鄂尔多斯盆地中部奥陶系马四段天然气成藏主控因素

鄂尔多斯盆地中部奥陶系马四段碳酸盐岩天然气具有一定的勘探潜力,但其天然气成藏主控因素尚不清楚,限制了该区勘探的深入,针对这一问题,利用钻井、测井、地球化学、试气等资料,分析奥陶系马四段天然气藏特征,从气源岩条件、储层特征、运移条件和遮挡条件等方面开展成藏主控因素研究.研究结果表明:马四段气藏类型主要为岩性气藏;气源岩条...

Key Controlling Factors of Natural Gas Accumulation in the Ordovician Ma Member 4 in the Central Ordos Basin

There is certain potential of exploring the carbonate gas in the Ordovician Ma Member 4 in the Central Ordos Basin. However, the key controlling factors for natural gas accumulation are not clear, limiting the exploration in this area. In response to this problem, the gas reservoir characteristics of the Ordovician Ma Member 4 was analyzed with reference to drilling, logging, geochemistry, gas testing and other data. The key controlling factors of hydrocarbon accumulation were studied from the aspects of gas source rock conditions, reservoir characteristics, migration conditions, and shielding conditions. The results showed that the gas reservoirs of the Ordovician Ma Member 4 were mainly lithological gas reservoirs; the richness of natural gas was controlled by the gas-source rock conditions; the natural gas of the Ordovician Ma Member 4 was the gas mixture generated by the upper Paleozoic coal-bearing source rocks and the Lower Paleozoic carbonate source rocks, dominated by the former, and the overall gas produced was less due to insufficient gas source; the characteristics of the reservoir made the natural gas mainly accumulated in the lime dolomite flat facies and dolomite lime flat facies with medium physical properties; the three-dimensional network system composed of pores, fractures and faults provided channels for natural gas migration; under the control of limestone shielding conditions, the natural gas was mainly distributed in the section with lithologic change of thick dolomite and limestone, and the central section with increased dolomite content of thick limestone. The understanding of the key controlling factors of natural gas accumulation in the Ordovician Ma Member 4 can provide a theoretical foundation for the exploration of marine carbonate rocks in the Ordos Basin.