| 其他摘要 | Subei basin is the foremost oil production and exploration area in Jiangsu oilfield. Exploration benefit has decreased since the late “9th Five-year Plan”. Owing to lacks of conservation traps favorable to oil accumulation and reserve replacement areas, the exploration complexion is serious. In order to cast off the disadvantage, we must enhance the study of complex fault zone, and find some new breakthrough in new series of strata, type and field. The focus of this paper is to study oil accumulation laws along the complex fault zones of Jinhu and Gaoyou sags in Subei basin. By using multi-disciplines, multi-theories and multi-methods, we have analyzed the structural styles, tectonic evolution and reservoir-forming elementary factors (such as oil source, reservoir bed, caprock and migration pathways). At the same time, we have studied comprehensively the fault control and impact of hydrocarbon migration, sediment, trap forming and hydrocarbon preservation, as well as hydrocarbon distribution and reservoir-forming patterns. The author has acquired some new knowledge about the tectonic frameworks and the reservoir-forming laws of fault zones. The following results in this paper have been made:
1. According to the analysis of regional data and the research on the characteristics and the forming mechanisms of the complex fault zones, such as Shigang, Tongcheng, Yangcun, Hanliu and Zhenwu, it is concluded that Jinhu and Gaoyou Sag are tenso-shear sags formed by the regional right-lateral shear couple. The brush-like, echelon, comb-like, floriform tenso-shear tectonic styles and the ladder-like, horst-graben-like, Y-type extensional tectonic styles develop there.
2. We have analyzed the types, spatial shapes and the petroleum geology significance of the structure accommodation zones, including Zhen②, Hanliu-Wu②, Zhenwu-Wubao, Wubao and Bianminyang.
3. The types of faulted slope-break zones were studied, as well as the distribution rules of faulted slope-break zones, depositional systems and sandstone bodies. The faulted slope-break zones of the sags have different types, such as salient-steep slope margin, steep slope- subsag margin, uplift-gentle slope margin and gentle slope- depression margin.
4. The hydrocarbon distribution and enrichment shows that most of deep faults are migration pathways of hydrocarbons, hydrocarbons distribute along the oil-generation center in zonary shape. The tenso-shear structural style controls trap formation and oil reservoir distribution.
5. According to the main migration pathways of hydrocarbons, the reservoir-forming patterns can be divided into two types, i.e. lateral migration and vertical migration. The former mainly develops in the north slope of Gaoyou sag, Weizhuang area, the west slope of Jinhu sag and Minqiao area. The later mostly distributes in the steep slope belts of Gaoyou and Jinhu sags, and is further divided into the reservoir-forming patterns of Jinhu and Gaoyou steep slope belt, according to the characteristics of fault zones.
6. Based on integrated analysis of the tectonic styles of complex fault zones, the characteristics of accommodation zones, the types of slope-break zones and the reservoir-forming control factors, we conclude that Bianminyang area, Zhenwu and Hanliu fault-terrace belts will become important blocks for exploration of structural reservoirs; the faulted slope-break zones of steep slope-subsag margin and gentle slope-subsag margin are the developing areas of high-quality reservoir bed such as fluxoturbidite sandstone bodies, and will become promising areas for seeking lithologic reservoirs. Such as the downthrow of Zhen② fault and the slope area of Shanhe subsag. |
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