论文部分内容阅读
在具有相同储集砂体和相似断层输导情况下,牛庄洼陷沙三中亚段砂岩体油藏长期存在以下难以解释的现象:1)现今砂岩孔隙度分布与油气分布不一致,高孔隙砂岩不含油而低孔隙砂岩含油;2)相同物性砂岩有的含油而有的不含油;含油砂体现今物性接近,但含油级别却存在很大差异。本文从古孔隙度恢复方面分析了牛庄洼陷西部地区沙三中砂岩储层在成藏期的储集条件,并探讨了成藏期储层临界孔隙度。研究发现:1)虽然现今储层物性下限很低,部分砂岩已经致密化,但成藏期的古孔隙度分布在18%~25%范围内,远大于成藏期临界孔隙度13.9%。但由于埋藏过程的差异导致砂岩储层后期减孔幅度不同,因而现今储层物性不能反映成藏期储层物性,成藏期孔隙度高并不能代表现今孔隙度高;2)成藏期高孔隙度带与现今油气分布范围高度一致,表明在相似断层输导条件下,由于储层物性级差优势形成油气优势运移通道,导致高孔隙度带砂体含油;因此,沙三中亚段岩性油藏富集在成藏期高孔隙带中,成藏期砂岩古孔隙度是油气成藏的重要控制因素,而现今砂岩储层高孔隙带在成藏期并不一定高。牛庄洼陷西部地区沙三中亚段储层中具有高古孔隙度的砂岩仍有较大勘探潜力。
In the case of the same reservoir sandstone and similar faults, the sandstone reservoirs in the Middle Third Member of the Middle Reaches of the Middle Reaches of the Third Member of the Niuzhuang Sag show unexplainable phenomena for a long time: 1) The present sandstone porosity distribution is inconsistent with the distribution of oil and gas, Sandstone oil-free and low-porosity sandstone oil; 2) some of the same physical sandstone oil-bearing and some oil-free; oil-bearing sand body properties close to today, but the oil level there is a big difference. In this paper, the reservoir conditions of sandstone reservoirs in the Third Member of the Middle Third Member of the Niuzhuang Sag in the Middle of Niuzhuang Sag have been analyzed from the aspect of ancient porosity recovery, and the critical porosity of reservoirs during the hydrocarbon accumulation period has been discussed. The results show that: 1) Although the lower limit of reservoir properties is very low and some sandstones have been densified, the paleo-porosity in the reservoir-forming period ranges from 18% to 25%, which is much larger than the critical porosity of 13.9% during hydrocarbon accumulation. However, due to the difference of burial process, the pore-reducing rate of sandstone reservoirs at the late stage is different. Therefore, reservoir physical properties can not reflect the reservoir property during the reservoir-forming period. The high porosity in the reservoir-forming period does not represent the high porosity. (2) The porosity zone is highly consistent with the current oil and gas distribution range, indicating that the dominant pathways of oil and gas migration are formed due to the difference in reservoir property, which leads to oil-bearing of high-porosity sand bodies under similar fault conditions. Therefore, The paleo-oil reservoirs are enriched in the high porosity zones during hydrocarbon accumulation. The paleo-porosity of sandstones during hydrocarbon accumulation is an important controlling factor for hydrocarbon accumulation. However, the high-porosity reservoirs in sandstone reservoirs are not necessarily high during hydrocarbon accumulation. The sandstone with high palaeo-porosity in the reservoirs of the Middle Third Member of the Middle Third Member in the Niuzhuang Depression still has great exploration potential.