A Prediction Model of Lost Circulation Pressure in Fractured Formation

Prediction of drilling fluid loss pressure is one of the key problems to be solved urgently for leak prevention and plugging in fractured formations. In this paper, the lost circulation in natural fracture formation is taken as the research object, and based on the rheological model of Bingham fluid and the transient equation of radial invasion of drilling fluid, the calculation model of equivalent permeability of lost fractures is deduced. On this basis, considering the influence of drilling fluid circulation pressure loss on bottom hole pressure, a calculation model of fractured formation lost circulation pressure is established. The indoor verification results show that the average error between the test leakage pressure and the model calculation lost circulation pressure is 5.04%. In addition, the prediction results of the actual drilling loss pressure in the field are consistent with the actual loss situation, and the prediction accuracy of the model is reliable. The research results of this paper can provide technical support for the prevention and control of lost circulation in fractured formations.