Influence of meandering river sandstone architecture on waterflooding mechanisms: a case study of the M-I layer in the Kumkol Oilfield, Kazakhstan

In order to explore the influence of sandstone architecture on waterflooding mechanisms using the architecture method,and taking as an example the M-I layer of the Kumkol oilfield in the South Turgay Basin,Kazakhstan,we portrayed the architecture features of different types of sandstones and quantitatively characterized heterogeneities in a single sand body in meandering river facies.Based on the waterflooding characteristics of point bar sand and overbank sand according to waterflooded interpretation results in 367 wells and numerical simulation results of well groups,we finally analyzed the remaining oil potential of the meandering river sandstone and pointed out its development directions at the high water cut stage.The result shows that because lateral accretion shale beds are developed inside single sand bodies,the point bar sand is a semi-connected body.The overbank sand is thin sandstone with poor connectivity,small area and fast lateral changes.The heterogeneity of the overbank sand is stronger than the point bar sand.The sandstone architectures control the waterflooding characteristics.In meandering river sandstones,the bottom of the point bar sand is strongly waterflooded,while the top of the point bar sand and most of the overbank sand are only weakly waterflooded or unflooded.The thickness percentage of unflooded zone and weakly waterflooded zone in point bar sand is 40％,and the remaining oil in its top part is the main direction for future development.

Research on 3D Distribution of Meandering River Sand Body Using Sedimentary Facies Method and 3D Geological Modeling

Sedimentary facies study is an important method in describing the property and distribution of reservoir. 3D geological modeling is a powerful tool in 3D characterization of geological bodies. By combining the sedimentary facies study with 3D geological modeling to generate 3D sedimentary facies model, the 3D geometry and distribution feature of sand bodies can be more accurately characterized, particularly in 3D view. In Liuchu oilfield of Jizhong depression, the Ed2IV formation was recognized as meandering river deposition facies and five sedimentary facies were identified, which include point bar sand, levee, channel margin, abandoned channel and floodplain. All the 24 sand body facies in Ed2IV were mapped and the 3D sedimentary facies model established based on 2D facies maps. The result shows that the 3D sedimentary facies model is well matched for the research result of sedimentary facies. Being an extension of traditional sedimentary study, the 3D sedimentary facies model can be used to describe the 3D geometry and distribution orders of a single sand body more reliably and more accurately.

Geomorphology Processes of Channel Planform Migration on Meandering Rivers

1 Introduction Morphological analysis on the planform migration structure of meandering river is an important basis for the reconstruction of evolution of paleochannel.Besides,it is a significant method for restoration of rivers through the

Trend judgment of abandoned channels and fine architecture characterization in meandering river reservoirs: A case study of Neogene Minhuazhen Formation NmⅢ2 layer in Shijiutuo bulge, Chengning uplift, Bohai Bay Basin, East China

Based on well logging responses,sedimentary patterns and sandstone thickness,the distribution characteristics of meandering river sedimentary sand body of Neogene Minghuazhen Formation NmⅢ2 layer in the west of Shijiutuo Bulge,Chengning Uplift,Bohai Bay Basin were investigated.A new approach to calculate the occurrence of the sand-mudstone interfaces using resistivity log of horizontal well was advanced to solve the multiple solution problem of abandoned channel’s orientation.This method uses the trigonometric function relationship between radius,dip and length of the resistivity log to calculate the occurrence qualitatively-quantitatively to help determine the true direction of the abandoned channels.This method can supplement and improve the architecture dissection technique for meandering river sandbodies.This method was used to study the dip angle and scale of the lateral accretion layers in point bar quantitatively to help determine the spatial distribution of lateral accretion layers.The fine architecture model of underground meandering river reservoir in the study area has been established.Different from traditional grids,different grid densities for lateral accretion layers and bodies were used in this model by non-uniform upscaling to establish the inner architecture model of point-bars and realize industrial numerical simulation of the whole study area.The research results can help us predict the distribution of remaining oil,tap remaining oil,and optimize the waterflooding in oilfields.

