随着高邮凹陷阜三段勘探程度不断提高,构造油藏勘探空间越来越小,迫切需要探索潜力较大的隐蔽油藏.从油气成藏基本条件入手,结合油藏分布特征,对高邮凹陷阜三段隐蔽油藏的主控因素及油藏类型进行了分析和总结.结果表明:三角洲前缘前端发育的水下分流河道及河口坝、滩坝等是形成隐蔽油藏的有利砂体类型,控制着岩性圈闭的分布;断层输导和封闭性控制油气分布层系及富集程度;构造背景与砂体展布配置关系控制油气运移趋势.在此基础上,总结了断层-岩性复合油藏和岩性油藏两大类阜三段隐蔽油藏类型,并细分为断层-河道或河口坝岩性、断层-滩坝岩性、岩性上倾尖灭、滩坝砂岩透镜体等4种类型;总结了阜三段具有"断岩、翘倾、独滩坝"的隐蔽油藏成藏特征,明确了隐蔽油藏勘探有利区在三角洲前缘前端,为高邮凹陷阜三段隐蔽油藏勘探指明了方向.

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.

苏北盆地高邮凹陷三垛组一段成藏条件较好且砂岩整体发育,储盖组合条件是油气成藏的关键因素之一,开展有效储盖组合分析及区带预测是评价垛一段成藏条件和勘探有利区的重要工作.研究认为垛一段内部发育多套储盖组合,是控制各亚段油气成藏及富集程度的重要因素.首先,根据泥岩盖层的稳定程度将储盖组合分为区域和局部2类;其次,在定性分析的基础上,为了更准确地判别有效储盖组合,解剖油藏进行定量分析,利用含油亚段、上覆亚段砂地比与油气成藏的关系,明确有效储盖组合的判别界限,建立有效储盖组合的定量判别门槛界限值,总结了3种有效储盖组合类型(下储上盖型、自储自盖型和混合储盖型);在此基础上,开展了有效储盖组合的区带预测,优选出了有利区块,指出黄珏东部—邵伯西地区是勘探构造、隐蔽圈闭的有利地区,部署实施了构造、隐蔽圈闭的钻探均取得成功,实现了三垛组勘探隐蔽油藏的首次突破.

高邮凹陷垛一段是区内主要含油气层系之一,具备充足的油源、良好的油气输导及合适的储盖组合条件,有利于油气成藏.油气藏主要分布在高邮凹陷深凹带,具有储量规模差异大、分布地区广泛、成藏层系相对集中及油气藏类型多样等特征.通过对构造背景、输导条件、储盖组合、砂地比及遮挡断层封闭性等方面的研究,分析了E2s1油气藏形成的控制因素,为E2s1油气藏勘探的挖潜和拓展提供了依据,在实践中取得了良好效果.

采用岩矿特征、重矿特征、砂地比变化、岩心观察描述、沉积相标志分析等方法,以砂层组为单元开展高邮凹陷垛一段物源体系、沉积相类型和沉积演化特征研究.结果表明,垛一段沉积期物源供给充分,具有多物源、多沉积体系发育的特征,物源主要来自北、北东方向;平面上,发育浅水辫状河三角洲、扇三角洲、曲流河等相类型,以及辫状河三角洲前缘分支河道、河口坝,扇三角洲平原河道、前缘分支河道,曲流河河床、泛滥平原等亚相和微相类型;纵向上,早期为湖泊-三角洲沉积体系,晚期逐渐演化为河流沉积体系,具有粗-细-较粗的沉积旋回演化;垛一段中部泥质岩类沉积较发育,可与下伏储层形成相对稳定的储盖组合;平面上深凹南部和西南部具有隐蔽圈闭形成的有利条件.

地质统计学反演充分融合地质信息、地震、测井等先验信息,通过马尔科夫链蒙特卡洛算法,产生一系列高分辨率的地质参数,是薄砂岩储层预测的核心技术.该技术在应用中包括反演前数据准备、地质统计学特征参数分析和反演综合评价三个步骤.在高邮凹陷刘五舍次凹,利用地质统计学反演进行薄砂体预测,反演结果与钻井资料高度吻合,符合地质认识,证实了地质统计学反演能有效提高薄砂岩储层的刻画精度.

