Application of Spectral Decomposition to Detection of Fracture-Cavity Carbonate Reservoir Beds in the Tahe OUfield,Tarim Basin,NW China

Ordovician fracture-cavity carbonate reservoir beds are the major type of producing formations in the Tahe oilfield,Tarim Basin.The seismic responses of these beds clearly changes depending on the different distance of the fracture-cavity reservoir bed from the top of the section.The seismic reflection becomes weak or is absent when the fracture-cavity reservoir beds are less than 20 ms below the top Ordovician.The effect on top Ordovician reflection became weaker with deeper burial of fracture-cavity reservoir beds but the developed deep fracture-cavity reservoir beds caused stronger reflection in the interior of the Ordovician.This interior reflection can be divided into strong long-axis, irregular and bead string reflections,and was present 80 ms below the top Ordovician.Aimed at understanding reflection characteristics,the spectral decomposition technique,which uses frequency to"tune-in"bed thickness,was used to predict Ordovician fracture-cavity carbonate formations in the Tahe oilfield.Through finely adjusting the processing parameters of spectral decomposition,it was found that the slice at 30 Hz of the tuned data cube can best represent reservoir bed development.Two large N-S-trending strong reflection belts in the mid-western part of the study area along wells TK440- TK427-TK417B and in the eastern part along wells TK404-TK409 were observed distinctly on the 30 Hz slice and 4-D time-frequency data cube carving.A small N-S trending reflection belt in the southern part along wells T403-TK446B was also clearly identified.The predicted reservoir bed development area coincides with the fracture-cavities connection area confirmed by drilling pressure testing results. Deep karst cavities occur basically in three reservoir bed-development belts identified by the Ordovician interior strong reflection.Spectral decomposition proved to be a useful technique in identifying fracture-cavity reservoir beds.     

Application of Spectral Decomposition to Detection of Fracture-Cavity Carbonate Reservoir Beds in the Tahe Oiifieid, Tarim Basin, NW China

Ordovician fracture-cavity carbonate reservoir beds are the major type of producing formations in the Tahe oilfield, Tarim Basin. The seismic responses of these beds clearly changes depending on the different distance of the fracture-cavity reservoir bed from the top of the section. The seismic reflection becomes weak or is absent when the fracture-cavity reservoir beds are less than 20 ms below the top Ordovician. The effect on top Ordovician reflection became weaker with deeper burial of fracture-cavity reservoir beds but the developed deep fracture-cavity reservoir beds caused stronger reflection in the interior of the Ordovician. This interior reflection can be divided into strong long-axis, irregular and bead string reflections, and was present 80 ms below the top Ordovician. Aimed at understanding reflection characteristics, the spectral decomposition technique, which uses frequency to ＂tune-in＂ bed thickness, was used to predict Ordovician fracture-cavity carbonate formations in the Tahe oilfield. Through finely adjusting the processing parameters of spectral decomposition, it was found that the slice at 30 Hz of the tuned data cube can best represent reservoir bed development. Two large N-S-trending strong reflection belts in the mid-western part of the study area along wells TK440- TK427-TK417B and in the eastern part along wells TK404-TK409 were observed distinctly on the 30 Hz slice and 4-D time-frequency data cube carving. A small N-S trending reflection belt in the southern part along wells T403-TK446B was also clearly identified. The predicted reservoir bed development area coincides with the fracture-cavities connection area confirmed by drilling pressure testing results. Deep karst cavities occur basically in three reservoir bed-development belts identified by the Ordovician interior strong reflection. Spectral decomposition proved to be a useful technique in identifying fracture-cavity reservoir beds.     

