博孜—大北地区是库车坳陷重要的天然气勘探领域之一,含气层系下白垩统为深层—超深层致密砂岩,在7 000 m以深仍发育有效储层且获得高产工业气流,明确这类储层的特征及成因机制,对优质储层分布预测、开发井位部署以及天然气的高效开发具有重要意义.利用岩心、测井资料和铸体薄片、阴极发光、扫描电镜等实验分析结果,对博孜—大北地区下白垩统储层进行了表征,分析了储层物性的控制因素,认为储层物性平面差异成因在于胶结作用和侧向"压实"作用强度差异.研究结果表明:博孜—大北地区下白垩统为扇三角洲-辫状河三角洲沉积体系下形成的裂缝型致密砂岩储层,成像测井解释的裂缝密度平均为0.56条/m,微观裂缝开度为20～50 μm.沉积相主控储层物性,经验公式恢复的砂岩原始孔隙度平均为38.5％;压实作用(包括垂向压实和侧向"压实")和胶结作用是主要的减孔效应,总压实减孔量为20.9％～30.3％,平均为25.8％,其中侧向"压实"作用同时也是产生构造裂缝的主要动力来源;溶蚀作用是主要的增孔效应,增孔量平均为4.0％;低密度(2.13 g/cm3)、强塑性和高热导率(平均为4.7 W/(m·K))使上覆膏盐层对储层起到有效的保护作用;异常流体压力(压力系数1.6～1.8)使储层经受的有效应力降低,有效保持储层物性.下白垩统储层经历了早期浅埋、缓慢深埋、快速深埋和急剧深埋4个阶段,在急剧深埋阶段早期(11～10 Ma)达到致密化,早于天然气的大规模充注期(3 Ma～),为"先致密后成藏".

Ultra-deep clastic reservoirs generally have poor physical properties and low single-well productivity, but Well BZ9, which is newly drilled in the Kuqa Depression of Tarim Basin, NW China, encounters a thick high-quality reservoir in the Bashijiqike Formation of Lower Cretaceous deeper than 7600 m and produces a high-yield industrial gas flow. In order to reveal the characteristics and genesis of the Bashijiqike Formation reservoir and reduce the exploration risk of ultra-deep oil and gas layers, we discussed its characteristics, genetic mechanism and oil & gas exploration significance based on cores, well logging and experimental analysis, combined with regional temperature–pressure conditions and burial evolution history. The following research results were obtained. First, the rock types of ultra-deep reservoir of the Bashijiqike Formation in this area are medium- and fine-grained feldspathic litharenite and lithic arkose with point-line contact between grains, and its reservoir space is dominated by primary intergranular pores. At present, it is still at its middle diagenetic stage. Second, different from other ultra-deep fractured low-porosity sandstone reservoirs, this set of ultra-deep reservoir is a pore-type reservoir with porosity of 4–13%, permeability of 0.1–50.0 mD and better porosity and permeability correlation. Third, during the sedimentation of the Bashijiqike Formation, thick sand bodies of delta front were widely developed, medium- and fine-grained sandstones accounted for more than 85% and grains had strong compressive capacity. After that, this reservoir experienced long-term shallow burial during the early–medium stage and rapid deep burial during the late stage, and the burial compaction effect was weaker. During the late stage, a canopy structure was formed from the overlying Paleogene thick gypsum salt bed due to thrust and compression, and it further suppressed vertical compaction. In the meantime, the study area was far from the orogenic belt and the structural transition zone, so the lateral compressive stress was weak. Therefore, the primary intergranular pores were preserved in large quantities. It is concluded that coarse lithology, weak compaction and low tectonic stress are the key factors to the development of this ultra-deep high-quality reservoir. In addition, the development of large-scale effective reservoirs deeper than 7000 m provides favorable material conditions for the high-abundance enrichment of natural gas and the reserves of trillion cubic meters in the Kuqa Depression, and the oil and gas exploration potential is huge.

下白垩统是塔里木盆地西南坳陷主要的勘探层系之一,油气资源丰富但勘探程度较低,新近部署的多口探井均遭遇失利.为指导油气勘探部署,利用露头、钻井、地震和实验分析等资料,对下白垩统残余分布、沉积体系类型及储集层差异演化特征进行了研究.结果表明:①下白垩统沿南天山和昆仑山山前存在喀什北缘、乌泊尔构造带、棋北构造带和柯东构造带4个集中分布区,从山前向盆地内部减薄尖灭,改变了以往呈连续带状分布的认识.②古地貌控制下发育辫状河三角洲和扇三角洲2种沉积体系;其中,辫状河三角洲以前缘亚相为主,厚层水道砂体叠置连片分布,而扇三角洲由平原和前缘亚相构成,具有厚层短轴粗粒特征.③受原始沉积组分和后期成岩改造影响,下白垩统发育次生孔隙型和原生孔隙型2类储层,储集物性表现为中低孔中低渗—特低孔特低渗差异分布,喀什北缘和柯东构造带有利储层相对发育.

