Late Quaternary shallow biogenic gas reservoirs have been discovered and exploited in the Qiantang River (QR) estuary area, eastern China. The fall of global sea level during the Last Glacial Maximum resulted in the formation of the QR incised valley. From bottom to top, the incised valley successions can be grouped into four sedimentary facies: river channel facies, floodplain-estuarine facies, estuarineshallow marine facies, and estuarine sand bar facies. All commercial biogenic gas pools occur in floodplain-estuarine sand bodies of the QR incised valley and its branches. The deeply incised valleys provided favorable conditions for the generation and accumulation of shallow biogenic gas. The clay beds that serve as the direct cap beds of the gas pools are mostly restricted within the QR incised valley, with burial depths ranging from 30 to 80m, remnant thicknesses of 10-30m, and porosities of 42.2-62.6%. In contrast, the mud beds cover the whole incised valley and occur as indirect cap beds, with burial depths varying from 5 to 35m, thicknesses of 10-20m, and porosities of 50.6-53.9%. The pore-water pressures of clay and mud beds are higher than that of sand bodies, and the difference can be as much as 0.48 MPa. The pore-water pressures of clay or mud beds can exceed the total pore-water pressure and gas pressure of underlying sand reservoirs. Shallow biogenic gas can be completely sealed by the clay and mud beds, which have higher pore-water pressure. The direct cap beds have better sealing ability than the indirect cap beds. Generally, the pore-water pressure dissipation time of clay and mud beds is conspicuously longer than that of sand beds. This indicates that the clay and mud beds have worse permeability and better sealing ability than the sand beds. However, once the gas enters the sand lenses, the pore-water pressure cannot release efficiently.

This paper deals with the sedimentary facies and evolution of the Qiantang River (QR) estuary, and the characteristics and formation of the incised valley sequences and the related shallow biogenic gas reservoir, on the basis of analysis of over 500 cores. The result shows that, since the last glaciation, the Late Quaternary formation of the QR estuary area underwent three stages: (1) deep-cutting stage; (2) rapid-filling stage; and (3) burial stage. The fall of global sea level during the last glacial maximum enhanced the fluvial gradient and river cutting, resulting in the formation of the large-scale QR and Taihu incised valleys, with the interfluve being exposed to air on both flanks of the incised valley. Fluvial terraces at the elevations are present near the present QR estuarine mouth, corresponding to 60-70, 90-100 and 115-125m burial depths. The valleys were filled rapidly with fluvial sediments during the post-glacial period; with the rise of sea level, the river mouth migrated to landward, and backwater and retrogressive aggradation was enhanced. The QR and Taihu incised valleys are associated with an early filling and transgressive channel-infilling sequence formation, and a late filling and transgressive floodplain-estuary formation. Subsequently, the QR valley was buried under estuarine-marine and estuarine sand bar sediments. From bottom to top, the incised valley successions can be grouped into four sedimentary facies: river channel, floodplain-estuary, estuary-shallow marine, and estuary sand bar. The thickness of the river channel-infilling deposits is controlled mainly by base level rising, backwater, retrogressive aggradation and neotectonism. Further, localized thickening took place where deeper scour pools were present in the incised valley or fluvial terraces were formed during the fall of elative sea level. During the deposition of the floodplain-estuary facies, the conditions of sea level rise, tidal regime, sediment supply and accommodation space were suitable for the development of a tidal ridge system; the sand lenses associated with this facies may represent a tidal ridge system in the incised valley. At the later stage when the estuarine sand bars were formed, the sedimentary conditions were no longer favourable, resulting in absence of sand ridge deposits. Biogenic gas is stored in the floodplain-estuary sand lenses of the incised valleys. The Changjiang River provides the major sediment supply for the QR estuary sand bar, and the QR carried sediments constitute only a small portion of the deposits.

应用露头层序地层学基本原理和方法，对巢湖凤凰山石炭系剖面进行重新研究。巢湖凤凰山石炭系总厚度为79.02 m，在这个剖面中可以识别出6种主要岩相、18种微相和n个三级沉积层序，其中六个三级沉积层序属于I型沉积层序，三个属于II型沉积层序，缺失第9和第1O沉积层序。三级沉积层序在不同的古地理单元和不同的沉积环境中可以进行对比。根据各微相特征和成因，揭示了沉积间断面上存在的多期古岩溶现象。阐述了三级层序及其对应的三级海平面升降旋回的特征。

对江苏南京孔山和安徽巢湖凤凰山石炭系碳酸盐岩C、O稳定同位素进行了测定。结果表明，苏皖地区石炭纪13C、18O记录是以4个同位素演化阶段为特征，前3个同位素演化阶段与同时代的北美石炭纪相似，仅仅是内部演化特征略有不同，这反映了区域性的沉积环境的不同变化。在金陵组下部、和州组下部、黄龙组中下部和船山组层段13C表现出明显的正漂移，这可能是受植物和生物量增长、有机碳储藏量增加所引起的。18O记录总体上与13C值呈相似的变化趋势。18O增加记录了气候变冷和冰川作用的结果，18O负漂移与气候变暖和冰川消融是一致的。在浅水潮坪环境，大气淡水的淋滤作用使13C和18O值明显降低。

