四川盆地九龙山构造须二段致密砂岩孔隙的成因及勘探意义

须二段砂岩以徽孔隙为主,少量的长石、岩屑溶孔,不见或罕见碳酸盐矿物的溶孔,利用同位素资料和热力学理论解释了这种现象。凡孔隙度大于5％的样品,就有绿泥石包壳发育,该层段表现为低电阻率和高含水饱和度,导致气、水层的误判。详细的岩石学研究使我们认识到粘土矿物在成岩过程中起到的特殊作用。自生粘土发育的样品,不论其产状如何,都比不含粘土而富含碳酸盐矿物的层段的样品储集性能好。提出了孔隙寿命的概念,并讨论了它在油气勘探中的意义。

ORIGIN OF PORES OF TIGHT SANDSTONE IN XUER SECTION, JIULONG MOUNTAIN AREA,SICHUAN BASIN, AND ITS SIGNIFICANCE IN EXPLORATION

The sandstone in Xuer section was mainly dominated by micropores. There were fewer feldspar and detritus solution pores and rare or no carbonate solution pores. This phenomenon has been explained by the steady carbon isotope of calcite and thermodynamics theory. The samples, the porosity of which is over 5%, must contain chlorite coatings and display high water saturation as well as low electric resistvity, which leads to mismisjudging gas an water layer. Detailed petrology researches show that clay minerals play a particular role in the process of diagenesis. The storage capacity of samples with clay is better than that with carbonates. A new concept of "pore life-span" is proposed and its significance in petroleum exploration is discussed in this paper.