Diagenetic history of tight sandstones and gas entrapment in the Yulin Gas Field in the central area of the Ordos Basin,China

The Ordos Basin is a large cratonic basin with an area of 250,000 km² in central China. Upper Paleozoic coals and shales serve as gas source rocks with peak generation and migration at the end of the early Cretaceous. Recent exploration has verified the huge gas potential in the “basin-centered gas accumulation system” (BCGAS). However, the mechanism for the gas accumulation is controversial. With an integrated approach of thin-section petrography, ultra-violet fluorescence microscopy, fluid inclusion microthermometry, Raman microspectrometry, scanning electron microscopy, and X-ray diffractometry, we identified diagenetic trapping and evaluated the diagenetic history of sandstone reservoirs in the Yulin Gas Field in the central area, where structural, stratigraphic and/or sedimentary lithologic traps have not been found. It was revealed that three phases of diagenesis and hydrocarbon charging occurred, respectively, in the late Triassic, late Jurassic and at the end of the early Cretaceous. In the first two phases, acidic water entered the reservoir and caused dissolution and cementation, resulting in porosity increase. However, further subsidence and diagenesis, including compaction and cementation, markedly reduced the pore space. At the end of the early Cretaceous, the bulk of the gas migrated into the tight reservoirs, and the BCGAS trap was formed. In the updip portion of this system, cementation continued to occur due to low gas saturation and has provided effective seals to retain gas for a longer period of time than water block in the BCGAS. The mechanism for the gas entrapment was changed from water block by capillary pressure in the BCGAS to diagenetic sealing. The diagenetic seals in the updip portion of the sand body were formed after gas charging, which indicates that there is a large hydrocarbon exploration potential at the basin-centered area.     

桂北地区硫铁矿地球化学特征及其意义

通过对桂北地区硫铁矿的铅、硫同位素进行计算和分析,认为该区硫铁矿的物质是多来源,多成因,多阶段演化的结果。推测成矿时代为海西—印支期,以印支期为主;硫源主要来自于同时代沉积的硫酸盐细菌还原作用;同一矿区中,铅、硫同位素组成相似,二者物质来源和成因一致。     

PROGRESS OF STUDIES ON THE INTERNAL TIDE GENERATED BY THE PASSAGE OF BAROTROPIC TIDE OVER CONTINENTAL SHELF/SLOPE

Various aspects of studies on internal tides are reviewed .Both beam-like structure and modal structure of internal tides may exist in the ocean . Bottom intensifications are caused by many factors .e.g. upstream blocking , which is the result of nonlinear interaction among waves . The energy may decay very fast so that internal tides are mostly locally generated .Internal tides may have considerable residual currents.In a 3-D frame, numerical study revealed that internal waves may interfere with each other to cause strong motions fer from the generation sources.The mechanism that determines how the lee waves break to form various nonlinear waves such as solitary waves, hydraulic jumps and internal surges or bores remains unclear. Analytic study is difficult , so numerical method may be effective . A radiation condition on the open boundary must be employed. A complete 3-D model may gain interesting result.Study on internal tides in China is limited to field observations and data analysis .     

An approach to reserve estimation enhanced with 3-D seismic data

Reserve estimation for hydrocarbon reservoirs can be improved by incorporating values extracted from three-dimensional (3-D) seismic data with those obtained from more conventional data sources of data, such as drill-core and well-log data. An example of this improved method is illustrated by an application to the QW pool located in the Buohaiwan Basin in eastern China. Parameter values extracted from 3-D seismic data extend the knowledge about the spatial distributions of such reservoir parameters as net thickness, porosity, and oil saturation. To assist in the extraction of these values, different pattern-recognition techniques can be applied. The results that are obtained by this method offer a more reliable and more credible approach to reserve estimation and can be applied at every stage of resource extraction from exploration to development.     

地块－海槽边缘带成油成气新概念

对准噶尔、塔里木等盆地沉积环境的研究表明,古生代时,中国西北区为海相沉积,沉积盆地的基底是一些离散的古老结晶地块,其上海水侵漫,地块之间为大洋或窄大洋的海槽。地块之间的海槽或地块与海槽过渡的边缘带盆地是油气形成的有利地带。在海槽遭受压缩褶皱而回返的造山过程中,＂地块－海槽＂体系发生转化,形成中新生代＂山系－盆地＂的陆相沉积体系。边缘带的油气源岩系被埋藏在盆地外围的山系之下。但其中形成的部分油气已运移到盆地内的储集层中聚集,形成＂外生内储＂的油气藏。在这种类型的盆地中,存在陆相生油和海相生油、＂内生内储＂和＂外生内储＂的两类生油岩系和两种生储组合配置体系。这一油气形成分布的理论,已不断地被油气地球化学研究和勘探实践所证实。＂地块－海槽＂边缘带油气形成观点的提出,突破了以现今盆地为界限研究古生代油气形成分布规律的传统观念,增大了中国西北区可以发现的油气资源量,扩展了找油找气的新领域,具有十分重要的意义。     

传统“珍珠水解液”的工艺改进研究

用双酶法改进传统的“珍珠水解液”的生产工艺,以珍珠层粉脱钙后所得的壳角蛋白、及经脱腥后的珠母贝全脏器为原料,经打浆、双酶水鲜、过滤、脱色、灌封、杀菌后,得水解液制品。经氨基酸分析仪测定,水解液中游离氨基酸总量≥２,５００ｍｇ／１００ｍｌ;其中必需氨基酸含量≥９００ｍｇ／１００ｍｌ;牛磺酸含量≥２３０ｍｇ／１００ｍｌ。     

海洋矢量过程旋转谱估计的统计分布及置信区间

本文利用一些复随机变量的分布和统计推断理论,导出了向量过程的正旋谱、负旋谱、谱差、总谱、外自谱、频域外自相关函数、外自谱的位相函数等估计量的渐近分布以及它们的置信区间,并简略地讨论了所得置信区间的最优性。最后用锚系海流计资料实例说明了所得置信区间公式在海流资料分析中的应用。     

深圳石岩水库污染状况及综合防治对策

采集石岩水库各来水支流和坝前共计8个样点3种不同深度的水样,由深圳市水质检测中心检测,检测地表水环境质量标准基本项目(除COD)和补充项目,共计28项.水质评价采用单项标准指数法和富营养化评价法.结果表明:根据单项标准指数法,全部采样点均检出超标污染物,共有12种污染物项目超标,其中总氮超标最严重;污染最严重的前3个样点分别是石岩河和深坑坜支流、麻布支流和石岩湖温泉度假村;根据富营养化评价法,水库的整体水质为中营养水平,个别样点已达到富营养化水平,磷是该水库富营养化的限制性营养元素;一些污染物有逐步沉积的现象,其含量随深度逐渐增加,如不加以控制,长期积累也会导致下层首先超标而影响水质.文中提出了对石岩水库污染水质的治理技术方法,并针对各个支流水质的污染特点提出了对应的防治措施.     

山东蓬莱金矿黄铁矿成分环带的成因及成矿意义

蓬莱金矿位于胶东半岛北部,是一个中型热液型脉状金矿。利用分析型高分辨电子显微镜(JEM-2000FX)并配以能谱仪(EDS)对主要的载金矿物黄铁矿进行微区分析,发现成矿阶段黄铁矿晶体内部Fe、S等成分呈环带状分布。本文从耗散结构理论出发,初步探讨黄铁矿内部成分环带的成因,并论述了它的成矿意义。