塔河油田二区奥陶系优势储集体特征及控制因素

塔河油田二区奥陶系碳酸盐岩油藏储集体类型由缝洞型、高能微孔隙型、压溶孔缝型组成。通过岩心薄片观察并结合地震、测井、录井和试油等资料,查明了受次生溶蚀作用控制的岩溶缝洞型、受高能沉积相带控制的微孔隙型和受压溶作用及白云化作用控制的压溶孔缝型储层的特征和分布,并且识别出溶蚀孔洞、溶蚀缝、构造缝、粒内孔、粒间孔、铸模孔、晶间孔、晶内孔、缝合线和微裂缝10种储集空间。实际上,上述储集体主要为高能沉积相带形成的颗粒灰岩演化而成,这些颗粒灰岩经过埋藏压实和胶结等作用形成了以次生微孔隙为主的微孔隙型储集体,经过压溶和白云岩化作用形成了受成岩演化控制的压溶孔缝型储集体,在塔北奥陶系岩溶期形成了岩溶缝洞型储集体。塔河油田二区南部受沉积相展布和成岩作用影响,颗粒灰岩和云斑状灰岩发育;北部古隆起风化剥蚀作用较强,发育大型溶洞储层;东部斜坡带古河流发育,溶蚀缝洞储层多沿古河道分布;西部受深大断裂控制,溶蚀孔洞沿断裂垂向发育。     

塔里木盆地北部塔河油田奥陶系加里东期岩溶作用及其油气地质意义

详细的钻井地质学、地球物理和地球化学研究表明,塔河油田南部奥陶系内部和顶部发育多幕次的加里东期岩溶作用,主要表现在奥陶系内部牙形石带缺失、钻井放空和泥浆漏失、地震剖面上奥陶统反射波组底部上超和顶部削截,以及溶洞充填方解石的Sr同位素特征等方面。加里东期岩溶储层主要受不整合面、断裂、岩性和古地貌等因素控制,表现出明显的断控和层控特征。由此预测该储层发育区位于古风化壳剥蚀区、加里东期断裂发育区和滩相储层发育区的叠合部位,主要位于阿克库勒凸起的轴部倾没端和塔河西南部、东南部的北东向、近南北向断裂发育区。     

塔里木盆地北部塔河油田奥陶系加里东期岩溶作用及其油气地质意义

详细的钻井地质学、地球物理和地球化学研究表明,塔河油田南部奥陶系内部和顶部发育多幕次的加里东期岩溶作用,主要表现在奥陶系内部牙形石带缺失、钻井放空和泥浆漏失、地震剖面上奥陶统反射波组底部上超和项部削截,以及溶洞充填方解石的Sr同位素特征等方面.加里东期岩溶储层主要受不整合面、断裂、岩性和古地貌等因素控制,表现出明显的断控和层控特征.由此预测该储层发育区位于古风化壳剥蚀区、加里东期断裂发育区和滩相储层发育区的叠合部位,主要位于阿克库勒凸起的轴部倾没端和塔河西南部、东南部的北东向、近南北向断裂发育区.     

塔河油田奥陶系海西早期、加里东中期岩溶对比研究

塔河油田为我国第一个、第一大古生界海相大油田,奥陶系是最主要的层位,产量占塔河油田总产量的75%以上,海西早期、加里东中期岩溶作用对塔河油田奥陶系碳酸盐岩储层的形成和分布具有重要的控制作用。通过岩溶的平面分布、缝洞充填物类型、古生物、锶同位素、碳、氧同位素、稀土元素、包裹体、荧光等可以区分海西早期岩溶和加里东中期岩溶;海西早期岩溶古地貌起伏较大,对储层具有明显的控制作用,加里东中期岩溶古地貌总体起伏较小,对储层的控制作用不明显。海西早期岩溶主要受构造、不整合面、古地貌和岩性的控制,其中构造是最重要的因素;加里东中期岩溶主要受构造、加里东中期Ⅰ、Ⅱ幕不整合面、岩性的控制,具有明显的断控和层控特征,最后对海西早期、加里东中期岩溶有利储层分布区进行了预测。     

塔里木盆地海相碳酸盐岩与油气

塔里木盆地碳酸盐岩主要分布于台盆区寒武系—奥陶系,它既可以作为油气的储层和源岩,也可以作为油气的盖层或遮挡体。碳酸盐岩主要发育于碳酸盐岩台地相和斜坡相之中,其中开阔台地及台地边缘坡折带的生物碎屑滩和砂屑滩、局限台地的白云岩坪是主要的储集相带。潜山溶孔溶洞型白云岩、石灰岩及礁滩复合体中的生物碎屑灰岩、砂屑灰岩、鲕粒灰岩、礁灰岩以及潮坪白云岩是主要的储集岩。寒武系—下奥陶统、中—上奥陶统都发育有较好的碳酸盐岩烃源岩。根据油气的分布与聚集特点,对碳酸盐岩油气藏作了分类。论述了塔里木盆地碳酸盐岩油气勘探的前景和重要目标。     

