中扬子区寒武纪层序地层研究

笔者建立了中扬子区寒武系层序地层格架,研究了中扬子区层序界面和体系域特点,分析了中扬子区层序样式的基本类型及其特征。共划分出2个二级层序、14个三级层序。寒武系下统划分了1个二级层序(SS3)、6个三级层序(SQ1-SQ6),平均延时约5.0Ma;体系域颜色普遍较深,泥质含量较高,是一套良好的烃源岩。寒武系中上统划分出1个二级层序(SS4)、8个三级层序(SQ7-SQ14),平均延时约2.9Ma;体系域颜色普遍较浅,云质含量较高,是一套良好的储集层。总体上H型样式为主,T型样式和TH型样式数量相当,反映寒武纪水体中等。二级层序体系域和三级层序体系域都表现出明显的南北向差异性。     

运用层序不对称性分析海平面变化特征

目前研究海平面变化的方法尚不能精确确定海平面变化，对记录海平面变化的沉积体或层序物质组成及结构特点的研究尚显薄弱。在分析层序不对称性与海平面变化的关系基础，提出层序不对称系数S0，认为海平面的升降变化对浅水沉积区影响显著，其结果必然造成层序S0的增加；海平面的升降变化对沉水沉积区影响不大，层序S0较为恒定。对进行详细研究中扬子区S0分布特点，运用S0曲线计算了中扬子区海平面变化特点，并与其他方法进行对比，认为可以用S0判断水体相对深浅，分析海平面变化。     

板内造陆变形及其后期转化的油气地质意义

板内造陆变形以平行不整合为标志，它是一个容易失稳的界面，后期构造变动中常常转化成拆离面。中浅构造层次形成脆性拆离断层（拆离带）；中深构造层次则形成韧性剪切断层（韧性剪切带）。板内造陆变形及其后期演化改善了储集岩性能，影响了油气运移和聚集。后期转化还可以使油气重新运移，也可形成新的油气圈闭，同时深刻影响油气演化，有利于再次生油气。     

构造变形过程中盖层封闭性研究

研究了埋藏—成岩—抬升变形过程中盖层封闭性的演化特点,开展了构造变形过程中盖层破裂实验。认为泥岩在高演化阶段封闭性变差并不具有普遍性,在深埋条件下和构造稳定区,高演化泥岩仍可具有良好的封闭性; 构造抬升是盖层封闭性发生破坏的主要因素; 力学实验表明,膏盐岩盖层在极小的埋深（1000 m左右）下就有很强的塑性,其极限强度很低,应变很大,是优质盖层; 泥岩盖层在浅埋藏条件下,容易产生破裂,但在深埋条件下（围压超过50 MPa）,泥岩表现出塑性流变,仍然具有较好的封闭条件; 泥灰岩破裂强度随着埋深的变化不明显,始终表现为比较强的脆性,高压下容易产生破裂。     

中上扬子海相层系埋藏史与构造运动的关系

依据复杂岩性条件下孔隙度—深度关系模型,采用回剥法重建埋藏史。结果表明,中上扬子地区的埋藏史可分为3种主要类型：早抬持续型、早抬再降型和晚抬持续型。埋藏史的类型受区域构造运动控制,具有明显的分带性。齐岳山断裂以西为晚抬持续型,齐岳山断裂与黄陵隆起之间为早抬持续型,黄陵隆起以东为早抬再降型。印支运动在中上扬子地区只对海相层系有一次短暂抬升剥蚀,剥蚀量小,对埋藏史特征影响不大。燕山运动表现形式、作用强度、对海相层系的改造程度均存在明显的地区差异性,导致海相层系埋藏史类型也有地区差异性。喜马拉雅运动波及整个中国南方,但岩石圈受力性质不同,表现为西挤东张,导致K2—E期间黄陵隆起以西持续抬升,形成“持续抬升型”埋藏史类型,以东则发生拉张断陷,形成“再降型”埋藏史类型。     

