Kinetic Modeling of Diagenesis of Eogene Lacustrine Sandstone Reservoirs in the Jianghan Basin,Southeastern China

In the Tuoshi oilfield,located in the Cenozoic Jianghan Basin of southeastern China ,there have been found hydrocarbon reservoirs hosted in lacustrine sandstones of the Eogene Xingouzui Formation.The main diagenetic features identified in these sandstones include the dissolution of detrital K-feldspar and albite grains,the precipitation of quartz as overgrowths and /or cements ,and the precipitation and /or transformation of clay minerals.These diagenetic features were interpreted to have occurred in early,intermediate and late stages,based on the burial depth.The kinetics of fluid-mineral reactions and the concentrations of aqueous species au each stage of diagenesis were simulated numerically for these lacustrine sandstones,using a quasi-sta-tionary state approximation that incorporates simultaneous chemical reactions in a time-space continuum.During the early diagenetic stage,pore fluid was weakly acidic,which resulted in dissolution of K-feldspar and albite and,therefore,led to the release of K^ ,Na^ ,Al^3 and SiO2(aq) into the diagenetic fluid.The increased K^ ,Na^ ,Al^3 and SiO2(aq) concentrations in the diagenetic fluid caused the precipitation of quartz,kaolinite and illite.At the beginning of the intermediate diagenetic stage the concentration of H^ was built up due to the decomposition of organic matter,which was responsible for further dissolution of K-feldspar and albite and pre-cipitation of quartz,kaolinite,and illite.During the late diagenetic stage,the pore fluid was weakly alkaline,K-feldspar became stable and was precipitated with quartz and clay minerals.When the burial depth was greater than 3000 m,the pore fluids became supersaturated with respect to allbite,but undersaturated with respect to quartz,resulting in the precipitation of albite and the dissolution of quartz.The diagenetic reactions forecasted in the numerical modeling closely matched the diagenet-ic features identified by petrographic examination, and therefore,can help us to gain a better understanding of the diagenetic processes and associated porosity evolution in sandstone reservoirs.     

综合地球物理勘探方法在团鱼山南部地区构造划分中的应用

本文旨在考察综合地球物理勘探方法在了解覆盖层厚度和基底深度、划分构造形态和走向等方面的有效性,在青海省团鱼山南部地区分别应用重力和可控源音频大地电磁方法开展了地质勘测。在地质解释过程中,综合工区地质资料,并按不同方法的特点进行相互约束。利用地球物理勘测结果,根据地层电性和密度属性,划分了区域的构造形态和走向,建立了团鱼山南部地区的地质构造模型。综合地球物理方法的应用,有效地降低了地球物理勘探的多解性,为精细地质解释提供了依据,为下一步开展全面物探工作和钻探布设奠定了基础。     

北非地区中生代盆地区域沉积中心发育机制新认识及油气差异富集效应

北非地区为世界上油气富集地区之一,区内油气分布表现出极大的不均匀性,以往研究对这一油气差异性富集控制因素的探讨较为薄弱。本研究重点从中生代期间发育的多个区域沉积中心的演化和形成机制的角度,探讨这一科学问题。对已有的基础地质和油气勘探资料的综合再分析表明,北非地区冈瓦纳大陆北缘发育维德迈尔—佩拉杰、苏尔特、东地中海三个彼此孤立存在的中生代沉积中心,这些沉积中心在空间上处于阿拉拉隆起、苏尔特隆起、黎凡特隆起三个海西运动中形成的NE向古隆起之上,具有“古隆起塌陷反转”的形成机理;沉积中心均靠近新特提斯洋边缘,总体呈现受海西运动形成的古隆起和新特提斯洋开启背景下的伸展作用联合控制。三个中生代沉积中心为中生代优质烃源岩发育区和油气富集区;受海西期塑造的古构造、海西构造剥蚀对砂岩储层的控制以及中生代烃源岩发育等有利因素所控,这些塌陷形成的中生代沉积中心及围区成为最为重要的油气富集区带。中生代盆地的这一形成过程为该区油气差异富集的重要控制因素。     

一种新的构造缝洞体系——褶溶体

缝洞体系是碳酸盐岩油气藏勘探的一个重要对象。以往的研究发现断溶体是一种重要的构造缝洞体系。最近我们在研究碳酸盐岩构造缝洞体系时发现了一个新的构造缝洞体系：褶溶体。褶溶体是一种褶皱作用控制下的溶洞裂缝体系。根据褶皱部位可以分为3种褶溶体：1）背斜褶溶体;2）向斜褶溶体;3）翼部褶溶体。背向斜褶溶体与褶皱过程中的虚脱和轴面节理有关;翼部褶溶体与层间滑动和翼部褶断有关。以背斜褶溶体最为重要,因为最易于富集油气,形成缝洞油气藏。褶溶体的形成与岩性、岩层厚度和褶皱的形成过程中的应力状态和岩层破裂过程及古气候、古地理等因素密切相关。     

川中龙王庙组气藏多期充注特征及对寒武纪早期海相烃源岩发育的指示意义

为了研究古老超深层天然气藏的充注模式,探讨寒武纪早期海相烃源岩的质量、规模和寿命,笔者等选取高石梯—磨溪地区龙王庙组气藏作为研究对象,结合区域构造演化史和烃源岩生烃史,应用盐水包裹体均一温度与储集层埋藏史温度对比的方法,建立了充注模式,并追踪其烃源岩层位为下寒武统筇竹寺组;从寒武纪早期古气候、古环境和古生物等的角度,分析了该时期形成海相烃源岩的有机生产力和保存条件。研究显示,四川盆地超深层气藏的形成经历了古油藏、古裂解气藏和晚期干气的多期充注阶段,气藏充注来源于古油藏裂解气和超晚期源岩释放的天然气。这一事实指示了,早寒武纪的全球背景为高质量、大规模和长寿命的优质烃源岩发育提供了基础,对于四川盆地超级气盆地的形成提供了理论依据。     

