Downhole pressure transmitter

Abstract

A downhole pressure transmitter apparatus and method of making the same. A pressure fitting can be provided in association with a tube formed into a spiral shape. One end of said tube is sealed and the other end of said tube is affixed to said pressure fitting. As the tube is exposed to a differential pressure, said tube unwinds, thereby creating a rotary motion that is proportional and linear to said differential pressure sensor, thereby providing an indication of pressure within a downhole environment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.

FIG. 1 illustrates a typical drilling operation in which a downhole pressure transmitter apparatus may be adapted for use, in accordance with one embodiment;

FIG. 2 illustrates a side sectional view of a downhole pressure transmitter apparatus, which can be implemented in accordance with a preferred embodiment;

FIG. 3 illustrates a top sectional view of the downhole pressure transmitter apparatus depicted in FIG. 2 in accordance with a preferred embodiment;

FIG. 4 illustrates a two-dimensional cross-sectional view of a downhole pressure transmitter apparatus, which can be implemented in accordance with an alternative embodiment; and

FIG. 5 illustrates an isometric view of the downhole pressure transmitter apparatus depicted in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment of the present invention and are not intended to limit the scope of the invention.

FIG. 1 illustrates a typical drilling operation in which a downhole pressure transmitter apparatus can be adapted for use, in accordance with one embodiment. As depicted in FIG. 1, a well bore 20, which may be open or cased, is generally disposed below a drilling rig 17. A drill string 19 with a drilling assembly 35 connected to the bottom, is disposed within the well 20, forming an annular flow area 18 between the drill string 19 and the well 20. On the surface, a mud pump (not shown) can be utilized to draw drilling fluid from the fluid reservoir (not shown) and pumps the fluid into the pump discharge line 37, along path 4. The circulating fluid flows, as shown by the arrows, into the drilling rig standpipe 16, through the drill string 19, and returns to the surface through the annulus 18. After reaching the surface, the circulating fluid is returned to the fluid reservoir via the pump return line 22.

The configuration depicted in FIG. 1 makes use of a downhole assembly 35 that communicates with a valve 41. Fluid can be pumped down the drill string 19. A momentary restriction may cause a pressure increase which is detectable by a pressure sensor. The configuration depicted in FIG. 1 represents one of many possible downhole drilling configurations in which the embodiments described herein can be implemented and is not considered a limiting feature of the present invention. For example, embodiments can be implemented in the context of other types of drilling operations, such as directional drilling operations.

FIG. 2 illustrates a side sectional view of a downhole pressure transmitter apparatus 200, which can be implemented in accordance with a preferred embodiment. FIG. 3 illustrates a top sectional view of the downhole pressure transmitter apparatus 200 depicted in FIG. 2 in accordance with a preferred embodiment. Note that in FIGS. 2-3, identical or similar parts or elements are generally indicated by identical reference numerals. The downhole pressure transmitter apparatus can be located, for example, within or in association with the downhole assembly 35 illustrated in FIG. 1, and can be utilized to measure hydraulic pressures for downhole drilling equipment.

The downhole pressure transmitter apparatus 200 generally includes a pressure fitting 202, which can be connected to or in communication with a spiral shaped tube 210 located within a housing 203. A calibration window 204 can be provided in association with the housing 203 in order to permit calibration of the downhole pressure transmitter apparatus 200. A sensing element 206 can be encased by or connected to the housing 203. A plurality of lead wires can extend from housing 203 and may communicate electrically with the sensing element 206. A connector 208 can also be provided, which can be utilized to connect the downhole pressure transmitter apparatus 200 to another device or unit, such as, for example the downhole assembly 35 illustrated in FIG. 1.

The tube 210 can be provided as a hollow tube, referred to as a Bourdon tube, and can be formed into a spiral shape. In general, a Bourdon Tube is a pressure measurement device and can be used in applications where relatively static pressure measurements are needed. A typical Bourdon tube contains a curved tube that is open to external pressure input on one end and is coupled mechanically to an indicating needle on the other end.

One end of the tube 210 is sealed and the other end is affixed to the pressure fitting 202. As the tube 210 is exposed to a pressure differential (i.e., between the pressure inside the tube 210 and outside the tube 210), the tube 210 unwinds, thereby creating a rotary motion. The tube 210 thus forms a coil. The rotary motion of the coil is proportional and linear to the pressure differential. The rotary motion can be captured using one of a number potential measurement technologies (e.g., RVDT, Potentiometer, Hall Effect, Magnetoresistive, Optical, Fiber Optic, etc.). For example, the sensing element 206 can function as a measurement device, such as an RVDT device, an RVR device, a Hall Effect sensor, a magnetoresistive sensor, or a fiber optic based sensor, depending upon design considerations.

