【作者】 王涛；

【导师】 符超峰； 李克永；

【作者基本信息】 长安大学 ， 矿产普查与勘探， 2018， 硕士

【副题名】以鄂尔多斯盆地佛古塬区长6储层为例

【摘要】 浅水型三角洲前缘是油气聚集的主要沉积相带,是一构造稳定、地形平缓、水体较浅、物源充足的沉积环境。鄂尔多斯盆地佛古塬区上三叠统延长组长6油层是主要产油层位。本次研究以佛古塬地区内459口钻井、测井及分析化验资料为基础,根据石油地质学、岩相古地理学、测井地质学、储层沉积学等理论,结合测井曲线特征,通过岩芯观察、铸体薄片、扫描电镜、压汞试验、粒度分析等方法进行综合研究。对佛古塬区长6地层进行对比与划分,对沉积微相、储层非均质性特征进行研究,并对储层非均质性特征的主控因素进行了分析,认为压实和胶结作用通常使得储层非均质性增强,而溶蚀作用使得储层非均质性减弱。具体结论如下:(1)佛古塬区长6油层发育浅水型三角洲前缘亚相,沉积微相主要有水下分流河道和水下分流间湾;(2)通过岩芯观察及岩性分析,佛古塬区岩石类型主要为长石砂岩,胶结物为绿泥石、方解石和石英;沉积构造常见平行层理、变形层理、交错层理和垂直虫孔等,见植物碎片、植物茎干;孔隙类型主要由粒间孔、粒内孔、溶蚀孔和裂隙孔组成;压汞试验结果表明储层孔隙结构以孔径小、喉道细为特征,具有中等排驱压力、略粗歪度、孔喉分选性好、连通性一般的特点,属小孔细喉-小孔微细喉型;(3)通过分析浅水型三角洲前缘沉积微相,发现其控制着储层岩性特征和物性的非均质性。平面上水下分流河道主砂体部位非均质程度较弱,河道边部和河口砂坝非均质程度较强;席状砂渗透率值大于分流河道的渗透率值,陆岸非均质程度较弱,向海岸强;水下分流河道凹岸渗透率值大于凸岸的渗透率值;河口坝上游非均质程度较弱于下游,中部渗透率值大于两边的渗透率值;(4)佛古塬区浅水型三角洲前缘储层非均质性主要受沉积环境和成岩作用等因素共同控制。浅水型三角洲前缘水浅流急,水动力条件强,在水下分流河道粒度相对均一,非均质性弱;河道侧缘、河口坝、水下天然堤等微相水动力条件弱,非均质性相对较强;成岩作用中压实作用和胶结作用使储层砂体致密,物性变差;次生溶蚀作用形成的粒间溶孔、粒内溶孔使储层储集空间变大,储层物性变好,使得储层非均质性增强。更多还原

【Abstract】 The shallow-water delta front is the main sedimentary facies of oil and gas accumulation which is a sedimentary environment with stable structure,flat topography,shallow water,and abundant sources.The Chang-6 reservoir of the Upper Triassic Yanchang Formation in the area of Foguyuan of the Ordos Basin is the main oil layer.This article based on the investigation of 459 wells,consist of well logs and analysis data in the Foguyuan area.According to petroleum geology,lithofacies palaeogeography,well logging geology,reservoir sedimentology and other theories,combined with logging curve characteristics,through core observation,casting thin slices,scanning electron microscopy,mercury injection test,particle size analysis and other methods to conduct a comprehensive study.Comparing and dividing the Chang-6 strata in the Foguyuan area,study the sedimentary microfacies,reservoir characteristics and reservoir heterogeneity,and the main controlling factors of reservoir heterogeneity characteristics were analyzed which was considered that the compaction and cementation usually make the reservoir heterogeneity enhanced and the dissolution make the reservoir heterogeneity weakened.The specific conclusions are as follows:(1)The Chang-6 reservoir in the Foguyuan area develops sub-facies of the delta front.the sedimentary microfacies mainly consist of underwater distributary channels and underwater split bay.(2)Through rock core observation and lithology analysis,the rock types in the Foguyuan area are mainly feldspar sandstones,and the cements include chlorite,calcite and quartz.the sedimentary structures mainly develop parallel bedding,deformed bedding,staggered bedding,and vertical wormholes,etc.,see plant debris,plant stems;pore type mainly consists of intergranular pores,intragranular pores,dissolved pores,and fracture pores;mercury injection test results show that the reservoir pore structure is characterized by small pore size and fine throats,It has the characteristics of medium discharge pressure,slightly rough twist,good pore throat sortability,and general connectivity.It belongs to the small hole fine throat-small hole fine throat.(3)By analyzing the sedimentary microfacies of the shallow-water delta front,it is found that it controls the heterogeneity of reservoir lithology and physical properties.on the plane,the heterogeneity of the main sand bodies in the underwater distributary channel is relatively weak,and the edge of the river channel and the estuary sand dam have a strong degree of heterogeneity;the permeability of the mat sand is greater than that of the distributary channel,and the heterogeneity of the land bank is relatively low,and is strong toward the coast;the value of the permeability of the concave bank of the underwater distributary channel is greater than the value of the permeability of the convex bank;the heterogeneity of the upper reaches of the estuary dam is weaker than the downstream,and the value of the central permeability is greater than the permeability values of both sides.(4)The heterogeneity of the shallow-water delta front in the Foguyuan area is mainly controlled by factors such as sedimentary environment and diagenesis.Shallow-water delta front water is shallow and its flow rate is very sharp,strong hydrodynamic conditions,relatively uniform particle size in the submarine distributary channel,weak heterogeneity,micro-phase hydrodynamic conditions such as side margins of river channels,estuary dams,and underwater natural embankments are weak,the homogeneity is relatively strong;compaction and cementation in the diagenesis make the reservoir sand body dense and physical properties deteriorate;the intergranular dissolution pores and intragranular dissolution pores formed by secondary dissolution make the reservoir storage space larger and the reservoir properties become better,makes the reservoir more heterogeneous.更多还原