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琼东南盆地具有高温、高压特征。盆地平均地温梯度在 4℃ /10 0 m以上 ,不同地带地温梯度存在明显差异 ,下第三系地温梯度明显低于上第三系。影响地温场的因素主要有火山活动、莫霍面埋深、断层活动和岩石性质。上、下第三系在构造背景、沉积环境等方面存在很大的差异 ,相应地划分为上、下两个超压系统。下超压系统主要由烃类的大量生成和裂解引起 ,强超压区分布在 2号断裂带以南 ;上超压系统主要由欠压实作用引起 ,强超压区分布较局限。上、下超压系统的形成时间一致 ,均在中新世以后。琼东南盆地独特的温压场在很大程度上决定了区内油气的演化与分布。超压环境中存在 3种成藏模式。下第三系勘探有 3个最有利区带和两个有利区带 ,上第三系勘探应重视盆地西北部的正常压力带、压力过渡带及东部浅层流体破裂较发育地带
Qiongdongnan Basin has high temperature and high pressure characteristics. The average geothermal gradient in the basin is above 4 ℃ / 10 0 m. There are obvious differences in geothermal gradient in different areas. The geothermal gradient in the lower Tertiary is obviously lower than that in the upper Tertiary. The main factors affecting the geothermal field are volcanic activity, Moho depth, fault activity and rock properties. The upper and lower Tertiary systems have great differences in tectonic settings and sedimentary environment, and are divided into upper and lower overpressure systems. The lower overpressure system is mainly caused by the massive formation and cracking of hydrocarbons. The strong overpressure zone is distributed south of No.2 fault zone. The overpressure system is mainly caused by under-compaction and the overpressure zone is more limited. The formation time of the overpressure system is the same after the Miocene. The unique temperature and pressure field in Qiongdongnan Basin largely determines the evolution and distribution of oil and gas in the area. Overpressure environment, there are three kinds of accumulation mode. There are three most favorable zones and two favorable zones in the Lower Tertiary exploration, and the normal pressure zone, pressure transition zone and shallow fluid fracture in the northwestern part of the basin should be emphasized in the exploration of the Tertiary.