东营凹陷低渗透岩性油藏储层非均质性特征及水驱剩余油分布规律

中国低渗油藏潜力巨大,受控于地下储层特性及开发技术水平,目前采出程度偏低。以东营凹陷H67块沙二段的低渗透岩性油藏为例,运用地震、测井、岩芯、分析化验及生产动态资料,分析了低渗透岩性油藏的储层非均质性特征,描述了其对注水开发的影响,阐明了剩余油的分布规律。研究表明,低渗透油藏储层孔喉半径小,平面与层内非均质性强,主要体现在稳定展布的夹层及韵律砂层渗透性相差大,平面上砂体及物性展布有明显的方向性;受控于储层非均质性,低渗透岩性油藏注水开发中存在地层能量不足、单井日液量低及平面水驱不均衡等特点,水驱后剩余油储量丰度依然较大,剩余油主要富集在层内及平面储层厚度大、物性差的区域。以上成果及认识对低渗透岩性油藏的开发具有重要的指导意义。     

冀中坳陷深县凹陷东营组砂岩储层特征及影响因素

冀中坳陷深县凹陷东营组砂岩储层岩石类型以长石岩屑砂岩或岩屑长石砂岩为主,岩石成分成熟度和结构成熟度均较低,反映了近物源和多物源的特征。通过对研究区的岩心化验分析资料、薄片和扫描电镜资料的分析,认为深县凹陷东营组储集空间类型主要包括原生孔隙和次生孔隙两类,其中以原生的粒间孔隙为主。研究区岩性孔渗资料的统计结果表明,储层的物性较好,基本为中高孔中渗型储层,根据深县凹陷储层评价标准,可以将深县凹陷储层分为4类,东营组储层主要是Ⅰ类和Ⅱ类储层。深县凹陷东营组主要为辫状河流相沉积,其沉积作用直接决定着储集砂体的类型、展布范围以及后期成岩改造作用。而储层储集性能主要受原始沉积作用及后期成岩作用共同控制,控制储层孔隙演化的成岩作用主要为机械压实作用和胶结作用。     

渤中凹陷A2—1构造东营组储层物性控制因素分析

根据岩石薄片、扫描电镜、物性和测井等资料,分析了渤中凹陷A2—1构造东营组砂岩储层品质控制因素,探讨了测试段产能差异的原因。通过分析认为：渤中凹陷古近系东营组储层物性主要受压实作用、沉积条件、碳酸盐胶结、溶蚀作用和黏土转化阶段控制。在负胶结物投点图上,犬部分砂岩都落在压实作用区间,显示了压实作用是减少孔隙的主要因素;沉积条件对储层物性的影响突出体现在粒度和泥质含量方面的影响,随着粒度变细、泥质含量增加,渗透率明显降低。储层中普遍含碳酸盐胶结物且含量较高,是DST2测试段渗透率低、产能差的重要原因之一。两测试段储层中溶蚀作用普遍存在,主要体现在对长石的溶蚀,DST2测试段是强超压的半封闭系统,溶出物不能有效带出系统而沉淀在孔隙和喉道中,对储层物性破坏较大。黏土转化阶段与渗透率的快速降低段有较好的对应关系,渗透率变差段主要出现在伊蒙混层有序混层带以下。     

低渗透油藏有效厚度下限标准研究

低渗透油藏储层物性较差,通常油层在酸化压裂等工艺技术措施下,才可产出工业油流,对低渗透油藏有效储层进行测井解释较为困难。从冷家堡油田冷46区块的油藏特征出发,建立了一套有效厚度下限标准研究方法。为检测油层有效厚度划分精度,在取心井中选取5口井进行岩心厚度与测井厚度对比,层划准率达100％。并据此标准划分39口单井有效厚度,有效地保证油层射孔,为注水开发提供可靠的依据。     

西湖凹陷花港组低渗透砂岩储层孔隙结构

为明确西湖凹陷花港组低渗透砂岩储层孔隙结构与产能之间的关系,利用500余块铸体薄片资料和311块常规压汞分析测试资料对该地区孔隙结构特征进行了分析和评价。通过对微观孔隙结构特征参数与储层宏观物性参数相关性分析,优选出最大连通孔喉半径和平均连通孔喉半径作为孔隙结构分级参数,并运用数据构型方法确定出孔隙结构分级界限,建立了适合工区低渗气藏的新的分级标准。利用该标准及孔隙与喉道大小的组合特征,将花港组H3段砂岩储层的孔隙结构划分为6种类型:大-中孔粗喉型、中-小孔中喉型、中-小孔中细喉型、小孔细喉型、细-小孔微细喉型和细孔微喉型。根据孔隙结构分类结果划分了4种储层类型,产能级别分别对应高产、中产、低产和特低产,其中一类储层主要对应大-中孔粗喉型和中-小孔中喉型孔隙结构类型,孔隙度和渗透率均较高,对应产能为高产,是该地区最有利的储层。     

