TECHNICAL SOLUTIONS FOR DRILLING WELLS IN CHALLENGING CONDITIONS

Abstract. Drilling modern wells in difficult mining and geological conditions poses a number of tasks for engineers that require special solutions. These include instability of borehole walls in difficult geomechanical conditions, drilling of directional wells with long horizontal boreholes and their completion by multi-stage hydraulic fracturing, drilling in conditions of a narrow «window» of drilling mud density, as well as drilling of wells with extended reach from the vertical. The article describes the main difficulties and problems encountered in solving these problems, such as: wellbore collapse, absorption during drilling in difficult geomechanical conditions, the impossibility of running casing strings and liners into wells with a large deviation from the vertical by traditional methods, difficulties in cementing long horizontal liners, running completion for multi-stage hydraulic fracturing of a formation with packers in an open hole, difficulties in drilling in conditions of insignificant difference in pore pressure gradients and hydraulic fracturing. Certain proven solutions are offered to overcome such problems and difficulties, examples of solutions to the described problems are given. Among these solutions are geomechanical modeling with subsequent calculation of wellbore stability, as well as optimization of well trajectories, the product of multi-stage hydraulic fracturing by the Plug & Perf method of isolation and perforation in order to achieve a larger number of stages, as well as solutions for improving the quality of cementing horizontal liners. Pressure-controlled drilling technology and flotation of casing and liners into ERD wells will be considered. It concludes with conclusions about the relevance of the solutions described, the possibility of combining them to increase efficiency or under complex conditions, as well as aspects that require attention when choosing technologies and their implementation, such as the importance of risk assessment and the importance of technical integration of technologies, as well as preliminary calculations and analysis of technology implementation experience.