潮汕坳陷中生界生烃历史及火成岩侵入影响分析——以LF35-1-1井为例

古地温梯度法热史反演揭示,潮汕坳陷LF35-1-1井区在白垩纪晚期经历了最高古热流(热流值为107mW/m2),随后遭受强烈抬升剥蚀,剥蚀量达2 000m;中—上侏罗统烃源岩在晚白垩世时期进入过成熟阶段,下白垩统烃源岩在白垩纪末达到成熟晚期的生烃状态;中生界有机质最高烃转化率出现的时间为晚白垩世。基于有限元方法的二维剖面模拟显示,LF35-1-1井底部的火成岩侵入体对剖面温度场的时空影响局限于短时期和小范围,侵入体对目的层有机质成熟状态的影响可以忽略,但推测火成岩侵入时可能有基底热物质上涌热源的存在。

Mesozoic hydrocarbon generation history and igneous intrusion impacts in Chaoshan depression, South China sea: a case of LF35-1-1 well

According to a thermal history reconstruction by geothermal gradient tools,it is revealed that well LF35-1-1 area may be in a highest palaeo-thermal flux(up to 107 mW/m2) during late Cretaceous and then severely uplifted and eroded,with the erosion thickness up to 2 000 m.The Middle-Upper Jurassic source rocks may reach a over-mature stage in late Cretaceous,and the Lower Cretaceous source rock may be in late maturation at the end of the Cretaceous.For these Mesozoic source rocks,the highest transfer rate of hydrocarbon may occur in late Cretaceous.A 2-D section simulation based on finite element approach has indicated that the igneous intrusion at the bottom of well LF35-1-1 only has limited impacts on geothermal gradient of the depositional sequences,i.e.in a short time and in a small space.Therefore,this igneous intrusion impact on organic maturation in the target formations can be ignored,but a upwelling hot flow might exist in the basement during the igneous activity.