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基于钻井、试气、分析化验等资料的综合分析,对鄂尔多斯盆地伊陕斜坡东部奥陶系马家沟组马五_(1+2)亚段致密碳酸盐岩储集层特征及其成因进行研究,并对天然气勘探潜力进行分析。研究提出致密碳酸盐岩储集层为孔隙度小于2%、渗透率小于0.1×10~(-3)mm~2的储集体。伊陕斜坡东部马五_(1+2)亚段致密碳酸盐岩储集层以含膏泥粉晶白云岩、泥粉晶白云岩及岩溶角砾白云岩为主,孔隙类型以裂缝-溶孔、裂缝-晶间孔为主,非均质性强,储集层呈薄层大面积展布。奥陶系顶部不整合面构造调整导致的储集层“造孔”与“填孔”作用,以及埋藏期溶蚀增孔与沉积充填减孔共同作用是储集层大面积致密化的主要原因。薄层白云岩致密储集层与上覆广覆式上古生界煤系烃源岩紧邻形成大面积致密碳酸盐岩气成藏组合,含气普遍,气藏埋深浅(1 900~2 500 m),与上古生界致密砂岩气组成立体含气模式,因此鄂尔多斯盆地伊陕斜坡东部勘探开发潜力大。
Based on the comprehensive analysis of drilling, gas testing, analytical laboratory and other data, the characteristics and causes of the tight carbonate reservoir in the Ma5 (1 +2) sub-member of the Ordovician Majiagou Formation in the eastern part of the Yi-Shan slope in the Ordos Basin Conduct research and analyze the potential of natural gas exploration. The study suggests that tight carbonate reservoirs are reservoirs with less than 2% porosity and less than 0.1 × 10 -3 mm 2 permeability. The tight carbonate reservoirs in the Mawu_ (1 + 2) sub-member of eastern Iraq-Shaanxi slope are dominated by gypsum-bearing dolomite, muddy dolomite and karst breccia dolomite, Solubility, fracture - intergranular pore-based, heterogeneity, the reservoir was thin layer of large-scale distribution. The role played by reservoirs “porosity ” and “fill hole ” caused by adjustment of unconformity structure at the top of Ordovician and the interaction between pore enhancement and sediment filling and pore reduction during burial period are the result of large area densification The main reason. Thin-layer dolomite tight reservoirs and the overlying Upper Paleozoic coal-bearing source rocks are formed in close proximity to large-area tight carbonate gas reservoirs, which contain gas in general and shallow gas reservoirs (1 900-2 500 m) and the upper Paleozoic tight sandstone gas composition of three-dimensional gas mode, so the eastern part of the Ordos Basin on Iranian slope of great potential for exploration and development.