Measurement Method for Density of Drilling Fluids at High Pressure and Temperature

Abstract

Large-scale deployment of CO₂ storage will require the drilling of numerous new wells, introducing additional operational challenges. One key concern is the potential influx of CO₂ into the wellbore during drilling operations, which can significantly alter the thermophysical properties of drilling fluids, including density and viscosity. A reduction in drilling fluid density or hydrostatic pressure may compromise well control and, in severe cases, lead to blowout incidents. It is therefore essential to quantify the impact of CO₂ dissolution on drilling fluid properties under representative downhole conditions, with pressures up to 400 bar and temperatures up to 100 °C. Conventional densitometers are not suitable for these measurements due to the presence of solid particles in drilling fluids. To address this limitation, a dedicated experimental method was tested based on monitoring the volume changes of the fluid under controlled pressure, temperature, and CO₂ loading conditions. This paper first presents a detailed description of the experimental methodology. Subsequently, representative results are provided for drilling fluid density measurements, highlighting the influence from dissolved CO₂, pressure and temperature on fluid density behavior.