肯基亚克油田盐下8010井沥青质初始沉积压力温度预测

PREDICTION OF ASPHALTENE INITIAL PRECIPITATION PRESSURE AND TEMPERATURE FOR WELL 8010 IN KENJIYAK OILFIELD

原油温度、压力和组成的改变均会引起沥青质发生絮凝和沉积,造成储层伤害和井筒堵塞。建立一种沥青质沉积条件的预测模型,根据盐下油田8010井的井筒流体组成、原油和C7+组分的相对分子质量、原油和各组分的密度、沸点等数据,可以方便快速地确定原油沥青质沉积初始压力和温度。结果表明,肯基亚克8010井原油的沉积初始温度为70℃,沉积初始压力为38.6MPa,比地层温度下的原油饱和压力高出6.6MPa。相应地可以推测出在1300～1400m井筒处开始发生沥青质沉积,沉积过程可能会持续几百米甚至直到地面泵阀处。实际发生的情况证实了这一预测的可靠性,为该油田制定预防和解除油井发生沥青质沉积的具体措施提供了理论依据。

Changes in temperature, pressure and components of crude oil will cause flocculation and sedimentation of asphaltene, which causes reservoir damage and wellbore plugging. A model to predict the original pressure of the crude asphaltene sedimentation was established, in which precipitated asphaltene was treated as solid phase. According to the data such as liquid composition in wellbore,density and boiling point of crude and each components in Well 8010, asphaltene original sedimentation pressure and temperature could be estimated through liquid and solid phase equilibrium calculation. The results showed that asphaltene onset precipitation pressure and temperature were 38.6 MPa and 70℃ respectively, and the onset precipitation pressure is more 6.6 MPa than the saturation pressure. Accordingly it could be calculated that asphaltene sedimentation occurred in depth of 1300m to 1400m and could stretch in range of several hundreds of meters in wellbore and even to wellhead. The reliability of the model was confirmed by actual situation. The theoretical basis was provided for laying down the measures to prevent and remove asphaltene sedimentation in wellbore in Kenjiyak oilfield.