塔河油田奥陶系油藏TK440井组注水压锥地质模式研究

塔里木盆地塔河油田奥陶系致密灰岩中的缝洞油藏储集空间主要为由天然裂缝和酸压裂缝沟通的一个或多个大型管道状洞穴构成的复杂系统.塔河油田四区TK440,TK449H和TK424C井等3口相互连通的油井见水直至水淹的开发过程表明产油层存在多个不同的边底水侵入通道,并不遵循由低到高逐渐见水的常规特征.在3口油井水淹之后,通过低部位的TK440井探索性注水使高部位TK424C井含水下降,而TK449H则变成不产水,使两口井的油产量明显提高.根据注水过程中的油水关系变化研究,提出TK440井组的储层概念模式和全新的注水压雏模式,即低部位注水可能实现对高部位水淹井从原水侵相反方向上补充刺余油体能量,导致高部位水淹井含水下降起到压制水锥的效果,从而达到提高采收率的作用.     

Characteristics and differential accumulation of oil/gas in Lower Paleozoic marine carbonate on northern slope of Tazhong Low Rise,Tarim Basin,NW China: a case study of Lower Ordovician Yingshan Formation

Marine carbonate reservoirs, as a focus of petroleum exploration and development all over the world, are involved with high exploration risk and prediction difficulty owing to high heterogeneity and diversity of reservoir beds. In the Tarim Basin, NW China, carbonate reservoirs with resources about 38 % of the whole basin in a large prospecting area are mainly distributed in the Cambrian and Ordovician in central (Tazhong) and northern (Tabei) Tarim. Recently on the northern slope, Tazhong Low Rise, Central Uplift, Tarim Basin, a breakthrough has been made in the karsted weathering crust of Lower Ordovician Yingshan Formation and reef-flat reservoir of Upper Ordovician Lianglitag Formation. As a new frontier of exploration, oil/gas distribution and controlling factors of carbonate reservoirs in the Yingshan Formation are not clearly understood. In this work, play elements of the Yingshan Formation, such as seal-reservoir bed assemblage, oil/gas properties, and faulting, were studied by core and slice observation and field investigation. High-quality reservoir beds of Yingshan Formation are quasi-layer distributed in the interstratal karst belt about 250 m below the unconformity. The reservoir beds of fracture–void and void are formed by faulting, associated fracturing, and karstification. The Yingshan Formation is a large-scale condensate gas reservoir with partly oil. Owing to different oil–gas infilling periods, isolated pools far from the faults are primarily oil in the Hercynian; oppositely, condensate gas reservoirs near the faults are intensely influenced by gas invasion during the Himalayan movement. Laterally, oil/gas distribution is controlled by stratal pinch-out and strike-slip faults. Vertically, cap rock of the third to fifth members of the Lianglitag Formation and Yingshan interior high resistivity layers are superimposed with Yingshan reservoir beds to form several seal-reservoir bed assemblages. Oil and gas are superimposed and affected by gas invasion with characteristics of oil in the upper horizon and gas in the lower horizon.     

塔河岩溶型碳酸盐岩缝洞系统流体动态连通性研究

塔里木盆地塔河油田下奥陶统碳酸盐岩储集体属于表生岩溶作用形成的喀斯特缝洞系统。其储集体孔隙空间类型主要为与原始组构无关的连通孔洞,其孔隙系统由岩溶洞穴、溶蚀裂缝和溶蚀孔三大类型的储集空间复合而成。油田开发实践证实,油藏呈现出多压力系统、差异连通的特征。文中针对缝洞型碳酸盐岩连通缝洞孔隙系统的特征,分析了区别于分散型碳酸盐岩储集体的特征。基于油藏的孔洞系统复杂的特点,说明利用各类动态资料对油藏储层缝洞体研究十分重要。通过动态研究方法,推测喀斯特缝洞系统中的连通体--“缝洞单元”。笔者提出了利用动态信息分析油藏之间缝洞连通性的研究思路和方法:（1）同一缝洞单元内,单井地层压力趋势下降相似;（2）井间干扰系统测试是较直接的连通确定方法;（3）开发井生产异常,导致同一缝洞单元相邻井出现相应动态变化;（4）注水井的示踪剂注入,检测邻近井检测示踪剂的含量、受效时间等,判断井间的连通级别;（5）不通缝洞单元的流体组分、密度和粘度等存在差异。结合塔河油田实际资料,共划分了42个缝洞单元,认为缝洞储集体的分布与岩溶古地貌、古水系和断裂带有一定的吻合性。     

