Zunce Wang

Test and Analysis of Vibration Characteristic on New Type Dynamic Hydrocyclone

Dynamic hydrocyclone is currently used in separating oil and water from the crude oil, in which the fluid rolling motion is drived by the external power. Compared with the static type, the dynamic hydrocylone has higher separating property, while its structure is more complex and its separating property is influenced seriously by all the rotary components. Based on the original model, dynamic hydrocyclone of the new type is designed and manufactured, while applying the vibration signal collection and analysis system of IOtech640 type in the vibration characteristic analysis of the model body. The result shows that, when the rotating speed rises from 600r/min to 2000r/min and the flux from 1 to 3 m3 /h, the level time-domain vibration peak of the monitoring site both the near the electromotor and the faraway is under 3.4×10−4 , while the vertical is under 3.2×10−4 , with steady frequency components in the vibration signal. It is illustrated that vibration intensity of the dynamic hydrocyclone of the new optimized type is lightened, which may confirm the improvement of the separation property and the operational life.Copyright

Study on the Flow Pattern of Downhole Oil-Water Separator with Different Inlet Patterns

Downhole Oil-Water Separator (DHOWS) is applied to separate oil from water under the well, separated oil is lifted to ground and output water is injected directly into another level. It is helpful to reduce environmental pollution, and avoid the invalid water cycling. In view of our native status in oil production, DHOWS with different inlet patterns are studied by CFD method and experiment research. The internal flow field distribution is received, and the influences on pressure drop and separation efficiency of the change in inlet channel, such as the length and patterns, are analyzed, which provide significant references for the application in oil fields and structural optimization of DHOWS. In the following section, the structure of DHOWS is briefly described. The two kinds of inlet structural model are introduced, and the inlet diameter is designed by the application of oil field. Based on CFD method, the flow field inside DHOWS with different inlet patterns was simulated by adopting RSM model, and the experiments are carried out. The main purposes are to investigate the effect of the change of the inlet diameter and the channel patterns on pressure drop and separation efficiency, so as to provide the theoretical basis for further study of DHOWS.

Experimental Study on Dynamic Hydrocyclone for Thin Oil Dewatering

The special dynamic hydrocyclone for the thin oil dewatering is developed combining with its advantage in creating high strength swirl field, aiming at the character of the thin oil. By lab experiment, the curves, between the input water cut, viscosity, speed of rotating wall, the ratio and the efficiency, are obtained. Then, the operating parameters are optimized for the dynamic hydrocyclone with specified construction. Subsequently, one process of series/parallel connection of several dynamic hydrocyclones is designed. The result of the experiments shows that applying the dynamic hydrocyclone in thin oil dewatering can lessen the water cut to under 5%, simultaneously, the manufacturing period of the product oil is reduced while the post disposal cost is also reduced since the oil concentrate-on has been controlled under 200mg/l in the sewerage. The research illustrates that the application of the dynamic hydrocyclone in thin oil dewatering is absolutely feasible, which can serve as the valuable experience of the dynamic hydrocyclone in extending application.Copyright

Optimization of the Turbulence Model on Numerical Simulations of Flow Field within a Hydrocyclone

Reynolds Stress Model and Large Eddy Simulation are used to respectively perform numerical simulation for the flow field of a hydrocyclone. The three-dimensional hexahedral computational grids were generated. Turbulence intensity, vorticity, and the velocity distribution of different cross sections were gained. The velocity simulation results were compared with the LDV test results, and the results indicated that Large Eddy Simulation was more close to LDV experimental data. Large Eddy Simulation was a relatively appropriate method for simulation of flow field within a hydrocyclone.

Analysis of Erosion and Failure in the Sudden Expansion Fracturing Tubing of Deep Gas Wells

With the increasing of flow rate during fracturing in deep gas well, the erosion of fracturing tubing is an issue of immense concern to the industry. Based on the Euler-Euler two–fluid theory, the numerical simulations have been performed to predict the flow field in the sudden expansion fracturing tubing. The velocity distributions and sand concentration profiles are obtained, and the simulation results show that separation and reflux come into being in the sudden expansion fracturing tubing when pumping sand slurries at high rate, and the sand concentration increases at some regions. The erosion and failure of the fracturing tubing are relevant to the sand concentration, the velocity and the impact angle. The erosion model was established with the erosion experiment, and the numerical simulation results were used to describe the erosion rate of sudden expansion fracturing tubing according to the established erosion models. The mainly erosion region obtained through the simulation is basically agree with the failure region of tubing during fracturing in deep gas wells.Copyright