本文从杭州湾地区末次冰期以来的地质背景入手，分析了该区晚第四纪地层层序、深切河谷形成和演化等。末次冰期低海平面时河流侵蚀切割老地层，在本区形成40-110m深的河谷，谷底为区域不整合面，自海向陆方向和平行海岸线方向均为一不等时面，是类层序边界。冰后期地层为一个完整的1类层序，但存在多个小的间断面。初始海泛面也是穿时的，在深切谷地带是滞流沉积物与溯源堆积物之间的界面，在河间地则为古土壤层的顶界面距今7000-6500a左右的浅海相泥质层中部为最大海泛面，是沉积层序中唯一的等时面。海进体系域的河漫滩沉积物为本区生物气藏的主要勘探目的层。

综合论述了生物气的特征及其研究进展，着重探讨了生物气成因、地球化学特征、勘探研究现状、生物气形成机制和控制因素，并介绍了生物气系统概念和特征，最后叙述了生物气藏的分布和我国生物气藏的远景。生物气是在还原环境的生物化学作用带内有机质为厌氧微生物所分解的最终产物，它以甲烷为主，并含部分二氧化碳及少量氮气和其它微量气体组分，生物甲烷气δ13C1值一般小于-55‰。生物甲烷气的形成途径主要有乙酸发酵和CO2还原2种类型。生物气生成与其所处的沉积环境、古气候、有机质的类型和丰度、水介质性质、地质作用、沉积时间等众多因素密切相关。生物气埋藏浅，分布广泛，一般存在于三角洲、大陆架和部分陆相沉积环境中，储层时代主要为白垩纪、古近纪、新近纪和第四纪。白垩纪的储量最丰富，古近纪、新近纪次之，第四纪生物气藏的规模一般较小。我国生物气勘探研究历史虽然不长，但生物气资源量丰富，具有良好的勘探前景。

在非均质、低渗透砂岩油田水驱开发的中后期，剩余油分布具有如下特点：注采井网不合理在单砂体中造成有采无注，有注无采及注采失调，从而形成剩余油。砂体单向受效，在翼侧形成剩余油。砂体非均质严重，在高渗透地带造成水窜，在低渗透地区形成剩余油。基于剩余油分布的上述特点，分析目前开发剩余油所普遍采取的两种方法具有的不足，即井网加密受到储量丰度的局限及油田综合调整具有复杂、工作量大、难于管理、成本高，使上述剩余油在注水与采油分井进行的开发模式下很难得到充分开发，因此提出了开发剩余油、提高非均质低渗透砂岩油田水驱采收率的新思路——同井分层注、采开发模式，并以大庆葡萄花油田南部（葡南）为例进行了效果预测，结果表明：利用该模式可使葡南油田水驱采收率比标定值提高3.7%。

对漠河盆地的地层层序、构造特征和构造单元、盆地演化过程等进行了研究。漠河盆地盖层主要为侏罗纪陆相煤系地层及白垩系火山岩，属典型的二元结构。晚侏罗世中期由于蒙古一鄂霍茨克洋的关闭，额尔古纳微板块与西伯利亚板块碰撞，使盆地西部产生逆冲推覆构造，地层缩短量在64km以上。晚侏罗世晚期到晚白垩世，盆地进入西太平洋构造域演化阶段，处于拉张环境，在盆地中部和东部发生了三期大规模的火山活动，形成火山断陷盆地。因此，漠河盆地经历了蒙古一鄂霍茨克洋和西太平洋两种不同构造域的演化阶段，具有西部挤压推覆、中部和东部拉张断 陷构造特点。

根据杭州湾沿海平原大量的钻井、静力触探井和分析化验等资料，研究了下切河谷（钱塘江和太湖下切河谷）充填物的沉积建造和沉积相，以及浅层生物气藏分布特征。末次冰期以来，随着海平面变化，杭州湾地区下切河谷演化经历了深切、快速充填和埋藏三个阶段。末次冰盛期，海平面下降的幅度大，增加了河流梯度、加强了下切作用，形成了钱塘江和太湖下切河谷，随后在冰后期被充填和埋藏，下切河谷的两侧为暴露地表的古河间地。根据岩石学、沉积结构和沉积构造特征，本区下切河谷充填沉积物具有向上变细的沉积层序，可以划分为4个沉积相类型：河床滞留沉积物到部分曲流河沉积体系的边滩沉积、河漫滩一河口湾沉积、河口湾一浅海沉积和河口湾砂坝沉积。在河漫滩一河口湾相沉积期间， 由于海平面上升、潮流体系、沉积物供给和可容空间条件适合一个潮流沙脊体系的发育，其中的砂质透镜体可能代表了下切河谷内发育的潮流沙脊。对于河口湾一浅海沉积和河口湾砂坝沉积而言， 由于沉积条件不再有利，没有形成沙脊沉积。所有的商业性生物气都存储在下切河谷内河漫滩一河口湾砂质透镜体中。

研究了盐阜拗陷晚白垩世泰州组沉积相类型、沉积特征，以及泰州组各亚段沉积相平面分布和盆地沉积演化规律。 结果表明：泰州组主要发育冲积扇、扇三角洲和湖泊3种沉积相，从盆地边缘到盆地中心，沉积相由冲积扇沉积渐变为扇三角洲或滨湖、浅湖、半深湖相沉积，自下而上由冲积扇沉积渐变为扇三角洲或滨湖，至浅湖、半深湖相，再到浅湖相沉积；晚白垩世泰州组沉积早期为断陷湖盆发育时期，以冲积扇、扇三角洲发育为特征，晚期为拗陷湖盆发育时期，湖平面持续上升，沉积范围扩大，浅湖相或半深湖相发育，而后湖平面下降，沉积物粒度变粗。不同时期、不同地区的沉积特征表现各异，但总体表现出拗陷由小到大，再缩小的发育特点。