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A method for predicting the build-up rate of ‘push-the-bit’ rotary steering system

2021; Elsevier BV; Volume: 8; Issue: 6 Linguagem: Inglês

10.1016/j.ngib.2021.11.010

2352-8559

Wenjun Huang, Ge Wang, Deli Gao,

Tunneling and Rock Mechanics

Push-the-bit rotary steering system can greatly improve the rate of penetration (ROP), hole conditions and hole extension length and represents the development direction of modern steering drilling technology. In order to accurately predict and evaluate the build-up rate of push-the-bit rotary steering system (RSS), this paper establishes the drilling trajectory prediction model and the calculation methods of 'limit build-up rate' and 'corrected build-up rate' for push-the-bit rotary steering system by comprehensively considering the interaction between thruster and sidewall and between bit and formation, the structure of RSS and other influential factors based on the mechanical model of the conventional RSS. Then, the influence mechanisms on the build-up rate are revealed from the aspects of 'leverage effect', 'pendulum effect' and 'thrust effect'. Finally, the influence laws of thrust force, weight on bit (WOB), borehole inclination angle, bit and formation anisotropy on the build-up rate are analyzed. And the following research results are obtained. First, the build-up rate of RSS is the comprehensive result of various effects, among which 'thrust effect' plays a dominant role and 'leverage effect' and 'pendulum effect' play secondary roles. Second, as for the push-the-bit rotary steering system, the proportion of 'leverage effect' increases, the proportion of 'thrust effect' decreases and the build-up rate declines with the increase of WOB. Third, the build-up rate is in a close relationship with structural parameters, thrust force, bit properties and drilling parameters of RSS. In conclusion, the research results can provide an important theoretical basis for the prediction of build-up rate of push-the-bit rotary steering system and the optimization of RSS structure.