BigPatents India

The present invention provides a drilling system for drilling oilfield boreholes or wellbores utilizing a drill string having a drilling assembly conveyed downbole 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 downbole locations. Chemical detection sensors for detecting the presence of gas (methanc) and H2S are disposed in the drilling assembly. Sensors for determining fluid density, viscosity, pH, solid content, fluid clarity, fluid compressîbility, and a spectroscopy sensor are also disposed in the BHA. Data from sucb 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 tbe drilling fluid composition, altering the drilling fluid pump rate or sbutting down tbe operation to clean wellbore. Tbe drilling system contains one or more models, which may be stored in memory downhole or at the surface. These models are utilized by tbe downhole proccssor 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.