| Oil is a non-renewable resource.With the sharp increase in oil consumption,the availability of medium-light crude oil is gradually decreasing,and the proportion and status of heavy oil resources in petroleum resources is becoming more and more important.Because heavy oil is extremely viscous and difficult to flow,many processes are used in the mining process.The use of these processes often changes the composition of the heavy oil or the environmental conditions,resulting in a decrease in the stability of the heavy oil and an increased risk of asphaltene accumulation.Therefore,studying the stability of heavy oil has important practical significance.The main research content of this thesis is the stability of heavy oil,including the improvement and characterization of heavy oil stability.Improving the stability of heavy oil with Guantao heavy oil and island heavy oil as research objects.Firstly,the stability of the asphaltene which is easy to cause instability in the heavy oil component is improved,and the saturation concentration of the asphaltene in the solution after adding different dispersing agents is determined by ultraviolet-visible spectroscopy.It was found that the ionic dispersing agent AA containing a sulfonic acid functional group and the nonionic dispersing agent NA1 of a polyhydric alcohol group can effectively increase the solubility of asphaltenes.Transmission electron microscopy,dynamic and static light scattering and electron microscopy were used to investigate the inhibition of asphaltene aggregation and association behavior by AA and NA1.It was found that both dispersants can reduce the size of asphaltene aggregate particles and reduce the degree of asphaltene aggregation.Finally,the infrared spectrum of asphaltenes before and after adding AA and NA1 was obtained by infrared spectroscopy.It was found that O of the sulfonic acid group in AA forms a hydrogen bond with the N-H bond and O-H bond in the asphaltene;A functional group such as a hydroxyl group O-H,an ether bond or an ester group in NA1 forms a blue-shifting hydrogen bond with a hetero atom such as N,O,S or the like in the asphaltene molecule and an aromatic conjugated ? bond.In addition,the improvement of the overall stability of heavy oil found that AA and NA1 have a general effect,indicating that the overall stability of heavy oil is also related to the action of other components.Further studies have found that nonionic surfactants have better improvement than ionic surfactants,but have certain selectivity.Among them,the improvement rate of NB3 stable pavilion heavy oil was 49.87%,and the stability effect of NB2 on Gudao heavy oil was 53%.It was further found that alcohol solvent B dissolved NB3 and then added into heavy oil to improve the effect.In addition,the dipole moments of various components of Guantao heavy oil and dispersing agents such as NB3 were measured.It was found that the polarity of NB3 is similar to that of Guantao colloid,and the dispersant which may be similar to the polarity of colloid is more beneficial to improve the overall stability of heavy oil.In the characterization of heavy oil stability,this paper innovatively established a method to characterize the stability of heavy oil by determining the difference in density between the upper and lower layers of the oil sample.Using this method,the density of the upper and lower layers of the oil sample is measured at 30?,and the measurement time should not exceed 30 min.When the difference in relative density between the upper and lower layers is less than 0.35%(±0.05),the oil sample is stable;when the difference is greater than 0.35%(±0.05),the oil sample is unstable. |
PDF Full Text Request