东濮凹陷前梨园洼陷热史及烃源岩热演化

Thermal History and Source Rock Thermal Evolution History in the Qianliyuan Sub-Sag, Dongpu Sag

摘要: 东濮凹陷为临清坳陷重要的生油构造单元，是渤海湾盆地最具有油气勘探潜力的凹陷之一。其中前梨园洼陷是整个东濮凹陷增储的主要地区，为了揭示其热史及烃源岩热演化历史，首先利用5口典型井的镜质体反射率数据恢复了前梨园洼陷的热历史，结果表明前梨园洼陷在沙河街组沉积开始至东营组沉积末期，经历了两期裂陷作用，地温梯度出现两期峰值，为39℃/km~48℃/km和38℃/km~40℃/km。再以热史为基础，结合沉积和构造发育史及烃源岩地球化学资料，模拟了前梨园洼陷5口典型井6套烃源岩的成熟度演化历史，揭示了前梨园洼陷烃源岩成熟度演化受东营组沉积时期古地温场控制，6套烃源岩成熟度都在东营组沉积末期达到最高，这将为前梨园地区深层油气勘探提供参考。

Abstract: The Dongpu sag is an important generation hydrocarbon area of tectonic units in the Linqing de-pression of the Bohai Bay Basin, which has the greatest potential for oil and gas exploration. The Qianliyuan sub-sag is the main area of increasing oil and gas reserves in the Dongpu sag. In order to reveal the thermal history and source rock thermal evolution history, the thermal history of the Qianliyuan sub-sag was reconstructed based on vitrinite reflectance data from 5 typical wells. The results show that Qianliyuan sub-sag has experienced two phases of rifting, and the geothermal gradient reached twice high peaks during the early stage of the Shahejie Formation depositional period (39˚C/km - 48˚C/km) and the late stage of the Dongying Formation depositional period (38˚C/km - 40˚C/km). Moreover, based on the thermal history results, combined with the sedimentary and tectonic histories and source rock geochemical data, six sets of source rocks maturity history of 5 typical wells were simulated in the Qianliyuan sag. The results reveal that source rock thermal evolution is controlled by the paleo geothermal fields of the Dongying Formation depositional period in the Qianliyuan sag. The maturity of 6 sets of source rocks reached a maximum at the late stage of the Dongying Formation depositional period. This work will provide reference for deep oil and gas exploration in the Qianliyuan area.