Downhole fluid properties optical analysis probe having a removable optical tip

An optical tip of a downhole fluid properties optical analysis probe installation method, said optical analysis probe comprising an optical tip partially mounted into a protective tube resistant to downhole conditions letting a distal end of the optical tip in contact with a multiphase flow mixture and coupled to an optical link mounted into the protective tube at the other end of the optical tip through a removable and watertight coupling being welds free and O-ring seal free, the protective tube comprising a first portion and a second portion, the first portion enclosing the optical link and comprising at least one first ring bulge close to a coupling zone, the second portion partially enclosing the optical tip and comprising at least one second ring bulge close to the coupling zone, wherein facing ends of the first portion and the second portion are surrounded by a coupling tube that is adjusted in size to fit in between said first and second ring bulges, and wherein a coupling and protecting sheath encloses said first ring bulge, said coupling tube and said second ring bulge, said sheath being configured so that during use, the effect of pressure of the multiphase flow mixture flowing in the hydrocarbon well tends to apply said sheath onto the first and second ring bulges and the coupling tube such as to additionally seal the protective tube against the optical tip and against the optical link, the installation method comprising:

• plugging facing ends of the first portion and the second portion into the coupling tube, and coupling together the optical link and the optical tip;
• sliding the coupling and protecting sheath from the optical tip towards the coupling zone so as to cover said first ring bulge, said coupling tube and said second ring bulge;
• and
• heating around the coupling and protecting sheath at least up to a temperature that causes shrinking of a heat shrink/retractable material forming the coupling and protecting sheath such as to generate a sealing.

An optical tip of a downhole fluid properties optical analysis probe replacement method, said optical analysis probe comprising an optical tip partially mounted into a protective tube resistant to downhole conditions letting a distal end of the optical tip in contact with a multiphase flow mixture and coupled to an optical link mounted into the protective tube at the other end of the optical tip through a removable and watertight coupling being welds free and O-ring seal free, the protective tube comprising a first portion and a second portion, the first portion enclosing the optical link and comprising at least one first ring bulge close to a coupling zone, the second portion partially enclosing the optical tip and comprising at least one second ring bulge close to the coupling zone, wherein facing ends of the first portion and the second portion are surrounded by a coupling tube that is adjusted in size to fit in between said first and second ring bulges, and wherein a coupling and protecting sheath encloses said first ring bulge, said coupling tube and said second ring bulge, said sheath being configured so that during use, the effect of pressure of the multiphase flow mixture flowing in the hydrocarbon well tends to apply said sheath onto the first and second ring bulges and the coupling tube such as to additionally seal the protective tube against the optical tip and against the optical link, the replacement method comprising:

• cutting and discarding the coupling and protecting sheath;
• disconnecting and discarding the optical tip from the optical link;
• plugging facing ends of the first portion and the second portion into the coupling tube, and coupling together the optical link and a replacement optical tip;
• sliding a replacement coupling and protecting sheath from the replacement optical tip towards the coupling zone so as to cover said first ring bulge, said coupling tube and said second ring bulge;
• and
• heating around the replacement coupling and protecting sheath at least up to a temperature that causes shrinking of a heat shrink/retractable material forming the replacement coupling and protecting sheath such as to generate a sealing.