原油沥青质初始沉淀压力测定与模型化计算

Measurement and modeling calculation of asphaltene onset precipitation pressure

温度、压力及组成的改变均会造成原油中沥青质产生沉淀,导致储层伤害和井筒堵塞。文中通过自主研制的固相沉淀激光探测系统,用透光率法首次测定了伊朗南阿油田原油样品在不同温度下的沥青质初始沉淀压力;同时利用Nghiem等建立的沥青质沉淀预测的热力学模型对油样沥青质初始沉淀压力进行计算,并与实验结果拟合。结果表明:利用透光率法测定该油田油样,在44,80,123℃下的沥青质初始沉淀压力点分别为42.8,39.7,35.2 MPa;沥青质初始沉淀压力随着温度的升高,在井筒温度范围内呈线性关系。模型计算与实验结果误差不超过15%,所以利用Nghiem模型对原油沥青质的初始沉淀压力进行预测是可靠的。

Changes in temperature and pressure will causes asphaltene precipitation and deposition,which damages reservoir and plugs wellbore.In this paper,the solid detection system independently designed by our laboratory was used to investigate asphaltene precipitation with light-scattering technique using NIR.The onset precipitation pressure under the different temperature of the oil sample from a typical oil well of South Azadegan Oilfield in Iran was measured to determine the thermodynamic condition of asphaltene deposition.At the same time,by using the thermodynamics model established by Nghiem model,the asphaltene onset pressure of oil sample was calculated and fitted with the experimental results.The results show that the asphaltene onset pressure under the different temperature of 44 ℃,80 ℃ and 123 ℃ were 42.8 MPa,39.7 MPa and 35.2 MPa and there was a linear relationship between the asphaltene onset pressure and the temperature.The deviation between experimental findings and model calculation results is less than 15%.Therefore,the prdiction result on the asphaltene onset pressure of crude oil by Nghiem model is reliable.