摘要
Late-stage is defined here as the period when Neotectonism occurred since 5.1 Ma. Most petroliferous basins in China lie in the areas where Neotectonism occurred intensively. In recent years, Chinese petroleum geologists have paid much attention to late-stage petroleum accumulation. The PL19-3 giant oilfield is situated where faulting activities occurred violently during Neotectonism. To understand the mechanism of lat-stage rapid accumulation, we discussed the most important aspects responsible for the formation of the giant oilfield, including oil generation, active oil-source rock occurrence, fault activity and fault conduits, late-stage rapid oil injection as well as the distinguishing indicators. This study shows that: (1) sufficient oil was supplied to the PL19-3 field since 5.1 Ma because the PL19-3 structure was surrounded by four sags in which three intervals of high-quality source rocks remained active during Neotectonism; (2) densely distributed faults and high porosity/permeability sandstone carrier beds comprised the effective conduit system for oil migration and injection; (3) oil migrated along the faults and charged the PL19-3 structure rapidly by means of seismic pumping which was triggered by frequent earthquakes during Neotetonism. It is documented that elevated reservoir temperature, abnormal geothermal gradients and abnormally high homogenization temperatures of the fluid inclusions are the indicators for late-stage rapid oil accumulation.
Late-stage is defined here as the period when Neotectonism occurred since 5.1 Ma. Most petroliferous basins in China lie in the areas where Neotectonism occurred intensively. In recent years, Chinese petroleum geologists have paid much attention to late-stage petroleum accumulation. The PL19-3 giant oilfield is situated where faulting activities occurred violently during Neotectonism. To understand the mechanism of lat-stage rapid accumulation, we discussed the most important aspects responsible for the formation of the giant oilfield, including oil generation, active oil-source rock occurrence, fault activity and fault conduits, late-stage rapid oil injection as well as the distinguishing indicators. This study shows that: (1) sufficient oil was supplied to the PL19-3 field since 5.1 Ma because the PL19-3 structure was surrounded by four sags in which three intervals of high-quality source rocks remained active during Neotectonism; (2) densely distributed faults and high porosity/permeability sandstone carrier beds comprised the effective conduit system for oil migration and injection; (3) oil migrated along the faults and charged the PL19-3 structure rapidly by means of seismic pumping which was triggered by frequent earthquakes during Neotetonism. It is documented that elevated reservoir temperature, abnormal geothermal gradients and abnormally high homogenization temperatures of the fluid inclusions are the indicators for late-stage rapid oil accumulation.
基金
supported by Program for Innovative Research Team in the University (Grant No. IRT0658)
National Natural Science Foundation of China (Grant No. 90914006)
关键词
新构造运动
巨型油田
渤中凹陷
积累机制
断裂带
后期
渤海湾
石油地质学家
Neotectonism
active oil-source rock (AOSR)
migration conduit
late-stage rapid accumulation
PL19-3 oilfield
Bozhong depression