低饱和度油藏原始饱和度计算及含水上升规律

受低幅度构造、地层倾角小、储层渗透率低、油源供给不足等因素影响,油层中存在自由水,若整个开发层系的油层大面积内均为油水同层,则称为低含油饱和度油藏。低含油饱和度油藏油井投产初期就具有一定含水率。由于室内岩心试验获得的油水相对渗透率曲线是在饱和油情况下进行,因此,油田实际含水与采出程度和利用室内试验曲线计算出的理论含水与采出程度曲线不能较好吻合,当油藏原始含水饱和度较高时这种误差会很大,导致含水与采出程度理论曲线无法正确预测油藏含水上升规律。根据试验获得的相渗曲线和实际生产数据,采用试验数据与生产实际相互印讧的方法,修正油藏含水上升规律,计算油藏原始含水饱和度,解决了油藏原始含油饱和度计算以及具有原始含水饱和度油藏含水上升规律预测问题,对正确认识油藏和开发指标预测具有重要意义。     

琼东南盆地松涛凸起低阻油藏特征及储层下限

综合利用常规测井、核磁共振测井、电阻率成像测井及地层测试数据,并结合岩芯实验分析结果对琼东南盆地松涛凸起区低阻油藏的储层特征进行精细表征,从宏观及微观等多方面深入分析了低阻油藏的成因及主控因素并定量确定低阻油藏的储层下限。结果表明,低阻油藏岩性以细砂岩为主,含少量粉砂岩、泥质粉砂岩及生屑砂岩,孔隙度及渗透率值变化较大,电阻率增大系数<1.5。研究区沉积环境主要为滨岸相环境,细粒物质含量偏高,较小的粒间孔隙及较差的孔隙结构造成地层中束缚水含量偏高,是造成研究区储层电阻率偏低的重要因素,泥浆侵入、导电矿物及黏土矿物附加导电性等对储层电阻率影响较小。在此基础上对低阻油藏储层下限进行了定量分析,确定了研究区低阻油藏储层孔喉半径、孔隙度、渗透率、电阻率、含油饱和度及泥质含量的下限值。此研究为琼东南盆地松涛凸起区低阻油藏的识别及勘探评价提供了理论基础,加速了研究区低阻油藏的开发进程。     

涠西南凹陷L1段油藏特征及规律统计分析

涠西南凹陷L1段以断块和岩性油藏为主,不同区域、不同深度油藏特征差异明显,且油水关系复杂。对L1段56个具有独立油水系统的油藏进行统计分析,结果显示L1段油藏特征具有较好的统计规律。原油物性统计表明：地下原油黏度与地面原油物性之间具有较好的相关性,由此建立的黏度预测公式,可以用于L1段地下原油黏度预测;产能研究表明：L1段产能主要受沉积微相、孔隙度、渗透率、原油黏度以及井筒温度的直接或间接影响,不同因素与产能之间的回归关系较好,可以用于指导今后L1段未测试探井的产能预测工作。     

饶阳凹陷潜山油气分布特征及富集规律

饶阳凹陷是冀中坳陷潜山油气勘探的重点地区之一。综合应用现代油气成藏、地球物理、地球化学等理论和方法,对饶阳凹陷潜山油气成藏的地质条件进行了分析。结果表明,该区带油源丰富,储集条件好,发育多套有效的储盖组合,各成藏要素时空配置良好,具有形成大规模油气田的有利条件。根据已发现油气藏构造特征、成藏条件及油藏类型得出,研究区油气藏集中分布于潜山顶、潜山坡及潜山内幕。在此基础上,提出了潜山油气藏多分布于近源的断裂带附近,水动力承压区、深凹陷、古隆起的叠置区,断棱、峰顶、内幕高点等位置的油气富集规律。     

东营北部凸起带古冲沟储层分布规律研究

在油田勘探与开发中 ,充分认识古冲沟油气藏的勘探与开发是十分重要和有意义的。本文利用东营北部凸起带的地质、钻井、航磁和地震等资料 ,对古冲沟在地震剖面上的特征和古冲沟储层预测方法等进行了研究与探讨     

F油田长6超低渗油藏主要开发问题及技术对策

F油田长6油藏是鄂尔多斯盆地内较早开发并具规模的超低渗油藏。为了提高开发效果,解决开发中的问题和矛盾,通过矿场开发实践,较为系统地总结了长6油藏开发中所应用的8项技术,并对各项技术的应用效果进行了评价。通过这些技术的矿场应用,油藏的开发达到了较为理想的开发效果。     

