苏里格气田取样代表性及凝析油污染研究

苏里格气田是典型的低渗低含凝析油凝析气田，开发过程中反凝析污染对气井产能的影响一直没有准确的定论。为了掌握反凝析污染的严重程度，需要对气藏流体相态进行准确研究。因为凝析气藏流体的取样方式对流体的代表性有很大的影响，故取样方式显得尤为重要。本文结合苏里格气田现场数据及测试情况，分析了三种凝析气藏取样方法的优缺点和适用情况，准确测试了苏里格气田凝析油含量及其闪蒸测试条件，并通过室内全直径岩心模拟实验及数值模拟分析的方法对苏里格气田凝析油污染程度做了测试分析与评价。结果表明对于苏里格气田这类低渗低含凝析油气田来说，取样方法至关重要，建议采用井口取样的方法对井底无积液的高产井进行流体取样且应采用液氮深冷的方式保证凝析油含量测试的准确性。岩心实验和数值模拟分析显示近井地带凝析油污染尤为突出，伤害程度最高可达50%。本研究中关于凝析油含量及其对地层污染的结论均高于以往研究，有一定的新认识。

Study on Sampling Representative and Condensate Oil Pollution in Sulige Gas Field

Sulige gas field is a typical low permeability and low condensate gas field. In the process of development, the effect of condensate pollution on gas well productivity has not been accurately determined. In order to master the severity of anti condensate pollution, it is necessary to study the phase state of the gas reservoir accurately. Because the sampling method of condensate gas reservoir has a great influence on the representativeness of the fluid, the sampling method is particularly important. In this paper, the advantages and disadvantages of the sampling methods of three condensate gas reservoirs and their application are analyzed in connection with the field data and test conditions of the Sulige gas field. The content of condensate oil in Sulige gas field and its flash test conditions are accurately measured. The pollution degree of the condensate oil in Sulige gas field is tested and evaluated through the simulation experiment and numerical simulation analysis in the indoor full diameter core. The results show that the sampling method is very important for low permeability and low condensate oil and gas fields in Sulige gas field. It is recommended that the wellhead sampling method be used for fluid sampling at the bottom of the well without liquid accumulation, and the accuracy of condensate content test should be ensured by liquid nitrogen cryogenic method. The core experiment and numerical simulation analysis show that the condensate oil pollution in the near well zone is particularly prominent, and the damage degree is up to 50%. In this study, the conclusions about the content of condensate oil and its pollution to the formation are all higher than that of the previous research, and some new discoveries have been made.