| The dependence of the world economy on oil has led to an increase in the consumption of petroleum resources,and the number of conventional oil reservoirs that can be mined has been decreasing.Therefore,the development of unconventional petroleum resources,such as heavy oil and super heavy oil,has attracted more and more attention from people.However,in the process of mining heavy oil resources,it is difficult to develop heavy oil wells for its high viscosity and poor flowability,and the various corrosive media contained in heavy oil often destroy the integrity of the mining system and make the development of heavy oil more difficult.In this paper,in order to solve the corrosion of heavy oil well pipe string,physical and chemical properties analysis and corrosion inhibition performance evaluation tests are used to screen two kinds of corrosion inhibitors,which are suitable for heavy oil wells in Tahe Oilfield,from five frequently used corrosion inhibitors.And the optimal additive concentration and compatibility of them are further analyzed.Meanwhile,the electrochemical corrosion characteristics of P110 and P110 S steels in the five corrosion inhibitors are studied by electrochemical testing methods,which lay a foundation for revealing the corrosion inhibition mechanism of corrosion inhibitors for heavy oil wells.The main conclusions of the paper are as follows:?1?Physical and chemical performance test results show that the p H values ? ? of the five corrosion inhibitors are all in the range of 5 to 9,which meets the experimental requirements.And they are testified as having good flowability at low temperature because of the pour points of them are all less than-20°C.In addition,the solubility of the five corrosion inhibitors are better in diesel oil and the the dispersibility of them are better in water when the concentration is 300 mg·L-1.At last,they all have a good demulsibility which have no tendency to emulsify.?2?At 140°C,the 2# imidazoline and 5# quaternary ammonium salt corrosion inhibitors have a better corrosion inhibition effect on of P110 steel and P110 S steel corrosion.And the corrosion inhibition effects of 4# quaternary ammonium salt,3# imidazoline and 1#imidazoline corrosion inhibitions are weakened in turn.And at the additive concentrations of100 mg·L-1,200 mg·L-1and 300 mg·L-1,the optimal concentrations of 2# and 5# corrosion inhibitors are 200 mg·L-1and 300 mg·L-1 respectively.?3?Compatibility experiments show that the 2# and 5# corrosion inhibitors have good compatibility with demulsifier used in oil fields.?4?Electrochemical analysis showed that the five corrosion inhibitors were mixed corrosion inhibitors.Among them,1#,3# and 4# corrosion inhibitors mainly inhibited the cathodic hydrogen evolution reaction of metals,while 2# and 5# mainly inhibited the anodic dissolution reaction of the metals.And as the additive concentration of corrosion inhibitors increases,the value of Rct increases,which indicates that the corrosion inhibitor molecules gradually form a protective film on the metal surface,and inhibits the corrosion reaction of the metal electrode.At the same time,the value of Rf increases,which shows that the adsorption film of the corrosion inhibitor on the metal surface is more dense and complete. |
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