Movable filter assembly for downhole spectroscopy

摘要

A downhole fluid analysis tool (10) has a tool housing and a fluid analysis device (30). The tool housing is deployable downhole and has at least one flow passage for a fluid sample. The fluid analysis device (30) is disposed in the tool housing relative to the flow passage. Inside the device (30), one or more sources (32,110,510) generate a combined input electromagnetic signal across a spectrum of wavelengths, and preferably a routing assembly (130) routes generated signals into reference and measurement channels (140,150). Preferably at least one wheel (202,210,220,250) having a plurality of filters (204,212,222) is rotated to selectively interpose one or more of the filters in the paths of the reference and measurement channels (140,150).