塔河油田十二区奥陶系油气分布规律及控制因素

塔河油田十二区奥陶系油藏为碳酸盐岩岩溶缝洞型油藏,油气水分布规律复杂。对原油的物理性质、平面及纵向上的分布特征、油水界面等的分析表明,区内主要为高黏度、含蜡、高含硫的超重质原油。平面上密度分布呈西部和东部低、中部高的特点;纵向上原油密度与深度关系不大。高产油区多沿主断裂带分布。油水界面不统一,但从东向西随中奥陶统顶面的降低而降低。认为该区油气分布不受现今构造位置高低的控制,而是受区域构造背景、断裂带的分布、储集层的发育程度、成藏演化过程以及不整合面等因素综合控制。     

T72界面与塔中隆起上奥陶统碳酸盐岩古岩溶储层

T7^2界面为上奥陶统桑塔木组泥岩与良里塔格组灰岩地震反射界面,是塔里木盆地塔中、塔北隆起上奥陶统内部的一个重要构造-层序转换面,是早古生代碳酸盐台地型沉积向陆源碎屑充填沉积转换的标志.过去普遍认为两个组之间为连续沉积,界面性质系海侵上超并赋予“淹没台地”的涵义.但随着近年塔河油田南部地区的勘探和塔中隆起区北缘Ⅰ号断裂带油气富集规律性的深入研究,表明T7^2界面是一个区域性的古暴露界面和沉积间断界面.界面之下的上奥陶统良里塔格组顶面有明显的削蚀和截切现象,残存厚度在塔北、塔中之间存在极大的差异,反映塔北隆起T7^2界面的构造及风化壳岩溶作用明显强过塔中隆起.古暴露和风化壳岩溶作用导致T7^2界面之下的良里塔格组碳酸盐岩广泛发育岩溶,是塔中低凸起北缘Ⅰ号断裂构造带的主要油气藏聚集层位;在塔河南部,形成了一套厚度最大可达300m并贯穿良里塔格组与下伏恰尔巴克组、一间房组和鹰山组的古岩溶洞穴系统,造就了塔河油田今天以南部斜坡区上奥陶统良里塔格组灰岩古岩溶洞穴系统为主要油气储层的勘探大场面.     

Ordovician Carbonate Reservoir Bed Characteristics and ReservoirForming Conditions in the Lungudong Region of the Tarim Basin

<正>Basic characteristics of Ordovician carbonate reservoir beds in the Lungudong region of northeastern part of the Tarim Basin are described in detail and the reservoir-forming conditions of oil and gas are preliminarily discussed in this paper by collecting and sorting out a large amount of data.The carbonate reservoir beds are mainly developed in open-platform and platform marginal facies;the reservoir beds have large changes in and low average values of physical property;the main type is fractured reservoir beds with the fracture-porous type second.The reservoir bed development is chiefly controlled by the distribution of sedimentary facies,tectonic activity and karstification. Whereas the accumulation and distribution of hydrocarbons in the region are controlled by an advantageous structural location,a good reservoir-caprock combination and a favorable transporting system,with the distribution characterized by zones horizontally and belts vertically,the oil and gas are mainly concentrated in areas with structural uplift,densely developed fractures,and surface karst,a vertical vadose zone,and a horizontal undercurrent belt of palaeokarst.     

