北部湾盆地迈陈凹陷区域探井数模分析与油气勘探方向

Numerical simulation research on a regional outpost well and its hint on the future hydrocarbon exploration direction of the Maichen Sag, Beibuwan Basin

张伟 何家雄 胡杨 刘菊 李晓唐

Zhang Wei He Jiaxiong Hu Yang Liu Ju Li Xiaotang

在深入分析北部湾盆地迈陈凹陷西南部边缘Y1井油气地质资料的基础上，采用PetroMod软件开展了该区油气地质及地球化学的数值模拟研究。研究结果表明，该区仅始新统流沙港组二段暗色泥岩达到较好烃源岩有机质丰度标准，但其成熟度较低，尚未达到成熟生烃门限。迈陈凹陷总体上地温场偏低，综合判识确定其成熟生烃门限为埋深2 600 m，比涠西南凹陷及乌石凹陷始新统烃源岩成熟生烃门限明显偏深。由于Y1井未处在生烃凹陷成熟烃源岩有效生烃灶供给范围内，故其不能获得充足的烃源供给，乃至在其局部构造及圈闭中富集成藏，而最终导致Y1井钻探圈闭为无油气聚集的空圈闭。因此，研究区今后应重视寻找古近系烃源岩有效供烃系统之内的有利区带及圈闭目标，以期获得商业性油气勘探的突破。

Based on the petroleum-geological data of the Y1 well that is located in the southwestern margin of Maichen Sag of the Beibuwan Basin,in this study,the petroleum-geological and geochemical numerical simulation has been conducted using the PetroMod software.The results show that only the dark mudstones in the second section of Eocene Liushagang Group meet the standard of sufficient organic matter abundance to be defined as hydrocarbon source rock,but they have not reached the hydrocarbon generation threshold because of their low maturity.In addition,the geothermal field of the Maichen depression is generally low,and the mature hydrocarbon generation threshold depth,by comprehensive judgment,has been determined as 2 600 m,which is obviously deeper than that of Eocene hydrocarbon source rocks of the Weixinan and Wushi Sags.As Y1 well is out of drainage range of effective hydrocarbon generation,its structure may not have received sufficient hydrocarbon charge,to become a hydrocarbon accumulation in local structures and trap.Thus,this should result in an empty trap where the Y1 well is targeted.Therefore,favorable zones and traps within the effective hydrocarbon drainage zone of Eocene hydrocarbon source rocks should be focused on,in order to achieve a breakthrough of the commercial hydrocarbon exploration.

10.11743/ogg20170113