Fine anatomy of reservoir architecture of point bar in meandering river: a case study of Minghuazhen Formation in northern block of Q oilfield,Bohai Sea

In order to solve dynamic Problems caused by the internal structure of fluvial reservoir,it is necessa-ry to study the fine anatomy of Point bar. Taking Minghuazhen Formation in the northern block of Q oilfield, Bohai Sea as an examPle,the authors studied identification marks,distribution Pattern and scale of Point bar based on coring,logging and dynamic data. The results show that the length of Point bar and the width of lateral accretion body are 713-911 m and 71-111m,resPectively;the diP angle and the thickness of lateral accretion bedding are 3. 5o-5. 9o and 0. 1-0. 5 m. The lateral accretion beddings are the key factor affecting the seePage velocity of the tracer.

Morphometric Assessment of Meandering River in Arid Region Using Improvement Model (Case Study: Maroon River)

To understand the natural environments of drylands, deserts, arid and semi-arid regions of the earth is to understand the processes and forms of their rivers. One of the river studies and fluvial processes are morphometry analyses. The channel forms in an alluvial plain reflecting the movement of water and the particle size of the load flowing down the channel. The dynamics of channel change has led to conflict with human resource development. Three basic channel patterns are detected in the region. They are braided, meandering and straight. In this research for assessment of meandering Maroon River, we used DEM (Digital Elevation System), Topography maps, Arc GIS software, Google earth, field work and library studies and mathematic formula. The two general indices for analyzing meandering patterns are 1) sinuosity coefficient 2) central angle. In this paper, the authors were used these factors and improved them. One of the results is creation of direction index and the second result is the Maroon River which has a type of sinuosity in any reach.

Meandering of Tributaries of the Tigris River Due to Mass Movements within Iraq

Tigris and Euphrates are the main rivers in Iraq. The former has 5 main tributaries while the latter has no tributaries within Iraq. All these rivers exhibit meandering and/or shifting of their courses due to many reasons;such as mass movements and alluvial fan's development. The meandering and shifting of river courses due to mass movements is dealt with in this study. Many examples are given from different parts of Iraq within different rivers and streams. In each case, the geology of the involved area is described;the reasons of the shifting and/or meandering of the river course are given. GIS technique was used to determine the coverage of the involved area. Landsat, Google Earth and DEM images were used to indicate the suffered areas from shifting and meandering of the rivers and streams. When possible, age of the shifting and/or meandering of the river and stream courses was estimated;using exposure age determination;mainly depending on the presence of river terraces, erosional forms, vegetation cover and the maturity of the involved area. Some of the given examples of shifting of river courses were found to be still active;others are inactive. In many cases, indications for very large mass movement phenomena were seen. Moreover, some of the large involved areas are highly populated, others includes few houses and/ or farms. The majority of the meanders are developed due to mass movement phenomena;others are caused by alluvial fans and/or tectonic features, lime plunging of anticlines.

Models and Monte Carlo Simulations of the Mean Sinuosity of Major Meandering Rivers

The purpose of this research is to investigate the sinuosity of major rivers in the United States and the world, and to compare them to that predicted by the existing theories. It is shown that the average sinuosity of meandering rivers deviates considerably from what has been reported previously as π. Calculations of the mean value of actual sinuosities of major rivers in the United States and in the World show that this average is very close to 2. Exact models as well as a Monte Carlo simulation for meandering rivers that is based on Gaussian probability distribution function are also presented, and the possibility of composite meandering is discussed.

Reconstruction of meandering paleo-channels using dense well data,Daqing Oil Field,Songliao Basin,China

Reconstructing meandering paleo-channels is attracting global research attention. We implemented a novel method by comprehensively integrating migration models and sedimentary structures. Firstly, the migration architectures of the corresponding characteristics in planform and cross-sectional models were summarised as expansion, translation, expansion and translation, expansion and downstream rotation, constriction and downstream rotation, and expansion and countercurrent rotation models. Secondly, full continuous core data from 270 dense drilling wells were collected from the Daqing Oil Field in the Songliao Basin, China, providing information on rock textures, sedimentary cycles, and boundary information for the two layers being studied. Through a comprehensive analysis of dense drill cores and logging data, the abandoned channels and the initial and final channel centrelines were identified. Consequently, four profiles, including one longitudinal and three transverse sections, were constructed to reveal the cross-sectional structures and planform migration architecture. Profile interpretation revealed the evolution from the initial channel centreline to the final centreline. Using a method of rational interpolation, we were able to reconstruct the migration architecture of the meandering channels. The results showed that the average ancient bankfull width(Wc) was approximately 100 m, a single meandering belt was800 m, the radius of the curvature was 250 m, the length of the channel bend was 700 m, the average meander wavelength was 1300 m, the sinuosity was 3.0, and the annual average discharge rate was 450 m3/s. Furthermore, we compared the results from empirical equations, which verified that our reconstruction is both feasible and potentially widely applicable.

