Abstract: Methods and systems that provide ways to detect the hydrocarbon flow while eliminating the hydrogen darkening effect in the downhole environment by separated strain and temperature measurement. The methods and systems use fiber optic sensing cables for real-time detection of hydrocarbon fluids (oil, gas, condensate or combination) in oil and gas wells, for example in cemented annuli between either a rock formation and a casing string, or between a larger diameter casing string and a smaller diameter casing string, or in a cement plug left in the well upon abandonment. Hydrogen darkening-resistant temperature and strain sensing fiber optic cables can be used in conjunction with hydrocarbon sensitive polymers to monitor hydrocarbon migration in the oil and gas well and/or to identify the zone(s) from which the hydrocarbons are flowing.

Abstract: Methods and systems that provide ways to detect the hydrocarbon flow while eliminating the hydrogen darkening effect in the downhole environment by separated strain and temperature measurement. The methods and systems use fiber optic sensing cables for real-time detection of hydrocarbon fluids (oil, gas, condensate or combination) in oil and gas wells, for example in cemented annuli between either a rock formation and a casing string, or between a larger diameter casing string and a smaller diameter casing string, or in a cement plug left in the well upon abandonment. Hydrogen darkening-resistant temperature and strain sensing fiber optic cables can be used in conjunction with hydrocarbon sensitive polymers to monitor hydrocarbon migration in the oil and gas well and/or to identify the zone(s) from which the hydrocarbons are flowing.

Abstract: A string of interconnected strain sensors applied to a cylindrical object for monitoring deformation of the object. The string of interconnected strain sensors is applied in a selected zig-zag pattern. A possibility is to drape a pliable support structure around the object, to which the the string of strain sensors has been mechanically coupled in the selected zig-zag pattern.