准噶尔盆地四棵树凹陷侏罗系—白垩系储层岩石力学参数研究

Research on rock mechanics parameters of the Jurassic-Cretaceous reservoir in the Sikeshu sag,Junggar Basin,China

随着准南前陆中生界油气勘探持续突破,构造解析与储层评价越来越重要,与二者密切相关的岩石力学参数研究却鲜有涉及。针对准南前陆四棵树凹陷侏罗系—白垩系岩芯、测井、地震资料现状,结合三轴岩石力学实验和三维岩石力学反演方法,明确研究区岩石力学参数特征。结果表明:研究区储层动、静态杨氏模量和泊松比均呈正相关线性关系,岩石力学参数受岩性变化控制,白垩系清水河组下部与侏罗系头屯河组、西山窑组、八道湾组杨氏模量较高、泊松比较低,白垩系清水河组上部、侏罗系三工河组杨氏模量较低、泊松比较高;随着杨氏模量增加、泊松比降低,岩石抗压强度增加。基于高泉地区岩石力学参数反演结果表明,杨氏模量越大、泊松比越小,裂缝发育指数越高,越容易形成裂缝。白垩系清水河组上部、侏罗系三工河组裂缝发育指数小于0.4,裂缝不发育、油气显示差;白垩系清水河组下部、侏罗系西山窑组与头屯河组裂缝发育指数大于0.4,裂缝发育、油气显示好,因此此研究成果对研究区深层油气勘探具有重要指导意义。

Structural analysis and reservoir evaluation has become increasingly important as petroleum exploration keeps making breakthroughs in the foreland of the southern Junggar Basin.However,the research on rock mechanical parameters which is closely related to them is rare.Based on the drilling core data,logging and seismic data of the Jurassic-Cretaceous in the Sikeshu sag,using the rock mechanics experiment and three-dimensional rock mechanics inversion,we defined the rock mechanics parameters in this study.The dynamic and static Young′s modulus shows a positively correlated linear relationship with the Poisson′s ratio.The rock mechanical parameters are controlled by the lithological variation.The lower K_(1)q and J_(2)t,J_(2)x,J_(1)b Formations have a higher Young′s modulus and a lower Poisson′s ratio,while the upper K_(1)q and J_(1)s Formations have a lower Young′s modulus and a higher Poisson′s ratio.When the Young′s modulus increases and the Poisson′s ratio decreases,the rock compressive strength increases.The inversion results of rock mechanical parameters in the Gaoquan area show that the higher the Young′s modulus and the lower the Poisson′s ratio,the higher the fracture index.The fracture index of the upper K_(1)q and J_(1)s Formations is lower than 0.4,indicating poor fracture development and petroleum display;while the fracture index of the lower K_(1)q and J_(2)t,J_(2)x,J_(1)b Formations is higher than 0.4,suggesting good fracture development and petroleum display.Therefore,the research results are instructive for the deep petroleum exploration in the study area.