Translated Abstract
Pipeline capacity for shipping crude oil and various refined oil increases with the development of oil industry, particularly with the gradual development of offshore oil resources. The addition of DRA( drag reducing agent) to pipeline for improving the pipeline shipping capacity and transportation efficiency is of great significance from the points of views of reducing energy consumption and investment. Flow drag reduction comes forth under this background. Flow drag reduction, through the addition of drag reduction agent to the fluids , can change the fluids flow pattern, and make reduce the frictional pressure drop of pipeline. So it is a new development in the oil transportation technology.
Experimental simulation of the drag reduction of the multiphase flow for subsea pipeline is carried out in this paper. A complex test loop with different pipe gemetry was set up for this simulation. The main idea of this paper is to realize the drag reduction, energy conservation and output increasing in the multiphase transport process of oil and gas.It mainly focus on the economy and security of pipeline transportation of oil and testing out the applicable methods of achieving drag reduction and DRA in different pipelines and different multiphase flow states. The work carried out in this experiment include drag reduction in single-phase oil, drag reduction in oil-gas two-phase flow and drag reduction in oil-water-gas three-phase flow. The DRA to join in single-phase oil is oil-soluble polyolefin,also to oil-gas two-phase flow. And polyolefin is put into oil-gas-water three-phase flow basing on oil phase. The pipeline status in this experiment mainly includes the horizontal, the tilt with 10° rising and the vertical.
First of all, the most important parameter in this experiment is the pressure drop, which is used with its corresponding relationship and transformation for evaluating the drag reduction. The horizontal pressure drop can be considered including only frictional pressure drop tilt and vertical pressure drop including friction pressure drop and weight-position pressure drop.With different flow types, the percentage is of difference between the two. The total pressure drop is the sum of the pressure drop in the three test section . The total drag reduction rate, which is calculated by the total pressure drop,gives a standard to evaluate drag reduction effectiveness of DRA in complex piping systems.
The laws of the drag reduction in single-phase oil are firstly summarized as follows. Adding polyolefin into single-phase oil ,the total rate of drag reduction is up to 21%. Moreover, with the liquid velocity increaseing, the total drag reduction firstly increases and then decreases. The best value is existing. Therefore, in complex configuration of single-phase oil pipelines, polyolefin can increase output effctively.
When adding polyolefin to oil-gas two-phase flow, the pressure drops of the horizontal , the inclined and the vertical section decreases in sequence. The total drag reduction in the experimental system can achieve up to 32%.With liquid velocity increasing, it declines on the form of logarithm. 200ppm polyolefin is the most significant dosage with the most obvious reduction of pressure drop. With increase of DRA input dose, the rate of drag reduction will have a best dose range. More than this range, the rate is nearly constant, even reduces. It has a great relationship with the fluid proportion in two-phase flow.With increasing of the amount of fluid drag reduction would be better. Therefore, the role of polyolefin playing in drag reduction is mainly to reduce frictional pressure drop and improve the flow characteristics.
For drag reduction in oil-gas-water three-phase flow, oil-soluble or water-soluble DRA is chosen according to different continuous phase of oil or water.After adding oil-soluble polyolefin the flow drag reduction effect is good.The largest total rate of drag reduction in experiment system can reach to 20% , even more. The greater liquid velocity , the better solubility of DRA in flowing fluid,and it operates more effectively
Translated Keyword
[Drag-reductionMultiphase flowPressure dropPolyolefin]
Corresponding authors email
