Permanent optical sensor downhole fluid analysis systems

Abstract

Systems for measuring the gas-oil ratio of fluid being produced in a wellbore are provided and generally include an uphole light source which produces a high amplitude near infrared signal at selected wavelengths, an uphole spectrometer, a processor coupled to the spectrometer for making GOR determinations, a plurality of optical cells in contact with wellbore fluid and located along various locations of the wellbore, and a fiber optic system which couples the uphole light source to the “input side” of each of the optical cells, and which couples the “output side” of each of the optical cells to the spectrometer. The light source preferably produces high amplitude NIR light at or around 1.72 microns (an oil peak), 1.67 microns (a methane peak), 1.6 microns (a baseline), and 1.58 microns (a carbon dioxide peak). Various sources are disclosed including tunable sources, diode arrays, and broad band sources. Various embodiments of the fiber optic system are provided including a dual path system, a shared path system, a main fiber line system, and a complimentary (redundant) system. Multicell configurations are provided for each fiber optic system embodiment. In addition, various embodiments of the optical cell are provided including a sampler cell which includes a floating piston which pulls in and pushes out sample fluid, and different probe cells.

Dependencies are inferred from the claim text.