松辽盆地徐家围子断陷火山岩裂缝形成机理  

Fracture Formation Mechanism of Volcanic Rocks in Xujiaweizi Fault Depression of Songliao Basin

作　　者：陈树民[1] 姜传金[1] 刘立[2] 初丽兰[1] 裴明波[1] 

机构地区：[1]大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712 [2]国土资源部油气资源战略研究中心,北京100034

出　　处：《吉林大学学报（地球科学版）》2014年第6期1816-1826,共11页Journal of Jilin University：Earth Science Edition

基　　金：国家"973"计划项目(2009CB219307)

摘　　要：松辽盆地徐家围子断陷是位于松辽盆地北部深层的半地堑型晚侏罗世早白垩世伸展断陷,火山岩发育。在已有研究成果的基础上,结合野外露头和岩心观测及镜下研究发现:本区火山岩构造裂缝和溶蚀裂缝都比较发育,具有明显的规律性,多数原生缝被后期的构造应力或溶蚀作用改造成次生缝。本区裂缝形成的控制因素较多,主要有应力、构造、岩性和岩相、溶蚀作用、风化淋滤、构造应力场演化等,其中构造应力场演化、岩性和岩相及风化溶蚀作用是控制裂缝形成的主要因素。构造裂缝以高角度的张扭性和张性缝为主,多为半充填和无充填,具有多期、多方向、组合复杂等特点,是晚侏罗世至新近纪各种地质作用相互叠加的结果。构造通过控制不同构造部位的局部应力场分布来控制裂缝发育程度,沿断裂带存在明显的应力集中,形成裂缝发育带,特别在正断层上升盘、断层端部、背斜轴部等应力集中部位容易形成构造裂缝。有效火山岩油气储层为各类原生孔隙与裂缝的有效组合。由于火山喷发多个旋回叠加,加之风化剥蚀及不整合面的存在,造成裂缝在纵向上发育具有旋回性,溶蚀裂缝主要在不整合面附近发育。在平面上,裂缝主要发育在断裂密集区、断裂交汇部位和背形或向形构造发育的地区。本区处于爆发相和溢流相火山岩的发育区,气孔和裂缝最发育,特别是溢流相的流纹岩中,裂缝和气孔均较为发育,是本区的优质储层最发育区,也是天然气富集区。Xujiaweizi fault depression is a Late Jurassic-Early Cretaceous deep half-graben type extensional fault depression in northern Songliao basin,and volcanic rocks developed.The article is mainly based on macro and micro studies on outcrops,cores and thin sections.Tectonic fractures and corrosion fractures are well developed,and show apparent regularity.Most of primary fractures aretransformed into secondary fractures by later tectonic stress or dissolution.Fractures formation are controlled by several factors, for instance, regional tectonic stress and its evolution, structure, lithology,lithofacies,dissolution,weathering.Among these,tectonic stress field evolution,lithology and lithofacies, weathering and dissolution are dominant factors. Most of tectonic fractures are characterized by high angle,tensional and torsional,part filled or unfilled,multi-period,and multi-directional,which is the results of the superposition of various geological and tectonic role from Late Jurassic to Neogene.Local development of fractures are controlled by local stress field distribution.In general,since obvious stress concentration,fault systems are fracture development zone.Local stress are especially concentrated in the hanging wall of normal fault,the end of normal and reverse fault,and anticline axis,where tectonic fractures are abundant.The effective hydrocarbon reservoirs in volcanic rocks are controlled by combination of primary pore spaces and structural fractures.The fracture development shows vertical cyclicity because of multi-eruption,weathering and unconformable surface. The dissolution fractures develop near unconformity.In plane,the fractures mainly developed in fault-concentrated area,faults intersection,anticline and syncline.Pores and fractures is the most developed in explosive and effusive facies,especially in effusive rhyolite.The rhyolite is the most advantageous reservoir and high yield gas production area.

关 键 词：火山岩 裂缝 构造应力场 火山岩相 形成机理 徐家围子断陷 松辽盆地 

分 类 号：P618.13[天文地球—矿床学]