Abnormally high pressures are currently limited and locally developed in the Funing Formation of the Gaoyou Sag, Subei Basin, eastern China, but the paleopressure and its evolutionary history remain unclear. Based on the determination of hydrocarbon charging periods by performing systematic fluid inclusion analysis on sixteen core samples from the Funing Formation, thermodynamic modeling with fluid inclusion data was adopted to reconstruct the paleopressure and redisplay its evolutionary history throughout geological time. Results showed that the Funing Formation experienced two episodes of hydrocarbon charging periods. Episode 1 occurred with the charging of lower maturity oils in the period from 52.8 Ma to 49.5 Ma, which was recorded by yellow-fluorescing oil inclusions. Episode 2 happened with the charging of higher maturity oils in the period from 47.0 Ma to 37.0 Ma, which was characterized by blue-fluorescing oil inclusions. Each episode was an abnormally high-pressured hydrocarbon charging process. The pressure coefficient of Episode 1 reached as high as 1.44, while that of Episode 2 reached as high as 1.40. The current formation pressure is the evolutionary result of paleopressure after a process of rapid increasing and decreasing and slow increasing and is not as high as what it reached during the hydrocarbon charging periods. This work is valuable for the exploration of conventional clastic oil reservoirs and unconventional shale oils in the Funing Formation.

高邮凹陷阜三段(E1 f3)是江苏油田复杂小断块油藏勘探的主要领域,也是隐蔽油藏拓展的重要阵地.基于岩心观察,结合粒度和电测曲线特征分析等,开展高邮凹陷E1 f3沉积微相、砂体展布特征与规律研究,总结控砂模式,提出高邮凹陷E1 f3发育河流作用控制的水下分流河道、河口坝和水下分流河道间湾,湖浪作用控制的滩砂、坝砂,以及陡坡带重力滑塌控制的近岸水下扇水道等3类6种沉积微相.物源条件、动力机制和构造格局共同控制了沉积微相及砂体展布,形成斜坡带控砂和断裂带控砂两类模式;斜坡带发育河流控砂和湖浪控砂两种模式,断裂带发育断坡控砂和陡坡控砂两种模式.E1 f3砂体展布及控砂机制分析为高邮凹陷E1 f3隐蔽型油气藏勘探指出方向,为资源接替奠定了基础.

底辟构造是岩浆岩重要的成圈类型,是油气聚集的重要场所.高邮凹陷的底辟构造主要发育盖层断层型底辟构造和基底型底辟构造两种类型,其分布分别受盖层断层发育位置及基底形态所控制,底辟构造的形成与基底长轴方向、盖层断层走向具有空间上的"位态"耦合关系.利用地球物理反射特征、核上层伴生断裂、底辟核的厚度与顶面关系等组合特征,开展高邮凹陷底辟构造的识别,并进行油气成藏配套关系分析,认为岩浆侵入形成底辟构造过程对油气成藏具有建设和破坏两种作用,其中早于或同步于三垛期形成的底辟构造是油气良好的汇聚场所,是勘探有利地区,而晚于三垛期形成的底辟构造对油气成藏不利.

苏北盆地高邮凹陷北斜坡阜宁组异常高压主要发育在阜宁组二段(阜二段)、阜宁组三段(阜三段)底部和阜宁组一段(阜一段)顶部.综合分析异常高压成因机制得知:生烃作用、黏土矿物脱水是阜二段异常高压的主要成因;流体传导超压是阜三段、阜一段异常高压的成因.在此基础上恢复了研究区阜宁组超压演化过程.

以断裂为沟通油气运移通道的下生上储式油藏,识别断裂的优势运移通道是寻找富集油藏的关键.通过吸收前人对断裂输导的研究成果和分析断裂的时空演化特征,认为成藏期断裂活动强度、成藏期断层之间的构造转换带、断面输导脊是影响油气输导的三个关键参数,并形成以其为评价参数的油气输导叠合评价法,该方法将断层输导性能划分为Ⅰ、Ⅱ、Ⅲ、Ⅳ四个等级,其中Ⅰ类最有利.将该方法应用在高邮凹陷汉留断裂带断裂优势通道的评价上,评价结果表明:YAN地区汉留断裂带发育多处Ⅰ、Ⅱ类优势油气输导通道,Ⅰ、Ⅱ类优势通道的发育部位与汉留断层上升盘油气的分布吻合度较好,可指导该区的勘探.

