Study On Fast Numerical Simulation Of Bottom Flow Field Of PDC Drill

As one of the main rock cutting tools, PDC bit has been widely used in petroleum exploration, and its performance directly affects the drilling efficiency, drilling quality, as well as the drilling cost. Hydraulic performance of drill bits determines the effects of rock debris migration and bit’s surface cooling. Therefore, making the hydraulic structure more reasonable by bottom-hole flow field analysis of PDC bit, plays an important role in cutting and carrying rock, and which will optimize drilling performance. Most of existing documents studying bottom-hole flow field of PDC bits were mainly concerning the single-phase flow field, and did not fully considering the effect of debris on flow field. In addition, it is tedious, time-consuming, and inefficient to use the traditional method to pre-process and post-process in simulating bottom-hole flow field of PDC bit.To solve above problems, this paper researches on bottom-hole flow field of PDC bits and quick analysis method based on the multiphase-flows theories. The main works are as follows:(1) Carrying out numerical simulations of flow fields under different drilling conditions, including single-phase flow field, gas-liquid flow field, bit-erosion flow field, liquid-solid flow field, gas-liquid-solid flow field. Taking into account the effect of debris on flow field, the multi-phase flow theory is improved further, and a calculation model of PDC bit multiphase flow field is established, which conforms to actual working condition.(2) Based on the five kinds of numerical simulation theories above, a modeling module, pre-processing module and post-processing module are developed by using the secondary development technology of UG, Workbench, CFX, as well as Microsoft-Excel, all of which make up the special simulation platform of PDC bit bottom hole flow field.(3) Taking a certain type of PDC bit with six blades as an example, single-phase flow filed, liquid-solid flow filed and gas-liquid-solid flow filed are simulated on the basis of the above module. Compared with conventional numerical simulation method, the proposed method shortens the research cycle significantly and improves the simulation efficiency. In addition, it turns out that the performance of personalized PDC bit used in Jilin Oilfield is good, whose hydraulic flow field analysis and structural design are optimized on this special module.The rapid numerical simulation method developed in this paper can enhance the efficiency of modeling and data-analyzing, which shortens the R&D cycle of personalized PDC bit, and has certain engineering value.