Research On The Prediction Model Of Barium Sulfate Scaling Based On The Principle Of Chemical Kinetics

Although waterflooding in oil development is a common and mature method for en-hancing oil recovery in fields,temperature and pressure variation during injection and the in-compatibility between the injected water and formation water will probably cause scaling in the hydrocarbon reservoirs,well bores and gathering pipelines.Among common scales,bar-ium sulfate is notorious for its low solubility,which increases investment to remove it and as a result,highly interrupt the normal production operation and makes severe economic losses.Hence,it is meaningful to develop dynamic scaling prediction model based on the character-istics of barium sulfate scaling process.This paper studied the following aspects:Firstly,based on a great deal of the records and literatures,the inorganic scaling mecha-nisms related to barium sulfate were elaborated.Key factors of barium sulfate scaling were analyzed and summarized,upon which barium sulfate scaling prediction model was folly an-alyzed and discussed.Secondly,the core-flooding ID scaling prediction model was thoroughly studied.A dif-ferent numerical method was employed for parameter fitting.A difference scheme was con-strUcted for transient analysis and its stability was proved.Then,the formation ID scaling predietion model for near-well zone was re-derived.The 2D formation ion distribution model with a point source term was developed and solved.The 2D coupled-flow core-flooding scaling prediction model was constructed and solved.Specific results are as follows:(1)Applied Lobatto-Newton method to solve steady state model and its inverse problem to obtain the dinensionless reaction coefficient;(2)A mixing scheme combining HAUC with centered-difference and numerical bound-ary condition was constructed for transient analysis of core-flooding ID scaling prediction model.Its stability was proved by finite Laplace transform and GKSO theory;(3)Based on core-flooding ID scaling prediction model,a transient analysis was con-ducted,in which ion distribution was modeled.Also,the effects of the two key parameters(dimensionless diffusion coefficient and dimensionless reaction coefficient)of the governing equation,mesh size,ion ratio and boundary conditions on the results of deposition prediction were analyzed.(4)The rectifications of the coefficient of second-order derivative term of concentrations and the impedance coefficient evaluation equation were justified by a step-by-step mathe-matical derivation;(5)Developed and solved the 2D formation ion distribution model with a point source;(6)Built and applied the 2D coupled-flow scaling prediction model to predict porosity,permeability and pressure drop change with respect to scaling.