Sammendrag
Over the past couple of decades efforts have been made in automating sensors for drilling fluid management on the rig. Such sensors make possible better continuous management of the drilling fluid, and as a consequence better control of the drilling process. Of particular concern are HPHT operations, where control of the fluids properties in the well, such as density and rheology, is critical in achieving a successful drilling operation. From at least 5th generation rigs and up, automatic fluids property sensors are to a certain extent available, and several advanced measurement systems are being applied on rigs in the North Sea today. Important areas not yet covered by existing automated sensors, such as PVT and thermodynamic properties, are pointed out.
The detailed information provided by automated sensors is important for achieving reliable diagnostics of cuttings transport and the connected wellbore mechanical frictions. Existing models for prediction of cuttings transport are highly dependent on fluid and cuttings properties. Wellbore mechanical friction may also be estimated through use of models, where the reliability of these models also depends on the quality of drilling fluid data, as both buoyancy and flow friction influence drillstring torque and hookload. Finally, use of automated friction tests combined with such analysis has demonstrated greatly improved reliability in diagnostics of wellbore condition during drilling.
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