Analysis on Three-Dimensional Numerical Simulation of Turbine Flow Characteristics

Transcription

1 Available online at Energy Procedia 16 ( International Conference on Future Energy, Environment, and Materials Analysis on Three-Dimensional Numerical Simulation of Turbine Flow Characteristics Fu Jianhong a Song Kexiong a,b Zhang Zhi a Zhao Zhiqiang c Zeng Dezhi a Liu Fei a,d Zheng Xin a* a State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan, 6500, China b Geology and Mineral Resources Institute,Chongqing,400042, China c West Engineering Corporation of SINOPEC Huabei Petroleum Administration,China d Research Institute of Petroleum Engineering, SINOPEC, Beijing 0,China Abstract By the use of modelling software, this paper set up the three-dimensional physical model of single-stage turbine and guided it into the pre-process software. After meshing the turbine flow channel, simulating the mud flow characteristics in Turbine with CFD, and calculating the pressure drawdown at the inlet/outlet and the pressure distributions in single-stage turbine. Such results indicate that the pressure drawdown of single-stage turbine is influenced by the mud discharge capacity, drilling fluid density and viscosity. The pressure drop increases with the augment of mud discharge, which is approximately linear. There are significantly positive correlations between the pressure drawdown and the increase of mud density. The research in the paper provides reliable guidance in turbine flow channel design and the drilling technological parameters optimizing Published by Elsevier B.V. Selection and/or peer-review under responsibility of International Materials Science Society Published by Elsevier Ltd. Selection and/or peer-review under responsibility of [name organizer] Open access under CC BY-NC-ND license. Keywords: Turbine; Entity Element Model; Pressure drop ; Flow characteristic; 1. Introduction With the advancement of oil exploration, the augment of drilling depth, and the increase of drilling difficulty, the relative well failure such as casing wear and drilling tool rupture has been keeping on increasing. However, owning the advantage of direct rock-breaking drilling and the wear of drilling tools * Corresponding author. Song Ke-xiong Tel.: ; address: @qq.com Published by Elsevier B.V. Selection and/or peer-review under responsibility of International Materials Science Society. Open access under CC BY-NC-ND license. doi:.16/j.egypro

2 60 Fu Jianhong et al. / Energy Procedia 16 ( reducing, the advent of turbine has not only greatly improved the penetrating rate, but also cut down the drilling cost. In recent years, the breakthrough in structure and turbo-drilling performance has made the turbine be able to serve more than 0 hours in average; the mean penetration rate of turbine is almost 3-5 times as table-drive drilling, which costs more than turbine drilling. The key to increasing the penetration rate of turbo-drilling is the selection of bit shape and the drilling parameters. It is a economical method to shorten the R&D cycle of turbine by applying the model software and CFD techniques into the analysis of velocity and pressure distribution of turbo-drilling flow field, instead of the fluid dynamic study of physical turbine type. The mechanical properties of turbo-drilling tool depend on its hydraulic performance, thus improving such properties and reduce the hydraulic loss for greater efficiency becomes the main aim of research. After 3-D numeric simulation of flow characteristics of single-stage turbine, this paper aims at providing guidance for the design of turbine flow channel and the optimization of monolithic structure to improve the hydraulic efficiency of the turbo-drilling tool. 2. Hydrodynamic model of turbo-drilling tool Continuity equation is the equation of mass conservation that any liquidity issues must satisfy. The differential form of flow continuity equation in turbine is as followed: ρ ( ρu ( ρu y ( ρu (1 x In equation (1,u x,u y,u z represent velocity components in x,y,z directions(m/s,t: time(s, ρ:density (kg/cm 3. The momentum equation in x,y,z directions are shown in equation (2,(3,(4 ( ρux xx yx zx ( ρu xu ρ = ρf (2 x ( ρu z = 0 y ρ (3 xy yy zy ( ρu yu = ρf y ( ρuz xz yz zz ( ρu zu ρ = ρf (4 z In equation (2,(3,(4,p is the fluid pressure of micro-element, (Pa, τ xx, τ xy, τ xz are the components of viscous stress τ,caused by the molecular velocity effecting on the infinitesimal surface, (Pa, j x j y j z represent the mass forces per unit in three directions, m/s2, if the mass force is gravitated only and the axis of z is vertically upwards,then j x =j y =0,j z =-g. 3. Foundation of physical model The 3-D turbo-drilling physical model has been set up with the modelling software, its structure parameters are as followed: contour diameter=241.3mm, turbine shell thickness b=.5mm, turbine OD D1=206.3mm, calculation diameter Dp=191.5mm, blades number=27, pitch t=22.31mm, axial length of single-stage turbine L0=5.44mm, calculation blade angle=33.7, discharge of single-stage turbine Q=40L/s. First to create a single model of turbine stator, rotor and shell, then to assemble stator, rotor and shell into a 3-D solid model with other relevant parts, this is shown in Fig. 1.

