Downhole fluid properties analysis probe, tool and method

A downhole fluid properties measuring tool comprising at least one downhole fluid properties optical analysis probe for analyzing at least one property of a multiphase flow mixture flowing in a hydrocarbon well,

• wherein said, at least one optical analysis probe has an elongated cylindrical body shape and comprises:
• an optical tip at one end of the elongated cylindrical body arranged to be in contact with the multiphase flow mixture;
• and
• an optoelectronics module at another end of the elongated cylindrical body arranged to be separated from the multiphase flow mixture and coupled to the optical tip by an optical fiber bundle;
• the optoelectronics module comprising at least one light source arranged to emit electromagnetic radiations in a wavelength range such that reflectance occurs when gas is present at the optical tip and fluorescence occurs when oil is present at the optical tip, at least one reflectance light detector arranged to be responsive to a reflectance light and to provide a reflectance signal and at least one fluorescence light detector arranged to be responsive to a fluorescence light and to provide a fluorescence signal;
• the optical fiber bundle comprising at least one first optical fiber coupling the light source to the optical tip, at least one second optical fiber coupling the optical tip to the reflectance light detector, and at least one third optical fiber coupling the optical tip to the fluorescence light detector, the at least one first, second and third optical fibers being mounted together into a protective tube resistant to downhole conditions.

A production logging tool comprises a central pressure-resistant rigid housing carrying external centralizers adapted for contact with a production pipe wall of a hydrocarbon well and at least one downhole fluid properties optical analysis probe for analyzing at least one property of a multiphase flow mixture flowing in a hydrocarbon well,

• wherein said, at least one optical analysis probe has an elongated cylindrical body shape and comprises:
• an optical tip at one end of the elongated cylindrical body arranged to be in contact with the multiphase flow mixture;
• an optoelectronics module at another end of the elongated cylindrical body arranged to be separated from the multiphase flow mixture and coupled to the optical tip by an optical fiber bundle;
• the optoelectronics module comprising at least one light source arranged to emit electromagnetic radiations in a wavelength range such that reflectance occurs when gas is present at the optical tip and fluorescence occurs when oil is present at the optical tip, at least one reflectance light detector arranged to be responsive to a reflectance light and to provide a reflectance signal and at least one fluorescence light detector arranged to be responsive to a fluorescence light and to provide a fluorescence signal;
• the optical fiber bundle comprising at least one first optical fiber coupling the light source to the optical tip, at least one second optical fiber coupling the optical tip to the reflectance light detector, and at least one third optical fiber coupling the optical tip to the fluorescence light detector, the at least one first, second and third optical fibers being mounted together into a protective tube resistant to downhole conditions;
• and wherein said, at least one optical analysis probe is secured on an inner face of the centralizers deploying arms such as to expose the optical tip to the multiphase fluid mixture flowing in the hydrocarbon well, the optoelectronics module of the downhole fluid properties optical analysis probe being located into said housing, the protective tube extending from the optoelectronics module to the optical tip through a pressure feedthrough into said housing.

A method for analyzing at least one property of a multiphase flow mixture flowing in a hydrocarbon well comprising:

• illuminating the multiphase flow mixture, by means of an optical tip coupled to a light source by a first optical fiber, with electromagnetic radiations in a wavelength range such that reflectance occurs when gas is present at the optical tip and fluorescence occurs when oil is present at the optical tip;
• detecting reflectance by means of a reflectance light detector coupled to the optical tip by a second optical fiber, and simultaneously detecting fluorescence by means of a fluorescence light detector coupled to the optical tip by a third optical fiber and associated with a low pass filter;
• estimating oil holdup, gas holdup, and water holdup based on a comparison between said reflectance and fluorescence detection;
• storing the oil/gas/water holdup estimations;
• and
• repeating the illumination step, the detection step, the estimation step and the storing step at various locations in the hydrocarbon well.