一种裂缝流体因子的提出及应用

为了解决各向异性下的流体识别问题,将纵波各向异性裂缝预测以及Russell的流体因子融合到直角坐标系中,提出了一种能够同时检测裂缝发育情况以及流体性质的新的裂缝流体因子(Factor of Fluid-filled Fracture,FFF),并通过一组岩性参数检验了裂缝流体因子在裂缝预测及流体识别中的有效性.在理论研究的基础上,选取松辽盆地某地区的火成岩裂缝及流体识别研究为应用实例.通过与测井流体及裂缝信息的对比验证,裂缝流体因子能够较为准确地预测研究区裂缝和流体的分布情况,且裂缝流体因子在单井上的计算结果与单井含气饱和度吻合度较高.此外,根据实际应用效果,指出裂缝流体因子在应用中的局限性:裂缝流体因子在平面成图时受地层厚度影响较大,且无法预测裂缝方向.     

中扬子区海相沉积盆地性质研究

分析了中扬子区海相沉积盆地基底和层序充填特性;研制了M判别图解,研究了沉积盆地的性质,认为盆地基底具有三分性,盆地层序充填具有阶段性和分区性,沉积盆地主体具有克拉通盆地的特点和性质。     

四川盆地川东南地区“源—盖”匹配关系研究

采用重建烃源岩生烃史("源")和泥质盖层排替压力演化史("盖")的方法,研究源—盖动态匹配关系,以确定泥质盖层封闭动态有效性。针对川东南地区丁山1井泥质盖层封闭性的研究结果表明:川东南地区寒武系泥质盖层不仅封闭性能形成时间早(早于震旦系烃源岩生烃时间),而且排替压力大(最大排替压力高达26MPa),封闭能力强,具备封闭超高压气藏的能力,"源—盖"匹配关系好,对下伏烃源岩具备有效封盖作用;志留系泥质盖层虽然现今排替压力较大,但封闭性形成时间晚于下伏寒武系烃源岩生烃时间,"源—盖"匹配关系不理想,有效封闭性较差;二叠系和三叠系泥质盖层封闭性形成时间分别早于志留系和二叠系烃源岩的生烃时间,具备有效封闭能力,且最大排替压力都大于10MPa,可封闭高压气藏。     

Main Controlling Factors on Hydrocarbon Accumulation and Distribution in Marine Sedimentary Sequences in South China

Multiple source rock assemblages were deposited in the sedimentary provinces in South China in geologic history,and some of them were destructed by and some survived against multiple tectonic movements.Therefore,multiple sources,mixed sources,and uneven distribution of sources occurred in the marine sedimentary basins in South China during the late stage of hydrocarbon pooling.Epidiagenesis of the marine carbonate reservoirs and its modification to reservoir poroperm characteristics determined the formation and the scale of natural gas pools.The exploration practices show that the large to medium gas fields mainly occur in areas with high-quality reservoirs.Detailed study of the paleo-oil accumulations and typical oil and gas reservoirs reveals that the basins experienced multiphase superimposition and modification,leading to the distribution of the Paleozoic paleo-oil accumulations and bitumen in the peripheral areas.The phenomenon that oil and gas production concentrates in the Sichuan basin indicates that the overall sealing conditions of a basin determine the oil/gas potentials and the scale of oil and gas production.This is a critical factor controlling the accumulation and distribution of gas in the marine sequences in South China.The early oil and gas pools in the Yangtze platform left billions of bitumen in the peripheral areas due to the destruction of seals.Since the Himalayan,"late-generation and late-accumulation" gas pools represented by the gas pools in the Sichuan (四川) basin were formed in the marine sedimentary sequences in South China as a result of the change of the sealing conditions.Current gas discoveries appear to be "paleo-generation and paleo-accumulation" gas pools but actually are "late-generation and late-accumulation" gas pools.These patterns of hydrocarbon pooling clearly depict themselves in western Sichuan basin and Weiyuan (威远)gas field.It is revealed that the gas pools in the Sichuan basin were mainly formed as a result of hydrocarbon phase change (thermal cracking of oil to gas),miscible migration,and dynamic equilibration since the Himalayan.A large number of gas pools were formed in the Himalayan and the gas pools in the marine sequences are characterized by late pooling; this kind of gas fields/pools are controlled by:(1) effectiveness of modification and superimposition of the marine basins,(2) effectiveness of the source rocks,(3) effectiveness of the overall preservation conditions,and (4) effectiveness of plays.