基于苏北盆地高邮凹陷戴南组断层-岩性油藏断层现今与成藏期垂向正应力研究,分析了断层垂向封闭性演化规律.高邮凹陷主要断层-岩性复合油藏现今断层正应力分布在13.8～25.0 MPa,断层垂向封闭性正应力临界值为13.8 MPa,成藏期正应力分布于8.9～20.2 MPa,多数控藏断层成藏期开启作为输导通道,现今封闭成为遮挡条件,但偶有例外,邵深1油藏控藏断层成藏期与现今皆封闭,此类油藏极有可能自生自储.

Fault sealing evolution is analyzed based on normal stress calculation,and combined with migration pathway pattern division,and favorable areas of fault-lithologic reservoirs of Dainan Formation are predicted in Gaoyou depression.It is concluded that the critical value of fault sealing is 13.8 MPa.Most of the reservoir faults are open in the accumulation period and closed now.However,there is one reservoir fault sealing all the time,which is Shaoshen 1 reservoir of own source type.Two types of migration pathway patterns were divided in theory which are the high-efficient and the low-efficient types respectively.The high-efficient type developed with bottom sand,while the low-efficient without bottom sand.East Lian 12 oil-west Yong 22 oil and east Shao 14 oil are the most favorable areas of fault-lithologic reservoirs of Dainan Formation in Gaoyou depression.Deep Shaobo sub-sag to the northwest of Shaoshen 1 reservoir is the secondary favorable area.

Based on the studies of fault sealing evolution, oil-bearing formation and hydrocarbon generation ability of highly-conductive mudstones in the Dainan Formation, the fault-lithologic reservoir systems of the Dainan Formation in the Gaoyou Sag have been classified into 3 types, including self-sourced, other-sourced and mixed-sourced. The self-sourced accumulation systems mainly locate in the deep Shaobo and Fanchuan Sags, and the Shaoshen1 resrvoir is typical. The other-sourced accumulation systems mainly distribute in the Majiazui, Zhou22 and Shao18 reservoirs. The mixed-sourced accumulation systems are represented by the Lian3, Lian7 and Yong22 reser-voirs. The fault-lithologic reservoirs of the Dainan Formation in the Gaoyou Sag are controlled by2 elements, oil source and migration pathway. The favorable zones for exploration include Huangjue-Majiazui, Lianmengzhuang-Yongan and Caozhuang-Xiaoliuzhuang.

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.

The fault systems are rich in Gaoyou sag,so the evaluation of the fault sealing is the important.There are many geological factors controlling the fault sealing,and the fuzzy mathematics is useful to fault sealing evaluation.The key of the work is to comfirm the weight coefficient and establish the attribution function.Firstly,the universe of discourse set of fuzzy mathemevaluation is ruled according to the major influencing facotors,to confirm their weight coefficients by qualitative arrangement and quantitative transform method.Secondly,the change law of fault sealing with the factor change is analysed,to built the suitable attribution functions.The fuzzy evaluation of fault sealing in Gaoyou sag has obtained good effects.

Faulted block reservoir is an important type in Wazhuangdong structural zone,and the fault sealing capability is the key factor in pool-forming.In this paper the qualitative study is conducted to build the qualitative judgment standard by use of all of 5 factors such as the lithology, stratigraphic sequences between the hanging wall and the footwall of a fault,and the occurrence of the fault and so on. The quantitative study is done to evaluate the fault sealing capability with SSF and the fault transverse sealing coefficient and the quantitative judgment standard is established in Wazhuangdong area.On this basis,comprehensive study on fault sealing capability is carried out with fuzzy mathematics method in the area,with first the fuzzy weight standard is built in the area,and secondly the weight averaging is chosen to fuzzy calculation. It was showed that the fuzzy mathematics method is the appropriate to this area.

The fractal dimension is an important fractal geology parameter for describing the characters of fractal space distribution of a complex dimension body.The fault system of structural horizon in Hongliu area was taken as a plane set to be studied with the fractal dimension.According to the fracture characters of the different structural horizons,the studied area was divided into three sub regions including Kendong fault block,Kenli fault block and Kendong 6 fault block.The fractal dimensions of fault systems in the structural horizons during three periods of T_6,T_2 and T_1 in each area were calculated.The researched result shows that the fractal dimension of the fault system can indicate the development degree of fractures to a certain extent and can be used to study fracture system being as an assistant method.