西非海岸盆地海底麻坑沉积特征研究——以尼日尓三角洲前缘深水区A油田为例  

Sedimentary Characteristics of Seabed Pockmarks from West Africa:A case study in an oilfield at the deep-water region in the Niger Delta front

作　　者：陈飞 蔡文涛 范洪军 梁旭 王海峰 CHEN Fei;CAI WenTao;FAN HongJun;LIANG Xu;WANG HaiFeng(CNOOC Research Institute Co.,Ltd.,Beijing 100028,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《沉积学报》2025年第1期99-107,共9页Acta Sedimentologica Sinica

基　　金：国家科技重大专项(2011ZX05030005)。

摘　　要：【目的】海底麻坑不仅是海底流体活动的记录和指示,也是影响油田开发和海上平台工程设施的关键因素。尼日尔三角洲盆地深水区油气资源极为丰富,是当今世界油气的重要区域,开展尼日尔三角洲盆地深水区麻坑沉积特征研究,对于海上油气田的开发具有十分重要的意义。【方法】运用沉积学的方法,通过对高分辨率三维地震数据以及分析化验资料的综合分析,对非洲西海岸尼日利亚深水区海底麻坑的沉积特征、成因机制以及研究意义等方面研究,详细论述了海底麻坑的沉积特征及其规模,建立了5种类型的海底麻坑,并探索了海底麻坑的研究意义。【结果】(1)依据麻坑平面形态特征,研究区主要有条带状麻坑和孤立麻坑2两种类型,平面呈现为圆形、椭圆形和新月形。条带麻坑带的长度介于0.5~3.0 km,宽度介于0.5~1.0 km,孤立麻坑宽度一般在10~300 m;(2)根据发育特征和沉积特点,将麻坑分为五种类型,即倾斜构造麻坑、断层麻坑、泥火山麻坑、古水道麻坑和沉积边界麻坑。剖面表现为U形或W形,地震呈现为杂乱反射;(3)研究区麻坑主要存在以下两种成因类型,一种为塑性流体所导致,另一种为油气沿断层溢漏所形成。高压的流体沿断层面挤入上覆沉积层,局部应力的减小,使海底表面发生塑性变形,形成向上运移通道,最终导致液化的沉积物被底流搬运,形成麻坑。【结论】麻坑研究对油气勘探开发和钻探及工程设施具有很好的指示作用,在油气田的开发过程中应引起足够的重视。[Objective]Seabed pockmarks are not only active records and instructions of the seabed fluid but also key factors affecting oilfield and offshore platforms.Therefore,their study is extremely important.The Niger Delta Ba-sin is extremely rich in deep-water oil and gas reserves and is an important oil and gas production area globally.There-fore,studies of their seabed pockmark characteristics have particular value.[Methods]Based on sedimentary princi-ples and methods and high resolution three-dimensional(3D)seismic data conducted on the sedimentary characteris-tics,genetic mechanism,and research significance of seabed pockmarks near West Africa,we identified and illus-trated the sedimentary characteristics and size and genetic mechanism of seabed pockmarks in the study areas,ex-ploring their significance.[Results](1)Based on the plane morphological characteristics of pockmarks,there are mainly two types of pockmarks in the study area:striped pockmarks and isolated pockmarks,which are circular,elliptical and crescent in shape on the plane.The length of the striped pockmarks is 0.5-3.0 km,the width is 0.5-1.0 km,and the width of the isolated pockmarks is generally 10-300 m;(2)According to the development characte-ristics and sedimentary characteristics,Pockmark distribution characteristics of pockmark were found to be isolated and banded in the study area,and the genesis of pockmarks is classified into five types:dip structure,fault,mud volcano,ancient channel,and sedimentary boundary.The profile is U-shaped or W-shaped,and the seismic reflec-tion is disordered;(3)They are primarily caused by plastic fluid and oil and gas leakage.One is caused by plastic fluid,the other is caused by oil and gas spilling along the fault.The high pressure fluid is squeezed into the overlying sedimentary layer along the fault plane,and the reduction of local stress causes the submarine surface sediment to un-dergo plastic deformation,forming an upward migration channel.The finally liquefied sediment is transported by the underflow,formi

关 键 词：海底麻坑 沉积特征 成因机制 西非 深海海底 

分 类 号：P618.13[天文地球—矿床学]