Research On The Swirling Separation Behavior Of Drilling Fluid Based On Non-Newtonian Fluid Characteristics

The main functions of the hydrocyclone include separation of solid phase,clarification,concentration,classification,etc.In the exploitation and refining of petroleum,the cyclone is also used in the removal of sand and mud fiom drilling fluid,separation of oil and water,and separation of impurities in coking oil.etc.At present,the existing research results are mainly about the structural design of the cyclone and the analysis of the operating parameters during the operation.There are few studies on the influence of the fluid properties of the drilling fluid on the motion of the swirling field,especially in the case of complex well conditions.For the non-Newtonian drilling fluid,for this purpose,three kinds of non-Newtonian fluids are used as the medium,and the motion of the swirling flow field is studied when the power law fluid,Herba-Ba fluid,and four-parameter fluid change when the rheological parameters change.The influence of characteristics provides a certain reference for engineering application.Using the FX-50 cyclone as the carrier,the fluids in the fluid dynamics simulation software Fluent(RSM)were used to calculate the drilling fluids in the three modes.To this end,the following results are obtained:(1)When the two-parameter constitutive model-power law mode is the fluid medium,when the consistency coefficient varies from 0.1 Pa·sn to 2.1 Pa·sn,the pressure and velocity in the swirl field are reduced as a whole.Trend;after the consistency coefficient reaches 1.5Pa·sn,the effect of increasing the consistency coefficient on the flow field motion is reduced.When the flow index is changed,the change trend is similar to the consistency coefficient.When the fluidity index increases,the pressure value and the velocity value show a decreasing trend.When the fluidity index reaches 0.9,the distribution of each characteristic is no longer regularly changed.In the cyclone,the moving distance in the axial direction is short,and the particles mainly rotate around the overflow pipe,which is difficult to separate.In terms of wall wear of the cyclone,the rheological parameters increase,the wear of the cone section of the cyclone decreases significantly,and the maximum value of wear gradually moves up.(2)When calculating the three-parameter model-Herbach mode,the He-Ba model introduces the fluid yield stress term compared to the power-law mode.When analyzing the influence of the yield stress term on the swirl field,the yield stress is 0.5 Pa.When the pressure is between 4Pa,the pressure values and velocity values in the swirl field are less affected.It can be concluded that the yield stress value has less influence on the swirl field in this interval.When analyzing the influence of consistency coefficient and fluidity index on the swirl field,it is found that the rheological parameters have similar effects on the swirl field in the power law mode.(3)In the calculation of the four-parameter mode,the viscosity term is increased compared to the Her-Ba fluid,and the change In the yield stress is similar to the Her-Ba mode,and the flow field changes little.When the viscosity value is changed,it is found that the pressure value and the velocity value gradually decrease with the increase of the viscosity value.When the value reaches 0.07 Pa·s,the change of the pressure value and the velocity value is no longer obvious.The calculated value and the viscosity value at this time are no longer obvious.The difference is small at 0.09 Pa·s,and the same is true for solid phase separation effciency.In the consistency coefficient and the fluidity index,the performance is similar to the above two fluids.(4)Comparing the differences of the three fluids at different feed rates,it is found that the flow field motion difference is very small in the three modes when calculating the low inlet velocity.With the gradual increase of the inlet velocity,the difference of the characteristics of the cyclone field in the three modes gradually increases,in which the pressure value is expressed as the power law mode is larger than the Her-Battery mode,and the Four-parameter mode is the smallest.With the relative static pressure error of 10%as the boundary,it is found that the power law mode is not suitable after the inlet velocity reaches 10m/s.After the inlet velocity reaches 40%,the Her-Ba mode is not suitable.