惠州凹陷新生代火山岩储层的分类评价及其石油地质意义

Classified Evaluationof the Early Cenozoic Volcanic Reservoirs in Huizhou Sag and Its Petroluem Geological Significance

【目的】珠江口盆地惠州凹陷在中生界基岩之上发育了一套新生代早期火山岩,是富生烃洼陷惠州26洼未来的重要勘探领域之一。火山岩储层储集空间类型多样、非均质性强,其有利储层特征及受控因素复杂,预测难度较大,需要对其加以研究。【方法】在少井地区开展新生代火山岩储层的地质-地球物理综合预测研究,建立了一套火山岩储层的分类评价流程。【结果】首先基于钻井、测井和地震资料联合开展火山岩岩相、机构识别,对火山岩进行初始储层级别的划分;其次通过恢复排烃期火山岩古地貌判断有机酸对火山岩的溶蚀作用强弱,据此升降级火山储层级别;最后通过波阻抗反演及相干-蚂蚁体属性分析孔隙度和裂缝发育条件,进一步对储层级别进行划分。最终获得火山岩储层分类结果。【结论】基于储层分类评价结果指出有利储层发育区及其控制作用,对同类火山岩油气勘探具有借鉴意义。

[Purposes]The Huizhou Sag in the Pearl River Mouth Basin is developed a set of early Cenozoic volcanic rocks on top of Mesozoic basement rocks,making it one of the significant exploration areas for the hydrocarbon-rich Huizhou 26 Sag.Volcanic rock reservoirs have diverse storage space types and strong heterogeneity,making prediction difficult due to the complexity of controlling factors affecting favorable reservoirs.[Methods]A comprehensive geological-geophysical prediction studies on the Cenozoic volcanic rock reservoirs is conductedin the less-well area,establishing classified evaluation technology for volcanic rock reservoirs.[Findings]Initially,volcanic lithofacies and fabric recognition were carried out based on drilling,logging,and seismic data to delineate the initial reservoir levels of volcanic rocks.Subsequently,by assessing the strength of organic acid dissolution on volcanic rocks through the restoration of the hydrocarbon expulsion period volcanic rock paleogeomorphology,the volcanic reservoir levels were upgraded or downgraded accordingly.Furthermore,utilizing impedance inversion and coherence-ant attribute analysis to porosity and fracture development conditions,the reservoir levels were further refined,ultimately resultinginthe classification of volcanic rock reservoirs.[Conclusions]The results of reservoir classification evaluation indicate the favorable reservoir development zones and their controlling effects,which are of reference significance for oil and gas exploration in similar volcanic rocks.