THE KUROSHIO MEANDER/SOUTHERN OSCILLATION CONNECTION AND DROUGHT/FLOOD CYCLES IN THE CHANGJIANG RIVER

In response to a suggestion that the large meander of the Kuroshio is a good predictor of droughtsin the Changjiang River Valley, it is argued that more recent inceptions of the meander lend statisticalweigh to the belief that the large meander is itself a consequence of E1 Nino, and hence of the SouthernOscillation. The meander usually lags. Thus, if the meander reliably predicts droughts, the Tahiti componentof the Southern Oscillation will usually give six months’ extra warning.

Fine Characterization Method for Interlayers in Complex Meander River Sandstone Reservoir: A Case Study of Um7 Sand of C Oilfield in Bohai Bay Area

Taking the Um7 meandering river complex sandstone reservoir of Bohai Bay C oilfield as an example, the interlayer type is defined according to the interlayer lithology and sedimentary genesis, and the identification mode of different types of interlayer is established, and the interlayer comparison of the whole area is carried out by using this mode. The results show that the interlayer can be further defined as the stable distributed interlayer and the randomly distributed interlayer according to the morphology of the interlayer. The distribution characteristics of the two types of interlayers are characterized by the well-to-well comparison method and the data analysis method, and the three-dimensional characterization is carried out. The results more closely reflect the spatial distribution of the interlayer, but also are closer to the underground real situation.

曲流水电开发背景下青居江心洲形态特征演变

嘉陵江青居曲流水电开发对下游青居江心洲产生了较大影响。为探明江心洲变化特征及其机理,以青居江心洲1977—2023年Landsat历史遥感影像为基础,提取青居水电站运行前后的江心洲矢量边界数据,并结合实地勘测,对江心洲面积、岸线距离变化等指标进行定量分析,并运用M-K趋势统计法,探讨水电开发前后青居江心洲的形态演变特征。结果表明:水电开发之前青居江心洲呈现动态波动变化的特点,总体呈增大趋势;水电运行之后,青居江心洲受到的侵蚀程度逐渐加剧,呈现面积下降、岸线后退趋势,但江心洲不同方位受到的冲淤情况不同。

辫状河—曲流河河型转换前后砂体差异性研究——以东营凹陷东辛地区东二段为例

不同河流相砂体形态特征和分布规律差异较大,河型的转换主控了不同时期砂体平面分布特征、几何参数及纵向叠置关系,进而决定了不同河流相类型储层的油气勘探与开发策略。基于东营凹陷东辛地区东二段岩心、测井曲线、三维地震等资料,借助定量岩心沉积构造、定量地震地貌等方法,得出以下结论:1)东二段4,3,2砂组主要发育辫状河沉积,1砂组主要发育曲流河沉积。2)东二段4,3,2砂组辫状河平均河道深度分别为17~52,20~59,19~52 m,平均河道宽度分别为1589~11602,2154~14597,1862~11923 m,定量地震地貌分析指示河道带宽度介于1000~7000 m;1砂组曲流河平均河道深度为11~30 m,平均河道宽度为665~4221 m,定量地震地貌分析指示河道带宽度介于700~3000 m。3)东二段4,3,2砂组辫状河砂体垂向以接触叠置式、下切叠置式为主,横向以独立接触式、侧切接触式、对接接触式为主;1砂组曲流河砂体垂向以分隔叠置式为主,横向以独立接触式为主。明确砂体几何形态及时空切叠方式,为东辛地区东二段河流相砂岩储层的勘探与开发提供了实际支撑。

