Study On Prediction And Prevention Technology Of Asphaltene Deposition Cracking In Crude Oil

In the mining process of crude oil, asphaltene deposition problem may occur on all aspects. Deposition may cause blockage in the borehole or ground pipeline, causing the oil well shutdown. Part of the wells of Halahatang oilfield had asphaltene plugging problems. Seriously affect production.This paper analyzes the asphaltene deposition mechanism and influence factors deeply. For Halahatang representative oil samples and sediment samples were experimental studies. We have established a dynamic forecasting model of asphaltene deposition, providing a theoretical guidance to clear and control the site problems. Last developed a new type of suitable asphaltene dispersing agents for that block.The following understanding:(1)Molecular structure and physical properties of asphaltenes is extremely complex. Deposition processes including precipitation, aggregation, surface contact and adhesion. Each process is affected by a variety of forces together. Macro analysis, crude oil composition, temperature and pressure conditions, the state of crude oil, the contact surface material is the major factors in the impact of asphaltene deposition.(2)XK404and HA15-10oil simpales are intermediate oil and asphaltene content of4.45%to6.32%. C7+components accounted for more than95%. They have complex structure and contain many hydroxyl groups, amino groups, carboxyl groups, carbonyl groups, and aromatic ring, fused ring group, easily lead to aggregation and precipitation of asphaltenes. Oil sample flow properties and asphaltene content has a negative correlation. The sediments of HA12-1and HA901H were studied. Indicate blockage to compact plate structure based asphaltene deposits and asphaltene content of about65%.(3)Dynamic experimental device and methods were designed to test asphaltene precipitation onset pressure for XK404and HA15-10oil simpales. Experiments show that the system temperature rises, and is not determined solely asphaltene precipitation pressure is increased or decreased. Crude oil gas ratio is higher, the higher the bubble point pressure, the higher asphaltene precipitation onset pressure.(4)The establishment of a dynamic prediction model can be used in pipe flow calculations asphaltene deposition by combining the asphaltene precipitation equilibrium model with solid particle deposition kinetics models.(5)XK404and HA15-10wells were calculated for instance. The results are consistent with the case of the construction site. We also have studied the position of asphaltene deposition and deposition rate change under different production systems. Studies have shown that lower oil production, the impact on the asphaltene deposition location is not obvious, but the deposition amount will rapidly increase. Wellhead pressure is reduced resulting in asphaltene deposition depth in the wellbore deepening, the deposition rate increases. When oil production and pressure reducing in post-production, asphaltene deposition problems in the wellbore will become more prominent.(6)For Halahatang asphaltene deposition, preferably with the development of a new type of asphaltene dispersant named LY and the comparative evaluation of the dissolution rate and its inhibition rate. Studies have shown that the rate of dissolution for asphaltenes deposits scene reached3.26mg/ml· min at room temperature. Prior to joining the concentration of0.5wt%, the inhibition rate was83.22%, the effect is the best. Meanwhile, the agent also has significant viscosity reduction effect.