Study On Slim-hole Drilling Hydraulic Parameters Design

The annulus pressure-loss of slim-hole drilling is higher than general drilling due to its narrow annulus. During calculating pressure-loss, the effects of drilling pipe joints, drilling string rotation, eccentricity and borehole wall roughness must be considered. Moreover, conventional optimum hydraulic parameters design models can't be used in slim-hole drilling. This paper focuses on Bingham fluid model, power law fluid model and H-B fluid model, determination of rheological parameter. Based on H-B fluid model, the annulus pressure-loss of laminar flow is studied, including effects of drilling pipe joints, drilling string rotation and eccentricity. With the narrow annulus pressure-loss theory of turbulent flow, which was studied by predecessors, we get the pressure-loss calculation equation of H-B fluid model during slim-hole drilling. Considered to effects of borehole wall roughness, design an experiment of annulus pressure-loss. Through this experiment, we get a calculation equation of annulus pressure-loss, including borehole wall roughness. Aimed to the characteristics of slim-hole drilling, an optimum hydraulic parameters design model of Bingham fluid model, power law fluid model and H-B fluid model, is studied, including the effects of laminar flow and turbulent flow. Based on this model, make a program of optimum hydraulic parameters design. Then, get a comparison between computational data and field data of two wells. It is proved that the design results of the study is more accordant to that of product well.