川西坳陷聚源—金马—鸭子河地区经历了多轮次构造运动,构造叠加关系复杂,明确关键构造形成时期及特征是油气勘探面临的难点问题.利用地震、地质手段刻画了聚源—金马—鸭子河内部的褶皱、断裂形变特征,明确它们之间的几何特征差异性,解析其内部构造所处力学环境的差异性及形变机制,分析其内部形变关系,指出聚源、金马、鸭子河各构造段的主要形变期和古形变特征,为恢复古构造及演化、正确认识该区油气分布规律、指导油气勘探提供科学依据.

苏北盆地以常压盆地著称,针对局部异常高压,利用实测资料结合测井压力预测,分析高邮凹陷北斜坡阜宁组地层压力纵向及平面分布特征;应用流体包裹体热动力学模拟方法恢复古压力,分析异常高压演化特征及其成因机制;探讨异常高压下油气成藏特征,并建立不同压力系统下油气运聚模式.研究表明:阜宁组在成藏期已发育异常高压,经历复杂增压—降压—缓慢增压过程后,至今仍在一定范围内保存异常幅度;异常高压为内坡阜宁组形成富集油藏提供重要动力条件,尤其对源下油气成藏起到明显控制作用.异常高压发育特征研究对拓展内坡油气勘探提供重要理论基础.

There is a close relationship between the existence of overpressure an d oil -gas distribution .By analyzing the formation mechanism of overpressure in the north slope of Sha -Hua-Wa area,the pressure of hydrocarbon generation and the dehydration of clay minerals were found to be the main causes of overpressure in this area .In the plane ,influenced by the igneous rocks ,the distribution range of overpressure is only distributed in Shanian slope and Hua -Wa slope .In ver-tical,affected by the nature of the faults ,the overpressure is only developed in the good blocked layers of Wubao fault .

According to data analysis of logging,testing and physical properties,it was found the overpressure compart-ments in the inner slope belt of the Hua-Sha-Wa area.Their distributions in plane were affected by igneous rocks and boundary faults.The differences of Yancheng sedimentary thickness covered the consistency of the development depth of the overpressure compartment.Due to abnomal high pressure,better physical properties,higher fluid production ability,and stronger the hydrocarbon expulsion capability of source rocks in the overpressure compartment,which leads to enriched oil-gas shows,the first member of Funing Formation has the conditions of hydrocarbon accumulation.

T3 3 reflecting layer is the geological interface between the main exploration layers of E 1 f2 and E1 f1 in Gaoyou Sag,and also the important seismic layer of E 1 f1 structural trap.The basic characteristics of its reflection wave group are three strong phases .The drilling practice in Xuzhuang area proved that reflection characteristics of T 3 3 seismic wave in the area had been changed .Combined with the knowledge of geology ,the forward modeling technique was used to research the characteristics and formation mechanism of T 3 3 reflection wave group in Wazhuang and Xuzhuang area of Gaoyou Sag .The formation mechanism of T 3 3 seismic reflection standard layer in Xuzhuang was defined ,and the corresponding relationship between the lithologic features and the seismic reflection characteristics was built .The research can provide theoretical ba-sis for the structure interpretation and trap description of the area .

From Late Cretaceous to Cenozoic, the Jinhu sag (south-west part of the Subei Basin) developed a complex fault system. The fault system includes extensional faults,strike-slip faults and reverse faults which were controlled by the unified regional stress field. The Fault system experienced four stages of evolution:initial extension, inheritance extension, intense extension, and superimposed strike-slip stages. The sag extended weakly in the initial extension stage and the faults had weakly controls on sedimentation except the major fault. In the inheritance extension stage, the basin experienced continual extension; some of the earlier faults were inactive. The major faults such as the Shigang fault and Yangcun fault strongly active and formed the main sags in the intense extension stage. The faults experienced dextral strike slipping and extension in superimposed strike-slip stage. And consequently, the structural pattern of the Jinhu sag was established. The Yangcun and Shigang faults are persistence active faults controlled by the pre-existing basement faults. The Tongcheng fault, a transfer fault which accommodated the strike-slip stress between the Shigang and Yancun faults, was formed in the late stage. The activity of fault system was mainly controlled by the pre-existing faults and region stress filed. Under the influence of the two stage tectonic movements, the Jinhu sag formed the hydrocarbon traps.

