Synthesis Of Oxazolidine And Application In Prevention Of Oilfield Gathering System’s Corrosion

With the development of petroleum industry, the corrosion of the oil sewage system is becoming more and more serious. How to prevent and reduce the corrosion of the oil sewage, has attracted the world’s common concern. Corrosion is controlled by environment and material factors. Therefore, the corrosion caused by the wastewater will be reduced by changing the environment or the composition of the materials. Water quality plays a role in the corrosion of the oilfield gathering system. So we can change the water quality to control corrosion by chemical method. H2 S is a kind of very strong hydrogen permeability medium. The corrosion caused by H2 S is the important trouble that not allowed to ignore. The oxazolidine compounds contains the reactive group as N-C-O which can be opened the ring to form Schiff base in water. Schiff base can absorb H2 S in water, Thus, the corrosion of the oilfield gathering system will be relieved.First of all, five kinds of oxazolidine and its derivatives were synthesized starting from alcohol amine, aldehyde or ketone through the means such as azeotropic dehydration and vacuum distillationto. And the best reaction conditions and optimum yield was confirmed by designing the L9 orthogonal test, the yields of the compound were 79.4%、93.3%、86.2%、42.3% and 51.2% respectively. At the same time, the stucture of the products wereproved with the aid of infrared spectrum and the gas phase mass spectrometry instrument.Secondly, in this paper, on the one hand, the absorption efficiency of the oxazolidines was investigated by measuring the different concentrations of hydrogen sulfide in the wastewater which added the five kinds of oxazolidine and its derivatives through the hydrogen sulfide detector. The result showed that five kinds of oxazolidine and its derivatives had good absorption efficiency, and in the wastewater of different hydrogen sulfide concentrations, their absorption efficiency were above 90%; on the other hand, the weight loss method was performed to study the preservative efficiency under different corrosion time, concentration of oxazolidines and corrosion temperature. The specific steps were as follows: The corrosion coupons was put in a sealing device full with the hydrogen sulfide solution and the corrosion coupons were rotated at a constant speed. The corrosion rate and preservative efficiency.was studied by calculating the loss weight of the corrosion coupons after a period of time. Besides, the anti-corrosion mechanism of five kinds of oxazolidines was investigatived by the scanning electron microscope(SEM), olympus microscope(DP72) and X-ray photoelectron spectroscopy(XPS).Finally, the adsorption complexation and optimize the preservative efficiency of the oxazolidines in the oilfield sewage pipeline was discussed by researching the oxazolidines combined with surfactant, corrosion inhibitors and inorganic nonmetallic ions in the simulated oil field produced water through the above research methods. The best anticorrosion efficiency of the complex were above 90% showed that the oxazolidines could get a better synergy with the compound, such as N,N-dimethyl ethanolamine, N-methyl diethanolamine, glycerol and morpholine.The better mixtures with good synergy were selected to improve the preservative efficiency of the oxazolidines in the oilfield sewage pipeline.In brife, the studies of this paper will put forward a new train of thought to repress the corrosion caused by the hydrogen sulfide in the wastewater, and further provide the basic data and guidance to the application of oxazolidine compounds in the industrial production.