超深层碎屑岩储层物性一般极差,单井油气产能低,但塔里木盆地库车坳陷新近钻探的博孜9井却在7600 m以深的下白垩统巴什基奇克组仍然钻遇了优质厚层储层,并获得了高产工业气流.为了揭示该储层的特征和成因、降低超深层油气勘探的风险,基于岩心、测井和实验分析等资料,结合区域温压条件和储层埋藏演化史,探讨了巴什基奇克组储层的特征、形成机制及其油气勘探意义.研究结果表明:①该区巴什基奇克组超深层储层岩石类型为中、细粒长石岩屑砂岩和岩屑长石砂岩,颗粒呈点一线接触,储集空间以原生粒间孔为主,现今仍处于中成岩演化阶段;②与其他超深层裂缝性低孔砂岩储层不同,该套超深层储层为孔隙型储层,孔隙度介于4％～13％,渗透率介于0.1～50.0 mD,孔渗相关性较好;③巴什基奇克组沉积期广泛发育三角洲前缘厚层砂体,中、细砂岩占比超过85％,颗粒抗压能力强,此后储层经历了早—中期长时间浅埋藏,晚期快速深埋,埋藏压实效应较弱,晚期上覆古近系巨厚膏盐岩层受冲断挤压形成顶蓬构造,进一步抑制垂向压实,同时研究区远离造山带和构造转换带,侧向挤压应力弱,原生粒间孔得以大量保存.结论 认为:粗岩性、弱压实和低构造应力是该套超深层优质储层发育的关键;7000 m以深规模有效储层的发育为库车坳陷天然气高丰度富集和万亿立方米储量规模提供了有利的物质条件,油气勘探潜力巨大.

Being widely developed in Subei exploration area,volcanic rocks are characterized by fast lateral and vertical change,complicated accumulation rule,which causes great difficulties for oil and gas exploration.By analyzing source rocks,matching characteristics of reservoir and cap rock,combining with seismic data,this paper studied the contact relationship of volcanic and source rocks,and studied the volcanic reservoir accumulation model.There are six types of reservoir accumulation model,including indirect contact of source rocks and volcanic rocks,direct contact of source rocks and volcanic rocks,volcanic rocks enwrapped by the source rocks,source rocks developed on and below the volcanic rocks,volcanic reservoir developed on the top of volcanic conduit and volcanic rocks acted as seal.These reservoir accumulation models were used to predict the volcanic reservoir at the Funing and Sanduo formations in Eogene.Totally,they can be summed up to three types of volcanic reservoir,including the relationship of source and reservoir represents as enwrapping(near source rocks),the relationship of source and reservoir shows as up and down(near source rocks),and faults act as the main hydrocarbon migration path.

Volcanic is characterized by irregular shape and fast change of lateral structure,which leads to the difficulty for volcanic identification. In order to more accurately and rapidly identify volcanic,we takes the Dafengxinghua area as example to study the seismic identification methods of volcanic.Three types of volcanic litho facies develop in Dafengxinghua area,including volcanic crater,volcanic conduit and volcanic intrusion rock.Different litho facies has different seismic reflection and attribute characteristics.Seismic section recognition method,amplitude and coherent time slices,seismic attribute analysis and impedance inversion were used to identify the three types of volcanic facies.The identification result matches well with drilling data,which indicates the flexibility of the method.

Early Paleogene-Neogene of the Dafeng-Xinghua region has been affected by extensional strike-slip,presenting a structural framework of òearly fault depression and late sagó.Research shows that hydrocarbon accumulation in the region has the laws as follows:the reservoir distribution is controlled by the hydrocarbon-generating center,the scale of reservoirs is determined by the size of sags,to discover good sand bodies is very important because the oil bearing series is single and the individual reservoir is thin and changes fast horizontally,the large fault leading to deep sags is critical to oil and gas migration and now oil reservoirs are located in the vicinity of the large fault.In addition,the activity of most reservoirs with the characteristics of lateral sealing has ceased before source rocks get mature.Structural traps are favorable oil and gas accumulation zones,so structural reservoirs and structural-lithologic reservoirs generated from small complex faults are the main types.Taken together,the main idea of "to discover oil in traps in oil-rich sand bodies based on faults" is put forward.

The comprehensive study of the tectonics-sequence stratigraphic-petroleum system shows that five sets of major regional and some local source rocks were developed in the tectonic evolution of South China, including the Lower Cambrian and Lower Silurian in the Caledonian cycle, the Middle Permian and Upper Permian in the Hercynian cycle, and the Lower Triassic in the Indo-Sinian cycle. Due to the inhomogeneous maturity of source rocks in this area, gas exploration would mainly be carried out in the Lower Paleozoic areas, while oil and gas exploration would be in the Upper Paleozoic ones. The reformation from the Indo-Sinian cycle to the Himalayan cycle exerted decisive influence on the hydrocarbon accumulation in the Mesozoic-Cenozoic basin and marine sequences in southern China. The petroleum systems formed in the medium-late period of the superimposed basins are of the greatest potential. The distribution of primary and secondary oil-gas pools was mainly affected by favorable sedimentary facies, ancient uplift and slope. The comprehensive evaluation concluded that the focuses for petroleum exploration in the marine sequences of southern China will be in the superimposed basins along the margin of Yangtze landmass, the Subei-southern South Yellow Sea basin and the marine sequences preserved under the over-thrust nappe along the northern margin of the Jiangnan uplift.

Based on comprehensive study on tectonic stress field,structural feature,and sedimentary formation,the tectonic evolution of Subei-South Nanhuanghai(North Jiangsu-Southern South Yellow Sea) superimposed basin since the late Triassic plate collision between the Huanan plate and Huabei plate can be divided into the following four stages: ① the foreland basin development stage under the influence of the late Triassic to Middle Jurassic paleo-Tethyan closing;② the thrust nappe development stage controlled by the Late Jurassic-Early Cretaceous oblique subduction of Izanagi oceanic plate;③ the basin extension development stage under the in-fluence of the late Cretaceous-Paleogene subduction of the Pacific plate,including the late Cretaceous depression development stage and Paleogene fault depression basin development stage;④ the depression development stage under the influence of Neogene Himalaya orogenesis.In relation to the development of the Paleogene half-graben-like fault depression,this paper focuses on the controlling effects of the left-lateral strike-slip and pul-lingapart movement along with the NWW basement faults and of the NE thrust nappe over the development of the basin and half graben-like fault depression,and points out the exploration prospect of marine petroleum system from the aspect of sedimentation,reworking,and preservation.