吉尔嘎朗图凹陷宝饶洼槽阿尔善组层序地层与隐蔽油藏

Sequence stratigraphy and subtle reservoir of Aershan Formation in Baorao Trough of Jiergalangtu Sag

二连盆地吉尔嘎朗图凹陷宝饶洼槽油气勘探实践表明阿尔善组具有巨大的资源潜力。文章运用以基准面旋回为基础的层序地层理论,将该区的阿尔善组划分为3个中期地层旋回(四级层序)MSC1、MSC2和MSC3,并将其归为1个长期地层旋回LSC1(三级层序)。在等时地层格架内,分析了含油储集层、盖层的分布及储盖组合的发育特征,指出阿尔善组发育MSC1+MSC2和MSC3两套储盖组合,其中MSC3为最有利的含油储盖组合。通过隐蔽油藏勘探方向分析,认为东南部缓坡带锡号断层下降盘和J68井区古鼻梁东北近岸水下扇和湖底扇发育,是隐蔽油藏勘探的有利区带。

The recent hydrocarbon exploration in Baorao Trough of Jiergalangtu Sag shows that Aershan Formation has huge resource potential. In this paper, the sequence stratigraphic theory based on base-level cycles is used to divide Aershan Formation into one secular cycle （the third-level sequence） and three corresponding middle-term stratigraphic circles （the forth-level sequence） MSC1, MSC2 and MSC3. Within the isochronal framework of the Sag, the distribution of reservoir rock and cap rock and the development characters of reservoir-cap rock assemblages are analyzed. The authors point out that two series of reservoir-cap rock assemblages, MSC1 ＋MSC2 and MSC3, are developed in the Formation, but MSC3 is more favorable. The subtle reservoir exploration analysis indicates that such areas as the dropped side of the Ⅱ fault of Xilin in the southeast glacis area and the developmental region of inshore subsea apron and sublacustrine fan in the northeast Gubiliang of the J68 well field are favorable regions for subtle reservoir exploration.