Key elements controlling oil accumulation within the tight sandstones
Key elements controlling oil accumulation within the tight sandstones
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DOI：
10.1007/s12583-015-0550-y
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发表时间：
2015-06
影响因子：
3.3
通讯作者：
Haiyan Hu;Zhiping Zeng;Jianzhang Liu
中科院分区：
文献类型：
--
作者：
Haiyan Hu;Zhiping Zeng;Jianzhang Liu
准噶尔盆地中部侏罗系发现了低孔低渗致密油砂岩储层，是一种非常规油气资源。为揭示成藏机理，从油源对比、孔隙演化、油气充注史等方面进行了较为全面的研究。结果表明，这些致密砂岩储层原油主要来自二叠系烃源岩，侏罗系烃源岩也有一定贡献。储层埋藏浅（<3 100 m），成岩作用弱，二叠系烃源岩充注二叠系烃源岩时孔隙度高（18.5%），GOI值高（bb0 5%）。侏罗系烃源岩充填时，砂岩储层已致密化，由于严重的压实和胶结作用，无法提供有效的成藏空间，其GOI值较低（<5%）。因此，储层孔隙度控制着致密砂岩的成藏。致密砂岩储层能否成藏取决于油气充注时的储层质量。在致密油砂岩储层勘探前，需要研究储层充注历史与孔隙度演化的关系，以降低勘探风险，明确可勘探目标。
Tight oil sandstone reservoirs with low porosity and permeability, which are an unconventional petroleum resource, have been discovered in the Jurassic intervals of the central Junggar Basin, the northwestern China. To reveal the accumulation mechanism, a relatively comprehensive research was conducted, including oil-source correlation, porosity evolution, and hydrocarbon charging history. The results show that crude oil of these tight sandstone reservoirs were mainly from Permian source rocks with some contribution from Jurassic source rocks. The reservoirs were buried at shallow depth (<3 100 m) and exposed to weak diagenesis, and thus had high porosity (18.5%) when the Permian-sourced oil from Permian source rock was charging, indicating high GOI values (>5%). In contrast, the sandstone reservoir had already become tight and did not provide available space to accumulate oil due to severe compaction and cementation when hydrocarbon from Jurassic source rock filled, evidenced by low GOI values (<5%). Therefore, reservoir porosity controls the oil accumulation within tight sandstone. Whether tight sandstone reservoirs accumulate oil depends on the reservoir quality when hydrocarbons charge. Before the exploration of tight oil sandstone reservoirs, it should be required to investigate the relationship between oil charging history and porosity evolution to reduce the exploration risk and figure out the available targets.