An Rotational Variable Differential Transformer (RVDT) device is a sensor that can be used to measure rotational angles. One example of a Hall effect sensor that may be implemented in accordance with one potential embodiment is disclosed in U.S. Pat. No. 7,002,229, entitled “Self Aligned Hall With Field Plate,” which issued to Isaac D. Cohen on Feb. 21, 2006. U.S. Pat. No. 7,002,229 is assigned to Honeywell International Inc. of Morristown, N.J., and is incorporated herein by reference. An example of a magnetoresistive sensor and/or Hall Effect sensor, which can also be adapted for use in accordance with one or more embodiments, is disclosed in U.S. Pat. No. 6,759,843, entitled “Sensing Methods and Systems for Hall and/or MR Sensors,” which issued to Gregory R. Furlong on Jul. 6, 2004. U.S. Pat. No. 6,759,843 is assigned to Honeywell International Inc. of Morristown, N.J., and is incorporated herein by reference,

The downhole pressure transmitter apparatus 200 offers a number of advantages and benefits. For example, apparatus 200 provides for media isolation, in that it isolates the measurement media from the sensing element 206. Apparatus 200 also offers high-temperature performance capabilities because it does not utilize silicon based electronics. The temperature range is limited only by the yield stress vs. temperature of the Bourdon Tube 210 and the limitations of the rotary sensing technology. Apparatus 200 additionally offers a flexible output format due to its inherent failure detection capabilities. Because apparatus 200 does not use silicon based electronics, the number of failure modes are dramatically reduced. The remaining failure modes such as broken or shorted wires can be detected and the monitoring system can respond accordingly.

FIG. 4 illustrates a two-dimensional cross-sectional view of a downhole pressure transmitter apparatus 400, which can be implemented in accordance with an alternative embodiment. FIG. 5 illustrates an isometric view of the downhole pressure transmitter apparatus 400 depicted in FIG. 4 in accordance with an alternative embodiment. Note that the configuration depicted in FIGS. 4-5 is similar to that depicted in FIGS. 1-3, the difference being that apparatus 400 utilizes a Bourdon tube 402 that is wrapped around the sensing element 406. Apparatus 400 generally includes a pressure fitting 402 similar to that of the configuration of FIG. 1-3. The configuration depicted in FIGS. 4-5 is, however, more compact than the configuration depicted in FIGS. 1-3 and is applicable across a number of different industrial, commercial and consumer applications.

It is contemplated that the use of the present invention can involve components having different characteristics. It is intended that the scope of the present invention be defined by the claims appended hereto, giving full cognizance to equivalents in all respects.

Claims

1. A downhole pressure transmitter apparatus, comprising; a housing;a nonsilicon based sensing element maintained within said housing;a pressure fitting connected to said housing; anda tube formed into a spiral shape, wherein one end of said tube is sealed and another end of said tube is affixed to said pressure fitting, wherein as said tube is exposed to a differential pressure, said tube unwinds, thereby creating a rotary motion that is proportional and linear to said differential pressure, thereby providing an indication of pressure within a downhole environment.

2. The apparatus of claim 1 wherein said tube comprises a Bourdon tube.

3. The apparatus of claim 1 further comprising a calibration window in said housing.

4. The apparatus of claim 1 wherein said rotary motion is captured utilizing said sensing element.

5. The apparatus of claim 4 wherein said sensing element comprises an RVDT device.

6. The apparatus of claim 4 wherein said sensing element comprises a Hall Effect sensor.

7. The apparatus of claim 4 wherein said sensing element comprises a magnetoresistive sensor.

8. The apparatus of claim 4 wherein said sensing element comprises a fiber optic based sensor.

9. The apparatus of claim 4 wherein said Bourdon tube is wrapped around said sensing element.

10. A downhole pressure transmitter apparatus, comprising; a housing;a nonsilicon based sensing element maintained within said housing;a pressure fitting connected to said housing; anda bourdon tube formed into a spiral shape, wherein one end of said bourdon tube is sealed and another end of said bourdon tube is affixed to said pressure fitting, wherein as said bourdon tube is exposed to a differential pressure, said bourdon tube unwinds, thereby creating a rotary motion that is proportional and linear to said differential pressure wherein said rotary motion is captured by said sensing element, thereby providing an indication of pressure within a downhole environment.

11. The apparatus of claim 10 wherein said sensing element comprises an RVDT device.

12. The apparatus of claim 10 wherein said sensing element comprises a Hall Effect sensor.

13. The apparatus of claim 10 wherein said sensing element comprises a magnetoresistive sensor.

14. The apparatus of claim 10 wherein said sensing element comprises a fiber optic based sensor.

15. A method for forming a downhole pressure transmitter apparatus, comprising: providing a nonsilicon based sensing element within a housing;providing a pressure fitting connected to said housing; andconfiguring a tube into a spiral shape;sealing one end of said tube;affixing another end of said tube to said pressure fitting, wherein as said tube is exposed to a differential pressure, said tube unwinds, thereby creating a rotary motion that is proportional and linear to said differential pressure sensor, thereby forming a downhole pressure transmitter apparatus that provides an indication of pressure within a downhole environment.

16. The method of claim 15 wherein said tube comprises a Bourdon tube.

17. The method of claim 15 further comprising providing a calibration window in said housing.

18. The method of claim 15 further comprising providing said sensing element for capturing said rotary motion.

19. The method of claim 15 wherein said downhole environment comprises a drilling environment.

20. The method of claim 18 further comprising wrapping said tube about said sensing element.