Abstract: A sensing cable includes a pair of sensing fibers that are connected to one another by a U-shaped turnaround section. The turnaround section is a section of sensing fiber coated with a jacket that includes metallic components. The turnaround section is bent and, then, annealed according to a method of the present invention. The turnaround section is robust and reduced in size (i.e., radius). The sensing cable also includes an inner sleeve that surrounds the sensing fibers and an elongated outer armor casing (i.e., including an armor tube and a sealing cap) that encases a terminating end thereof. The armor tube and the sealing cap protect the sensing fiber from mechanical and chemical harm, are reduced in size and facilitate insertion of the sensing cable into downhole environments. The sensing cable has improved operating range up to 300° C.

Abstract: A holographic pressure sensing apparatus includes a first optical fiber with a diffractive element at its end face, and a light-coupling component for receiving from the first optical fiber end face first and second images respectively formed by interaction with the diffractive element of a first light of a first wavelength and a second light of a second wavelength. Displacement of the light-coupling component, toward or away from the first optical fiber end face, will adjust an overlap of the first and second images, such that a change in a measurement of said overlap will indicate a change of the pressure in the fluid surrounding the casing.

Abstract: A sensing cable has a sensing fiber assembly, which includes a pair of sensing fibers joined by a turnaround section with a modal filter, at a terminating end of the sensing fibers. The sensing cable also includes an inner sleeve that surrounds the sensing fiber assembly and an armored casing that caps the terminating end of the inner sleeve. The sensing cable has a low profile and its components are each made of high temperature and hydrogen tolerant materials and are capable of prolonged operation at high temperatures, such as up to 300° C., in hydrogen environments over long lengths of fiber. A distributed thermal sensing (DTS) interrogator is connected to the sensing cable and performs DTS measuring according to protocols and algorithms that leverage the modal filter of the turnaround section to calculate temperature readings along the sensing fiber assembly.

Abstract: A holographic pressure sensing apparatus includes a first optical fiber with a diffractive element at its end face, and a light-coupling component for receiving from the first optical fiber end face first and second images respectively formed by interaction with the diffractive element of a first light of a first wavelength and a second light of a second wavelength. Displacement of the light-coupling component, toward or away from the first optical fiber end face, will adjust an overlap of the first and second images, such that a change in a measurement of said overlap will indicate a change of the pressure in the fluid surrounding the casing.

Abstract: A method for calculating a temperature along a length of a sensing fiber of a distributed thermal sensing (DTS) system. The sensing fiber, which has two ends, is heat resistant for operation up to 300° C. The DTS system includes a two-channel DTS interrogator that is attached to each of the two ends of the sensing fiber. The DTS interrogator interrogates the sensing fiber from both ends, calculates a temperature difference between co-located positions along the length of the sensing fiber for each end, and determines an error associated with the temperature difference. Based on the determined error, a corrected temperature value along the length of the sensing fiber is calculated and outputted.

Abstract: A sensing cable includes a pair of sensing fibers that are connected to one another by a U-shaped turnaround section. The turnaround section is a section of sensing fiber coated with a jacket that includes metallic components. The turnaround section is bent and, then, annealed according to a method of the present invention. The turnaround section is robust and reduced in size (i.e., radius). The sensing cable also includes an inner sleeve that surrounds the sensing fibers and an elongated outer armor casing (i.e., including an armor tube and a sealing cap) that encases a terminating end thereof. The armor tube and the sealing cap protect the sensing fiber from mechanical and chemical harm, are reduced in size and facilitate insertion of the sensing cable into downhole environments. The sensing cable has improved operating range up to 300° C.

Abstract: A method for calculating a temperature along a length of a sensing fiber of a distributed thermal sensing (DTS) system. The sensing fiber, which has two ends, is heat resistant for operation up to 300° C. The DTS system includes a two-channel DTS interrogator that is attached to each of the two ends of the sensing fiber. The DTS interrogator interrogates the sensing fiber from both ends, calculates a temperature difference between co-located positions along the length of the sensing fiber for each end, and determines an error associated with the temperature difference. Based on the determined error, a corrected temperature value along the length of the sensing fiber is calculated and outputted.

