Brittleness characteristics of tight oil siltstones

岩石易碎物直接影响水库断裂，它的评估为建立是必要的在水库改过以前折断条件。动态、静态的易碎物数据在 Songliao 盆从 Qingshankou 形成的 siltstones 被收集。易碎塑料的转变基于压力紧张关系被调查。结果建议静态的有弹性的参数计算的易碎物索引否定地与压力落下系数和定义为规范的幼仔模量和泊松比率的一般水准的易碎物索引 B 2, 被相关，强烈与压力落下被相关。易碎物索引 B 2, 幼仔模量，和泊松比率与易碎的矿物质内容相关；也就是说石英，碳酸盐，和黄铁矿。我们也基于索引 B 2 调查了在毛孔液体和孔和动态易碎的特征之间的关联。毛孔液体增加岩石和还原剂易碎物的粘性；而且与增加孔，岩石易碎物减少。浸透气体的 siltstone 易碎物索引在浸透油或浸透水的 siltstone 比那高；在浸透油、浸透水的 siltstone 的易碎物索引的差别是很小的。由比较岩石力学和超声的实验，我们比从超声的实验获得了的发现从岩石力学实验获得的易碎物索引小；不过，两个都与象他们的差别一样增加孔减少。没有影响他们，超声的波浪通过岩石标本宣传，而岩石力学实验是破坏的并且导致 microcracking 和孔增加；因而，低孔的岩石的易碎物被内部 microcrack 系统的形成影响。

Rock brittleness directly affects reservoir fracturing and its evaluation is essential for establishing fracturing conditions prior to reservoir reforming. Dynamic and static brittleness data were collected from siltstones of the Qingshankou Formation in Songliao Basin. The brittle-plastic transition was investigated based on the stress-strain relation. The results suggest that the brittleness indices calculated by static elastic parameters are negatively correlated with the stress drop coefficient and the brittleness index B2, defined as the average of the normalized Young＇s modulus and Poisson＇s ratio, is strongly correlated with the stress drop. The brittleness index B2, Young＇s modulus, and Poisson＇s ratio correlate with the brittle minerals content; that is, quartz, carbonates, and pyrite. We also investigated the correlation between pore fluid and porosity and dynamic brittle characteristic based on index B2. Pore fluid increases the plasticity of rock and reduces brittleness; moreover, with increasing porosity, rock brittleness decreases. The gas-saturated siltstone brittleness index is higher than that in oil- or water-saturated siltstone; the difference in the brittleness indices of oil- and water-saturated siltstone is very small. By comparing the rock mechanics and ultrasonic experiments, we find that the brittleness index obtained from the rock mechanics experiments is smaller than that obtained from the ultrasonic experiments; nevertheless, both decrease with increasing porosity as well as their differences. Ultrasonic waves propagate through the rock specimens without affecting them, whereas rock mechanics experiments are destructive and induce microcracking and porosity increases; consequently, the brittleness of low-porosity rocks is affected by the formation of internal microcrack systems.