ON THE ISSUE OF ESTABLISHING THE DURATION OF WELL DRILLING WITHOUT THE DRILL STRING ROTATION

Abstract

The relevance of the research is determined by the need for detailed modeling the evolution of viscous mixture dynamic structure, changes in the volumetric concentration of drilled cuttings in the annular annulus of the well, which is constantly accumulated during drilling, as well as monitoring its critical values, leading to problems with the functioning of special equipment. The purpose of the research is the numerical modeling within the framework of computational fluid dynamics (CFD) of cuttings accumulation developing in time and space in internal systems with an eccentric fixed core (pipes, channels) under various conditions of flow of Herschel–Bulkley type drilling fluids, characterized by an arbitrary change in their rheological properties; understanding the features of cuttings accumulation, as well as determining clogging intensity and the time for cleaning wells. Methods for studying the processes under consideration are based on integrated approach to physical, mathematical and computer modeling of hydrodynamics and convective mass transfer in heterogeneous inhomogeneous continuous media complicated by rheological non-Newtonian effects; combined direct and indirect analysis of the capabilities of the constructed model to predict the essence of cleaning and drilling wells by comparing the simulation results with the available experimental data. Results demonstrate the features of the influence of rheological parameters on cuttings accumulation rate in the annulus and patterns of removal/deposition of particles of drilled rock when changing the flow regimes of the mixture. The possibilities of the method for studying hydraulic transport within the framework of the ANSYS software EL approach using the CFD-DEM model in predicting the pressure drop in the well, the evolution of the dynamic structure of the mixture depending on the intensity of the annulus clutter with cuttings, changes in the average mass velocity at the well inlet in comparison with the available experimental data. The conditions for calculating the maximum recommended drilling time for arbitrary combinations of values of technological and rheological parameters of the drilling fluid are numerically determined and recommended for practice.

Keywords

• well
• horizontal section
• annular flows
• rheology
• drilling
• herschel–bulkley fluid
• modeling
• hydrodynamics
• mass transfer
• transport
• treatment