Preparation And Sustained Release Performance Of Solid Asphaltene Inhibitors

In the process of crude oil development,asphaltene deposition will seriously increase the difficulty of oil exploitation,reduce the recovery of crude oil,and even cause a large number of oil wells to be scrapped.At present,the main means of asphaltene inhibition is to add chemical agents,i.e.asphaltene inhibitors.However,the current asphaltene deposition inhibitors have the disadvantages of short inhibition period and poor inhibition effect.In this paper,solid asphaltene inhibitors are studied and explored based on the solidification theory of liquid agents.This paper mainly includes two parts.In the first part,the type and dosage of liquid asphaltene inhibitor and the composition of the system were determined by asphaltene dispersion test method with asphaltene deposition inhibition performance as the index.Secondly,the influencing factors of inhibition effect and the inhibition mechanism of asphaltene inhibitors were studied.In the second part,the composition of solid asphaltene inhibitor system was determined by weight loss method and asphaltene dispersity test method,taking solubility and asphaltene deposition inhibition of solid asphaltene inhibitor as indexes.Secondly,the influence factors of solid dissolution and inhibition were studied.Finally,the dissolution mechanism and inhibition mechanism of solid asphaltene inhibitors were analyzed.The main results are as follows.In the part of liquid asphaltene inhibitor,an excellent asphaltene inhibitor I₂₂ was selected.The indoor experiment showed that the inhibition rate of I₂₂ on asphaltene deposition volume of crude oil could reach more than 95%at the dosage of 30 mg L^-1.The concentration of inhibitor,the source of asphaltene,the concentration of asphaltene,the standing time and the centrifugal speed have certain influence on the inhibition effect.The inhibitor molecule contains ester bond and hydrogen bond,which makes the original closely packed asphaltene structure be separated.The inhibitor molecule may also play the role of dispersing asphaltene molecule.The inhibitor molecule adsorbs on the surface of dispersed asphaltene molecule,which can inhibit the continuous polymerization of asphaltene molecule and improve the effect of dispersing asphaltene.For the solid asphaltene inhibitor part,the temperature resistance limit of the solid inhibitor（60%inhibitor content）prepared with curing agent B as the skeleton material is between 115-120℃,and the solid can still maintain its complete morphology after 72 h heating below the temperature resistance limit.Laboratory experiments show that the inhibition effect of the solid inhibitor is not less than 60%of the original liquid agent under the same amount of dissolution,which shows that the solid agent has the effect of slow release and high efficiency.The increase of temperature and inhibitor content can promote the release rate of solid inhibitor.The solid inhibitor can be regarded as a combination of capsules,in which the skeleton material is wrapped with inhibitor molecules.When dissolved in underground crude oil,the skeleton material gradually dissolves,and the skin layer of the capsule gradually becomes thinner,in which the inhibitor molecules can be released,playing a sustained-release effect.