摘要
四川盆地川东北地区中三叠统雷口坡组整体沉积环境以蒸发台地相为主,沉积了以大套膏岩和白云岩为主的蒸发岩。雷口坡组可细分为雷四、雷三、雷二和雷一段。雷四段地震响应表现为"弱波峰、较低频、较连续反射结构"的曲线特征。储层总体为Ⅲ类储层,以低渗为主,个别储层段表现为Ⅱ类储层。储集空间类型主要有溶洞、溶扩缝、构造缝,为一套岩溶储层。研究认为,雷口坡组雷四段储层发育与分布受沉积相和风化壳共同控制;研究区发育的台地蒸发相、泻湖相形成的云岩,在雷口坡组末期岀露地表遭遇剥蚀形成风化壳,并受大气淡水沿不整合面及裂缝的淋滤、溶蚀作用形成一套优质储层。
The overall sedimentary environment of the Mid-Triassic Leikoupo Formation in the Northeastern Sichuan Basin is dominated by evaporite platforms where a set of thick and wide-spreading evaporites predominantly of gypsums and dolomites were deposited.The Leikoupo Formation can be subdivided into four members.The seismic responses of the fourth member feature in weak amplitude,low frequency and relatively continuous reflection configuration.Most reservoir rocks within the fourth member are type-III of low permeability,some of them show characters of type-II.Their pore spaces are dominated by caverns,dissolution-widened fractures and structural fissures.The development and distribution of the reservoir rocks in the member were controlled by both sedimentary facies and weathered crust.Dolomites of platform evaporate facies and lagoon facies in the study area were exposed and eroded into weathered crust during the last period of the Leikoupo Formation deposition.In addition,the dolomites also experienced leaching and corrosion of meteoric water along unconformities and fractures,resulting in a set of high-quality reservoir rocks.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2012年第5期785-790,795,共7页
Oil & Gas Geology
关键词
沉积相
储层特征
雷口坡组
川东北地区
depositional facies
reservoir characteristics
Leikoupo Formation
northeastern Sichuan Basin