Distribution Prediction of Middle-deep Lacustrine Source Rocks in Eocene Wenchang Formation in the Kaiping Sag,Pearl Mouth Basin

Oil and gas shows are rich in drilling wells in Kaiping sag,however,large oilfield was still not found in this area.For a long time,it is thought that source rocks were developed in the middle-deep lacustrine facies in the Eocene Wenchang Formation,while there is no source rocks that in middle-deep lacustrine facies have been found in well.Thickness of Wenchang Formation is big and reservoirs with good properties could be found in this formation.Distribution and scale of source rock are significant for further direction of petroleum exploration.Distribution characterization of middle-deep lacustrine facies is the base for source rock research.Based on the sedimentary background,fault activity rate,seismic response features,and seismic attributes were analyzed.No limited classification method and multi-attributes neural network deep learning method were used for predicting of source rock distribution in Wenchang Formation.It is found that during the deposition of lower Wenchang Formation,activity rate of main fault controlling the sub sag sedimentation was bigger than 100 m/Ma,which formed development background for middle-deep lacustrine facies.Compared with the seismic response of middle-deep lacustrine source rocks developed in Zhu I depression,those in Kaiping sag are characterized in low frequency and good continuity.Through RGB frequency decomposition,areas with low frequency are main distribution parts for middle-deep lacustrine facies.Dominant frequency,instantaneous frequency,and coherency attributes of seismic could be used in no limited classification method for further identification of middle-deep lacustrine facies.Based on the limitation of geology knowledge,multi-attributes of seismic were analyzed through neural network deep learning method.Distribution of middle-deep lacustrine facies in the fourth member of Wenchang Formation is oriented from west to east and is the largest.Square of the middle-deep lacustrine facies in that member is 154 km²and the volume is 50 km³.Achievements could be bases for hydrocarbon accumulation study and for exploration target optimization in Kaiping sag.     

白云凹陷第三系储层中铁白云石的成因机理及与CO2活动的关系

白云凹陷第三系储层中发育大量的铁白云石,受研究区热流背景的影响,铁白云石主要见于高地温梯度地区埋深1000～3000m、地层温度60～130℃的浅—中部地层中及CO_2热流体活动区域。铁白云石的δ~(13)C值(-2.83‰～-1.83‰)具有无机成因的特征,与研究区气藏中幔源岩浆成因CO_2的δ~(13)C值较为一致,铁白云石的δ~(18)O值(-9.45‰～-5.37‰)和~(87)Sr/~(86)Sr值(0.7101～0.7161)也反映了其沉淀受到深部热流体活动的影响。以两口典型CO_2气井为例,储层中流体包裹体均一温度及蒙脱石向伊利石的演化特征证明储层经历了热流体侵入;CO_2热流体活动区域不仅是铁白云石集中分布地带,并出现片钠铝石+铁白云石+菱铁矿等示踪CO_2运移、聚集的自生矿物组合。地层中铁白云石、高岭石含量与气藏中CO_2的含量呈正相关关系,绿泥石含量与CO_2、铁白云石含量呈反消长关系。高地温梯度地区丰富的CO_2热流体活动是该地区储层中铁白云石沉淀与含量高的重要原因,无机岩浆成因CO_2是铁白云石沉淀的主要碳源,CO_2热流体充注造成绿泥石等黏土矿物异常转化,为铁白云石沉淀提供了所需的Fe~(2+)、Mg~(2+)离子。     

东营凹陷烃源岩排烃的地质地球化学特征

利用地质地球化学信息研究烃源岩的排烃行为是一种重要而有效的手段,东营凹陷较为丰富的地质地球化学信息对研究烃源岩的排烃行为具有重要的意义.东营凹陷烃源岩排烃的地质地球化学特征显示其排烃行为存在较强的非均质性:单层泥岩边缘地区排烃效率高,内部排烃效率相对较低,这种现象在厚层泥岩中(大于 30 m)表现更为明显,其中通常存在一定的相对"滞排区";不同的压实阶段,排烃效率也不相同,快速压实带较缓慢压实带及稳定压实带排烃效率稍高.东营凹陷存在两类超压体系:一类是相对开放性质的,幕式排烃是其重要的排烃方式之一,其排烃效率较常压系统高,排烃效率平均在 50%左右(常压体系排烃效率一般在 40%左右);另一类是相对封闭性的,为良好的超压"封存箱",其排烃效率较常压系统低,排烃效率平均在 20%左右,其地质地球化学行为显示一定的滞排特征,排烃行为不明显.研究结果认为压实不均衡是东营凹陷形成沙三中异常高压的主要原因,生烃作用是其形成沙四上超压的主要机制,而沙三下同时具备压实不均衡及生烃作用的双向增压效应.     

北部湾盆地涠西南凹陷油气运聚成藏特征

北部湾盆地涠西南凹陷是个断陷湖盆,在油气运聚体系中,断裂可以起到沟通烃源岩的作用,将烃源岩和储层连通在一起; 不整合面造成不同层系的接触与连通,从而为其附近发育的各种圈闭提供油气侧向运移的通道,并形成油气藏。涠西南凹陷已发现的油气分布特征总体上呈“断裂沟源、断脊运移、两面控藏、复式聚集、满凹含油”的油气分布格局,形成了一个“一源多储、复式聚集、连片含油”的油气聚集区。     

东营凹陷油气运聚古地下水动力场剖面数值模拟

本文对东营凹陷油气运聚古地下水动力场剖面数学模型的建立、古水文地质参数的再造、模拟初始值的恢复进行了阐述。在此基础上,进行了东营凹陷油气运聚古地下水动力场剖面数值模拟。模拟结果与已知油田的分布具有较好的一致性。推断的东营凹陷油气聚集有利地段,可以作东营凹陷油气田进一步勘探开发的依据。     

储层致密化与油气充注的关系:以三肇凹陷白垩系扶余油层为例

为了明确松辽盆地三肇凹陷扶余油层储层致密化与油气充注相关性,利用微米CT、流体包裹体显微分析、盆地模拟等方法,研究了该储层微观孔喉特征,且定量分析了其成藏期.根据储层孔隙演化信息分析了研究区储层致密化过程和油气成藏的关系.结果发现:三肇凹陷扶余致密储层岩石类型以长石岩屑砂岩和岩屑长石砂岩为主,孔喉特征表现为窄喉道、宽孔...     

