渝页1井地质背景及钻探效果

我国南方海相页岩分布广、厚度大,有机质丰度高、热演化程度高,由于地质及地形条件复杂、含气性变化大,页岩气资源潜力有待查明。位于重庆市彭水县境内的页岩气取心井——渝页1井揭示了高陡构造带上黑色页岩及其中的含气特点。该井钻揭下志留统龙马溪组黑色页岩层系地层厚度为225.78 m(未穿)。实验分析结果表明:该井龙马溪组黑色页岩具有有利的页岩气成藏条件及典型的浅层页岩气特点,有机碳含量平均达到了3.7%,有机质成熟度(Ro)平均为2.04%。黑色页岩中裂缝及微孔隙发育,储集空间包括了黏土矿物粒间微孔隙、页理间孔隙、溶蚀孔隙、成岩微裂缝及构造裂缝等。实验计算龙马溪组黑色页岩含气量介于1.0～3.0 m3/t。研究表明,渝页1井所揭示的下志留统龙马溪组和上奥陶统五峰组暗色页岩分布广泛,页岩气资源潜力大。

Geologic setting and drilling effect of the shale cored well Yuye-1,Penshui County of Chongqing

Marine shale is widely distributed in South China with a huge thickness and a high level of organic matter abundance and maturity. However, due to its complexity of geological and topographical conditions and great change in its gas bearing property, the shale gas resource potential needs to be identified. In view of this, samples collected from the Yuye 1 well, located in the Penshui County of Chongqing, help us understand the characteristics of black shale and its gas bearing property in the high steep structure. From the drilling results of this well, the thickness of black shale in the Silurian Longmaxi Formation is 225.78 m (not being penetrated yet). Through experimental analysis, samples from this well demonstrate that black shale in the Longmaxi Formation has favorable conditions for shale gas reservoirs with typical features of shallow shale gas. Its organic carbon content is up to 3.7% and Ro is 2.04 at average. Moreover, fractures and micro pores are so well developed that the reservoir spaces include micro pores between grains of clay minerals, the pores between slices beds, dissolution pores, structural fractures, diagenetic micro cracks and so on. In laboratory, the gas content in black shale of the Longmaxi Formation is calculated to be within the range of 1.0 ~ 3.0 m3/t. This experimental study shows that there is great potential of shale gas resource in the Yangtze area.