塔北地区辫状三角洲沉积特征及油气勘探意义  

Depositional characteristics of braided river delta in northern Tarim basin and its significance in petroleum exploration.

作　　者：张希明[1] 刘青芳[1] 

机构地区：[1]国土资源部西北石油地质局

出　　处：《石油勘探与开发》1999年第1期21-24,共4页Petroleum Exploration and Development

基　　金：国家"八五"科技攻关项目

摘　　要：塔里木盆地北部地区的三叠系、白垩系卡普沙良群发育较典型的辫状三角洲沉积，依沉积特征可划分为平原亚相、前缘亚相、边缘席状砂亚相。辫状三角洲砂体与扇三角洲及其它类型三角洲砂体相比，有其独特的沉积特征及成因特点：古隆起、古构造高地控制了它的成生发育，砂体主要赋存于向湖盆延伸的斜坡地带，分布广、厚度相对稳定；由于辫状河道在一定坡度和较高推移速率及悬浮比率下直接进入滨、浅湖，主要由富砾的砂岩相构成骨架相；由于河道（水道）的反复迁移摆动，砂体在平面上呈“席状”展布，连续性好，面积可逾１０００ｋｍ２，厚度多为１５～８０ｍ；砂岩杂基含量不高，储集空间是以粒间原生孔隙为主的复合孔隙，具较高的孔隙度和渗透率。辫状三角洲砂体是塔北地区最好的储集层，加之该区优越的烃源条件，其勘探潜力巨大。正确区分和识别辫状三角洲沉积具有重要的理论及实际意义。图３参３（邹冬平摘）Typical braided river delta sediments are developed in Permian and Kapushaliang (Lower Cretaceous) in northern Tarim basin, and can be divided into braided river plain subphases, braided river front subphases, predelta subphases and marginal sheet sand subphases. Compared to fan delta and other types of delta, braided river delta has its own depositional and genetic characteristics. Paleouplift and highs in paleostructures control their development and generation. Sandbodies are located on the slope stretched toward the lake basin, widely distributed and relatively stable in thickness. Because braided river enters into shore and shallow lake phases directly under certain slope with fairly high traction velocity and a suspension ratio, the main backbone phase are rich conglomeratic in nature; and the river channels moved back and forth, so that sandbodies distributed planely in the form of “sheets” with a good continuity in an area of over 1000km 2, and most of their thickness are 15 80m; and they contain less mixed bases, their reservoir spaces are mainly mixed pore spaces with inter granular pore as major ones, having fairly high porosity and permeability. Therefore, braided river delta sandbodies are the best reservoir beds in northern Tarim region. In addition, there are superior hydrocarbon source rocks in this region. Thus this region has a great exploration potentiality for oil and gas. To recognize and identify braided delta have an important significance both theoretically and practically. Subject

关 键 词：细气勘探 沉积特征 塔北地区 三角洲 

分 类 号：P618.130.8[天文地球—矿床学] P512.2[天文地球—地质学]