致密储层脆性特征及对天然裂缝的控制作用——以鄂尔多斯盆地陇东地区长7致密储层为例

发布时间：2019-03-02 16:47

【摘要】：研究致密储层脆性特征及对天然裂缝的控制作用对天然裂缝定量预测具有重要意义。在总结了国内外脆性测试的20余种方法的基础上,重点论述了非常规油气中脆性评价方法的发展和应用情况,并以鄂尔多斯盆地陇东地区长7致密储层为例,在天然裂缝发育特征的基础上,对储层脆性特征进行评价,并探讨储层脆性对裂缝的控制作用。研究表明,陇东地区长7储层发育多组高角度构造裂缝,这些裂缝广泛分布在不同的岩性中。储层中不同岩性脆性特征差异性较大,其中砂岩脆性最大,含泥质砂岩次之,泥岩脆性最小,表现出随着泥质含量增加,脆性指数逐渐减小的特征。在特定的古构造应力背景下,储层脆性控制了天然裂缝的发育特征及发育程度。当岩层脆性指数大于某一值时更易发育高角度裂缝,而低于这一值时更易发育中-低角度裂缝。脆性也控制了储层自身的破裂能力。随着岩层脆性指数增大,在构造应力作用下岩层越易发生破裂导致裂缝发育程度较高;而脆性指数越低,岩层越易发生形变而非破裂,裂缝发育程度较弱或基本不发育。
[Abstract]:It is of great significance for quantitative prediction of natural fractures to study brittle characteristics of tight reservoirs and control of natural fractures. On the basis of summarizing more than 20 methods of brittleness test at home and abroad, the development and application of fragility evaluation method in unconventional oil and gas are discussed emphatically, and taking Chang7 tight reservoir in Longdong area of Ordos Basin as an example. Based on the development characteristics of natural fractures, the characteristics of reservoir brittleness are evaluated, and the control effect of reservoir brittleness on fractures is discussed. The results show that there are many high angle structural fractures in Chang 7 reservoir in Longdong area, which are widely distributed in different lithology. In the reservoir, the brittle characteristics of different lithology are quite different, in which the brittleness of sandstone is the largest, that of argillaceous sandstone is the second, and the brittleness of mudstone is the least, which shows that with the increase of muddy content, the brittle index decreases gradually. Under the specific paleotectonic stress background, reservoir brittleness controls the developmental characteristics and degree of natural fractures. When the brittleness index is greater than a certain value, it is easier to develop high-angle fractures, but lower than this value, it is easier to develop middle-low angle fractures. Brittleness also controls the fracture ability of the reservoir itself. With the increase of brittle index, the more prone to fracture under the action of structural stress, the higher the degree of fracture development, and the lower the brittle index, the more prone to deformation rather than fracture, and the weaker the degree of fracture development or the less development of fracture.
【作者单位】：中国石化石油勘探开发研究院;中国石油大学(北京)地球科学学院;中国石化中原油田分公司勘探开发科学研究院;中国石油长庆油田分公司勘探开发研究院;山西省地质调查院;
【基金】：国家科技重大专项(2011ZX05013-004)
【分类号】：P618.13

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