尼日尔三角洲前缘重力流水道砂体的沉积构成特征  

Sedimentary Architecture Characteristics of the Gravity Flow Channel Sandbodies in the Niger Delta Front

作　　者：赵鹏飞[1] 李丹[2] 杨香华[2] 赵晓明[3] 

机构地区：[1]中国海洋石油有限公司油气储量办公室,北京100010 [2]中国地质大学,武汉430074 [3]西南石油大学,成都610500

出　　处：《地质科技情报》2014年第2期28-37,共10页Geological Science and Technology Information

基　　金：十一五国家重大油气专项(2008ZX05030-005-003);十二五国家重大油气专项(2011ZX05030-002-002)

摘　　要：尼日尔三角洲油气资源丰富,是目前尼日利亚主要的油气勘探区。研究区K油田位于尼日尓三角洲前缘深水区,其A油藏储集砂体为重力流水道及其伴生的天然堤和决口扇,其中重力流水道砂体储集物性最好,平均孔隙度可达24.21%,平均渗透率可达1.413μm2。三角洲前缘深水区的重力流水道、天然堤及决口扇分别对应钟型-箱型、指状与漏斗型测井相,其地震几何形态特征和成因标志典型,空间配置关系明确。重力流水道砂体在空间上具有侧向和沿古水流方向迁移特征,使得其平面上呈现出弯曲的条带状;重力流水道复合体由多个正韵律水道砂层叠置而成,水道轴部主要由厚层砂岩夹薄层泥岩组成,水道边缘砂泥互层。地震剖面上,水道下切较深,具有典型冲刷充填几何形态,其内部发育强振幅叠瓦状、波状反射构造;重力流水道两侧的天然堤与决口扇呈楔状或丘状,地貌上略高于重力流水道。上述重力流水道及共生的成因相构成一个内部结构清晰且成因构成单元完整的重力流水道体系,可以作为大陆边缘三角洲前缘深水区油气田勘探和开发研究的典型范例。Niger delta is the major oil and gas exploration area in the offshore of West Africa. The study ar- ea, the K oilfield is located in the deepwater area in the Niger delta front. The major reservoir sandbodies are gravity flow channel sandbodies and the associated levee and crevasse splay in A oil reservoir. The res- ervoir property of gravity flow channel sandbody is the best, whose average porosity is up to 24.21G and average permeability is up to 1. 413 05 μm2. The log facies of gravity flow channel, levee and crevasse splay in the channel-complex set correspond respectively to bell shaped-box, finger like and funnel shaped type, and their seismic geometry characteristics are typical. The genesis marks and the space configuration of each element are clear. The gravity flow channel sandbodies display migration in both lateral and along the paleocurrent direction. The gravity flow channel sandbodies present meandering strip on the plane. The gravity flow channel set consists of multiple channel sandbody profiles. The axis of channel consists of thick sandstone with thin mudstones, and the edge of channel is composed of sandstones which interbeded with mudstones. In seismic profile, deep and narrow channels show typical infilling geometric shape, and with imbricated strong amplitude and wavy reflection structure. The levee and crevasse splay on both sides of the gravity flow channel are characterized by wedge or hummocky seismic reflection structure. The a- bove mentioned gravity flow channel and its associated genesis facies form a complete gravity flow channel system, which can serve as a typical case of the oil and gas exploration and development in the delta front in the deepwater area of continental margin.

关 键 词：尼日尔三角洲 K油田 重力流水道砂体 沉积构型 

分 类 号：P512.2[天文地球—地质学]