While water exists in the waxy crude oil, gelling process of this non⁃Newtonian oil⁃water two⁃phase system not only has the properties of waxy crude oil but also its own specific characteristic as decrease of temperature. Both the gelling temperature limit and change rule of gelling strength in W/O waxy crude oil emulsion system under different emulsified water fractions, were investigated by rheological measurement. The results indicate that the characteristic gelling temperature and the strength of the gels increase with the increasing of emulsified water fraction, when the temperature decreasing at a certain rate; the gelling temperature in W/O waxy crude oil emulsion system of any given emulsified water fraction rises with the increasing of cooling rate, while the gelling strength decreased with the cooling rate rising under the constant pressure. The research results of the effect of emulsified water on the gelling characteristic for waxy crude oil at cooling process provides necessary support for the development and application of flow technology for multiphase transportation.

Granular layer filtration is widely used in the treatment system of oilfield produced water, and water distribution of granular layer filter which directly affects the purification effects of produced water plays the same significant role as the selection and arrangement of granular layer. The model of filter was built and unstructured grids were generated by Gambit. The flow rate field in the model was calculated by Fluent combined with DPM model. Based on the DPM model in Fluent software, a numerical simulation of pressure field distribution, filtration pressure drop along the axis, pathlines of particles, and particles distribution and aggregation behaviors were simulated and calculated. Then, water distribution characteristic in pressure filter of produced water was described, and optimization of water distribution process was realized. The results showed that the good performance of water distribution was obtained and the pressure drop in the filter with sieve tubes was reduced by 30.56% compared with the filter with slots. Furthermore, the filter with nine sieve tubes was optimized by its excellent water distribution characteristic. Such a numerical simulation method can provide effective support for optimization of filtration process and purification of produced water.