viscosity of the fluid surrounding the sensor unit 250a, as indicated by block 192.
Although the above two methods for calculating viscosity and density have been described, it should be understood that any method such as a ratio measurement of the power produced by the two sensor units 250a and 250b could be used. It is.

  Provided that the wires in the sensor units 250a and 250b have a similar configuration (preferably the same configuration) and are exposed to the same temperature and pressure, the instabilities resulting from these variables are eliminated and a stable oscillator. Data indicating that is obtained. When both concepts are combined, i.e., comparison or ratio measurement and the stable geometry described above with respect to sensor units 150 and 200, the resonator is stable and can provide both density and viscosity. What can be done is possible.

  It will be understood from the foregoing description that various modifications and changes may be made in the preferred and alternative embodiments of the present invention without departing from its true spirit. The devices included herein can operate manually and / or automatically to perform a desired task. This operation may be performed as needed and / or based on the generated data, detected conditions, and / or analysis of results from downhaul operations.

  This description is intended to be illustrative only and should not be construed in a limiting sense. The scope of the invention should be determined only by the language of the claims. The term “comprising” in a claim is intended to mean “including at least” such that the recited list of claimed elements is an open group. “A”, “an”, and other singular forms are intended to include the plural forms unless specifically stated otherwise.

FIG. 3 is a schematic partial cross-sectional view of a downhole wireline tool having an internal viscometer-density meter, with the wireline tool suspended from the rig. FIG. 2 is a schematic partial cross-sectional view of a downhole drilling tool having an internal viscometer-density meter with the downhole drilling tool suspended from a rig. FIG. 2 is a schematic view of a portion of the downhole tool of FIG. 1 having a probe registered to the side wall of the wellbore and a viscometer-density meter disposed in an evaluation channel in the downhole tool. FIG. 3 is a schematic view of a portion of another version of the downhole tool of FIG. 1 having a cleaning channel utilized in combination with a double packer. It is a side view of the viscometer-density meter arrange | positioned in the evaluation cavity. It is sectional drawing of the sensor unit of the viscometer-density meter of FIG. 4 which shows the suspended wire. It is a disassembled perspective view of the sensor unit of the viscometer-density meter shown in FIG. 2 is a logic flow diagram illustrating a method for simultaneously calculating viscosity and density. 3 is a logic flow diagram illustrating another method of calculating viscosity and density simultaneously. FIG. 5 is a graph showing a chi-square performance surface cut by a fixed f ₀ hyperplane showing the minimum values used in viscosity and density calculations. It is a disassembled perspective view of another sensor unit of a viscometer-density meter. FIG. 10 is a top view of the sensor unit shown in FIG. 9. It is a side view of another version of a sensor unit. 12 is a cross-sectional view of the sensor unit of FIG. 11 taken along line 12-12 of FIG. Two or more viscometer-density meters, one of which is placed in a fluid of unknown viscosity and density and another of the viscometer-density meter is placed in a fluid of known viscosity and density FIG. 3 is a fragmentary schematic view of another version of a downhole tool having FIG. 14 is a logic flow diagram illustrating a method for simultaneously calculating viscosity and density using the configuration illustrated in FIG. 13. FIG. 14 is a logic flow diagram illustrating another method for simultaneously calculating viscosity and density using the configuration shown in FIG. 13.

Explanation of symbols

10 downhole tool 12 rig 14 well well 18 probe 20 well well wall F geological formation

Claims (24)