3 Fu Jianhong et al. / Energy Procedia 16 ( Fig 1 Single-stage turbine model assembly 4. Finite element meshing and processing After the establishment of physical model, the turbine flow path was meshed, then the model could be put into the pre-processing module of flow field. The processed internal structure is shown in Figure 2, and the meshing structure of model is shown in Figure 3. Fig 2 processed turbine internal structure Fig 3 Model meshing structure 5. Numeric simulation results Setting drilling fluid density as 1.77g/cm3, plastic viscosity as 30mPa.s, discharge capacity Q=40L/s, at one atmospheric pressure, the average pressure of single-stage turbine on outlet/ inlet surface can be respectively figured out: 0.147Mpa for outlet and 0.26Mpa for inlet.therefore, the pressure drop ΔP under such conditions is 0.113Mpa,but for level 1 turbines,δp¹=9.16mpa.the pressure distribution of singlestage turbine is shown in Figure 4,and the velocity distribution on inlet/outlet surface is shown in Figure 5, which shows that the inlet velocity is 4m/s and the outlet rate is 7m/s~m/s, obviously, they are basically consistent with the theoretical average circumferential speed at the blade outlet. Fig 4 Single-stage turbine pressure distribution Fig5 Single-stage turbine velocity distribution

4 62 Fu Jianhong et al. / Energy Procedia 16 ( The velocity distribution in longitudinal section is shown in Figure 6, it is clear seen from the figure that the velocity in single-stage turbine model increases by degree from the inlet to the outlet, but is not evenly distributed. The different blade installation angles and flow parameters affect the hydraulic efficiency a lot, which involves detailed analysis in filament line of the turbine flow. filament line in longitudinal section is shown in Figure 7.which indicates the fluid particles inside the single-stage turbine model distribute along the flow pattern direction of blade, most of them flows along the direction of blade structure while the rest small part appear vortex or stall flow. Fig 6 Longitudinal velocity for single-stage turbine Fig 7 Flow chart in longitudinal section Setting drilling fluid density as 1.77g/cm 3, and plastic viscosity as 30mPa.s, the relationship between pressure drawdown and discharge capacity of level 1 turbine is shown in Figure,from which it can be seen that turbine pressure drawdown increases with the augment of discharge capacity. Setting inlet discharge as 40L/s, and plastic viscosity as 30mPa.s, the relationship between pressure drawdown and density is shown in Figure 9,which indicates that turbine pressure drawdown increases while the drilling fluid density keeps rising. Setting inlet discharge as 40L/s, and drilling fluid density as 1.77g/cm 3,the influence of viscosity on turbine pressure drawdown is shown in Figure,with the positive correlation between pressure drawdown augment and viscosity increase delivery capacity L/s drilling fluid density g/cm3 Fig Turbine pressure drawdown and fluid discharge Fig 9 Turbine pressure drawdown and fluid density

5 Fu Jianhong et al. / Energy Procedia 16 ( drilling fluid plastic viscosity mpa s 65 Fig Turbine pressure drawdown and plastic viscosity of drilling fluid 6. Conclusion: (1 A 3-D physical model of single-stage turbine was set up,and the relative 3-D numeric simulation of flow properties of turbo-drilling tools with CFD shows that slippage and vortex phenomena may occur in percussion condition. (2Turbine pressure drawdown increases with the augment of drilling fluid discharge capacity, which is approximately linear. Moreover, the increase rate of pressure drawdown is positive correlated with the rise of drilling fluid discharge, mud density and the viscosity. (3 The analysis of the flow characteristics of turbine provides reliable guidance in turbine flow channel design and turbine drilling technological parameters optimizing. Furthermore, the flow field numeric simulation results offer relevant bases for the adjustment of flow parameters, such as drilling fluid density, discharge and viscosity, thus to improve the hydraulic efficiency of turbo-drilling tools. References [1] Yuanhua Lin,Dezhi Zeng,Runfang Li, Linear Research on New Blade-type of Turbo-drill and Its Computer-aided Design,Journal of Chongqing University,2004. [2] Иоаннесян Р.А.....Развитие турбинного бурения. Строительство нефт. и газ. скважин на суше и на море, 2007,(1: 4-. [3] Chunfei Tan,Jiachan Wang,Weijian Zhen,Boru Xia, Research on TDR1-7 Deceleration Turbo-drill in the Ultra-deep Well of Tahe Oilfield, Journal of Oil Drilling & Production Technology,20. [4] Ning Zhao, Application of New Turbo-drill in Deep Well, Journal of Oil Drilling & Production Technology,2004 [5] Daliang Fu,Xiaodong Zhang,Yanwei,Fu, Enormous Economic Potentiality of Turbo-drilling Technology, Journal of Petroleum,2000. [6] Jin Fen,Manlai Zhang,Xiaoguang Liu, Application of CFD Software to Simulate Mechanical Properties of Φ115mm Turbodrill, Journal of Natural Gas Industry,2006. [7] Zengliang Li,Yanjun Yan,Yuhong Gu, Energy Loss Analysis of Turbine in Turbo-drill, Journal of Petroleum Machinery,1997. [] Shiqi Yang,Dunsong Xue Jinglun Cai, Advances in Drilling Technology of the New Turbine Journal of Petroleum University,2002. [9] Banlie Wang,Jizhi Li, Oil Field Hydraulic Machinery, Press of Petroleum Industry,1993.