陆相湖盆深水底流改造砂:沉积特征、成因及其非常规油气勘探意义  

Deepwater Bottom Current Rework Sand(BCRS) in Lacustrine Basins:Sedimentary Characteristics,Identification Criterion,Formation Mechanism and Its Significance for Unconventional Oil/Gas Exploration

作　　者：潘树新[1,2] 陈彬滔[1,2] 刘华清[1,2] 李相博[1,2] 赵占银[3] 林铁峰[4] 张庆石[4] 

机构地区：[1]中国石油勘探开发研究院西北分院,甘肃兰州730020 [2]中国石油天然气集团公司油藏描述重点实验室,甘肃兰州730020 [3]中国石油吉林油田公司,吉林松原138001 [4]中国石油大庆油田公司,黑龙江大庆163000

出　　处：《天然气地球科学》2014年第10期1577-1585,共9页Natural Gas Geoscience

基　　金：国家重点基础研究发展计划(编号:2007CB209604);青西老君庙构造带整体评价研究(编号:2013E-3304);中国石油天然气股份有限公司重大专项(编号:2014B-0302)联合资助

摘　　要：深水底流改造砂是海相盆地重要的储集层之一。与海相盆地相比,陆相湖盆深水区是否存在大规模底流改造砂及其沉积特征、识别标志、形成机制、分布规模、外部形态、与深水重力流砂体的差异性及其油气勘探价值都值得去探索。利用松辽盆地的岩心及青海湖卫星照片资料,对上述问题进行了探讨和深入研究。陆相湖盆底流改造砂由泥质粉细砂岩和粉细砂岩组成,单层厚度为0.5~280cm;发育冲刷面和截切等底面侵蚀构造,常见的层理有交错层理、平行层理、透镜状层理及饥饿层理等。湖泊底流改造砂具有与湖相暗色泥页岩呈互层展布、细粒、发育牵引流构造和常与重力流交替出现这4个基本特征。研究表明,风驱底流对三角洲前缘和深水重力流砂体的再改造是形成深水底流改造砂的主要成因。深水底流改造砂在沉积特征、展布方向及成因机制等方面与深水重力流砂体存在显著差异。底流改造砂体在陆相盆地深水区广泛分布,厚层的底流改造砂可以形成致密油气藏,同时底流改造砂的广泛分布提高了泥页岩脆性矿物的含量,其分布区也是泥页岩油气藏勘探的甜点区。研究结果对于拓展我国陆相盆地非常规油气藏的勘探领域具有重要的意义。Bottom current rework sand（BCRS）of deep water is the most important reservoir in marine basins.Compared with marine basins,whether the large scale BCRS was developed in the deep water area of continental lacustrine basins or not,and its sedimentary characteristics,identification criterion,formation mechanism,distribution,external morphology,differences with deep water gravity sandbody,and its value in oil/gas exploration are the important issues worth exploration.Based on core,seismic data,laboratory analysis and satellite photos of Qinghai Lake,the above issues have been discussed in this paper.BCRS of continental lacustrine basins was composed of muddy siltstone-fine sandstone and siltstone-fine sandstone,where the thickness of single layer was 0.5-280 cm.Cross bedding,parallel bedding,lenticular bedding,and starvation bedding were well developed.BCRS has four basic features which include fine-grain interbedded with lacustrine black shale,sedimentary structure formed by tractive current,and interacted with gravity flow.The results show that delta front and deep water gravity sandbodies reworked by wind-driven bottom current is the main reason for the development of deep water BCRS.Significant differences can be found between deep water BCRS and deep water gravity sandbodies in sedimentary characteristics,distribution direction,mechanism,and etc.BCRS were widely distributed in deep water area of continental lacustrine basins.Tight oil/gas reservoir can be developed in thick BCRS.The abroad distribution of BCRS can improve the content of brittle minerals in muddy shale.The distribution area of BCRS can be＂sweet points＂for oil/gas exploration in shale.The study results of this paper played an important role in expanding the unconventional oil/gas exploration in continental basins of China.

关 键 词：底流 底流改造砂体 细粒沉积 非常规油气藏 陆相盆地 松辽盆地 

分 类 号：TE121.1[石油与天然气工程—油气勘探]