运用大视域拼接扫描电镜定量研究泥页岩微观非均质性

Application of Large Horizon Splicing SEM Images in Quantitative Study on Micro-heterogeneity in Shale Reservoir

为研究泥页岩的微观非均质性,建立非均质性的定量评价标准,运用扫描电镜大视域拼接技术对泌阳凹陷核桃园组核三段的4块黑色泥页岩样品的扫描电镜图片进行了分析处理,从而获得一系列高精度、大视域的成像图,然后通过背散射成像与能谱分析获得了大视域成像图片所对应的矿物分布情况。选定变异系数(C.V)并结合代表视域边长(REL)来建立非均质性定量评价模型,确定C.V=0.1为非均质性强弱的标准。运用这一判别指标,对四川盆地龙马溪组的L1和牛蹄塘组的N1的泥页岩进行了矿物和孔隙的微观非均质性定量评价。结果表明,孔隙非均质性是L1>N1,矿物非均质性是N1>L1;且四川盆地泥页岩的微观非均质性小于泌阳凹陷泥页岩的微观非均质性。

The prediction and exploration of the "sweet spots"of oil and gas were directly affected by reservoir heterogeneity.Large horizon splicing scanning electron microscopy,combined with the representative elementary length(REL)and the variation coefficient of the statistical method,have been used to established heterogeneity quantitative evaluation stand- ard.The variation coefficient (C.V)of 0.1was considered as the standard of heterogeneous strength.Using such standard of heterogeneity,minerals and pore microscopic heterogeneity of the Longmaxi Formation shale (L1)and Niutitang Formation shale(N1)in the Sichuan Basin was quantitatively evaluated.The results showed that Llhas pore heterogeneity higher and minerals heterogeneity lower than N1,and further pointed out that the minerals microscopic heterogeneity of the Longmaxi and Niutitang Formations in the Sichuan Basin was less than that of the Hetaoyuan Formation in the Biyang Sag.