准噶尔盆地车排子地区火山岩裂缝形成期次分析

Analysis on the formation periods of fractures of volcanic reservoirs in Chepaizi area,Junggar Basin

准噶尔盆地车排子地区石炭系广泛发育火山岩,多期次构造运动的影响使得火山岩产生大量天然裂缝。通过岩心观察、薄片鉴定和成像测井资料等分析,认为石炭系火山岩主要发育构造裂缝,多期裂缝相互切割及充填现象明显,裂缝走向主要为NE、NW、NNE和NNW向,其中优势方位为NE向和NW向。结合裂缝切割关系及构造演化背景,采用岩石声发射实验和碳氧稳定同位素分析测试手段确定石炭系火山岩裂缝具有4个形成期次,分别对应海西运动期、印支运动期、燕山运动期和喜马拉雅运动期。研究认为,各期次构造运动的性质控制着不同期次裂缝的类型、规模及方位分布,海西—印支期构造活动最为强烈,是研究区构造裂缝形成的主要时期。

The Carboniferous volcanic rocks are widely developed in Chepaizi area,Junggar Basin, and a large amount of natural fractures are formed by the influence of multi-stage structural movement.According to core observation, thin section identification and imaging logging data analysis, it is considered that the Car- boniferous volcanic rocks mainly develop structural fractures with multiple crosscutting relationships and filling sequence.Structural fractures strike can be grouped into NE-trending, NW-trending, NNE-trending and NNW-trending,among them NE-trending and NW-trending are predominant.Integrated with fracture crosscutting relationships and tectonic evolution background, by means of experiments and tests, such as a- coustic emission experiment of rock, carbon-oxygen stable isotopic analysis of fracture fillings, the fractures of Carboniferous reservoir in Chepaizi area were formed in four periods,the four-periods fractures may cor- respond to the Hercynian Period,the Indo-Chinese Epoch,the Yanshanian Period and the Himalayan Peri- od.The study showed that the various stage of structural movement controls the types,scales and orienta- tion distribution of different periods of fractures, and the Hercynian Indosinian stage is the main forming period of fractures of volcanic reservoirs because of the most actively tectonic movement.