国内外生物礁油气勘探现状与我国南海生物礁油气勘探前景

世界生物礁油气资源非常丰富,随着生物礁油气勘探开发的不断深入,生物礁油气探明储量和产量不断增加,所占比重越来越大。南海是我国最大的边缘海,其特殊的构造背景、多种类型礁的发育和良好的生储盖组合等都决定了南海生物礁油气勘探的广阔前景。建议加快南海勘探开发的步伐,充分利用南海丰富的油气资源。     

综合地球物理方法在华南桂中海相残留盆地沉积相预测中的应用

沉积相研究是盆地隐蔽油气藏勘探中重要的研究内容之一,综合利用地球物理方法有效识别构造、岩性或沉积相差异是盆地隐蔽油气藏勘探的前提.本文基于重力、航磁、地震等综合地球物理资料,通过重磁异常正演剥离和剖面正反演拟合技术研究了华南桂中地区海相地层的密度分布特征,预测了岩相、沉积相的变化规律.研究发现,本区中、下泥盆统海相地层存在横向的岩性、岩相变化,研究区西北、东南部的台地相区重力异常高、岩石拟合密度值高;中部“X”型台地边缘相区重力异常杂乱、岩石拟合密度变化范围大;东部台沟相区重力异常低、岩石拟合密度值低.利用综合地球物理方法预测沉积相为盆地岩性圈闭油气藏和生物礁油气藏勘探提供了新的研究思路,研究成果已得到初步检验,但还有待进一步完善与实践.     

五台山古元古代巨型叠层石的结构特征及成因意义

山西省五台山地区的古元古代滹沱群地层中发育大量各种形态和大小的叠层石,最近在东冶亚群地层中发现体量巨大的叠层石。本文在对其进行形态学分析、显微结构分析、地质剖面实测以及生长环境特征分析研究后认为,这一宏观上的穹窿形叠层石是由柱状叠层石组成的生物岩礁,柱体在底质基础上放射状生长,其表面圆形、长条形的凸起为叠层石柱体顶部横断面及斜切面形态。通过标本切片,镜下观察到组成柱体并充填柱间的均为泥晶方解石,并发现纤细的丝状微生物遗迹,这些丝状体相互交织构成暗层的重要组分。叠层石体量巨大,需要较长时间内相对稳定的深水环境;泥晶方解石结晶较好,指示水动力条件相对较弱、沉积速率较快的温暖浅海环境,可能形成于潮下带。     

南方海相碳酸盐岩分布区1994—1996年电法勘探找油实践

运用ＭＴ法，ＥＭＡＰ法，ＣＳＡＭＴ法，ＴＥＭ法和ＬＯＴＥＭ法等多种方法，在南方开展了区域构造和局部构造两大类电法勘探。电磁波易穿透高阻的碳酸岩。对低阻层较为敏感，适合于在高阻岩层中寻找低阻目标。实践表明，电法勘探适用于大区评价，盆地优选，选择有利于保存地区发展局部构造，寻找潜伏礁体和区域性盖层，识别火成岩体以及落实推覆构造等方面。     

南盘江地区二叠纪生物礁造架生物的初步研究

在云南东南部、贵州西南部和广西西北部毗邻的南盘江地区,广泛地发育着二叠系生物礁。迄今为止,在本区已发现了42个生物礁露头区。在古代生物礁的研究中,最重要的是研究每个礁体中的造架生物。通过对本区15个礁体的详细研究,这些礁体中的造架生物主要是:串管海绵、纤维海绵、水螅和硬海绵类;次要生物为苔藓虫、管壳石等。在串管海绵亚目中,已发现了塞巴加斯科、瓜达卢佩科、泡腔科、隐腔科和内孢粒腔科的12个属,纤维海绵亚目中有小领针属和盔海绵属。本文中介绍3个新种、2个比较种、3个种、3个未定种。     

Variations in Neoarchean microbialite morphologies: clues to controls on microbialite morphologies through time

The Neoarchean Carawine Formation, Hamersley Group, Western Australia is a carbonate ramp that preserves diverse microbial structures which are characteristic of specific depositional environments. These distinctive structures are distributed in five shallow subtidal and two deeper‐water facies in the Oakover area of the Carawine Formation. The shallow subtidal facies are composed of biohermal and bedded stromatolites, centimetre‐scale ridge‐shaped microbialites and wavy‐laminated microbialites. The deeper‐water facies are composed of fenestrate microbialites, planar laminated dolostone and dolostone with rolled‐up microbial laminae. Microbialites in the Carawine Formation lie within a continuum of Archean to Proterozoic microbial facies. Some shallow‐water microbial facies in the Carawine Formation are similar to Proterozoic facies, such as large bioherms internally composed of a variety of stromatolite morphologies. In contrast, fenestrate microbialites grew in quiet subtidal environments and are common in Archean rocks but have not been documented in similar Proterozoic environments. The similarity of shallow‐water facies across the Archean–Proterozoic transition, before and after the oxidation of the atmosphere and surface oceans, indicates that stromatolite growth in shallow subtidal environments was not strongly affected by the chemical changes associated with oxidation of the oceans or by biological responses to those chemical changes. Rather, stromatolite morphology was controlled mostly by the physical environment and the corresponding biological responses to that environment. In contrast, the absence of fenestrate microbialites from Proterozoic deep subtidal environments suggests that the morphology of deep subtidal microbial structures was influenced by chemical or biological changes that occurred in association with oxidation of the surface oceans.