从化石群及壳体同位素看古近纪东营湖湖水化学

从"海源陆生化石"、壳体O、C和S同位素等几个新的角度和方法对山东东营凹陷古近纪古湖泊湖水化学性质进行讨论.通过与现生"海源陆生生物"的比较,得出原先认为是"海相"标志的有孔虫、钙质超微化石、沟鞭藻和疑源类、多毛类和鱼类等实际上是"海源陆生化石",它们生活在以Cl-和Na+为主的咸水湖泊环境.超微化石S同位素分析表明,渐新世与始新世钙质超微化石的87Sr/86Sr 比值都明显高于同时期海水的87Sr/86Sr比值,而与现代河、湖水的87Sr/86Sr比值相近,进一步揭示它们生活的环境不是海,而是与海无关的湖.介形虫壳体O、C同位素分析则表明,古东营湖是一封闭型咸水湖泊,从另一角度也否定了与海连通的可能性.根据不同层段同位素特征讨论了湖水矿化度的相对变化.     

东营凹陷含烃流体驱动过程中的地球化学效应

油藏中烃类的地球化学特征具有明显的非均一性,油气运移和成藏过程对其有重要的影响。以东营凹陷为例,在不同流体压力系统成藏条件研究、烃源岩与储层的烃类地球化学差异对比的基础上,综合分析了烃类的驱动机制。在以古近系为烃源岩的陆相断陷盆地(凹陷)中,垂向运移的影响大于横向运移,总体表现为饱和烃的轻/重比(nC21+nC22)/(nC28+nC29)随运移变低,表征原油成熟度的甾烷异构化参数C29ββ/(αα+ββ)也随运移方向变小,成藏过程中动力和阻力相互作用导致的运移和保存之间存在一定的平衡关系,同时影响了油气组分的变化,反之则相反。在研究东营凹陷烃类驱动过程中地球化学分异机制的基础上,明确了不同流体单元的差异性及其对烃类地球化学特征的影响,深入分析了不同区带的油气运移及成藏方式。     

准噶尔盆地吉木萨尔凹陷井井子沟组微裂缝微观特征及成因

笔者等利用岩芯、薄片、扫描电镜和分析化验等资料,开展了吉木萨尔凹陷井井子沟组致密砂岩储层微裂缝特征分析,并揭示了微裂缝成因。研究表明：① 基于裂缝与颗粒之间的分布关系,将井井子沟组致密砂岩储层微裂缝分为粒内缝、粒缘缝和穿粒缝3种类型,其中粒内缝最发育,穿粒缝次之,粒缘缝最不发育;利用延伸长度、面密度和开度等参数评价了3种类型微裂缝分布,研究区开启性裂缝占60%以上,以穿粒缝开启性最好。② 微裂缝发育控制的因素主要有构造作用、岩石成分和结构等,微裂缝主要发育在中砂岩、细砂岩中,颗粒粒度越粗、分选越好,微裂缝越发育;储层抗压能力较弱,致使粒内缝和穿粒缝的成为主要微裂缝类型;点—线接触使得颗粒间的接触面积较小,有利于微裂缝发育。③ 研究区微裂缝成因主要为原生、成岩和构造成因,粒内缝为原生成因和成岩成因,粒缘缝为成岩成因和构造成因,穿粒缝为构造成因,穿粒缝有助于储层渗流能力的发育,是优质储层发育的有利因素之一。研究成果对于准噶尔盆地致密砂岩储层微裂缝的成因及优质储层评价具有指导意义,并对类似地质条件的致密储层油气勘探可以起到一定的借鉴作用。     

Distribution Patterns of Calcite Cement in the Turbidite Sandstones of the Shahejie Formation in the Dongying Depression, Eastern China

Calcite cements are volumetrically dominant among the most diagenetic constituents in turbidite sandstones of the Paleogene Shahejie Formation in the Dongying Depression. The results show carbonate cements mainly occur in three phases: Calcite I (pre-compaction), Calcite II (post-compaction) and ankerite in the turbidite sandstone. The isotopic composition of Calcite I and Calcite II range from ?4.3‰ to 4.4‰, ?3.5‰ to 4.3‰ PDB, respectively, suggesting that the calcite cements are mainly derived from the interbedded shales. The early calcite cement precipitated from the mixing of lacustrine and meteoric waters at 38–69°C. The late-phase calcite precipitated from pore waters modified by water-rock interactions at 64–126°C. Two distribution patterns of calcite cements can be identified, depending on their position within the sandstone. The peripheral cementation of the sandstones is near the sand-shale contact. The development of cement is controlled by sandstone thickness and the properties of the interbedded shale. For scattered cementation, the distribution of the calcite cement is not controlled by the sand-shale contact. Calcite cement was preferentially distributed in coarse-grained sandstones, indicating that sandstones with high original permeability are the preferred pathway for the migration of early diagenetic fluids.