泥页岩脆性矿物含量对泥页岩油藏的开采有重要影响,脆性矿物含量高的地区一般被认为是有利的压裂段.但脆性矿物含量不代表岩石强度,有些脆性矿物(如白云石)压裂梯度较大,断裂韧性高,产生裂缝所需能量较多.为了弥补单一脆性筛选压裂有利层段的不足,采用一种利用矿物学和岩石力学综合评价泥页岩的可压裂性的方法.根据元素俘获测井技术评价连续地层脆性矿物含量高、针对断裂韧性难以测量,以弹性模量间接表征断裂韧性,认为脆性矿物含量高,弹性模量低的即为有利压裂段.将该方法应用于大民屯凹陷A井E2s]段的可压裂性评价并优选有利层段,结果表明该井E2s42段脆性矿物体积分数普遍大于50%,上段和下段的可压裂性好于中段,中段白云石较为富集,尽管脆性指数较大,但压裂所需能量较高,为非压裂有利区;上段和下段,认为可压裂指数大于0.7的即为有利压裂段,由此优选6个层段,为该井有效开发提供了依据。
The brittle mineral contents possess important influences on the mud shale reservoir development, the areas with the high content are generally chosen as favorable fractured intervals. However, the content does not in- dicate the rock strength, for some brittle minerals such as dolomite, the fracturing gradients are larger, their fracturing toughness is rather high, so more energy is required to produce the cracks. In order to overcome the shortcomings of the favorable fracturing intervals chosen by the single brittleness, a new friability evaluating method is intro- duced by integrating the mineralogy and rock mechanics. Element capture logging technique is adopted to evaluate the brittle mineral contents for the continuous formations, and moreover for the problem of the fracturing toughness difficult to measure, the Young's modulus is introduced to indirect characterize the toughness: for the high-content of the brittle minerals, the belt with lower Young's modulus is considered to be pretty favorable fractured interval. The method was applied in the friability evaluation and favorable interval optimization for Member E2S4^2 in Well A of Damintun Sag. The results show that the contents of the brittle minerals in the member are generally greater than 50%, the friabilities of the upper and lower intervals are better than the that of the middle, the middle is not suit- able for fracturing because of the more enrichment of dolomite, and furthermore more energy is required although the friability index is larger; For the upper and lower parts, 6 favorable intervals are optimized for their fracturing indexes are greater than 0.7, all the achievements have provided a certain references for the exploration and devel- opment of Well A.