摘要
针对KL油田沙四段扇三角洲巨厚砂砾沉积体优势储层认识不清的问题,利用丰富的井壁取心、薄片、扫描电镜等资料,系统研究莱州湾凹陷南斜坡KL油田沙四段扇三角洲沉积特征,并对形成储层控制因素及储集空间类型进行了探讨。结果表明:沙四段为暖温带干旱背景下的退积型扇三角洲沉积,发育平原和前缘亚相,岩性自下向上发育棕褐色砂砾岩、凝灰质含砾砂岩、杂色含砾砂岩、灰色粗砂岩,局部夹薄层凝灰岩;岩石成分主要为石英、长石以及火山岩碎屑,填隙物以泥质、凝灰质为主,可见白云石。同时发现沉积作用和成岩作用共同控制该套沉积体有效储层形成,扇三角洲前缘沉积的含砾砂岩和粗砂岩分选较好,粒间孔发育,成岩期溶蚀作用改善储集空间效果明显,孔隙类型主要为粒间孔,其次是溶蚀孔;扇三角洲平原沉积的砂砾岩分选极差,粒间孔不发育,溶蚀作用效果差,又受压实作用、胶结交代作用等影响,储集空间变差。指出了南斜坡带沉积体优势储层的分布规律,认为扇三角洲前缘沉积的杂色含砾砂岩为有效储层的主体,是今后勘探评价的重点。
Sedimentary characteristics of a fan delta in the 4 th Member of the Shahejie Formation located on the south slope of the Laizhou Bay Depression are studied,aiming at finding out the major reservoir of the fan-delta sand of the KL Oilfield.Data of wall sample,thin slice and scanning electron microscope are used for the purpose.Reservoir controlling factors and reservoir space types are also discussed.Results suggest that the fan delta was a retrogressive one developed in a warm and dry climate,consisting of brown conglomerate,green gray tuffaceous gravel sandstone,colored gravel sandstone,and gray coarse sandstone from the bottom up,with thin layers of tuffs locally.Clastic components including quartz,feldspar and volcanic rock debris are cemented by muddy,tuffaceous,and dolomitic interstitial materials.Both the deposition and diagenesis control the formation of reservoir.Gravel sandstone and coarse sandstone deposited in the fan delta front are well sorted,and their pores are dominated by the type of intergranular,followed by dissolution pores.The diagenetic dissolution can improve the reservoir space obviously.The fan-delta plain sediments,however,are poorly sorted with less intergranular pores.The dissolution effect is not well developed under heavy compaction,instead,the accumulation space is further deteriorated.Based upon the distribution pattern of the deposits on the southern slope,it is concluded that the gravel sandstone deposited in front of the fan delta is the most effective reservoir and exploration target.
出处
《海洋地质前沿》
CSCD
2018年第2期38-45,共8页
Marine Geology Frontiers
基金
国家科技重大专项"渤海海域大中型油气田地质特征"(2011ZX05023-006-002)
关键词
莱州湾凹陷
近源陡坡
扇三角洲
砂砾岩
控制因素
Laizhou Bay
near-source steep slop
fan delta
sandstone
controlling factor