低渗储层岩石物理建模新方法及其在东海Z气田中的应用

低渗储层孔隙结构复杂,非均质性强,不同类型低渗储层之间也常存在较大物性变化,难以采用统一的岩石物理模型表征储层参数与弹性参数之间的关系。针对上述难题,提出了低渗储层分层岩石物理建模方法：针对中低孔-中低渗储层采用基于DEM理论的流体均匀饱和模型;针对特低孔、特低渗储层采用基于KT理论的流体非均匀饱和模型。基于分层岩石物理建模预测的纵、横波速度与测井真实速度吻合较好,验证了该方法的可靠性。在建立准确岩石物理模型的基础上,进一步分析了弹性参数受泥质含量、孔隙度、孔隙形状等因素影响的变化规律,从而指导低渗储层的岩性及“甜点”预测。     

渤东低凸起L3构造东营组含煤地层低渗储层特征及成因

渤东低凸起东营组储集层以低渗为特征,低渗成为制约该区东营组勘探的重要因素.通过多种分析测试方法,研究了渤东低凸起L3构造东营组低渗储集层特征,探讨了低渗储集层成因.L3构造东营组储集层砂岩溶蚀作用发育,斜长石含量低,碳酸盐胶结物含量低,高岭石含量高,石英加大明显.储集层主要以中孔低—特低渗为主,孔径小,连通差,吼道窄,排驱压力大.微量元素分析表明,研究区东营组沉积时为淡水环境;测井和岩心观察证实,地层中含多层碳质泥岩和煤层.早期腐殖酸的溶蚀作用,造成低温下不稳定的斜长石大量溶蚀,这些溶蚀孔隙在后期深埋过程中受压实和成岩作用影响被复杂化、细小化是储集层低渗的主要原因.早期碳酸盐胶结物少,岩石抗压实能力差也是储层低渗的重要原因.     

东营凹陷“相—势”控藏作用原理分析及思索

根据东营凹陷洼陷带岩性油藏勘探形成的“相—势”控藏理论,结合国内外“相”、“势”控藏研究文献调研,对“相—势”控藏作用原理进行了解剖,并以东营凹陷陡坡带砂砾岩扇体为例进行“相—势”控藏作用研究,验证了北带砂砾岩体成藏受“相—势”控制,总结了东营北带的“相—势”控藏特征,完善和发展了“相—势”控藏理论。同时在研究中发现,由于油气成藏是一个动态过程,虽然现今储层有利相带及成藏动力的耦合是成藏的关键,但是研究证实储层的物性、地层压力的动态演化对圈闭合油气充满度影响很大。应对油气成藏关键时期及其以后的储层物性及地层压力分布规律及其动态演化进行研究,实现含油气盆地的构造演化史、沉积埋藏史、热演化史、成烃史、油气充注史、“相—势”控藏历史等的有机统一,进一步完善和发展“相—势”控藏理论,必将带来陆相断陷盆地油气勘探理论新的突破。     

Pore fluid evolution,distribution and water-rock interactions of carbonate cements in red-bed sandstone reservoirs in the Dongying Depression,China

The compositions, distribution and its interaction with rocks of the evolving pore fluids controls the distribution of carbonate cements and reservoir storage spaces. The reservoir quality of the red-bed sandstone reservoirs in the Dongying Depression was investigated by an integrated and systematic analysis including carbonate cement petrology, mineralogy, carbon and oxygen isotope ratios and fluid inclusions. The investigation was also facilitated by probing the mineral origins, precipitation mechanisms, pore fluid evolution and distribution, and water-rock interaction of carbonate cements and their influences on reservoir quality. Diagenetic-evolving fluids in the interbedded mudstones are the main source for the precipitation of calcite cements that completely fill the intergranular volume (CFIV calcite) with heavier oxygen and carbon isotopes. The ferro-carbonate cements in the reservoir sandstone are enriched in lighter carbon and oxygen isotopes. In addition to the cations released by the conversion of clay minerals in reservoirs, products of organic acid decarboxylation and the associated feldspar dissolution process provide important sources for such carbonate cementation. The carbon isotopes of CO₂ and the oxygen isotopic composition of fluids equilibrated with the CFIV calcite, ferro-calcite, dolomite and ankerite cements indicate that the pore in the red-bed reservoirs experienced high salinity fluids, which evolved from the early-formed interbedded mudstones, through organic acid input and to organic acid decarboxylation. Pore fluids from nearby mudstones migrated from the edge to the centre of sandbodies, causing strong calcite cementation along the sandbody boundaries and forming tight cementation zones. Pore fluids associated with organic CO₂ and acids and organic acid decarboxylation are mainly distributed in the internal portion of sandbodies, causing feldspar dissolution and precipitation of ferro-carbonate cements. The distribution of pore fluids caused the zonal distribution of carbonate cements in sandbodies during different periods. This may be advantageous to preserve the porosity of reservoirs as exemplified by the distribution of high-quality reservoirs in the red-bed sandbodies.     

