东海陆架盆地丽水凹陷热演化模拟及现今地温场特征

东海陆架盆地丽水凹陷烃源岩埋深大、钻井少、油气发现少，至今对其生油气能力具有较大的争议。为明确烃源岩热演化史，从少量具备实测地层温度和镜质体反射率（Ro）资料的钻井出发，利用正演模拟方法，通过地温与地层深度相关性分析，将钻井地温研究结果外推到无井区。在恢复丽水凹陷探井岩石圈结构及其演化史的基础上，首次系统建立了丽水凹陷的区域地温场并分析其对烃源岩演化的作用。研究表明，古新统下段月桂峰组底界（T100）烃源岩大部分都已成熟，次洼中心局部过成熟；月桂峰组顶界（T90）烃源岩大部分处于低熟—成熟阶段，次洼中心局部高—过成熟；灵峰组顶界（T85）烃源岩处于未熟—低熟状态，西次洼中心有成熟烃源岩。烃源岩特征及演化分析表明，古新统下段月桂峰组烃源岩是丽水凹陷的主力生油气烃源岩。

Thermal evolution modeling and present geothermal field of the Lishui Sag of East China Sea Basin

Hydrocarbon source rocks are deeply buried in the Lishui Sag of East China Sea Basin, where drilling wells are rare and encountered only a few oil and gas discoveries. There are hot debates over the hydrocarbon generating capacity of the basin. Careful study has been made for this time to clarify the thermal evolutionary history of source rocks. Starting from drilling wells with measured formation temperature and vitrinite reflectance (Ro) data, using the forward simulation method, and through the correlation between temperature and stratum depth, we extrapolated the results of drilling temperature research to non-well areas. On the basis of restoring lithospheric structure and its evolution history, the regional geothermal field of the Lishui Sag has been systematically established for the first time. The impacts of geothermal field onto source rock evolution are analyzed. Data shows, most of the source rocks at the bottom of Yueguifeng Formation in the lower part of Paleocene are mature and the sub-depression center is partly over-matured; most of the source rocks at the top of Yueguifeng Formation are in the stage of low-maturity and maturity, the sub-depression center is partly high-mature to over-mature; the source rocks at the top of the Lingfeng Formation are immature to low-maturity, and there are mature source rocks at the center of the western sub-depression. According to the analysis of source rock characteristics and evolution, the source rocks in the lower Paleocene Yueguifeng Formation should be the main source rocks for hydrocarbon generation in the Lishui Sag.