准噶尔盆地下侏罗统页岩气形成条件

准噶尔盆地是中国西部的大型含油气盆地之一，沉积了多套烃源岩层，其中，侏罗系是盆地最重要的气源岩，蕴含巨大的页岩气资源。通过钻井、录井、露头、岩芯资料及样品分析结果，从泥页岩的展布及埋藏条件、有机地球化学特征、储层条件和含气特征几方面，研究下侏罗统页岩气的形成条件并对页岩气有利的勘探层位和区带进行了预测。准噶尔盆地下侏罗统泥页岩广泛发育，以盆地西北缘及南缘沉积厚度最大；埋藏深度1 000～9 000 m，整体上具有自北向南逐渐增加趋势；泥页岩有机碳含量较高，有机质类型以III 和II2 为主，具有倾气特征，有机质演化处于未成熟高成熟阶段。泥页岩储层具有孔隙度低、黏土含量高的特点，储集空间以微裂缝为主。实验测得下侏罗统泥页岩平均吸附含气量为1.42 m3/t。泥页岩段气测显示活跃，通过现场解吸试验证实了泥页岩中有天然气赋存。综合对比研究认为，准噶尔盆地下侏罗统八道湾组为页岩气最有利的勘探层位，达巴松中拐地区为页岩气勘探最有利目标区。

Shale Gas Accumulation Conditions of Lower Jurassic in Junggar Basin

Junggar basin is a large petroliferous basin in western China，in which there has deposited several hydrocarbon sourcerocks. Jurassic，one of the most significant gas sources，is considered to contain a huge potential of shale gas resources. Basedon drilling data，logging data，outcrop data，core data and laboratory test results of rock samples，we analyzed the shale gasaccumulation conditions through the distribution of dark shale and burial depth，organic geochemical characteristics，reservoirconditions and gas-bearing features of lower Jurassic and predicted favorable formation and zone for shale gas exploration. Shaleinterval of lower Jurassic is widely distributed. In the northwestern margin and southern margin，the dark shale is thickest. Theburial depth of lower Jurassic shale tends to deepen from north to south with a range between 1 000 m to greater than 4 500 m.The organic carbon content is relatively high，and the main type of organic matter is III and II2，which is gas-prone. The thermalmaturity of Lower Jurassic shale is from immature to high mature. The shale reservoir is characterized by low porosity，highclay minerals content and micro fracture for storage. The measured absorbed gas content is averaging 1.42 m3/t，the gas loggingshow of dark shale is active. In addition，the in situ gas desorption test identified the existence of nature gas in lower Jurassicshale. As a result，Lower Jurassic Badaowan shale is the favorable Formation，Shawan Dabasong region is the favorable zonefor shale gas accumulation.