Continuous Tube Fluid Dynamics Study

This paper is finished under the support of the project-coiled tubing operation optimization decision-making research on mathematical model building and solving the system software module, which is major project of kei igawa drilling engineering co.. LTD.With the develop of unconventional oil and gas resources, such as shale gas. tight gas in the exploration and development, the proportion of coiled tubing fracturing technology is increasing as for tight gas and shale gas reservoir stimulation, are increasingly brought to the attention of the people, through the study of coiled tubing fluid dynamics to improve understanding of coiled tubing fracturing technique.Fracturing technology of coiled tubing is currently an effective well stimulation for the tight gas and shale gas reservoir, through the study of coiled tubing fracturing fluid dynamics is good to improve the understanding of fracturing technology of coiled tubing.For fluid dynamics of coiled tubing for fracturing, through a large number of literature researching at home and abroad, this paper studied the fluid dynamics theory of coiled tubing. On the basis of theoretical research, coupled with fracturing construction situation of coiled tubing on site, we developed a fluid dynamics analysis software for coiled tubing. The purpose is to predict fluid friction pressure drop in coiled tubing, flow regime, velocity and so on when fracturing, to determine fluid pumping pressure and lay the foundation for determining reasonable pump pressure, displacement, and optimizing coiled tubing.The research work and results are obtained as follows:1. In this paper, all kinds of coiled tubing and fluid related information home and abroad were collected and organized, and the parameters database of coiled tubing and fluid were established.2. Based on the related literature researching at home and abroad, this paper established governing equations of fluid dynamics for coiled tubing, including continuity equation, momentum equation and energy conservation equation. And this paper also studied two basic approaches of the fluid, namely the Lagrange method and Euler method.3. In this paper, a fluid friction pressure drop calculation model of coiled tubing was established through single-phase flow and two-phase flow respectively. And single-phase fluid include Newtonian fluid and Power-law fluid and Bingham plastic fluid. In addition, this paper also studied fluid friction pressure drop of outer annulus, determined the method for calculating the pump pressure and the pressure at any location.4. Through CFD software, this paper studied the fluid flow characteristics of coiled tubing in roller, found that the existence of the secondary flow and studied the influence of velocity, curvature ratio and diameter on the fluid friction pressure drop.5. On the basis of fluid dynamics theory and finite element numerical simulation research, based on Visual Basic 2013 platform system, combined with the basic technical parameters of coiled tubing, commonly used on-site fluid type and wellbore structure, this paper developed an analysis software for fluid dynamics of coiled tubing.6. The software was tested for 14 wells, including WeiYuan H3-1. The calculation results and actual construction results in line with the above 92%, can effectively guide the coiled tubing construction work.