川中龙岗地区侏罗系沙溪庙组一段河道砂体特征及沉积过程重建

发布时间：2018-05-14 02:16

本文选题：川中地区 + 侏罗系　；参考：《西南石油大学》2017年硕士论文

【摘要】：川中龙岗地区侏罗系沙溪庙组砂体广泛发育,但砂体特征及展布规律不清。为明确河道砂体基本特征及砂体演化过程,结合野外露头、岩心观察、薄片鉴定及测井-地震预测成果综合开展研究。研究结果表明,龙岗地区沙溪庙组主要为河流-湖泊沉积环境,可识别出辫状河、河漫平原、滩坝、泥坪等多个沉积相带,沙一段河道砂体多属辫状河心滩沉积,岩性以灰色、紫红色粗砂岩为主,少量中粒砂岩及含砾粗砂岩,多呈厚层块状砂体产出,总体上成熟度偏低。河道砂体岩石类型以长石岩屑砂岩和岩屑长石砂岩为主。砂岩碎屑颗粒成分以石英为主,次为长石和岩屑。按粒度划分砂岩以细砂岩为主,次为中砂岩,分选中等—好,磨圆为次圆状,颗粒间以点—线接触为主,颗粒支撑为主,胶结类型以孔隙式胶结为主,部分层段发育绿泥石粘土衬边,构成薄膜式胶结,局部基底式、再生式胶结。河道砂体储集空间包括原生孔、次生孔隙以及裂缝,以粒间溶孔、粒内溶孔及构造缝为主;因中下部长石含量相对较高,粒内溶孔相对发育。河道砂岩孔隙度主要分布在1.5～8%之间(平均值为2.8%),渗透率分布在0.1～1× 10-3μm2之间(平均渗透率为0.3×10-3μm2)。总体具低孔、低渗背景下局部发育相对高孔储层(φ6%)的特征。孔喉结构具高排驱压力、高中值压力、高汞不饱和体积和最大连通孔喉半径、中值孔喉半径小、退汞效率低特征。储层受沉积和次生溶蚀作用控制明显,裂缝存在是获得工业油气流的重要条件。在凉高山湖盆萎缩、大范围湖退背景下,因盆地西部相对抬升,湖盆西部、西南部沉积基底相应大范围上扬,湖水沿近南西～北东向退出。龙岗地区紧邻沉积中心,在下部残留滨-浅湖相沉积基础上逐渐演变为泛滥平原～河流相沉积,河道砂体逐渐发育。沙一段河道砂体具高幅箱型-钟形测井响应特征,地震剖面显示为同相轴下拉、透镜状,平面上呈条带状分布。砂体宽约390～3440m(平均1170.8m),厚约4～33.75mm(平均13.74m),宽厚比为26:1～312:1(平均106:1)。由沙一段底部向上200m范围内共发育五期河道,河道砂体平面变化频繁。河道砂体几何参数定量分析表明,龙岗沙一段河道属低弯度(平均弯度1.044)辫状河,河道宽约0.6～2.8km,受北东向物源影响导致平面摆动频繁,除第三期河道受间歇性物源供给不足外,其余几期河道砂体总体表现为逐渐发育的规律。龙岗地区沙溪庙组底部向上100～200m范围内河道砂体展布范围和发育程度达到最大,砂体在龙岗中部龙岗9井区最为发育,连通性较好,与断层或裂缝形成良好搭配关系有利于油气的富集成藏。
[Abstract]:The sand bodies of Shaximiao formation of Jurassic system in Longgang area of central Sichuan are widely developed, but the characteristics and distribution of sand bodies are unclear. In order to clarify the basic characteristics and evolution process of channel sand body, combined with field outcrop, core observation, slice identification and logging and seismic prediction results, a comprehensive study was carried out. The results show that the Shaximiao formation in Longgang area is mainly fluvial and lacustrine sedimentary environment, and many sedimentary facies belts such as braided river, Manhe plain, beach dam, mud flat and so on can be identified. The sand bodies of the channel in the first section of the sand are mostly braided river core beach deposits, and the lithology is gray. The purplish red coarse sandstone, a small amount of medium-grained sandstone and gravel-bearing coarse sandstone, is mostly produced by thick layer massive sand bodies, and the maturity is low on the whole. The main rock types of channel sand body are feldspar lithic sandstone and lithic feldspar sandstone. The grain composition of sandstone clastic is mainly quartz, followed by feldspar and lithic. According to the granularity, the sandstone is mainly fine sandstone, the second is middle sandstone, the separation is medium good, the grinding circle is subcircular, the grain is mainly point-line contact, the grain support is the main, and the cementation type is mainly pore cementation. Chlorite clay lining formed thin film cementing, local substrate cementation and regenerative cementation in some layers. The reservoir space of channel sand body consists of primary pore, secondary pore and fracture, mainly intergranular dissolved pore, intragranular dissolved pore and structural joint, because of the relatively high content of feldspar in the middle and lower part, the intragranular dissolution pore is relatively developed. The porosity of channel sandstone is mainly between 1.5% and 8% (average value is 2.8%), and permeability is between 0.1 脳 10 -3 渭 m 2 (average permeability 0.3 脳 10 -3 渭 m 2). Under the background of low porosity and low permeability, relatively high porosity reservoirs (蠁 6) are developed locally. The pore throat structure is characterized by high displacement pressure, high unsaturated volume of mercury, maximum connected radius of pore throat, small radius of median pore throat and low efficiency of mercury removal. The reservoir is obviously controlled by sedimentation and secondary dissolution, and the existence of fractures is an important condition for obtaining industrial oil flow. Under the background of the atrophy of the Liangshan lake basin and the large-scale lake retreat, because of the relative uplift in the western part of the basin, the sedimentary basement in the western part of the lake basin and the southwestern part of the lake basin rise in a large scale, and the lake water exits from the lake along the near south-west to the north. The Longgang area is adjacent to the sedimentary center, and on the basis of the residual shore-shallow lacustrine facies in the lower part, it gradually evolves into the flood plain ~ fluvial facies, and the channel sand body develops gradually. The channel sand body of the first member of the Shahejie formation is characterized by a high-amplitude box-bell-shaped logging response. The seismic profile shows a cophase axial pull-down, a lenticular shape, and a strip distribution on the plane. The width of the sand body is about 390m (mean 1170.8mg), the thickness of the sand is about 40.75mm (mean 13.74mg), the ratio of width to thickness is 26: 1 / 312: 1 (mean 106: 1). From the bottom of the first section of sand to 200 m above, there are five stages of river channel, and the plane of channel sand body changes frequently. The quantitative analysis of the geometric parameters of the channel sand body shows that the channel in Longgang sand section is a braided river with low bend (mean curve 1.044), and the channel width is about 0.6 ~ 2.8km. the plane swinging frequently due to the influence of the north-east source, except for the lack of intermittent material supply in the third stage of the channel. The other several periods of river channel sand body overall performance is the law of gradual development. At the bottom of Shaximiao formation in Longgang area, the distribution and development degree of channel sand body reaches the maximum within 100 ~ 200m above the bottom, and the sand body is the most developed in Longgang 9 well area in the middle of Longgang, and the connectivity is good. A good collocation with faults or fractures is beneficial to oil and gas rich integrated reservoirs.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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