Abstract: A description of a cable for connection to sensors permanently downhole is provided, the cable comprising a plurality of elongate conductors capable of operative connection to sensors, a sheath surrounding the elongate conductors and holding the conductors so as to extend substantially parallel to an elongate axis, wherein the sheath has a cross-section, perpendicular to the direction of the elongate axis, which has a major dimension and a minor dimension. The cross-section of the cable is thus flattened and can be in the shape of an ellipse, a crescent or comprise a circle with wing-like portions attached on opposite sides of the circle. The sheath is made from a resilient material, so as to provide a robust outer surface of the cable which ensures the cable can be placed downhole without breaking. A number of the elongate conductors are grouped together and inter-weaved in a helical arrangement, so as to reduce electrical cross-talk between the conductors.

Abstract: Single point optical probes for measuring three-phase characteristics of fluid flow in a hydrocarbon well and methods of processing signals generated by the probe are disclosed. A single fiber optic probe is coupled to a light source and apparatus for detecting reflectance and fluorescence. Light is delivered to the tip of the probe where it exits the probe and illuminates the liquid ambient the probe tip or is internally reflected in the probe when gas is located at the probe tip. If the fluid at the probe tip is oil, the light exits the probe, illuminates the oil, and causes the oil to fluoresce. According to one signal processing method of the invention, the reflectance signal is binarized at a threshold to provide a gas/liquid quasi-binary signal which changes over time. A time fraction of the signal values is used to calculate the gas holdup.

Abstract: Single point optical probes for measuring three-phase characteristics of fluid flow in a hydrocarbon well and methods of processing signals generated by the probe are disclosed. A probe having a single fiber optic is coupled to a light source and apparatus for detecting reflectance and fluorescence. Light is delivered to the tip of the probe where it either is internally reflected in the probe or exits the probe and illuminates the fluid (liquid) ambient the probe tip. If the fluid at the probe tip is oil, the light exits the probe, illuminates the oil, and causes the oil to fluoresce. If the fluid is water, no fluorescence occurs. If the fluid is gas, at least some light is internally reflected in the probe. A detection system including at least one beam splitter and fluorescence and reflectance detectors is provided in conjunction with the probe. Preferably, the fluorescence detector is coupled to the fiber optic by a wavelength division multiplexer.

Abstract: Single point optical probes for measuring three-phase characteristics of fluid flow in a hydrocarbon well and methods of processing signals generated by the probe are disclosed. A single fiber optic probe is coupled to a light source and apparatus for detecting reflectance and fluorescence. Light is delivered to the tip of the probe where it either exits the probe and illuminates the liquid ambient the probe tip or is internally reflected in the probe when gas is present at the probe tip. If the fluid at the probe tip is oil, the light exits the probe, illuminates the oil, and causes the oil to fluoresce. Signal processing methods for determining holdup are disclosed. According the invention, a method for determining continuous phase velocities includes injecting a fluorescent dye into the fluid at a measured distance upstream of a probe. The time between injection and detection of the dye is used to calculate average continuous phase velocity.

Abstract: After an oil well has been drilled, lined and cased, and is producing, it may be desirable in situ (either at the wellhead or downhole) to measure, and log (record), the rate at which fluid, and its several distinct components, is flowing out of the geological formations through which the bore has been drilled and is passing into and up the casing. A useful type of detector system for this purpose is an optical probe (31), and the invention proposes a novel design of probe which has a doubly-angled tip, there being measured the light totally internally reflected at the interface (37), which depends on the ratio of the refractive indices of the probe tip and fluid component in which it is immersed.