Developing a phenomenological model to simulate single and mixed scale formation during flow in porous media:Coupling a salt precipitation model with an ion transport equation under dynamic conditions

Water flooding and pressure maintenance are recommended to improve oil recovery practices after low recovery of petroleum reservoirs occurs during primary production.Salt crystal formation is a frequent occurrence when using these techniques.Several experimental,numerical,and theoretical studies have been done on the mechanisms underlying scaling and permeability reduction in porous media;however,there has not been a satisfactory model developed.This study developed a phenomenological model to predict formation damage caused by salt deposition.Compared with existing models,which provide a scaling tendency,the proposed model predicts the profile of scale deposition.The salt precipitation model simulates reactive fluid flow through porous media.A thermodynamic,kinetic,and flow hydrodynamic model was developed and coupled with the ion transport equation to describe the movement of ions.Further,a set of carefully designed dynamic experiments were conducted and the data were compared with the model predictions.Model forecasts and experimental data were observed to have an average absolute error(AAE)ranging from 0.68%to 5.94%,which indicates the model's suitability.

Experimental study on the compatibility of scale inhibitors with Mono Ethylene Glycol

When both of the scaling and hydrate risks occur in deep water wells or subsea pipelines at the same time,the compatibility between scale and hydrate inhibitors should be paid more attention to for the risk prevention.In this paper,a new deep-water gas field found in the South China Sea is taken as a reference of project background to investigate the compati bility between scale inhibitors and hydrate inhibitors experimentally.Firstly a preliminary qualification evaluation of scale inhibitors was caried out,in which the static scale inhibition eficiency,the scale induction time,and the minimum effective concentrations of the selected scale inhibitors were tested.Then the effect of commonly used thermodynamic hydrate inhibitor MEG(Mono Ethylene Glycol)on the anti-scaling performance of scale inhibitors was evaluated.MEG-resisted scale inhibitors were further optimized.Finally,an extended discussion on the compati-bility of scale inhibition with hydrate inhibition was conducted.The experimental results showed that the scale inhi bitors HPMA and MA/AA were recommended with the best working concentration of 30 ppm.The high concentration inhibitors(30 wt%)can coexist with the same volume of pure MEG for more than 12-14 h at room condition and 60°C without any precipitation.The anti-scale fficiency of inhibitor with 30 ppm concentration is still up to 90%even at the presence of 20wt%MEG(after2-4 h at 95°C).Hence,in deep-water wellbore,compatible scale and hydrate inhi bitors can be injected together using one chemical pipeline.Besides,it is also found that the polymer scale inhibitors generally have good compatibility with MEG.It deserves further studies and can be regarded as one direction for scale inhibitor improvement in the future.