Through the analysis of the major and minor roles and complementary roles among the fault sealing influence factors in Gaoyou sag, it is confirmed that the sand contents, the fault throw and the fault activity stage are the controlling factors, and it is proposed that there are two double factors complementary group in Gaoyou sag. One group is the fault throw and the sand contents, another group is the fault activity stage and the sand contents. Based on the above, the evalua- tion criterion of the fault sealing properties by double factors complementary method is built through the analysis of the re- lation between two double factors complementary groups and the fault sealing. The evaluation criterion is applied and ac- quired better effect in Gaoyou sag.

It is concluded by drill cores observation and thin sections identification that the intrusive rocks in the North Jiangsu Basin are mainly composed of diabase and few lamprophyre,whose mineral and lithological features,logging response and seismic reflection characteristics are obviously different from sedimentary rocks. Based on statistical data of drilling and logging,combined with result of 3D seismic data interpretation,the distribution of intrusive rocks have the following characteristics:(1) vertically,the most important horizon is the Paleocene Funing Formation,secondly,the Eocene Sanduo and Dainan Formation;(2) the thickness of a single layer is generally from several meters to several dozens meters;(3) there are three intrusive types,including bedding intrusion,cut-bedding intrusion and along fault intrusion;(4) horizontally,the distribution area of the intrusive rocks is more than 1000 km2,which are widespread in the Gaoyou sag and the Jinhu sag with the shape of dish or string of beads. In the North Jiangsu basin,the distribution of Cenozoic intrusive rocks are related to deep faults,meanwhile,the intrusive rocks have important influence on reservoir accumulation. It is worth to pay more attention to study the Cenozoic intrusive rocks in the North Jiangsu basin.

In Gaoyou Sag,diabase is widespread,where the mudstone usually came into being metamorphoses.Based on analysis of core samples,well logging,and other test data,rock types of mudstone metamorphic zone are mainly slate and hornstone with more pores and fractures,especially hornstone,which can form favorable reservoir with low average porosity of 13.4% and high average permeability of 1 885.4 ×10-3μm2.The more recent to diabase is,the higher degree of metamorphism is,and the better reservoir properties of metamorphic zone is.The diabase metamorphic zone in Gaoyou Sag has favorable reservoir accumulation conditions and good prospects of oil exploration.In high degree exploration area,it's a new way to enhance the exploration of this new type of trap.

The analysis of the subsidence history of the Gaoyou depression in northern Jiangsu basin during the Late Cretaceous to the Cenozoic is concerned with the decompaction correction based on the backstripping method and stratigraphic framework thickness model of the sedimentary strata in the Gaoyou depression,estimation of the thickness of the denudational strata in the depression during the latest Sanduoan based on the time difference of acoustic waves and vitrinite reflectivity,and calculation of the tectonic subsidence and total subsidence in the depression based on the Airy isostasy hypothesis.The results of research show that the Gaoyou depression is a typical rift basin,and has gone through the evolutionary stages of downwarping-faulting,faulting-downwarping,and rift faulting-downwarping,including three phases of subsidence and two phases of uplifting.The depocenters in individual stages are all controlled by main boundary faults,and display a beaded alignment around the boundary faults.

根据断陷湖盆边界断裂及伴生次级断层的剖面形态、平面展布和应变机制,将高邮凹陷南部陡坡带的边界断裂结构分为单断式和阶梯式2种。不同断裂结构影响着盆地沉积、充填过程和地貌特征,从而影响了其中储层的发育程度、生储盖组合、圈闭类型及油气成藏规律。研究表明:高邮陡坡带戴南组油藏具有断裂沟通油气、断层控砂沉积、垂向运移为主、上下叠合成藏的成藏模式。