摘要
对渤海湾盆地东营凹陷RD1井Es4（上）亚段的研究发现,来自同一套烃源岩的油气,在不同部位或不同深度的储集段,其油气性质存在明显差异,有些层段的原油偏稠化程度较高,有些则质轻、色纯。含气层则分布于Es4（上）亚段的较深部位,常见残留沥青质分布。这一现象说明,随着时间的变化和不同层段地下环境条件的不同,油气保存程度存在差别。进一步研究证实,油气保存时间的长短与地下成岩演化机制有关。通过对RD1井Es4（上）亚段的分析,发现这一特定的成岩环境具备弱酸（pH值5.7-6.8）和偏还原（氧化还原电位小于-10 mV）条件。同时,成岩期矿物也具备某些可以识别的特征,如光学镜下的自生高岭石晶簇和自形黄铁矿的出现以及有机相的蓝色荧光色调等。具备该成岩环境的储集体,油气能够长时期保存;在这一环境影响带的上方,原油极易稠化;而在其下方,原油则易发生裂解,形成气藏。这一成岩环境条件的落实对于解决新、老地层油气成藏潜力、液态烃保存的有效性等问题,具有重要的参考价值。
Studies of the upper 4th member of Shahejie Formation of Paleogene in Well RD1 in the Dongying Sag of the Bohai Bay Basin have indicated that, oil-and-gas from the same source rock in different stratum has different characteristics. Some are heavy oil; the others are high-gravity oil with pure color. Gas reservoirs locate deep in the upper 4th member of Shahejie Formation of Paleogene, where dry bitumen are usually found. This phenomenon shows that, oil-and-gas storage conditions are different due to time changes and different underground environments in different stratum. Further studies prove that, oil-and-gas storage time length is determined by underground diagenetic process. Analysis of the upper 4th member of Shahejie Formation of Paleogene in Well RD1 shows that, the specific diagenetic environment is characterized by feeble acid （pH=5. 7-6. 8） and oxygen-free （Eh〈-10 mV） conditions. Diagenetic minerals are also distinct, for example, crowds of authigenic kaolinite and automorphic pyrite as well as blue fluorescence of organic phase under microscope. Oil-and-gas may store for a long time in reservoirs under the above-mentioned diagenetic environment. Over the belt, oil is heavy. Under the belt, oil cracks to gas. Studies of the specific diagenetic environment have great value for petroleum accumulation potential in new and old formations and storage availability of liquid hydrocarbon.
出处
《石油实验地质》
CAS
CSCD
北大核心
2008年第1期11-15,共5页
Petroleum Geology & Experiment
基金
中国石油化工股份有限公司科研项目(P06010)
关键词
油质差异
油气保存
地下成岩环境
东营凹陷
渤海湾盆地
crude oil characteristics difference
oil-and-gas storage
underground diagenetic environment
the Dongying Sag
the Bohai Bay Basin