Abstract: A sensing cable has a sensing fiber assembly, which includes a pair of sensing fibers joined by a turnaround section with a modal filter, at a terminating end of the sensing fibers. The sensing cable also includes an inner sleeve that surrounds the sensing fiber assembly and an armored casing that caps the terminating end of the inner sleeve. The sensing cable has a low profile and its components are each made of high temperature and hydrogen tolerant materials and are capable of prolonged operation at high temperatures, such as up to 300° C., in hydrogen environments over long lengths of fiber. A distributed thermal sensing (DTS) interrogator is connected to the sensing cable and performs DTS measuring according to protocols and algorithms that leverage the modal filter of the turnaround section to calculate temperature readings along the sensing fiber assembly.

Abstract: A flow monitoring system includes a pipe for transporting a fluid therethrough. An optical fiber generally spirals about the pipe along a longitudinal portion having a predetermined length to serve as a single transducer for detecting flow information from the longitudinal portion. A linear polarizer/analyzer circuit communicates with the optical fiber. A light source communicates with the linear polarizer/analyzer circuit and generates a light signal along the optical fiber at a frequency greater than a period of a disturbance to flow past the predetermined length of the transducer. A reflector is disposed along the optical fiber for reflecting the light signal along the optical fiber. An optical detector communicates with the linear polarizer/analyzer circuit. The optical detector determines from the light signal dynamic events along the optical fiber indicative of flow disturbances passing by the transducer.

Abstract: A flow monitoring system includes a pipe for transporting a fluid therethrough. An optical fiber generally spirals about the pipe along a longitudinal portion having a predetermined length to serve as a single transducer for detecting flow information from the longitudinal portion. A linear polarizer/analyzer circuit communicates with the optical fiber. A light source communicates with the linear polarizer/analyzer circuit and generates a light signal along the optical fiber at a frequency greater than a period of a disturbance to flow past the predetermined length of the transducer. A reflector is disposed along the optical fiber for reflecting the light signal along the optical fiber. An optical detector communicates with the linear polarizer/analyzer circuit. The optical detector determines from the light signal dynamic events along the optical fiber indicative of flow disturbances passing by the transducer.

Abstract: An optical fiber sensor system includes an optical fiber. A linear polarizing component is configured to communicate with the optical fiber. The linear polarizing component includes a polarization sensing fiber to be disposed adjacent to and preferably collinear with the optical fiber. A light source communicates with the linear polarizing component for generating a light signal along the optical fiber. A reflector is disposed along the optical fiber for reflecting back the light signal along the optical fiber. An optical detector communicates with the linear polarizing component. A signal processor communicating with the optical detector and configured for determining from the reflected light signal dynamic events along the optical fiber.

Abstract: An optical fiber strain-temperature sensing system includes first and second optical sources respectively generating first and second light signals having different wavelengths. Optical circulators direct the light signals to an external sensing cable for the respective generation of first and second Brillouin scattered light signals. First and second frequency mixers have a first input respectively coupled to the first and second optical light sources. The optical circulators direct the first and second Brillouin scattered light signals respectively to second inputs of the first and second frequency mixers. First and second transducers are respectively coupled to an output of the first and second frequency mixers and are respectively configured for generating first and second electrical signals indicative of a Brillouin frequency shift of the first and second light signals.

Abstract: A distributed temperature sensing system and method includes an optical sensing waveguide. The optical sensing waveguide is a single mode waveguide having a substantially pure silica core and a large outer diameter. The system further includes an optical instrument optically connected to the optical sensing waveguide. The optical instrument is configured for generating an optical excitation signal along the optical sensing waveguide, and is also configured for receiving a return optical signal indicative of the temperature at one or more locations along the optical sensing waveguide.