Lower limit of hydrocarbon accumulation in the Kuqa Depression, Tarim Basin, NW China

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• 作者：Hang Jiang ; Xiongqi Pang ; Rui Yu ; Dongxia Chen ; Di. Chen ; Jiahui Zhao and Tao Hu
• 刊名：Geological Journal
• 出版年：2017
• 出版时间：January/February 2017
• 年：2017
• 卷：52
• 期：1
• 页码：141-153
• 全文大小：1847K
• ISSN：1099-1034

文摘

The lower limit of hydrocarbon accumulation in the Kuqa Depression is investigated. The Kuqa Depression in the Tarim Basin is one of the largest gas-producing regions in China. High yields of hydrocarbons have been found in depths below 7000 m, which suggests that the deep strata have great potential for hydrocarbon exploration. However, for effective deep exploration, the effective limits such as maximum depth or minimum physical properties of reservoirs have not yet been established. The lower limit of hydrocarbon accumulation, i.e. the conditions at which hydrocarbon accumulation is no longer possible, is determined by analysing the characteristics of effective reservoir space, reservoir permeability, fluid potential differences inside and outside the reservoir, and drilling results of exploratory wells in actual geological conditions. Research shows that the lower limit of hydrocarbon accumulation is reached when irreducible water saturation reaches 100%, reservoir permeability reaches as low as 0.01 × 10⁻³ µm², fluid potential ratio of outside to inside the reservoir (fluid potential ratio of the surrounding rock to sandstone reservoir) is less than 5.5, and exploratory wells reach reservoirs that are all dry layers. From these four aspects, the lower limit of hydrocarbon accumulation corresponds with reservoir porosity of approximately 2.5%, permeability of approximately 0.01 × 10⁻³ µm², pore throat radius of approximately 0.003–0.004 µm, and burial depth of approximately 8200 m. Determining the lower limit of hydrocarbon accumulation in the Kuqa Depression will contribute to predicting favourable exploration areas and evaluating effective resources. Copyright