A new method for predicting the density of drilling fluid based on non-parametric regression under HTHP

Temperature and pressure are important factors affecting the density of drilling fluid. As exploration and development gradually progress to deep layers and deep waters, formation temperature and pressure are getting higher and higher. Ignoring the influence of temperature and pressure on the density of drilling fluid will lead to large deviations in drilling hydraulic calculations and increase the probability of accidents such as lost circulation and overflow. In this paper, the density change of a set of field oil-based drilling fluids is measured through laboratory experiments. The temperature range is 20-180°C, and the pressure range is 0.1 MPa-180 MPa. A high-temperature and high-pressure density prediction model for oil-based drilling fluids is established based on the weighted linear regression method. Based on the established model, the high-temperature and high-pressure density of the experimental drilling fluid is predicted. The results show that the prediction error is less than 5%, and the calculation accuracy is high, which can guide on-site operation and construction.