四川盆地雷口坡末期古岩溶特征及其对储层的影响——以龙岗地区雷口坡组四~3段为例

四川盆地龙岗地区中三叠统雷口坡组顶部雷四3段发育一套风化壳岩溶型白云岩储层。储层似层状成规模分布。古岩溶作用以表生裸露期风化壳岩溶作用为主,受古地质背景和风化壳岩性组合影响,古岩溶特征主要表现为:溶蚀时间较短,溶蚀作用较弱,充填作用及膏溶作用较强。在研究区内风化壳岩溶作用是影响储层发育的关键因素,它对储层既有建设性作用又有破坏性作用。     

On the Mechanism of Transformation fromPrimary Ores into Oxidized Ores in FinelyDisseminated Gold Deposits

This paper, taking the finely disseminated gold deposits in southwestern Guizhou and northwestern Guangxi as examples, discusses the difference between the occurrence of primary ores and that of oxidized ores, analyzes the occurrence mechanism in terms of crystallochemistry and geochemistry, and especially studies the chemical model for supergene leaching transformation of clay minerals in the two types of ores. This study proposes a new idea for dressing and smelting technology for primary gold ores.     

准噶尔盆地阜东斜坡区中上侏罗统储集层特征差异及控制因素分析

准噶尔盆地是中国西部地区最重要的含油气盆地之一,阜东斜坡区中上侏罗统头屯河组和齐古组是近期勘探重点。根据野外露头、钻井岩芯和分析化验资料,详细分析头屯河组和齐古组储集层特征差异,包括储集层岩矿特征和物性特征差异。岩矿特征中重点对碎屑、填隙物以及孔隙类型和结构特征进行对比分析,物性特征中重点对储集层类型进行研究,发现齐古组储集砂层储集质量总体上要好于头屯河组。通过综合分析,认为阜东斜坡区中上侏罗统储集层特征差异主要受构造、沉积相、异常压力和成岩作用复合控制,构造演化的差异是导致头屯河组和齐古组储集层特征差异的最关键因素,头屯河组物性最好储集层的微相类型为水下分流河道,齐古组物性最好储集层的微相类型为分流河道,异常压力对原生孔隙保存以及黏土矿物发育位置起到重要影响,成岩作用对于重点层位储集层物性好坏起到决定性作用,其中凝灰质的蚀变序列对于后期油气开发有重要参考价值。     

Geochemical Characteristics of the 1st Member of Paleogene Dainan Formation in Gaoyou Depression of the North Jiangsu Basin, and Its Geological Significance

苏北盆地高邮凹陷所经历的风化作用以物理风化为主,化学风化程度很弱.其中南部陡坡带的大部分地区所经历化学风化程度相对北部缓坡带较强,说明古气候条件更为温暖潮湿;北部缓坡带及黄珏、邵伯地区所经历的物理风化作用相对较强且差异较大,说明曾经历较强的构造运动.研究区源岩主要为长英质物质和再旋回沉积物质,受中基性物质的影响较小.高邮凹陷边缘及吴堡低凸起附近地区戴一段下部地层具有下伏阜宁组地层的海相地化特征,因此研究区物源中可能有较多部分来自基底母岩被剥蚀和再旋回沉积的产物.地化数据反映研究区构造背景为安第斯型活动大陆边缘,由于地史及动力学机制的差异,其构造背景有别于东太平洋典型的安第斯型活动大陆边缘,可反映我国东部大陆边缘特殊的地体构造特征.     

Formation and characteristics of post-earthquake debris flow: a case study from Wenjia gully in Mianzhu, Sichuan, SW China

During the three flood seasons following the Wenchuan earthquake in 2008, two catastrophic groups of debris flow events occurred in the earthquake-affected area: the 2008-9-24 debris flow events, which had a serious impact on rebuilding; and the 2010-8-13/14 debris flow events, which destroyed much of the progress made in rebuilding. The Wenjia gully is a typical post-earthquake debris flow gully and at least five debris flows have occurred there. As far as the 2010-8-13 debris flow is concerned, the deposits of the Wenjia gully debris flow reached a volume of 3.1 × 10⁶ m³ in volume and hundreds of newly built houses were buried. This study took the Wenjia gully debris flow as an example and discussed the formation and characteristics of post-earthquake debris flow on the basis of field investigations and a remote sensing interpretation. The conclusions drawn from the investigation and analysis were as follows: (1) Post-earthquake debris flows were a joint result of both the earthquake and heavy rainfall. (2) Gully incision and loose material provision are key processes in the initiation and occurrence of debris flows and a cycle can be presented as the following process: runoff—erosion—collapse—engulfment—debris flow—further erosion—further collapse—further engulfment—debris flow enlargement. (3) The amount of rainfall that triggered debris flows from the Wenjia gully was significantly less than the average daily rainfall, while the intraday rainfall threshold decreased by at least 23.3%. (4) The occurrence mechanism of Wenjia gully debris flow was an erosion type and there was a positive relationship between debris flow magnitude and rainfall, which fitted an exponential model. (5) There were five representative characteristics of Wenjia gully debris flow: the long duration of the occurring process; the long distance of deposition chain conversion during the process of damage; magnification in the scale of debris flow; and the high frequency of debris flow events.