Control of friction resistance in drilling of horizontal well with long horizontal section

The horizontal well with long horizontal section can increase the length and quantity of oil reservoir encountered and can raise the single well production of oil and gas, so that it enjoys obvious technical advantage in development of thin reservoir and the offshore and onshore development. However, owing to the long horizontal section, in the course of drilling operation, the serious friction resistance problem will be encountered. Taking a horizontal well with long horizontal section in Shengli Oilfield as example, the finite element method is used to analyze its influence law for and inherent influence mechanism for friction resistance from the viewpoints of optimization of wellbore section structure parameter and selection of drilling operation parameters. The research results indicate that, the curvature radius of building-up section of such well has relatively obvious influence on friction resistance of horizontal well with long horizontal section, so that it should be selected properly after considering the characteristics of formation, the difficulty in control of building-up rate and the drill-pipe delivery capacity in later phase, too quick raising of drill pipe will lead to serious friction between drill pipe and well wall on building-up section, and in the course of lowering of drill pipe, the relationship among lowering efficiency, deformation of drill pipe and friction resistance shall be properly balanced, so as to prevent the drill pipe from being jammed. In the course of combined drilling operation, the speed of rotary table in low-speed area will not cause obvious change in friction resistance.