龙门山中段前缘须家河组裂缝特征与油气的关系

Characteristics of fissures and their bearings on oil and gas accumulation in the Xujiahe Formation in central Longmen Mountains,western Sichuan

关键词:  龙门山  须家河组  裂缝特征  油气

Key words:  Longmen Mountains  Xujiahe Formation  fissure  oil and gas

摘要:

龙门山前深层须家河组气藏主要受裂缝控制,裂缝的发育与构造、断裂密切相关。应用声发射试验、包裹体测温和碳、氧同位素等方法,对龙门山中段前缘深层上三叠统须家河组裂缝特征进行了研究,把须家河组裂缝分为构造裂缝和成岩裂缝两类。龙门山前须家河组中存在印支期、燕山期和喜马拉雅期的多期构造作用,其中印支期和燕山期破裂作用相对较弱,形成的裂缝较少,而喜马拉雅期破裂作用较强,形成了大量的断层和构造裂缝。对须家河组致密砂岩储层来说,发育的构造裂缝是油气藏高产的必要条件。

Abstract:

The oil and gas accumulation in the deep-seated strata of the Xujiahe Formation in the frontal areas of the Longmen Mountains tends to be controlled by the fissures that,in turn,are associated with geological structures and faults.The characteristics of fissures are explored with the aid of acoustic emission,homogenization temperature of inclusions,and carbon and oxygen isotope data.The fissures in the Formation include structural fissures and diagenetic fissures.There once occurred multiple phases of tectonic movements in the Formation,including the Indosinian,Yanshanian and Himalayan orogenies,of which the former two were relatively weak and only minor amount of fissures are observed whereas the latter were highly severe and accounted for the formation of numerous faults and structural fissures which may be essential conditions for the enrichment of oil and gas in the dense sandstone reservoirs of the Xujiahe Formation.