塔河油田奥陶系碳酸盐岩岩溶储集体类型及划分方法研究

塔河油田奥陶系油藏储集体类型的多样性和复杂性,给常规测井定量解释带来了很大困难。此类油藏储集体类型的划分和识别对油田开发极为重要。根据6口关键井的电成像测井(FMI)和岩心样品特征,将塔河碳酸盐岩储集体划分为未充填洞穴型、垮塌充填洞穴型、机械充填洞穴型和裂缝型4类。依据其中5口井的常规测井响应和4类储集体划分结果,选用GR、RD、RS、K3(深浅侧向电阻率倒数差的绝对值)、AC、DEN和CNL共7种测井信息作为神经网络的输入学习样本,经学习训练建立了储层划分的神经网络模型。通过检验井对比,说明基于神经网络模型,通过常规测井的多参数约束,可以判断岩溶型储集体类型。经本次研究,初步形成了储集体半定量评价标准。     

缝洞型碳酸盐岩储层多类多尺度建模方法研究:以塔河油田四区奥陶系油藏为例

碳酸盐岩缝洞型储层历经多期构造运动以及强烈的风化、剥蚀和淋滤作用,储集空间类型多样,形态极不规则且随机分布,导致储层三维空间描述困难,现有的碎屑岩储层建模方法难以直接借鉴。文中提出碳酸盐岩缝洞型储层应该按照大型洞穴、溶蚀孔洞、大尺度裂缝、小尺度裂缝的"多类多尺度建模"的基本思路。以钻井和地震识别成果作为大型洞穴确定性数据,以地震波阻抗的大型洞穴发育概率体作为井间约束数据,在垂向岩溶分带和平面古地貌分区的岩溶相控下,采用具有趋势的序贯指示模拟方法,建立大型洞穴离散分布模型;以大型洞穴分布作为"相控"约束条件,以井孔解释的溶蚀孔洞作为硬数据,采用序贯指示模拟算法,建立溶蚀孔洞随机分布模型;根据蚂蚁体地震属性自动拾取的断裂信息,人机交互补充和修正地震解释断层数据,建立确定性的大尺度裂缝离散分布模型;基于大尺度裂缝离散分布模型建立井间裂缝发育概率体,根据井孔裂缝密度、裂缝产状,结合退火模拟和基于目标的示性点过程模拟方法,建立小尺度裂缝离散分布模型。以塔河油田四区奥陶系缝洞型油藏为例,建立研究区缝洞型储集体空间展布模型,再现缝洞型储层的结构形态。     

塔里木盆地塔河奥陶系碳酸盐岩储层埋藏成岩和构造-热流体作用及其有效性

对层状风化壳模式的认识一度支撑着塔里木盆地下古生界深层碳酸盐岩油气勘探,但这类深层碳酸盐岩储层显示出的强烈非均质性使得勘探风险愈来愈大。研究以塔里木盆地塔河地区中—下奥陶统碳酸盐岩储层为典型实例,重点论述了成岩作用和构造—热流体复合作用对储层的制约,并结合表生岩溶等其它要素开展了储层分布综合解释。研究认识到:①奥陶系碳酸盐岩正常深埋藏成岩作用的主要效应是碳酸盐的沉淀而不是碳酸盐的溶解,建设性改造主要与表生岩溶作用（古喀斯特）或构造—热流体作用有关,并导致了碳酸盐岩储层强烈的非均质性。②从中下奥陶统到上奥陶统,下部碳酸盐岩地层热流体活动迹象明显优于上部地层。③奥陶系碳酸盐岩构造—热流体的建设性改造作用主要发生在中—晚泥盆世与二叠纪叠加改造的断裂构造交汇区,以及中—晚奥陶世、前石炭纪形成的表生岩溶发育区;有效储层与高能沉积相带关系有限。为此,提出了奥陶系碳酸盐岩构造—流体作用与储层形成概念模式,这为进一步认识储层的形成分布规律提供了新的线索。     

Logging Evaluation of the Ordovician Carbonate Reservoir Beds in the Lungudong Region,Tarim Basin

<正>In recent years,great progress has been made constantly in oil and gas exploration in the Lungudong region of the Tarim Basin.However,progress has been slow in the evaluation of its main oil-producing horizons-the Ordovician carbonate reservoir beds.Based on previous researches and on the various data such as drilling,geology and oil test,in combination with the interpretation of each single-well imaging and conventional logging data,and through analysis and comparison,the identification methods in imaging and conventional logging for four types of carbonate reservoir beds in this region are summarized in this paper.Calculation formulas for four reservoir bed parameters,i. e.shale content,porosity,permeability and oil saturation in this region are proposed;and reservoir beds in this region are divided into three levels(Ⅰ,ⅡandⅢ) by combining oil test data and logging data,The lower limits of the effective porosity of reservoir beds and the fracture porosity of effective reservoir beds are determined as 1.8%and 0.04%,respectively.The physical property parameters are calculated by conventional logging curves,and the most advantageous areas for reservoir development are predicted comprehensively.On the plane,the high-value zones of reservoir bed parameters are mainly concentrated in the N-S-trending strike-slip fault,the Sangtamu fault horst zone and near the LG38 well area;vertically,the reservoir bed parameters of the Yijianfang Formation are better than those of the Yingshan and Lianglitage formations.     

