Numerical study on the geometry evolution prediction of fracturing tool used for unconventional oil and gas exploitation.

With the increasing requirement for energy, unconventional oil and gas resources such as shale gas, shale oil and coalbed methane play a vital role in energy supply. Therefore, the erosion phenomenon which causes serious tool damage during exploitation has attracted tremendous attention and research interest. The objective of this paper is to investigate the effect of flow characteristics on the geometry evolution process of the downhole fracturing tool. Computational fluid dynamics (CFD) simulation with standard k-ε turbulence model and Lagrangian particulate flow model is carried out to investigate the fracturing process. Effects of flow rate, fluid viscosity and proppant size on pressure drop and erosion rate are studied. It is found that erosion rates increase significantly with the increasing flow rate, while decrease with increase of fluid viscosity and proppant size. Furthermore, second and subsequent impacts occur during fracturing. The maximum erosion rate appears around the port of sliding sleeve. The geometry evolution of sliding sleeve can be predicted through the analysis of erosion information. Moreover, a general agreement between numerical results and field data is achieved. These numerical simulations can provide useful guidance for prolonging the erosion life of fracturing tool and improving exploitation efficiency. [ABSTRACT FROM AUTHOR]