改进后的烃类流体包裹体热力学模拟方法及其在油气成藏研究中的应用

烃类包裹体成分和热力学行为非常复杂,准确恢复捕获条件一直是一个难点。以往的研究一般用盐水包裹体的均一温度来代替捕获温度,但是均一温度和捕获温度之间有误差,用均一温度代替捕获温度不够准确,因此需要校正。笔者对烃类和同期盐水包裹体的均一温度先校正后模拟,减少了烃类包裹体热力学模拟误差;通过对储层流体包裹体进行显微荧光、显微测温、显微共聚焦激光扫描、显微傅里叶变换红外光谱等实验分析,得到流体包裹体均一温度(90~170℃)、盐度(0.71%~11.1%)、气液比(7%~9%)、CH4的摩尔分数(20%~25%)和CH2/CH3(4~8)等参数;结合盐水包裹体均一温度校正曲线,利用FIT-Oil软件进行PIT(烃类包裹体热力学)模拟,恢复储层包裹体的捕获压力和捕获温度,提高了包裹体捕获条件获得的精度。为了验证此方法的准确性,以人工合成包裹体作为标准样品,获得盐水包裹体均一温度与捕获温度关系校正曲线,参数校正后利用软件计算出的捕获温压与实验设定的温压条件吻合良好。以东营凹陷丰深10井沙四下亚段储层包裹体为实例,进行了古温压和成藏期的估算,与前人通过其他方法得出的结论一致,证实了捕获条件获得的准确性。

Improved Simulation Method of Petroleum Inclusions Thermodynamics and Its Application in Hydrocarbon Accumulations

Composition and thermodynamic behavior of hydrocarbon are complicated ;so it is difficult to recover its trapping conditions .In this paper ,by ways of petroleum inclusions and the corresponding period aqueous inclusions homogenization temperature correction before simulation , we reduced the petroleum inclusions thermodynamic error , increased the accuracy of trapping conditions . Through microthermometry ,fluorescence spectroscopy ,confocal scanning laser microscopy ,and Fourier transform infrared spectrum analysis we obtained the homogenization temperature(90 170 ℃ ) ,salinity (0 .71%11 .1% ) ,gas and fluid ratio(7% 9% ) ,and mole percent content of CH4 (20% 25% ) ,CH2 /CH3 (4 8) of reservoir fluid inclusions .Based on these thermodynamic parameters ,using PIT simulated data of FIT Oil and aqueous inclusions homogenization temperature calibration curve ,we recovered the trapping pressure(22 27 Mpa) and temperature(125 157 ℃ )of reservoir inclusions .By taking the synthetic hydrocarbon inclusion as a standard sample ,we applied the PIT to the reservoir fluid inclusions of Fengshen 10 well in Dongying sag Es4 x to estimate the original temperature , pressure , and the accumulation period ;by which the accuracy of the PIT method is verified .Because of its high effectivity that determine period of hydrocarbon accumulation , the method can be applied widely in various oil fields .