鄂尔多斯盆地南部直罗油田长8油层油气沸腾包裹体群研究

摘要

运用激光拉曼光谱、包裹体充填度测定等方法对鄂尔多斯盆地直罗油田富南3井、6井长8油层裂缝岩芯充填物中包裹体群进行分析,发现富南3井、6井与英旺油田英16井长8油层中油气沸腾包裹体群完全相同,密集分布的气泡不停晃动,证实油气沸腾包裹体群不是孤立的、偶然的地质现象.富南3井、6井和英16井长8油层裂缝岩芯的原始裂缝性质为滑动-剪切裂缝和剪切裂缝,在区域构造的作用下,反复发生拉张-挤压交替活动；在拉张发生的瞬间,与裂缝沟通的油层里的原油发生减压沸腾,原油中的轻质馏分和其他流体进入裂缝空间；在随后的挤压发生时,裂缝基本封闭,一部分流体返回原来的油层,一部分被挤到别的裂隙空间形成新的油藏；残留在裂缝里的碳酸钙,在较高的地层压力下逐渐结晶,并把残留的轻质馏分包裹,形成油气包裹体；这些油气包裹体形成压力较高,又包裹着成分类似液化气的轻质馏分,在常温常压下就处于沸腾状态；这样的过程反复进行,在裂缝充填物中形成了沿着晶体生长线以及成片、成带分布的油气沸腾包裹体群.上述油气沸腾包裹体群的形成过程就是油气的地震泵运移机制,丰富了油气运移地震泵地质模型.%By the means of laser Raman spectroscopy and filling degree of inclusion) the inclusion groups of fillings of Chang-8 oil-bearing beds from wells Funan3 and Funan6 in Zhiluo Oilfield, the southern of Ordos Basin were studied. The results showed that the oil/gas boiling inclusion groups of Chang-8 oil-bearing beds from wells Funan3 and Funan6 were exactly the same to that from well Yingl6 in Yingwang Oilfield, and a lot of bubbles moved constantly; the geological phenomenon for oil/gas boiling inclusion groups were not isolated and occasional. The characteristics of incipient fracture core of Chang-8 oil-bearing beds from wells Funan3, Funan6 and Yingl6 were shear-slip and shear fractures, and tensile-bearing stress was alternately active under the action of regional structure; decompression boiling of oil in the oil-bearing bed happened in an instant when tensile stress was active, light cut fraction and other fluids flowed into fracture because of the connection of fracture and oil-bearing bed; fracture closed on the whole while the bearing stress was active, a part of fluid returned to the original oil-bearing bed, and another was overflowed onto other fracture so that new oil reservoir formed; calcium carbonate, which remained in the original fracture, crystallized gradually under the high strata pressure and wrapped the rudimental light cut fraction, so that the oil/gas inclusion groups formed; the formation pressure of the inclusion was high, and the inclusion included light cut fraction, so that the inclusion was in a state of boiling at normal temperatures and pressures; the above process happened again and again, and the oil/gas boiling inclusion groups, which distributed along the line of crystal growth, formed lamellar and ribbon in the fillings of fractures. The formation processes of oil/gas boiling inclusion groups were the migration mechanism of seismic pumping and enriched the geological model of seismic pumping.