凝析气藏相态恢复规律认识及样品代表性判断  

Understanding on phase-behavior restoration laws and estimating representative samples in condensate gas reservoirs

作　　者：汪来潮 彭小东 殷修杏 陈建华 周小涪 WANG Laichao;PENG Xiaodong;YIN Xiuxing;CHEN Jianhua;ZHOU Xiaopei(CNOOC Zhanjiang Company,Zhanjiang,Guangdong 524057,China;CNOOC Hainan Company,Haikou,Hainan 570312,China)

机构地区：[1]中海石油(中国)有限公司湛江分公司,广东湛江524057 [2]中海石油(中国)有限公司海南分公司,海南海口570312

出　　处：《天然气技术与经济》2022年第6期30-34,41,共6页Natural Gas Technology and Economy

摘　　要：相态特征测试是凝析气藏开发的基础,它对该类油气藏的储量计算、分析开采效果和制订合理开发方案有着重要的作用。但是在现场往往由于一些原因,比如采用MDT泵抽的方式在低于原始地层压力的某一压力下取样,取得的样品存在失真的可能,因此需要确定样品的代表性。为了确定流体样品的代表性,以相态恢复方法为研究对象,采用添加平衡油的手段,分析了恢复后流体露点压力和气油比随平衡油添加比例的变化关系曲线。研究结果表明:(1)在设定一系列添加平衡油比例的相态恢复过程中,随着添加平衡油比例的增多,流体由凝析气状态先转变为挥发油与凝析气过渡带状态,最终彻底转变为挥发油状态,恢复后的流体饱和压力先属于露点压力且呈上升趋势,后属于泡点压力且呈降低趋势,存在一个拐点即最高点;(2)流体在恢复后饱和压力最高点的状态下,其油气藏类型属于一种近临界态油气藏。结论认为:通过恢复后的相图分析流体在取样条件、转样条件下是否处于单相状态,从而可判断样品是否存在失真的可能性。A Phase-behavior test on condensate gas reservoirs is the foundation for their development.And it plays an important role in calculating reserves,analyzing an exploitation effect and formulating rational development schemes.However in fact,there exists one possibility of distortion in samples due to some reasons,such as sampling at a certain pressure lower than the original formation pressure by means of MDT pumping.It is necessary to make clear what representative samples are.So,one method of phase-behavior restoration was used to analyze the variation relationship curve of fluid dew-point pressure and gas/oil ratio with the adding proportion of equilibrium oil after restoration by adding equilibrium oil.It is indicated that when the fluid dewpoint pressure is at its highest point after restoration,oil and gas reservoirs are near critical.In conclusion,the possibility of sample distortion can be judged by analyzing whether the fluid is in the state of single phase under sampling and samples’delivery conditions based on the restored phase-behavior diagrams.

关 键 词：凝析气藏 样品代表性 相态恢复 露点压力 平衡油 

分 类 号：TE372[石油与天然气工程—油气田开发工程]