【作者】 牛永斌；

【导师】 钟建华；

【作者基本信息】 中国石油大学 ， 地质学， 2010， 博士

【摘要】 塔河油田2区奥陶系油藏处于岩溶残丘到岩溶洼地过度的斜坡带上。根据奥陶系油藏特点,采取地下与野外相似露头对比研究,应用测井、录井和地震等资料对研究区奥陶系岩石地层重新进行了修定,建立了精确的地层格架。在地层格架内按照单井相—>剖面相—>平面相的研究思路对奥陶系沉积相和沉积演化进行了研究,沉积相对研究区奥陶系储集体发育具有重要的控制作用。研究区奥陶系储集体基质的物性总体较差,基质孔隙度和渗透率对储集体的储集性能基本无贡献。决定储集体储集性能的是溶蚀孔缝、裂缝和大型溶蚀孔洞。根据岩心、薄片和扫描电镜等观察结果以及录井、测井等资料将储集空间按成因、几何形态划分为孔、缝、洞三大类和16小类。按构成储集体的储集空间的成因和形态及规模划分为:滩相溶蚀孔隙型、云斑灰岩白云石粒间孔隙型,裂缝型和岩溶洞穴型四类储集体。东南部边缘一间房组发育滩相溶蚀孔隙型储集体,且为多期旋回形成的复合体,多期滩相储集体纵向叠置、横向连片,规模较大;其发育范围和程度受沉积微相控制;此外,构造运动和早期暴露蜂窝状溶蚀也是滩相沉积体形成优质孔隙型储集体的重要因素。上奥陶统尖灭线附近及以北地区中-下奥陶统裂缝和溶洞洞穴均较发育,一起构成了奥陶系复杂的缝洞型油藏;95.6%的溶洞发育在T74以下0～100m。通过碳氧稳定同位素、锶同位素、中子活化稀土元素分析认为主要为海西早期岩溶洞穴。岩溶洞穴中充填物的类型有三种:(1)垮塌角砾充填;(2)砂泥质充填;(3)方解石充填。垮塌角砾充填洞穴储集体物性好于泥质充填和巨晶方解石充填洞穴。裂缝和岩溶洞穴垂向上可以组合为孤立洞,上洞下缝,上缝下洞和缝-洞-缝四种类型;它们的发育程度和范围受构造运动、岩性、古地貌和古水系等多种因素的控制。云斑灰岩白云石粒间孔隙型储集体储集空间主要为埋藏溶蚀作用形成的白云石的粒间孔;白云石成因有两种(1)埋藏溶蚀基础上的白云石交代形成的白云岩颗粒;(2)在构造断裂控制下热液白云石化形成的白云石颗粒;以第一种成因形成的白云石粒间孔最为常见。该类储集体的发育受缝合线、岩性、成岩作用和热液作用等因素的影响,在裂缝的沟通下能形成非常有效的储集体。在熟悉井史的基础上,应用生产动态数据、措施作业和示踪剂测试对研究区井组间进行连通性分析。综合奥陶系油藏缝洞分布,地层压力系统,流体性质、储集体连通性等信息,参考奥陶系T74顶面的岩溶地貌和奥陶系油藏的动态生产资料,以利于后续开发动态研究为目的,把奥陶系储集体划分15个缝洞单元;上奥陶统尖灭线附近及以北剥蚀区缝洞单元内部缝洞匹配较好、连通性较好的区域油井产量相对较高;南部缝洞单元内部缝洞匹配较差、连通性较差的区域油井产量也较低。更多还原

【Abstract】 Ordovician reservoirs of block 2 of Tahe Oilfield are in the transitional slope from high land to depression of the karst. Based on the character of Ordovician reservoirs, the adoption on contrasting study of similar outcrops with underground and the application on well-log information, logging information and seismic data, etc, the paper had a redefinition to the Ordovician strata, and the stratigraphic framework accurately was modified in the research area. According to the thinking of single well facies—section facies—plane facies in the stratigraphic framework, the paper studied on the Ordovician sedimentary facies and evolution. In research area, sedimentary facies had a great significant influence on the development of reservoirs.Physical properties of Ordovician resevoirs matrixs in the research area were poor in all, and porosity and permeability had basically no contribution to accumulation and permeation.The reservoir properties were decided by dissolution fissure and pore, fracture and sizable dissolution cave and pore. The reservoir spaces determined by the observation of cores, thin sections and SEM and the information of engineering logging and well-logging,etc, was divided into three main types (pore, fissure and cave)and other 16 ones. According to the means that these reservoir spaces formed reservoirs type and scale, the reservoirs could be divided into dissolution pores type of reef-bank facies, fracture type, karst cave type and dolomite limestone type. Dissolution pores type of reef-bank facies was developed in Yijianfang formation in the south, and it belonged to the complex body of multi-cyclicity. The multi-episodic reservoirs of reef-bank facies superimposed vertically and continued laterally. It developed widely along the margin of the southeast, and had a large scale. Its development degree and range were controled by the sedimentary microfacies. Additionally, tectonization and early exposed honeycomb dissolution were also the important factor for reef-bank facies to form the high quality reservoir of pore type. Lower-Middle Ordovician reservoirs of fracture and cave types developed in the north, which formed the complex fractured-cave carbonate reservoir. The 95.6 % of karst cave developed in the depth of 0～100m that was below the T74, and decreased gradually as the increase of depth. By the analysis of C, O stable isotopes, Sr isotope and rare-earth elements of neutron activation, it thought that the karst cave formed mainly in the early Hercynian. The fillings type in the karst cave included: (1)collapse breccia; (2)arenopelitic fillings; (3)calcites. In combination with the collapse breccia, the reservoirs filled with pelite and the giant calcites were poor. The fracture and karst cave could be vertically divided into four combined types: upper-cave and lower-fracture, upper-fracture and lower-cave and fracture-cave-fracture. The range and develop degree are controlled by tectonization, lithology, palaeogeomorphology and palaeodrainagepattern, etc. The reservoir space of dolomitic limestone was inter-granular pores of dolomite formed by burial dissolution. The cause of formation included:(1)metasomatism of dolomite based on the burial dissolution;(2)hydrothermal fluid dolomitization controlled by the structural fracture. The dolomitic sand-clastic block mass formed by the first reason was the most common. Development of the reservoirs was mainly influenced by stylolite, lithology, diagenesis and hydrothermalism, etc.Based on the knowledge of well history, the application of dynamic producing data and important changing event of production operation and tracer test data, this paper carried out the connectivity analysis to inter well-groups of research area. According to the synthesis of fracture-cave distribution, the pressure system of strata and reservoir connectivity, referring to the karst topography of T74 top surface and dynamic producing data of Ordovician reservoirs, the research area was divided into 15 units of fracture-cave so that the dynamic research of following development would be more convenient. The matching of fracture-cave was better near the pinch outlines of Upper Ordovician and inside the fracture-cave unit of the north denuded zone, the well yield was higher in the area that had good connectivity. The matching of fracture-cave was worse inside the fracture-cave unit of the south, and the well yield was lower in the area that had worse connectivity.更多还原