Experimental And Theoretical Study On Paraffin Deposition In Deep-sea Condensate Gas Reservoir

The phase change of high temperature and high pressure gas reservoir is complicated.Oil and gas reservoirs or hydrocarbon-containing segment display have been found in the western areas of the South China Sea,the reservoirs reach temperatures as high as 242 degrees Celsius,with pressures of up to 77.1 megapascals.The fluid properties of the formation are complex and varied for its diverse stratigraphic conditions.It's hard to acknowledge the existence of fluid in high-temperature and high-pressure gas reservoirs currently,especially the condition of high temperature and high pressure condensate gas reservoir paraffin deposition.Experimental Study on Paraffin Deposition in High Temperature and High Pressure Condensate Gas Reservoir,serving as an effective guide for reviewing of complex fluid.Based on the comparative analysis of paraffin deposition mechanism and paraffin deposition test,this paper presents the experimental study on the phase behavior of high temperature high pressure and high wax content condensate gas reservoir and the paraffin deposition of condensate gas reservoir.Based on the experimental results,the numerical simulation of high temperature and high pressure condensate gas reservoir was carried out in the process of the high temperature and high pressure condensate gas reservoir.Analysis of the ratio and the point of paraffin deposition temperature under different pressure conditions and the amount of wax deposition in different oil and gas;as the basis for the establishment of condensate gas reservoir,wellbore temperature and pressure prediction model,the specific conditions of high temperature and high pressure deep condensate gas reservoir of paraffin deposition prediction.The following conclusions are obtained:(1)different gas oil ratio,different temperature and pressure under the condition of constant expansion.The experimental results show that when the actual pressure is lower than the dew point pressure,fluid in condensate oil(liquid);the gas oil ratio is larger,the smaller the dew point pressure(at the temperature of 136?,gas oil ratio 12857m~3/m~3 the gas oil ratio 8000m~3/m~3 and gas oil ratio 5500m~3/m~3 dew point pressure were 39.115MPa,41.443MPa and 46.125MPa);the higher the temperature,the samples of the dew point pressure decreases;with the increase of the fluid velocity,the dew point pressure decreases,but the decline is small.(2)the experiment and simulation show that the maximum mass ratio of YC13-1 surface oil is about 12%,and the wax content is increased with the temperature decreasing.When the pressure increases,the wax precipitation point slightly increased,the temperature is higher than 30 ?,no matter how much pressure paraffin wax will not precipitate.(3)the experiment and Simulation of the high temperature and high pressure condensate gas reservoir paraffin deposition show that the condensate oil content is low in the condensate of the gas oil ratio of 12857m~3/m~3,and the maximum reverse condensate volume is only about 1%under the condition of 150.With the increase of pressure,the temperature of paraffin deposition point decreases.After the temperature is higher than 24 ?,no matter how the pressure changes,paraffin wax will not be deposited.Under high pressure,the temperature of paraffin deposition is very low,and the pressure of paraffin deposition is very low under high temperature.The paraffin deposition of condensate gas increases with the decrease of temperature,and the mass ratio of the system is less than 1.2%.(4)the gas oil ratio of condensate gas reservoir increases,the dew point pressure increases,and the condensate volume increases.The lower the gas oil ratio is,the higher the wax deposition pressure is,the higher the maximum wax deposition is,and the higher the wax deposition temperature is.This shows that the condensate gas condensate flow than the low oil body high gas oil ratio is more prone to wax deposition.On the whole,the condensate gas is most likely to wax out under the condition of low temperature and low pressure.(5)oil and gas multiphase pipe flow theory based on the prediction model of condensate gas well bore temperature of paraffin deposition is established,according to the different pattern of judgment,the calculation formula of the pressure gradient in different temperature gradient is established;wellbore formation conditions and sea conditions,to predict wellbore static wax precipitation point.Based on the data of single well production in YC13-1 gas field,the position of wax precipitation is predicted.The study shows that the limit depth is 150m,and when the oil pressure is higher than 2Mpa,there will be no paraffin deposition in the formation and wellbore.