塔河油田下奥陶统碳酸盐岩储层对比及储层剖面模型

塔河油田奥陶系储层为岩溶缝洞型的碳酸盐岩储层，缝洞储层的形成与古岩溶作用密切相关，风化壳期岩溶作用对储集空间的发育程度有明显的控制作用。不同的储集空间类型受控于不同的岩溶古地貌单元。裂缝性储层主要分布于风化壳型岩溶不发育地区，或褶皱和断裂构造较发育的变化强烈部位；裂缝-孔洞型储层的分布与古岩溶发育带和岩溶斜坡地区密切相关；裂缝-溶洞型储层其分布与裂缝及古岩溶发育带密切相关，常常是在古岩溶高地边缘或部分岩溶斜坡区，多位于多组构造线的交汇处及褶皱的轴部等。为进一步探讨研究区缝洞型碳酸盐岩储层的空间展布规律，根据暴露区淡水岩溶作用发育特点，依据碳酸盐岩储层的波阻抗响应特征、测井曲线、测试成果及开发动态资料，在恢复古岩溶地貌的基础上，对塔河油田（6区）的岩溶值得层进行了划分与对比。研究结果显示高产井多位于古岩溶地貌相对较高部位，而产量较少或没有出油气的井，则位于岩溶地貌相对较低部位。表明早期的古地貌形态对奥陶系碳酸盐岩溶蚀孔洞的发育具有明显的控制作用。岩溶储层的垂向发育和分布主要受碳酸盐岩古岩溶风化壳垂向分带性的影响，纵向上由风化壳顶面向下储层发育逐渐变差。以奥陶系古风化壳顶面为界，向下每60m为单位，对深度0-60m、60-120m、120-180m、180-240m岩溶储层的纵横向分布特征进行了分析，并建立了相应的储层剖面结构模型。     

塔里木盆地塔河油田奥陶系大型油气藏形成条件

塔河油田位于塔里木盆地北部沙雅隆起阿克库勒凸起的西南部，它是在长期发育的阿克加勒鼻状古隆起基础上形成的下奥陶统盐碉岩溶－缝洞型大型油气田。受区域构造－沉积背景控制，塔河地区下奥陶统属于碳酸盐岩开阔台地环境，一直处于继续性隆起状况，是油气运聚的长期指向区，并经历了多欠的构造运动。岩溶作用和成岩作用的叠加改造，形成了具强烈非均质性的岩溶－缝洞型储层，油气主要赋存于距风化壳不整合面200m范围内的岩溶缝洞系统中。勘探成果表明，长期发育的继承性古隆、丰富的多油源供给、强烈非均质性的岩溶－缝洞型储层及优良的储盖配置、多层次和多类型圈闭的广泛发育、以及由岩溶缝洞－断裂－不整合面组成的疏导体系，是形成塔河大型油气田的重要条件。     

塔河油田西南部地区中—下奥陶统碳酸盐岩储层缝洞发育特征与分布

岩溶-裂缝是塔河油田西南部地区上奥陶统覆盖区中—下奥陶统碳酸盐岩储层主要储集空间类型。依据岩心观察、显微镜薄片鉴定、扫描电镜、钻井、深浅侧向和FMI成像测井等资料,综合识别了中—下奥陶统储层裂缝和孔洞发育段,认为该区储层缝洞发育特征与塔河油田主体区有较大的不同,其主要的储集空间类型为半充填—未充填的构造缝和溶蚀扩大缝,且以高角度斜裂缝和垂直裂缝为主,低角度裂缝较少;微裂缝和中缝发育,大裂缝和孔洞总体不发育,利用储层多因素综合评价方法指出了研究区内裂缝和孔洞发育的有利地区。