Study On Rheological Behavior Of Heavy Oil And Its Influence On Flow Performance

The flow performance of heavy oil is not only reflected in the high viscosiy,but alos in its sensitivity when the fluid velosity changes.This paper investegated the latest researches of reheological heavy oil.I found that the velocity is also a key factor that affect viscosity besides temperature.Former study failed in figuring out the flow perforamance of heavy oil when it flowing at a low velocity in porous media.It can actually be a more complex situation in the rock than the common sense thought that it can be described as Bingham or Power fluid model.Thorough the laboratory test of heavy oil samples collected from oil field,I used a paraller plate rotary rheometer to detect the rheological property.Considering the situations of underground flow,there are four test items designed which are shear rate sweep,shear rate back-off,test ater constant speed disturbing and start under a series of shear rates.The phenomenon of viscosity dropping was detacted when the heavy oil sample was cut at a low shear rate.In this way,a three-stage fluid model was establishend after data analysis.This paper deduced a conversion relationship between shear rate and seepage velocity.By combining the fluid viscosity and percolation velocity in laboratory,I optimized the exsisting non-linear flow mathematical model.Next,This paper used numerical simulation as a method frome black oil model,the viscosity of oil was considerated as a variable parameteer and a non-linear calculation module based on experimental results was established.The C++ program working for numerical simulation to solve non-linear flow procedure in heavy oil was built independently to realize the immediate changes of viscous oil with flow rate dynamic fluctuation.In addition,this paper put the oil field data into practice and set up a two-dimension planar case with a five-point well pattern.By controlling variables,I studied several parameters of viscous oil viscosity reduction,critical flow velocity and viscosity recovery effect of non-Newtonian fluids.Through Quantitative analysis,this paper figured out the way that rhelogical effects on non-linear flow performance at a constant temperature and provided a new method for heavy oil water floodingdevelopment research.The key study results are present as follow.Throught the designed rheological test,the change law of the viscous oil viscosity at a low ratewas detected and a conversion relationship between the shear rate and the infiltaration velocity was established on the capillary tube model.The viscosity of the oil phase is used as a variable that changes with flow velocity and a numerical simulation program for the study of heavy oil non-linear flow was copiled in C++ Language.The program operated well and passed the necessary reliablity tests.The results found that the greater viscosity decrease and the higher critical flow rate range reach,the oil recovery rate will also be imprved in the initial stage of water drive but the area of water flood through will decrease,which can be a drawback to achieve a fine exploitation.However,the viscosity recovery effect benefit the stable of production and its calculated recovery rate was even higher in the simulation.Taking the rheological behavior into consideration,the dynamic changes of viscosity will disturb heavy oil flow and has negative impact on water figuring and hydration problems when use the water drive development method.In addition,a reasonable indicator of injection for this kind of sensitive heavy oil was introduced.