大民屯凹陷古今地温场特征及其成藏意义

Geothermal Characteristics of Damingtun sag and Its Significance for Petroleum Accumulation

利用系统测温资料和试油资料研究了大民屯凹陷现今地温特征 ,利用磷灰石裂变径迹、流体包裹体均一温度恢复了古地温 ,利用EasyRo模型反演热史变化 ,并与东西部凹陷热史进行了对比。研究认为 :(1)大民屯凹陷现今地温梯度较低 ,平均为 2 .9℃ / 10 0m。 (2 )磷灰石裂变径迹恢复古地温揭示大民屯凹陷古地温梯度较高 ,其中安福屯洼陷和荣胜堡洼陷分别 4 .0 7和 3.6℃ / 10 0m ,皆高于东部凹陷 (平均为 3.3℃ / 10 0m)。从而解释了其较低的生烃门限。 (3)流体包裹体均一温度研究结果认为地质历史时期研究区热流体活动较强烈。以高凝油为主的安福屯洼陷油气充注为幕式快速运聚成藏 ,而以正常稀油为主的荣胜堡洼陷油气运聚为在异常高压下的快速运移和浮力作用下的缓慢运移相结合。 (4 )大民屯凹陷的热史演化特征明显不同于东部凹陷 ,与西部凹陷也有差异 ,整个热史演化程度较低 ,有利于高凝油油藏的保存。

The present temperature has been studied with testing data and the paleotemperature has been restored with fission track in apatite and fluid inclusion in Damingtun sag. The thermal history has been displayed by the model of EasyRo and the comparison has been carried out with East sag and West sag. Conclusion has been drawn as follows: (1) The present geothermal gradient is low, the average is 2.9℃/100m. (2) The paleotemperature restored by fission track in apatite shows that paleotemperature is relatively high,and that of Anfutun sag is 4.07 ℃/100m while that of Rongshenpu is 3.6℃/100m. (3) The homogenization temperature of fluid inclusion shows that the thermal fluid was active. The filling model of Anfutun sag features with high pour point oil is episodic while that of Rongshengpu sag features with normal oil is the combination of episodic movement under the overpressure and the relative slow movement forced by buoyancy. (4). The thermal history difference exists between Damingtun sag and East sag and West sag. The former features with low thermal evolution as a whole, which is favarable for the preservation of high pout point reservoir.