西湖凹陷中部深层甜点气藏发育条件与分布预测  

Development conditions and distribution prediction of deep sweet spot gas reservoirs in the middle of Xihu Sag

作　　者：张武 邹玮 侯国伟 刁慧 肖晓光 余箐 ZHANG Wu;ZOU Wei;HOU Guowei;DIAO Hui;XIAO Xiaoguang;YU Qing(CNOOC China Limited,Shanghai Branch,Shanghai 200335,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200335

出　　处：《中国海上油气》2024年第5期83-93,共11页China Offshore Oil and Gas

基　　金：中国海洋石油有限公司“十四五”重大科技项目“海上深层/超深层油气勘探技术”课题二“弧后盆地深层/超深层油气成藏条件与成藏机制研究-西湖凹陷(编号:KJGG2022-0402)”;“十四五”全国油气资源评价项目“中海油矿业权区及周边空白区油气资源评价(编号:QGYQZYPJ2022-3)”部分研究成果。

摘　　要：深层致密气藏特征及甜点分布预测是制约油气高效勘探与开发的关键问题。通过铸体薄片、扫描电镜、激光微区碳氧同位素、天然气碳同位素及含烃包裹体测温等实验分析,结合测井及地震资料,论述西湖凹陷中部深层甜点发育条件及分布规律。结果表明:①中部Y构造花港组发育厚层洁净粗粒砂岩,次生溶孔发育且孔喉半径集中,4200~4500 m发育大量特低孔低渗甜点;②心滩微相优质砂体、有机酸溶蚀改造及晚期高熟气强充注是Y构造深层规模成藏的关键,H3气藏为先致密后成藏气藏,断砂耦合控制了强溶蚀区的发育且利于晚期高熟气的充注,邻近断层处形成局部甜点;③地质-地球物理联合预测显示H3砂组高气饱甜点主要分布于F1断层上盘,平面预测结果与实钻结果吻合好。基于成藏模式形成的地质-地震甜点预测技术,能明显提高深层/超深层复杂地质条件下的甜点预测精度,对深层、少井区甜点预测具有推广借鉴意义。The prediction of the characteristics of deep tight gas reservoirs and the sweet spot distribution is the key problem that restricts the efficient exploration and development of oil and gas.The development conditions and distribution laws of the deep sweet spot in the middle of the Xihu Sag were discussed through the analysis of carbon and oxygen isotopes,carbon isotopes of natural gas,and hydrocarbon inclusion temperature with the help of cast thin slice,scanning electron microscopy,and laser microregion,as well as well logging and seismic data.The results show that:①Huagang Formation in the middle Y Structure develops clean coarse-grained sandstone in thick layers.The secondary dissolution pores are developed,and the pore throat radius is concentrated.In addition,a large number of sweet spots with ultra-low porosity and low permeability are developed from 4200 to 4500 m.②Microfacies high-quality sand in river islands,organic acid dissolution transformation,and strong high-mature gas charging in the late stage are the keys to deep large-scale accumulation of Y Structure.H3gas reservoir first is a tight gas reservoir and then a reservoir-forming gas reservoir,and the fault-sand coupling controls the development of a strong dissolution zone and facilitates the high-mature gas charging in the late stage.Moreover,a local sweet spot is formed near the fault.③The joint geological-geophysical prediction shows that the sweet spots with high gas saturation of the H3sand group are mainly distributed in the upper wall of the F1fault,and the plane prediction results are in good agreement with the real drilling results.The geological and seismic sweet spot prediction technology based on the reservoir formation model can obviously improve the prediction accuracy of sweet spots in deep/ultra-deep complex geological conditions,and it is of reference significance for the prediction of sweet spots in deep areas with fewer wells.

关 键 词：西湖凹陷 深层 花港组 发育模式 甜点预测 

分 类 号：TE122.2[石油与天然气工程—油气勘探]