Underground, It Stimulated Increment Flow Theory And Numerical Simulation

The problem about how to make use of the downhole hydraulic power is researched exploringly. As an important theoretical and practical subject in the world petroleum area, it is a new idea, a new conception and an inevitable tendency for increasing the drilling rate and decreasing the drilling cost. This paper is part of the project named "the Research about Downhole Pressure-Increasing by Hydraulic and High Efficiency Rock-Cutting Theory for the Deep Well in West of China" which has been supported by the National Natural Science Fund in 2003. In this paper, through the numerical simulation analysis of the flow field in the self-excited oscillation and external-excited oscillation cavity, the mechanism of self-increasing flow in external- excited oscillation cavity was clarified and the relation between the self-increasing flow and the related factors was discovered.By the study of the theory about flow characteristic in the cavity, the mathematical model applied in the flow field of the self-excited oscillation and external-excited oscillation cavity was established, then the numerical simulation about three-dimensional flow field is carried on through the fluid dynamics software of ANSYS.The flowing field in self-excited oscillation cavity is a kind of axial-symmetrical turbulent jet flow. Through the fluid dynamic software, we studied the pressure in the flowing field of the cavity with the numerical simulation method, and analyzed the relation between the pressure of the cavity and the structure of cavity and quality of the fluid. And we found out that the main factor related to the pressure are flow rate, the ratio of jet nozzle diameters, the density and viscosity of the fluid.The device for self-increasing flow was just utilize the under pressure in the self-exciting oscillation cavity to introduce the annular fluid leading to the external excited oscillation. While simulated and calculated the flowing field in the external excited oscillation cavity, we applied the mono-factor method and analyzed the seven factors, such as entry flow rate, the ratio of upper and lower jet nozzle diameter, the length of the cavity, the diameter of cavity, the diameter of the external-excited hole, the density and viscosity of the fluid. Then we found that the primary factors influence the self-increasing flow are the entry flow and the ratio of jet nozzle diameters. The self-increasing flow is most while the ratio of jet nozzle diameters is 1.5. The relation between self-increasing flow and the entry flow is linearity.According to result from numerical simulation, we found out the experiential formulas of the self-increasing flow. In order to convenient to optimize self-excited oscillation cavity, we programmed a program making use of these formulas.