A viscometer-density meter for a downhole tool that can be placed in a well bore that penetrates an underground layer, such that the downhole tool conveys at least a portion of the formation fluid to the viscometer-density meter. And
At least two spatially arranged connectors, and suspended in tension between the at least two connectors so that the viscometer-density meter is located in the downhole tool and the downhole tool is in the underground layer A wire that is arranged for receiving fluid from the underground layer and is available for interaction with the fluid;
A sensor unit positionable in the downhole tool, wherein the connector and the wire are configured to form a frequency oscillator;
At least one magnet for generating a magnetic field interacting with the wire;
A viscometer-density meter characterized by comprising:   The viscometer-density meter according to claim 1, wherein the connector and the wire are made of a single type of material.   The viscometer-density meter of claim 1, further comprising means for preventing rotation of the wire relative to the connector.   4. The viscometer-density meter of claim 3, wherein the means for preventing rotation of the wire further comprises a boss having a non-circular cross section connected to the wire.   The viscometer-density meter of claim 1, further comprising an analysis circuit that receives feedback from the wire for calculating at least two parameters of fluid interacting with the wire.   The viscometer-density meter according to claim 5, wherein the two parameters are viscosity and density.   The viscometer-density meter according to claim 1, wherein the connector and the wire are made of a material having a similar coefficient of thermal expansion to form the frequency oscillator. The wire further comprises a flow tube suspended by the connector;
The flow tube, the connector, and the wire are composed of a material having a similar coefficient of thermal expansion to form the frequency oscillator.
The viscometer-density meter according to claim 1. A downhole tool that can be placed in a well pit with a wall and penetrates a subterranean layer with fluid,
A housing enclosing at least one evaluation cavity;
At least one extendable from the housing for sealing engagement with the wall of the wellbore and in communication with the evaluation cavity for receiving fluid from the formation and depositing such fluid in the evaluation cavity A fluid communication device having two inlets;
Viscometer-density meter;
Including
The viscometer-density meter is
At least two spatially disposed connectors, and a wire suspended in tension between the at least two connectors and thereby available for interaction with the fluid in the evaluation cavity;
A sensor unit disposed within the evaluation cavity, wherein the connector and the wire are configured to form a frequency oscillator;
At least one magnet for generating a magnetic field interacting with the wire;
including,
A tool characterized by that.   The downhole tool according to claim 9, wherein the connector and the wire are made of a single type of material.   The downhole tool according to claim 9, further comprising means for preventing rotation of the wire relative to the connector.   The downhaul tool according to claim 11, wherein the means for preventing rotation of the wire further includes a boss having a non-circular cross section connected to the wire.   The downhaul tool of claim 9, further comprising an analysis circuit that receives feedback from the wire to calculate at least two parameters of fluid interacting with the wire.   The downhole tool according to claim 13, wherein the two parameters are viscosity and density.   The downhole tool according to claim 9, wherein the connector and the wire are made of a material having a similar coefficient of thermal expansion to form the frequency oscillator. The wire further comprises a flow tube suspended by the connector;
The flow tube, the connector, and the wire are composed of a material having a similar coefficient of thermal expansion to form the frequency oscillator.
The downhaul tool according to claim 9 characterized by things. A comparison chamber containing a fluid of known characteristics, wherein the downhole condition in the chamber is similar to the downhole condition in the evaluation cavity;
Also provided is a sensor unit in the comparison chamber, whereby one sensor unit disposed in the unknown parameter fluid in the evaluation cavity and a known parameter fluid in the comparison chamber. Including the other sensor unit,
The downhaul tool according to claim 9 characterized by things. A method for measuring at least two unknown parameters of the fluid in a well bore through a formation having an unknown fluid comprising:
Placing the fluid communication device of the downhole tool in sealing engagement with the wall of the wellbore;
Drawing fluid from a formation into an evaluation cavity in the downhole tool;
A viscometer-density meter having a wire disposed in the evaluation cavity and suspended between two connectors, the wire and the connector being configured to form a frequency oscillator. Sampling the fluid data;
A method comprising the steps of:   The method of claim 18, wherein the evaluation cavity is a flow path.   The method of claim 18, wherein the evaluation cavity is a sample chamber.   The method of claim 18, further comprising calculating at least two parameters utilizing data sampled within the evaluation cavity.   The method of claim 21, wherein the at least two parameters include viscosity and density.   The method of claim 18, further comprising sampling data for a known fluid in a comparison chamber having a temperature and pressure related to the temperature and pressure of the fluid in the evaluation cavity.   24. Further comprising calculating at least two parameters of the unknown fluid in the evaluation cavity using data sampled from the comparison chamber and data sampled from the evaluation cavity. The method described in 1.

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