松辽盆地白垩系浅水湖泊三角洲沉积微相研究——以大庆杏树岗油田杏三区东部葡Ⅰ1-3小层为例

Sedimentary microfacies of the Cretaceous shallow-water lacustrine delta deposits in the Songliao Basin: An example from the Pu I 1-3 oil reservoirs of the eastern Xing-3 block,Xingshugang Oil Field,Daqing

根据密井网测井、录井以及其它分析化验资料,结合区域地质背景,对松辽盆地杏树岗油田杏三区东部白垩系姚家组一段葡萄花Ⅰ组油层1-3小层(葡Ⅰ1-3小层)沉积微相类型、特征、组合模式和不同地质时期沉积微相平面展布特征及其演化规律进行系统的研究。结果表明,葡Ⅰ1-3小层为浅水湖泊三角洲沉积,主要发育三角洲分流平原和三角洲内前缘2种沉积亚相,含11种沉积微相,具有不同的沉积特征和测井相模式;利用自然电位曲线幅变值和砂体厚度,有效识别天然堤、水上决口沉积、溢岸薄层砂3种有成因联系、测井曲线形态类似的沉积微相;进一步根据各沉积微相的测井曲线形态组合、沉积成因及沉积作用的不同,总结出7种沉积微相组合模式。葡Ⅰ1-3小层沉积演化经历了早期湖退、中期稳定、晚期湖侵3个阶段,不同时期的沉积特征、沉积微相展布各异,总体表现出湖盆发育规模由大变小,再变大,骨架砂体厚度和理想钻遇率逐渐减小的特点。

On the basis of well logs, mud logs, analytical data and regional geological background, the present paper conducts a systematic study of the types, characteristics, association patterns, planar distribution and evolution of the sedimentary microfacies in the Pu I 1-3 oil reservoirs of the eastern Xing-3 block, Xingshugang Oil Field, Songliao Basin. The shallow-water lacustrine delta deposits in the Pu I 1-3 oil reservoirs consist of two sedimentary subfacies including the delta distributary plain and delta front subfacies; 11 sedimentary microfacies including the distributary channel, abandoned channel, natural levee, crevasse splay, overbank thin-bedded sheet sandstone, interdistributary bay, subaqueous distributary channel, subaqueous crevasse splay, distributary channel mouth bar, sheet sandstone and subaqueous interdistributary bay microfacies, and 7 sedimentary microfacies associations including the distributary channel-overbank thin-bedded sheet sandstone, distributary channel-natural levee-overbank thin-bedded sheet sandstone, distributary channel-natural levee-crevasse splay-overbank thin- bedded sheet sandstone, distributary channel-abandoned channel-overbank thin-bedded sheet sandstone, distributary channel-interdistributary bay, subaqueous distributary channel-distributary channel mouth bar-sheet sandstone-subaqueous interdistributary bay and subaqueous distributary channel-sheet sandstone microfacies associations. On the whole, the Pu I 1-3 oil reservoirs have undergone several evolutionary stages of early regression, middle stable deposition and later transgression, during which the lake basin displayed the wide-narrowwide scales, and gradual decrease of the thickness and ideal drilling rates of the skeletal sandstones.