河流相致密砂岩气地质甜点评价——以四川盆地川中地区侏罗系沙溪庙组二段1亚段为例

四川盆地侏罗系沙溪庙组储层具有孔隙度和渗透率低、非均质性强、砂体叠置关系复杂的特点,导致地质甜点判别困难、预测精度较低。为实现气藏的高效开发,通过分析、研究沉积作用、成岩作用和源-储配置关系对天然气聚集成藏的影响,建立了研究区沙溪庙组二段1亚段致密砂岩气地质甜点评价标准。研究结果表明:①沉积微相和河道类型控制了砂体规模及储层的物性,顺直河或低弯度曲流河边滩砂体厚度大、物性好,是优质储层发育区。②岩浆岩岩屑含量和成岩相不同是导致储层质量差异的主要原因。其中绿泥石胶结相物性最好。③源-储配置关系控制储层中天然气的充注程度,与烃源断层直接相接或距离烃源断层较近的砂体含气性最好。④储层质量和含气性共同控制单井天然气产量。根据研究提出的地质甜点评价标准,将研究区地质甜点分为3类。Ⅰ类甜点主要为顺直河或低弯度曲流河边滩砂体,孔隙度大于12%,渗透率大于0.30×10^(-3)μm^(2),以绿泥石胶结为主,且距烃源断层近,含气性好,含水饱和度小于30%,泊松比小于0.24,单井产气强度大于0.10×10^(4)m^(3)(/d∙m)。Ⅱ类甜点主要为中弯度曲流河砂体,孔隙度10%~12%,渗透率为0.15×10^(-3)~0.30×10^(-3)μm^(2),以伊利石或伊/蒙混层胶结为主,距烃源断层相对较远,含水饱和度为30%~40%,泊松比为0.24~0.25,单井产气强度为0.05×10^(4)~0.10×10^(4)m^(3)(/d∙m)。Ⅲ类甜点主要为小型中弯度曲流河边滩,孔渗性差,主要发育伊利石或伊/蒙混层胶结,且远离烃源断层,含气性较差。

碳酸盐岩岩溶古河道发育特征与成因演化:以塔里木盆地塔河油田12区中——下奥陶统为例

为了明确塔里木盆地塔河油田12区中—下奥陶统顶面古河道的成因,利用地震剖面分析、地震属性提取等技术,结合钻井资料刻画了古地貌、古水系发育特征,定量描述古河道的河曲特征,并基于现代岩溶理论建立了古河道成因演化模式。结果表明:中—下奥陶统顶面古河道为“深切河曲”古岩溶地貌,深切河曲特征表现为河谷主要呈“V”字形,两侧河谷坡岸对称,谷壁陡峭,发育由于截弯取直形成的离堆山、天生桥等标志性地貌;中—下奥陶统顶面古河道发育“高弯曲率”河曲形态,深切河曲的单个河曲弯曲率C值都在2.20以上,平均值为4.27,SN向河曲带弯曲率C值为1.87,EW向河曲带的弯曲率C值为2.38;塔河油田12区中—下奥陶统顶面深切河曲经历志留系沉积期、自由河曲期、深切河曲期等3个演化阶段,其成因与华力西早期运动构造作用关系密切。

基于数字岸线系统分析塔里木河英巴扎至乌斯满河道演变特性

为了探明塔里木河干流英巴扎至乌斯满河道的演变规律和趋势,对该河道1993—2022年间的Landsat系列卫星影像进行了解译,通过数字岸线系统分析了河道变迁速率。从1993年至2022年,英巴扎至乌斯满河段弯曲系数总体呈现上升趋势,河道呈淤积态势。英巴扎至沙子河口生态闸段相比于沙子河口至乌斯满段演变幅度更加剧烈,且河道往南北两岸的最大迁移速率分别为20.01 m/a和40.36 m/a。2010—2011年裁弯取直现象频发,平均变迁速率最大为72.27 m/a。基于卡尔曼滤波器对2032年河势演变趋势进行预测,河道上段最大迁移距离可达730 m,下段为218 m。应对河道上段进行整治,调整水流和控制河势,以确保河道两岸防洪安全和岸线的合理利用,提高向下游生态输水的保证率。

鄂尔多斯盆地延安地区山西组山2段浅水曲流河三角洲沉积模拟实验研究

【目的】勘探实践表明,鄂尔多斯盆地东南部延安气田主力产气层山西组山2段砂体呈狭长条带状分布,与北部各大气田上古生界砂体大面积连片分布存在显著差异,厘清山西组山2段砂体成因机理对理解该区砂体分布规律具有重要意义。【方法】以盆地东南部山西组山2段为地质原型,利用水槽沉积模拟实验探讨其砂体形成演化过程及控制因素。【结果与结论】平缓坡度与低水流强度是山2段分流河道呈低弯度曲流态的重要因素,水平面的变幅速率是控制山2段砂体纵向延伸的关键因素,砂体的大小及长宽比受岸线及流量变化控制,砂体整体的延伸距离及长宽比分别与水退的幅度和速率成正比。山西组沉积期,在水平面大幅度下降、岸线向湖区长距离迁移背景下,曲流河三角洲前缘砂体延伸较远距离;砂体叠置样式具有“垂向叠置”、“垂向切割”和“侧向迁移”的特征。该认识对山西组砂体分布预测和寻找优质储层具有重要的指导意义。

