Apparatus and method for evaluating downhole fluids

1. An apparatus for evaluating downhole fluids comprising:

an environmental sensor configured to estimate one or more downhole environmental parameters in a borehole environment;

an optical block having an adjustable opening that receives electromagnetic energy emitted by an electromagnetic energy source;

a controller operatively associated with the optical block for adjusting the opening size, wherein the opening size is adjusted based on a signal from the environmental sensor, the signal indicative of the one or more estimated downhole environmental parameters; and

an electromagnetic energy sensor that receives the electromagnetic energy emitted by the electromagnetic energy source after the emitted electromagnetic energy interacts with a downhole fluid.

2. An apparatus according to claim 1 , wherein the opening is a slit, and the opening size is a slit width.

3. An apparatus according to claim 1 , wherein the controller is configured to estimate the one or more environmental parameters and adjust the opening size based on a signal-to-noise ratio associated with the one or more environmental parameters.

4. An apparatus according to claim 1 , wherein the estimated downhole environmental parameter includes a temperature.

5. An apparatus according to claim 1 , wherein the estimated downhole environmental parameter includes pressure, temperature, phase, flow rate, content, cleanliness, vibration, acceleration, position and any combination thereof.

6. An apparatus according to claim 1 , wherein the controller is disposed at a surface location, at a downhole location, or is distributed among a plurality of locations.

7. An apparatus according to claim 1 , wherein estimated parameters include substantially real-time estimated parameters.

8. An apparatus according to claim 1 , wherein the controller provides substantially autonomous control of the opening size adjustment.

9. An apparatus according to claim 1 , wherein the optical block includes a MEMS structure, the adjustable opening being adjustable by controlling the MEMS structure.

10. An apparatus according to claim 1 , further comprising an actuator operably associated with the optical block and the controller, wherein the actuator adjusts the opening size in response to a signal from the controller.

11. An apparatus according to claim 10 , wherein the actuator includes a piezoelectric motor, a mechanical actuator, an electro-mechanical actuator or a combination thereof.

12. An apparatus according to claim 1 , wherein the electromagnetic energy source includes one of a broadband source, a narrow band source, a laser diode, and an LED.

13. An apparatus according to claim 1 , wherein the electromagnetic energy source includes a near infrared light source.

14. An apparatus according to claim 1 , wherein the electromagnetic energy sensor includes one or more of a photodetector and a photosensitive array.

15. An apparatus according to claim 1 , wherein the environmental sensor includes a fluid sensor.

16. An apparatus according to claim 1 , further comprising a grating receiving electromagnetic energy from the adjustable opening, the grating being operable to separate the received electromagnetic energy into a plurality of spectra.

17. An apparatus according to claim 16 , wherein the grating comprises a tunable grating.

18. A method for evaluating downhole fluids comprising:

emitting electromagnetic energy toward an optical block having an adjustable opening;

estimating one or more downhole environmental parameters via an environmental sensor disposed in a borehole environment;

adjusting the opening size based on a signal from the environmental sensor, the signal indicative of the one or more estimated downhole environmental parameters using a controller; and

receiving, with an electromagnetic energy sensor, electromagnetic energy emitted by the electromagnetic energy source after the emitted electromagnetic energy interacts with a downhole fluid.

19. A method according to claim 18 , wherein estimating one or more downhole environmental parameters includes using an output signal from the electromagnetic energy sensor, using an output signal from one or more fluid property sensors, or any combination thereof.

20. A method according to claim 18 , wherein the estimating one or more downhole environmental parameters includes estimating an intensity detected by the sensor, includes estimating a signal-to-noise ratio, estimating a temperature, estimating a fluid content or any combination thereof.

21. A method according to claim 18 , wherein estimating the one or more parameters includes estimating the parameters in substantially real-time.

22. A method according to claim 18 , wherein adjusting the opening size comprises substantially autonomous control by the controller.

23. A method according to claim 18 , wherein adjusting the opening size includes using a piezoelectric motor, a mechanical actuator, an electro-mechanical actuator or a combination thereof.

24. A method according to claim 18 , wherein emitting electromagnetic energy includes using a broadband source, a near infrared light source, a narrow band source, a laser diode, an LED or combinations thereof.

25. A method according to claim 18 , wherein adjusting includes adjusting the opening size based on a signal-to-noise ratio associated with the one or more environmental parameters.

26. A method according to claim 18 , further comprising receiving electromagnetic energy from the adjustable opening with a grating and separating the received electromagnetic energy into a plurality of spectra.

27. A method according to claim 26 , wherein the grating comprises a tunable grating.

28. An apparatus according to claim 1 , wherein the controller is configured to automatically adjust the opening size in response to the signal from the environmental sensor.

29. A method according to claim 18 , wherein the opening size is automatically adjusted in response to the signal received by the controller from the environmental sensor.