Numerical Simulation of Compressible Flow in Gas Liquid Separator

The Gas Liquid Separator (GLS) has been widely used by petroleum industry, chemical engineering, the area of environmental protection, etc. A large quantity of works on the GLS available in literature includes experimental data, numerical simulations and field applications. However, previous studies on the GLS were based on gas incompressible circumstances. In fact, the gas flows from high to low pressure area that it lead to the density fluctuations of gas in separator, the changes of density cause volume expansion of gas, so that separation performance of the GLS is reduced. Numerical simulation for the GLS was developed based on compressible and incompressible flow. Research results show that flow field of two ways and separation performance were different.Copyright

Experimental Study of Down Hole Gas Liquid Separators

The technology of Down-hole Gas Liquid Separation and Water Re-injection (DGLSWR) is an economical and effective method to solve gas well fluid accumulation. The separation performance of designed Down-hole Gas Liquid Separator (DGLS) is very important for DGLSWR systems applications. The principle of work and Characteristics of DGLSWR systems are introduced in this paper. Separation performance of DGLS was studied using computational fluid dynamics (CFD) simulation combining laboratory experiment. Relations of main operating parameters, such as flow rate and gas liquid ratio with pressure drop were studied. The effect of flow rate, gas liquid ratio and main structural parameters such as cone angle and exhaust on DGLS separation performance was also studied. Appropriate structure and operating parameters were determined. Field tests indicated satisfactory results as well.© 2009 ASME

Study on Separation Performance of the Compound Hydrocyclone Under Self-Vibration Condition

The compound hydrocyclone, combining merit of both dynamic hydrocyclone and hydrocyclone, is an efficient separator. Flow field and separation performance are affected by unavoidable vibration, when it operates. This paper discusses vibration of the compound hydrocyclone using modal analysis. Characteristics of modal parameters such as natural frequency, damping and mode of vibration are obtained. The main objective of this work is to investigate the effect on flow field and separation performance caused by the behavior of vibration. The finding showed the flow rate and running of the electric motor not only cause the vibration but also affect principal factor of the separation performance. This work provided a foundation for stable operation of compound hydrocyclone.Copyright

Study on Characteristics and Operating Parameters of Axial Rotating Hydrocyclone

The axial rotation of the hydrocyclone affects its internal flow characteristics and separating effect directly, as some local applications require the static hydrocyclone rotates about its own axis. Based on CFD, velocity distribution in the axial rotating hydrocyclone is studied. It is shown that as the rotation speed increasing, the tangential velocity improves and its gradient reduces in free vortex region observably, while the radial velocity has an incremental trend in the section of the small cone. The laboratory experiments are carried out for the static hydrocyclone of disposal capacity of 4 m3 /h at 100r/min ∼ 300r/min. The relationships among rotation speed, flowrate, pressure drop and separated efficiency are achieved, which agree well with the numerical simulation results. The results indicate that the disposal capacity of hydrocyclone subjected to the rotation wall can be more flexible than that with no-rotating wall, the scope of best disposal capacity gradually enlarges with the increase of rotation speed of wall. Appropriate rise of the rotation speed is favor of the separation efficiency at the steady flowrate, however the increase of the flowrate and rotation speed induces the growth of the hydrocyclone’s pressure drop correspondingly to some extent.© 2009 ASME

Study on Flow Field Character Around Bypass Crossover Sub in Fracturing Process of Horizontal Wells

Based on Reynolds Stress Model (RSM), numerical simulation of flow field around Bypass Crossover Sub in the fracturing process of horizontal wells is carried out by Computational Fluid Dynamics (CFD) analysis. Distribution rules of axial velocity, tangential velocity and radial velocity of fluid field in calculation region are achieved. Results show that strong vortexes and reverse flow exist at the slots on Bypass Crossover Sub, which brings the impact of the fluid on the wall at certain angle. Impacting velocity and angle at different positions of the wall are studied in detail. A Laser Doppler Anemometer (LDA) is applied to examine the flow field velocity distribution. Experimental results agree well with the numerical simulation results, which prove the validity of turbulence model and computational method. Numerical simulation is carried out at different Length-Breadth ratio of slots on the Bypass Crossover Sub. Effect of the Length-Breadth ratio on the scale of vortexes, speed distributions and flow field near the wall area is discussed. All of these will provide some reference on structural optimization and the analysis of erosion.Copyright