Thermal History Reconstruction and Hydrocarbon Accumulation Period Discrimination of Jinhu Depression in Subei Basin
Thermal History Reconstruction and Hydrocarbon Accumulation Period Discrimination of Jinhu Depression in Subei Basin
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发表时间：
2011
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通讯作者：
Fang Jing
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作者：
Fang Jing
在镜质组反射率分析和磷灰石裂变径迹包裹体体系测试的基础上，进行了古地温梯度计算和热史重建，确定了金湖坳陷西斜坡和边民阳构造带的古地温梯度。根据镜质组反射率计算，西坡古地温范围为45.6~128.4℃，古地温梯度为45.5℃/km，汴民阳构造带古地温范围为26.4~120.3℃，古地温梯度为42.7℃/km。根据磷灰石裂变径迹，计算出西坡古地温梯度为40.7℃/km，岷阳构造带古地温梯度为45.8℃/km。通过与金湖坳陷不同构造带的对比分析，得出古地温梯度高于现今地温梯度的规律：西坡古地温比现今高10.4~15.2℃/km，汴民阳构造带古地温比现今高12.4~15.3℃/km。通过对西坡和汴民阳构造带典型井的热史模拟，可以看出古地温梯度随着地层时间的变化而降低。结果表明，K2t~E1f的地温梯度大于E2d~Ny。在三多构造事件引起隆升和侵蚀之前，坳陷古温度达到最高。坳陷成熟史反映金湖坳陷1 000 m深度Ro值为0.4%。烃源岩处于低成熟阶段。1 900 m深度Ro值为0.65%，温度达到90℃，烃源岩进入峰值阶段。西坡崔2井流体包裹体样品均一温度在62~93℃之间。通过对典型单井埋藏史-热史及流体包裹体均一温度的综合分析，确定金湖凹陷成藏期在47~41.5 Ma之间。据此判断，三多期（E2s）是金湖坳陷的主要油气成藏期。
Based on the analysis of the vitrinite reflectance and apatite fission track inclusions system testing,we carried out the calculation of paleotemperature gradient and reconstruction of thermal history,and then identified the paleotemperature gradient of west slope and Bianminyang tectonic zone of Jinhu depression.According to the vitrinite reflectance,we calculated that the range of the paleotemperature being between 45.6~128.4℃ and the paleotemperature gradient was 45.5 ℃/km in the west slope,the paleotemperature in Bianminyang tectonic zone was 26.4~120.3℃ and the paleotemperature gradient was 42.7℃/km.According to the apatite fission track,we calculated that the paleotemperature gradient in the west slope was 40.7℃/km,and in Bianminyang tectonic zone was 45.8℃/km.From the comparative analysis with different tectonic zones of Jinhu depression,we concluded a law that the paleo temperature gradient was higher than present-day geothermal gradient,specifically as follows: in the west slope,paleotemperature was 10.4~15.2℃/km higher than the current,and in Bianminyang tectonic zone paleotemperature was 12.4~15.3℃/km higher than the present.By the thermal history modeling of typical wells in west slope and Bianminyang tectonic zone,it could be seen that the paleo-geothermal gradient became lower with the stratigraphical time changed for the new.It shows that the geothermal gradient of K2t~E1f was higher than E2d~Ny.Before the uplift and erosion caused by the Sanduo tectonic events,the paleo-temperature of depression had reached the maximum.The maturity history of depression reflected that the Ro was 0.4% in the depth of 1 000 m of Jinhu depression.The source rock was at the low-mature stage.The Ro was 0.65% in the depth of 1 900 m and the temperature reached 90℃,the hydrocarbon source rocks entered the peak phase.The homogenization temperature of fluid inclusion samples was between 62~93℃ of Well Cui 2 in the west slope.Through the comprehensive analysis of the burial history-thermal history of typical single-well and the homogenization temperature of fluid inclusions,it can be identified that the accumulation period of Jinhu depression was between 47~41.5 Ma.Then it could be judged that the Sanduo period(E2s)was the main hydrocarbon accumulation period of Jinhu depression.