THE APPLICATION FEATURES OF DIRECTIONAL BHAS WHILE DRILLING DIRECTIONAL WELLS

Abstract

The article presents a scientific and practical approach to assessing the energy efficiency of directional bottom hole assembly on the basis of the mud motor. The main design feature of these assemblies is the presence of a bent angle in the spindle section of the mud motor. The conditions of operation of such assemblies are considered for a combined drilling method with a various number of stabilizers. Particular attention is paid to determining the causes of unproductive energy costs on the work of the directional bottomhole assemblies in the borehole.The mathematical model improved by the authors includes the geometric features of the assembly design, the bent angle of the spindle of the mud motor as to its body, the number of the stabilizers and the location of their installation, the borehole inclination angle, the physical and mechanical characteristics of the subsurface rock that forms it. The authors calculated the energy consumption for rotation and the axial displacement of the assemblies in the directional well taking into account the deflection forces on the bit and the reaction on the stabilizers. The researchers suggest the use of the indicator of specific energy costs to overcome the forces and moments of the environment resistance during the work of the directional assemblies using the method of combined drilling.Using the results of analytical research and the developed approach the authors study energy costs for thework of the directional bottom hole assemblies with a various number of the stabilizers. The study is conducted for the slick assemblies, as well as for assemblies with one- and two-stabilizers. It is established that directional assemblies with one stabilizer are characterized by the highest values of the forces of resistance of axial displacement and rotation in the directional well. As they are high-torque, energy-consuming and the most energy-intensive systems, their practical use is limited. The main factors in the formation of energy costs for the work of directional assemblies while applying the combined drilling method are the number of the stabilizers and the inclination range.