利用压汞资料进行低渗储层孔隙结构特征分析——以Wll-7油田流沙港组三段储层为例

储层孔隙结构是影响低渗储层微观孔隙内流体运移与聚集的主要因素,决定了储层的优劣。以w11－7油田流沙港组三段储层为例,应用压汞资料定性与定量研究储层孔隙结构特征。研究结果表明,孔隙结构分为三类,总体上具有“喉道细、分选差、连通性差”的特点,这种较差的孔隙结构发育特征是造成储层呈低渗一特低渗的核心因素。在此基础上应用多元判别方法优选出排驱压力、中值压力、最大孔喉半径、孔喉半径均值、分选系数五类孔隙结构分类评价参数,并结合常规物性将储层分为三类,其中Ⅱ、Ⅲ类是广为发育的储层。     

Quantitative characterization of connectivity and conductivity of sandstone carriers during secondary petroleum migration,applied to the Third Member of Eocene Shahejie Formation,Dongying Depression,Eastern China

Studies on migration pathways remain qualitative, albeit extensive quantification of migration forcing. In this study, hydrocarbon carriers are defined as carrier units and their corresponding carrier beds for the Third Member of Eocene Shahejie Formation in the Dongying Depression, Bohai Bay Basin, eastern China, on the basis of their lithofacies and physical properties, spatial relationships, and data availability; secondary migration conduits are then quantified. A carrier unit is defined as a stratigraphic unit that contains microscopically porous and permeable carrier beds and is covered by regional seals. The carrier beds are macroscopically and physically connected to each other within a carrier unit and are hydrodynamically connected during secondary migration. A method of quantifying sandstone carrier units using common physical properties is developed. First, a carrier unit containing potential carrier beds is identified on the basis of lithofacies and their lateral changes. Second, physical connectivity of sandstone carrier beds is assessed on the basis of percolation theory. Third, the hydrodynamic connectivity of a sandstone carrier unit is analyzed using effective parameters that may reflect the hydraulic circulation in the carrier unit. Last, the conductivity of a sandstone carrier bed is quantitatively characterized using appropriate physical property parameters. The results for sandstone carrier units in the Third Member of the Shahejie Formation are used in numerical models addressing Pleistocene secondary migration. The model results explain the discovered accumulation and hydrocarbon shows well; and the model predictions on exploration targets have been confirmed by drilling.     

Sequence stratigraphy,sedimentary facies and reservoir quality of Es4s,southern slope of Dongying Depression,Bohai Bay Basin,East China

Thin-bedded beach-bar sandstone reservoirs are common in the Eocene Shahejie Formation (Es4s) of Niuzhuang Sag, along the southern gentle slope of the Dongying Depression. Here we report on the link between sequence stratigraphy, sedimentary facies and diagenetic effects on reservoir quality. Seismic data, wireline logs, core observations and analyses are used to interpret depositional settings and sequence stratigraphic framework. Petrographic study based on microscopic observation of optical, cathodoluminescence (CL), confocal laser scanning (LSCM) and scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were used to describe the fabric, texture, allogenic and authigenic mineralogy of these highly heterogeneous sandstone reservoirs. The Es4s interval is interpreted as third-order sequence, composed of a lowstand systems tract (LST), a transgressive systems tract (TST) and a highstand systems tract (HST). On the fourth order, twenty-nine parasequences and seven parasequence sets have been identified. Sand bodies were deposited mainly in the shoreface shallow lake beach-bar (clastic beach-bar), semi-deep lake (carbonate beach-bar) and the fluvial channels. The depositional and diagenetic heterogeneities were mainly due to the following factors: (1) fine grain size, poor sorting, and continuous thin inter-bedded mud layers with siltstone/fine-sandstone having argillaceous layers in regular intervals, (2) immature sediment composition, and (3) even with the dissolution of grains and several fractures, destruction of porosity by cementation and compaction. Secondary pores from feldspar dissolution are better developed in sandstones with increased cementation. Grain coating smectite clays preserved the primary porosity at places while dominating pore filling authigenic illite and illite/smectite clays reduced permeability with little impact on porosity. Due to the high degree of heterogeneity in the Es4s beach-bar interval, it is recognized as middle to low permeable reservoir. The aforementioned study reflects significant insight into the understanding of the properties of the beach-bar sands and valuable for the comprehensive reservoir characterization and overall reservoir bed quality.