四川盆地寒武纪龙王庙组沉积相演化及石油地质意义

Sedimentary facies evolution characteristics and petroleum geological significance of Cambrian Group in Sichuan Basin

 张玺华 罗文军 文龙 罗冰 彭翰霖 夏茂龙

 中国石油西南油气田分公司勘探开发研究院，四川 成都 610041

 Research Institute of Exploration and Development, Southwest Oil and Gas Field Company, PetroChina, Chengdu 610041, China

 近年来，四川盆地寒武纪龙王庙组勘探取得重大战略突破,颗粒滩相沉积是储层发育有利相带，寒武纪龙王庙组沉积演化及展布规律研究至关重要。应用层序地层研究思路分析龙王庙组时空沉积演化过程，明确了龙王庙组发育2期沉积旋回，龙王庙组下旋回沉积期盆地自西向东表现为缓坡沉积特征，颗粒滩受乐山￣龙女寺古隆起控制，发育在川中地区。四川盆地龙王庙组上旋回沉积期表现为“两隆一凹”沉积格局，该时期川中地区颗粒滩大面积分布，川东地区逐步演化为台地边缘相带，发育颗粒滩白云岩，两者之间的重庆￣泸州地区为低洼地貌特征，发育厚层膏岩澙湖沉积，该期龙王庙组沉积表现为碳酸盐岩台地沉积特征。文中建立了四川盆地龙王庙组沉积新模式，揭示了四川盆地寒武纪龙王庙组沉积期碳酸盐缓坡向台地演化的过程，指出重庆￣泸州膏岩澙湖沉积造就川中、川东为2个独立滩相储层发育岩性区，川东地区龙王庙组台缘带滩相储层为龙王庙组油气勘探重要新领域。

 A great exploration finding has been made in Cambrian Longwangmiao Formation in Sichuan Basin recently, which shows that beach facies deposits are favorable facies belts for reservoir development, so it is very important to study the sedimentary evolution and distribution of the Cambrian Longwangmiao Formation. The application of sequence stratigraphy to Longwangmiao Formation evolution of sedimentary process shows that the Longwangmiao Formation developed two sedimentary cycles. The lower cycle of Longwangmiao Formation from the west to the east has the sedimentary characteristics of slope shoal, and the beach facies developed in the central Sichuan Basin is controlled by the Leshan-Longnyusi paleouplift. The upper Longwangmiao Formation cycles, Sichuan Basin, shows two high concaves and one deposition pattern, the central Sichuan region is characterized by large overlap of shoal bodies, and eastern Sichuan Basin gradually evolved into the platform edge facies, where deposited grain shoal dolomite; Chongqing-Luzhou area has the low-lying geomorphic features, and distribution of thick gypsum rock lagoon sedimentary period of the Longwangmiao Formation shows characteristics of carbonate platform deposition. This article establishes a new sedimentary mode of Longwangmiao Formation, revealing the sedimentary process of Cambrian Group in the Sichuan Basin is the process of evolution from carbonate gentle slope to platform, and pointing out that the gypsum lagoon sedimentation creates two independent beach facies reservoirs in the central and eastern Sichuan Basin. The beach facies of platform margin belt of Longwangmiao Formation in the eastern Sichuan area turns out to be an important field for oil and gas exploration.

10.6056/dkyqt201804003