断块型深层低渗油藏天然气驱最小混相压力及相态特征

本文以大港油田深层低渗油藏X断块为研究对象,采用细管实验和PVT测试仪器,测定了大港油田X断块地层原油和Y气藏天然气的最小混相压力,地层原油的基本物性参数,以及注入天然气对原油高压物性参数的影响。实验结果表明：大港油田X断块地层原油属于轻质原油,能够与Y气藏天然气实现混相,且最小混相压力为45 MPa,低于地层压力(49.8 MPa)和国内常用高压天然气压缩机的压力等级(50 MPa),因此,在X断块实施天然气混相驱具有理论可行性；地层原油的气油比、泡点压力、体积系数、压缩性、气体平均溶解系数均较高,多次接触实验结果表明,注入天然气与原油在最小混相压力条件下能够实现多次接触混相。为了实现大港油田深层低渗油藏X断块的高效开发,建议在X断块实施天然气混相驱。

Minimum Miscibility Pressure and Phase Behavior of Natural Gas Flooding in Deep-Seated and Low Permeability Fault-Block Reservoir

With deep-seated and low permeability reservoir X Block in Dagang Oilfield as the research object, PVT test equipment is applied and slim tube experiment is performed to measure the minimum miscibility pressure between oil from X Block and natural gas from Y gas reservoir in Dagang Oilfield, basic properties of oil, and the influences of natural gas injected on oil PVT parameters. Experimental results show that, the oil from X Block is light, and it can achieve miscibility with natural gas from Y gas reservoir. The minimum miscibility pressure between oil from X Block and natural gas from Y gas reservoir is 45 MPa, which is lower than the formation pressure (49.8 MPa) and pressure grade of high pressure natural gas compressor commonly used in china (50 MPa). Therefore, it is theoreticallly feasible to implement natural gas miscible flooding in X Block. The gas oil ratio, bubble point pressure, volume coefficient, compressibility factor and average gas solubility coefficient are high. The result of multiple-contact experiment indicates that, natural gas injected and oil can achieve multiple contact miscibility at minimum miscibility pressure. In order to realize high efficient development of deep-seated and low permeability reservoir X Block of Dagang Oilfield, it is suggested that natural gas miscible flooding be implemented in X Block.