Method and apparatus for logging a well using a fiber optic line and sensors
A system and method to log a wellbore, comprising a logging tool adapted to be deployed in a wellbore environment, the logging tool including at least one sensor for taking a measurement of the wellbore environment. The sensor is a fiber optic sensor and the system includes a fiber optic line in optical communication with the sensor. The data measured by the sensor is transmitted through the fiber optic line on a real time basis to the surface, Where the data is processed into a real time display. In one embodiment, the fiber optic sensor is a passive sensor not requiring electrical or battery power. In another embodiment, a continuous tube with one end at the earth's surface and the other end in the wellbore is attached to the logging tool and includes the fiber optic line disposed therein.
1. A fiber optic flow sensor adapted to be disposed in a wellbore, comprising:
a fiber optic line carrying an optical signal;
a spinner adapted to spin when in contact with fluids flowing through the wellbore; and
a modulator functionally connected to the spinner, the modulator modulating the optical signal depending on the spinning of the spinner,
wherein the modulator is located on the spinner and the spinner and modulator are constructed so that the modulator becomes aligned with the fiber optic line once every revolution of the spinner.
2. The system of claim 1 , wherein a pulse is reflected through the fiber optic line each time the modulator becomes aligned with the fiber optic line; and an acquisition unit receives the reflected pulse and determines the velocity of the fluids flowing through the wellbore based on the frequency of reception of the reflected pulses.
3. The sensor of claim 1 , wherein the spinner includes a blade coupled to a disc.
4. The sensor of claim 3 , wherein the blade is located external to a housing of the spinner, and the disc is located internal to the housing.
5. The sensor of claim 4 , wherein the housing is sealed.
6. The sensor of claim 4 , wherein the blade and the disc are magnetically coupled across the housing.
7. The sensor of claim 3 , wherein the modulator is located on the disc.
8. The sensor of claim 7 , wherein the modulator is located at a side of the disc.
9. A fiber optic flow sensor adapted to be disposed in a wellbore, comprising:
a fiber optic line carrying an optical signal;
a spinner adapted to spin when in contact with fluids flowing through the wellbore; and
a modulator functionally connected to the spinner, the modulator modulating the optical signal depending on the spinning of the spinner,
wherein the optical signal is modulated by imparting a strain on the fiber optic line,
wherein the modulator comprises a fiber-bragg grating incorporated on the fiber optic line.
10. The sensor of claim 9 , further comprising:
a permanent magnet coupled to the spinner;
a coil attached to a housing; and
wherein the permanent magnet and the coil become magnetically connected as the spinner revolves.
11. The sensor of claim 10 , wherein the magnetic connection generates a voltage that causes a piezoelectric material mechanically coupled to the fiber optic line to constrict and strain the fiber optic line.
12. A method to calculate the flow of fluids within a wellbore, comprising:
providing a spinner adapted to spin when in contact with fluids flowing through the wellbore; and
modulating an optical signal transmitted through a fiber optic line depending on the spinning of the spinner wherein said modulating step comprises aligning a modulator with the fiber optic line once every revolution of the spinner.
13. The method of claim 12 , further comprising determining the velocity of the fluids flowing through the wellbore based on the frequency of modulations.
14. A method to calculate the flow of fluids within a wellbore, comprising:
providing a spinner adapted to spin when in contact with fluids flowing through the wellbore; and
modulating an optical signal transmitted through a fiber optic line depending on the spinning of the spinner wherein said modulating step comprises imparting a strain on the fiber optic line.
15. The method of claim 14 , wherein the imparting step comprises:
creating a magnetic connection related to the revolution of the spinner; and
generating a voltage that causes a piezoelectric material mechanically coupled to the fiber optic line to constrict and strain the fiber optic line.