Study On Dynamic Scaling Mechanism Of LH Oilfield

One of the most significant issues affecting oilfield development,gathering,and transportation is scaling.The LH oilfield group’s formation water contains Ca²⁺,Mg²⁺,and other scale forming ions,the overall salinity is high,the temperature is 116～120°C,the production fluid volume of a single well is 191～2385m³/d,and the highest water content is 98%.As the production fluid volume is low and the water content is high,scale will occur.The study of dynamic scaling mechanism is of great significance to the safe production of LH oilfield.The dynamic scaling mechanism and law are investigated experimentally in this paper,and the combined action of crystallization scaling,particle deposition,and dirt removal is determined.The scaling rates of hot wall is about 10^-2～10^-1mm/d,and that of cold wall is about 10^-3～10^-2mm/d.The scaling rate increases with the increase of the concentration of scaling ion,temperature,p H and the decrease of shear stress.The order of the influence of various factors on hot wall scaling is:temperature>shear stress>scale ion concentration>p H;and the order of the influence of various factors on cool wall scaling is:shear stress>scale ion concentration>temperature>p H.Based on the experimental results,the dynamic scaling rates prediction models to predict the dynamic scaling rates on hot and cold walls are established.The average relative deviation between the calculated and experimental values is 9.4%and 12.7%,respetively.The models have high accuracy and reliability.A software for predicting dynamic scaling rates is developed-OFDSRPS-based on the pressure and temperature calculation models of pipeline and wellhole,as well as the dynamic scaling rates prediction models.The scaling rates at certain temperatures and pressures can be predicted by this software.Besides,the scaling rates along the entire pipeline or wellbore can also be predicted.The scaling rates of water samples in LH oilfield was explored experimentally.The average relative deviation between the predicted and measured values is 12.0%.The scaling rates of LH oilfield is predicted by OFDSRPS.The maximum scaling rates of LH16,LH20 and LH21 oilfields are 1.12mm/a,0.06mm/a and 0.21mm/a,which provide an important basis for the selection of anti-scaling measures in LH oilfields.