Baker Hughes Corporation

Valeri Papanyan

Volker Krueger

John W Harrell

Ronald Gene Bland

John Barton Weirich

Hatem N Nasr

William W Smith, Jr

A formation fluid analysis tool has an optical probe that is inserted into the formation. The optical probe carries an internal reflectance crystal and is inserted into the formation so as to get past the mud cake, the flushed zone and the invaded zone and thus be in contact with virgin formation fluid. An acousto-optical tunable filter (AOTF) transmits a single wavelength of light from a broad band light source, the wavelength being controlled by a microwave signal from a processor. This monochromatic light is carried by an optic fiber to the internal reflectance crystal where it undergoes total reflection at the crystal faces in contact with the formation fluid. An evanescent wave propagates into the fluid with a depth of penetration related to the absorption of the light in the fluid. The reflected light carries information about this absorption which is determined by the chemical composition of the fluid. A return fiber conveys the reflected light back to a spectrometer. A processor determines the absorption at the wavelength of the monochromatic light by comparing the energy in the reflected light to the energy in the incident light. By repeating this process at a number of different wavelengths, the absorption spectrum of the fluid is determined. Principal component analysis or least squares analysis of this absorption spectrum using known absorption spectra of constituents likely to occur in the fluid gives the composition of the fluid in terms of these constituents.

Optical probe for analysis of formation fluids

The present invention provides a drilling system for drilling oilfield boreholes or wellbores utilizing a drill string having a drilling assembly conveyed downhole by a tubing (usually a drill pipe or coiled tubing). The drilling assembly includes a bottom hole assembly (BHA) and a drill bit. The bottom hole assembly preferably contains commonly used measurement-while-drilling sensors. The drill string also contains a variety of sensors for determining downhole various properties of the drilling fluid. Sensors are provided to determine density, viscosity, flow rate, clarity, compressibility, pressure and temperature of the drilling fluid at one or more downhole locations. Chemical detection sensors for detecting the presence of gas (methane) and H,S are disposed in the drilling assembly. Sensors for determining fluid density, viscosity, pH, solid content, fluid clarity, fluid compressibility, and a spectroscopy sensor are also disposed in the BHA. Data from such sensors may is processed downhole and/or at the surface. Corrective actions are taken based upon the downhole measurements at the surface which may require altering the drilling fluid composition, altering the drilling fluid pump rate or shutting down the operation to clean wellbore. The drilling system contains one or more models, which may be stored in memory downhole or at the surface. These models are utilized by the downhole processor and the surface computer to determine desired fluid parameters for continued drilling. The drilling system is dynamic, in that the downhole fluid sensor data is utilized to update models and algorithms during drilling of the wellbore and the updated models are then utilized for continued drilling operations.

Drilling systems with sensors for determining properties of drilling fluid downhole

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Houston, TX, United States of America

Valeri Papanyan