低渗透岩石压敏特征研究

低渗透岩石具有较为明显的压力敏感性。在分析传统的CMS300全自动覆压压力敏感实验研究特点的基础上,充分考虑岩石受压缩的时间效应,对胜利渤南油田不同类型的低渗透岩石进行了系统的CMS300随机覆压和控时覆压的敏感性测试,获得了多种低渗透岩石压敏特征曲线,并探讨了岩石压敏特征与岩石本身属性的关系。结果表明,随机覆压下,储层物性随围压的增加呈单调圆滑下降的趋势;控时覆压下,岩石气测渗透率随覆压的变化呈台阶式变化;粘土总量和有无方解石胶结对低渗透岩石压敏效应的影响更为显著。

Stress sensitivity characteristics of low-permeability rocks

Obvious stress sensitivity exists commonly for low-permeability rocks. On the basis of analyzing the CMS300 automatic stress sensitivity testing procedure and considering the time effect, systematic investigation on stress sensitivity characteristics of low-permeability rocks from Bonan Oilfield was carried out by testing random & controlled stress sensitivity. The characteristic curves of stress sensitivity were obtained, and the relationship between the curves and properties of rocks was discussed. As a result, the tendency of curves is humdrum decrease with the random stress increasing while there are some steps under the controlled stress. The factors including clay content & calcite cement have an important effect on the stress sensitivity of low-permeability rocks.