Research On The Accumulation, Sedimentation And Inhibition Process Of Heavy Oil Asphaltenes

As the asphaltene is the most polar component in heavy oil,it is affected by temperature,pressure and the change of the composition of heavy oil,which can produce deposition.This phenomenon can occur at various stages in the process of heavy oil production.When asphaltene deposition occurred in the reservoir,asphaltene particles would adsorb on the surface of the rock,reduce its permeability,change the wettability,and cause reservoir damage;when asphaltene deposition in the process of exploitation,it can plug of the well pipe,a separator and other equipment,and reduce the efficiency of production;when asphaltene deposition in the processing of heavy oil,it would cause catalyst plugging,and reduce its activity,which affects production efficiency seriously.At present,aiming at the problem of asphaltene deposition,there has been a lot of study,which mainly focus on asphaltene structure,properties,self-association characteristics and different types of inhibitors on asphaltene aggregation process of settlement and a part of inhibitors has been used in oil fields.But there are little researches about effect of different heavy oil exploitation conditions on asphaltene aggregation settlement process,and there are few reports and field studies cannot accurately understand influences of different factors on the asphaltene aggregation settlement.Therefore,this paper in view of the three heavy oil exploitation technology,conducted heavy oil thermal recovery experiment,air injection and low temperature oxidation and catalytic upgrading experiment in laboratory to study the effect of different conditions on asphaltine aggregation sedimentation process,and the effects of the different inhibitors on asphaltene flocculation behavior inhibition,which provides an important theoretical basis for heavy oil exploitation and recovery processing of heavy oil.As raw material,Lukeqin heavy oil was used to carried out thermal effect,low temperature oxidation and catalytic upgrading experiments,respectively.The experimental results show that the thermal effect of temperature increase of asphaltene in crude oil is more stable,but standing for a certain period of time,the aggregation degree of asphaltene aggregates rebound,indicating thermal recovery process for asphalt dispersion in the short term;for air injection low temperature oxidation experiment,as the reaction gas oil ratio and the increase of temperature,the oxidation of oil the acid value and the content of asphaltene,polar increased,leading to the flocculation starting point of asphaltenes indicates that asphaltene decreased gradually,more and more unstable,therefore,the degree of aggregation of asphaltene increases,the average diameter increased,indicating low temperature oxidation induced asphaltene precipitation intensified;for catalytic reforming experiments,with the increase of change matter of time and temperature,catalytic modification enhanced,asphaltene cracking,modified oil light components increased,thus the asphaltene more and more stable,increase the degree of dispersion,poly The collective diameter decreases,indicating that the catalytic modification had positive effect on the asphalt stability system of heavy oil.In order to prevent the Lukeqin heavy oil asphaltene coagulation occurring,this paper chose nine inhibitors of asphaltene to study their physical and chemical effects on asphaltene aggragation.The results show that adding nine inhibitors directly,asphaltene floc point increased that these inhibitors can stabilize the heavy oil system of asphaltenes,but their inhibition effects are different,the order is P3>P2>P1>DR>DBSA>DP>IL-C>IL-A>IL-B.The asphaltenes dispersion studies show that,the suppression effect of P3 was the best,because under the effect of P3,asphaltene aggregated into dispersed rod,and there almost does not exist the sheet-like aggregates structure.The chemical effect of inhibitors suggest that after the addition of copper,PC inhibitors can not only interact with asphaltene by hydrogen bonding,but aslo make the asphaltene cracking to decrease polarity.And PC inhibitors have a long alkyl side chains,make asphaltene particles in dispersion,so the stability effect of PC inhibitor is stronger.The final analysis of the mechanism of PC inhibitor on asphaltene precipitation behavior was provided.