Patent Application
20070272406
So that the manner in which the features and advantages of the present invention, which will become apparent, are attained and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the appended drawings which form a part of this specification. It is to be noted, however, that the drawings illustrate only some embodiments of the invention and therefore are not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.
Referring to
There are many different types of fiber optic temperature and pressure sensors that may be employed with the invention. For example, the fiber optic temperature and pressure sensors may comprise intrinsic sensors that are part of the fiber (e.g., fiber Bragg gratings (FBG), long period gratings (LPG), intrinsic Fabry-Perot interferometers (IFPI), etc.); and/or extrinsic sensors where sensing occurs outside the fiber (e.g., extrinsic Fabry-Perot interferometers (EFPI), intensity-based sensor designs, etc.). The sensors also may comprise point sensors having interaction lengths of, e.g., micrometers to centimeters. In still another alternative, the sensors may comprise distributed sensors, such as distributed temperature sensors (DTS) embodied in one or more fibers in the fiber optic cable and having interaction lengths of, e.g., centimeters to kilometers.
For example, sensors of the EFPI type may be used to monitor strain, temperature, and pressure and are well suited as embedment gauges. FBG sensors monitor strain and temperature, and have excellent multiplexing capability. Distributed and LPG sensors also measure multiple variables, while distributed sensors provide averages over an interaction length with Raman backscattering, OFDR, or Brillouin methods. In addition, the invention may further comprise acoustic and seismic sensors 41 for detecting vibration of the submersible pump 1i and vibration from sources external thereto.
As shown in
In one embodiment, at least one of the fiber optic temperature and pressure sensors 31 is an upper sensor 31a located above the pump 11, and at least one of the fiber optic temperature and pressure sensors is a lower sensor 31b located below the pump 11. In one embodiment, the upper sensor 31a monitors pressure and temperature of fluid transmitted to the surface 23, and the lower sensor 31b is integral with the pump 11 (e.g., the motor of the pump) and monitors motor temperature. In one embodiment, the lower sensor 31b is adjacent motor end turns of the motor within oil in the motor, such that pressure measured by the lower sensor 31b is a pressure of the well at a seal at a depth of the motor oil. In addition, the lower sensor 31b can support the weight of the well tubing and supporting rods for the fiber optic temperature and pressure sensors.
Referring now to
Referring now to
The method may further comprise monitoring pressure with a Fabry-Perot sensor, monitoring temperature and strain with a Bragg-Grating sensor, and monitoring temperature with a distributed temperature sensor embodied in the fiber optic cable. The method also may further comprise monitoring vibration of the submersible pump and vibration from seismic sources that are external to the submersible pump with acoustic and seismic sensors. In addition, step 105 may comprise providing the fiber optic cable with a multi-mode fiber and two single-mode fibers, permitting formation of a profile of temperature gradients from the submersible pump down through perforations of the well with the multi-mode fiber, and transmitting light to discrete fiber optic temperature and pressure sensors with the single-mode fibers.
In another embodiment, the method may further comprise integrating one of the fiber optic temperature and pressure sensors with the submersible pump to monitor a temperature thereof, and further comprising locating a fiber optic temperature and pressure sensor above the submersible pump to define an upper sensor, and monitoring pressure and temperature of fluid transmitted to a surface of the well with the upper sensor. Alternatively, when the submersible pump is an electrical submersible pump (ESP) having a motor, the lower sensor is adjacent motor end turns of the motor within oil in the motor, and measuring pressure with the lower sensor at a seal at a depth of the motor oil, and supporting a weight of well tubing and supporting rods for the fiber optic temperature and pressure sensors with the lower sensor.
While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.
