断层成岩封闭及其应用

DIAGENETIC SEALING CHARACTERISTICS OF FAULTING ZONE AND ITS APPLICATION

影响断层封闭性的成岩作用类型主要包括:充填作用、压实作用和胶结作用。断裂带充填物中泥质含量越高,其孔渗性越差,形成封闭的可能性越大。压实作用是控制断裂带充填物致密性和断裂静止期封闭强度的关键,压实作用越强,断裂带越紧闭,封闭性越好。流体进入断裂破碎带,随压力和温度的降低,热液矿物发生沉淀结晶,逐渐胶结裂缝和角砾岩。断裂带胶结矿物主要有方解石和石英,温度和压力是控制胶结作用发生的主要因素。夏503井断裂带内泥质充填物发育,厚1 m左右,由于埋藏深,压实作用强,断裂带充填物致密坚硬。扫描电镜观察,裂缝和岩石孔隙中充填有沉淀结晶矿物,这种胶结作用发生的范围大致在断裂带附近3 m左右。在充填、压实、胶结共同作用下,夏503井断层封闭性强,是控制江家店油田成藏的关键。

The diagenetic types which influence the fault sealing properties mainly include packing action, compaction, and cementation. The more shale contents of filler, the lower porosity and permeability of faulting zone, and the less possibility to seal. Packing action plays a vital role in control of the compactness of filler and the sealing strength of faulting zone when it is dormant. The faulting zone＇s sealing effect is directly proportional to the strength of packing action. After entering the shattered fault zone, hydrothermal minerals precipitated and crystallized with the decrease of temperature and pressure, and then they cemented fractures and breccias gradually. The main cementing minerals in faulting zone are calcite and quartz, and temperature and pressure play critical roles in cementation. The Well Xia-503 Faulting Zone occurs compact argillaceous fillers with one meter thickness approximately for being deeply buried and strongly cement. The observed result of scanning electron microscope shows that there are precipitating crystallization minerals in the fractures and pores of rock, and the sphere of cementation is 3 meters around the fault zone. Combined with packing action, compaction and cementation, Well Xia-503 Fault seals strongly, that is critical factor in hydrocarbon accumulation of Jiangjiadian Oilfield.