Analysis of the work of steps using the eccentricity limiter for drilling wells with a diameter of 393,7 mm

Abstract

Based on the results of the analysis of theoretical and practical studies of drilling large diameter boreholes, a method is proposed for designing the bottom hole assembly with two rock cutting tools, taking into account geological and technical factors that influence the formation of the well trajectory. Prospects for controlling the direction of the wellbore are substantiated using the limiter of the eccentricity value. The calculation of double-hole assemblies of the bottom of the drill string with different diameters of eccentricity limiters, allowing to achieve eccentricities of 10 mm, 20 mm, 30 mm and 40 mm has been performed. The analysis of the operation of the mentioned bottom hole assemblies when drilling a well to a depth of 900 m is carried out. The analysis is carried out in the field of construction of deep boreholes of large diameter and the efficiency of drilling a pilot hole of a smaller diameter with simultaneous formation of the final diameter using a reamer is substantiated. A brief analysis of modern foreign and domestic studies and publications related to the expansion of the pilot wellbore is presented, as well as the influence of the expansion eccentricity on the elastic-deformation state of the BHA and, as a result, on the deviation of the well is considered. A conclusion is made about the possibility of using the phenomenon of eccentric expansion to control the trajectory of the wellbore. The graphical dependences of the change in the intensity of the borehole deviation during deepening using the eccentricity of the limiter for a specific BHA, including a bit with a diameter of 295.3 mm and a reamer with a size of 393.7 mm, are shown. It is shown that with this type of arrangement at different values ​​of eccentricities, it is possible to achieve the intensity of borehole curvature in the range from 0 deg/10 m to 0.44 deg/100 m, 0075, indicating a change in the direction and magnitude of eccentricity during drilling. The graphical dependences of the change in the zenith angle of the well when deepening it for the assembly of the bottom of the drill string with different diameters of the eccentricity limiter are given. The graphical dependencies indicate that when using stops of different sizes, which make it possible to control the eccentric displacement of the reamer at the final drilling depth of a section of 500 m, it is possible to reduce the increase in the zenith angle of the well from 17.5 degrees to 10 degrees. It is concluded that by using the limiters of the eccentric displacement of the expander relative to the pilot borehole, it is possible to control the deviation of the well during the construction of conditionally vertical and inclined sections.