安塞油田黑山梁区长6油层组单砂体构型分析及平面展布特征

安塞油田黑山梁区块位于延安市安塞区,三叠系延长组长6油层组是其主力产油层。目前该区已进入注水开发阶段,但砂体展布、非均质性、砂体叠置规律等认识不清,导致开发过程中存在注水受效程度不均衡,整体水驱效果差等问题。为此,本次研究依托丰富的测井、录井资料,以及岩心、镜下薄片资料和分析测试数据,开展地层精细刻画、沉积微相、砂体平面分布及单砂体叠置规律的综合研究。结果表明:黑山梁地区长6时期主要发育三角洲前缘亚相,岩性以细粒长石砂岩为主,分选性中等-好,磨圆度中等,水下分流河道和分流间湾微相较为多见,河口坝微相发育较少;水下分流河道为优势相,砂岩分布广、厚度大,沿河道方向延伸,早期形成的河口坝由于波浪作用和分流河道侵蚀作用被破坏,河口坝无法保存完整,仅有部分痕迹。砂体类型包括水下分流河道砂和河口坝砂两种,单砂体垂向叠置可分为孤立型、叠加型和切叠型3种;侧向拼接样式可分为孤立式、对接式和侧切式3种。研究区内砂体沿北东-南西方向呈长条状展布,由于河道频繁摆动和分叉,砂体切叠现象明显,顺物源方向砂体连通性较好,垂直物源方向砂体被分流间湾泥隔开,砂体连通性较差,并结合生产动态数据,认为砂体连通程度越高,水驱动用效果越好。基于该研究成果建立了研究区曲流河三角洲沉积模式,为后期油藏完善注采井网、分层注水开发方案调整提供地质依据。

长江中游武汉河段江心洲的差异化冲刷规律

近20 a长江中游分汊河段的江心洲经历了冲刷并发生蚀退,但对微弯河段和顺直河段的江心洲差异化冲刷尚未有清晰认识。选取长江中游武汉河段的白沙洲和天兴洲作为研究对象,采用遥感影像、水文资料及野外调查,分析了白沙洲与天兴洲形态变化及差异化冲刷的原因。结果表明:1989—2020年,白沙洲洲体萎缩将近43.83%,天兴洲洲头浅滩变化较大,整体出露面积相对稳定;白沙洲与天兴洲的归一化植被指数(NDVI)整体较小,洲体植被覆盖空间差异性减小;这2个江心洲枯水期出露面积的变化主要体现在洲头浅滩;位于顺直河段的白沙洲洲头及侧向洲体遭遇冲刷,左侧洲体出现窝崩现象,其主要原因是白沙洲大桥桥墩的壅水与阻流作用;位于微弯河段的天兴洲自三峡工程蓄水后洲头遭受冲刷,2004年洲头守护工程实施和人工抛石有效地抑制了冲刷并实现了促淤作用。因此,江心洲的冲刷差异性主要体现在河段形态、主支汊相对位置和有无守护工程。

准噶尔盆地腹部下侏罗统曲流河地震沉积学解析

为深入探查埋深大、压实作用强、成岩程度高、储层物性差陆相油藏的区域分布规律,在准噶尔盆地腹部通过层序地层理论和基于地震拉平数据体提取的瞬时相位、均方根振幅、分频属性,对下侏罗统进行了地震沉积学解析。共识别出3个层序,SQ1~SQ2湖侵体系域均以曲河流沉积体系为主,SQ2高位体系域至SQ3以三角洲沉积体系为主。地震属性分析具有很好的一致性,结果表明:河道的形态清晰,位置可靠;河流在迁移演化过程中,河道单一,牛轭湖、决口扇等微相较发育;河流经历了低弯度-宽河床到高弯度-窄河床,再到中弯度-宽河床的演化,流向则由南北向逐渐演变为北东-南西向。研究结果可为利用地震资料识别曲流河的研究提供借鉴和指导。