塔中顺南地区中—下奥陶统岩溶储层特征研究

发布时间：2018-12-21 20:02

【摘要】：岩溶储层是塔中顺南地区中-下奥陶统重要的储层类型之一,具有极好的勘探开发前景。通过岩心观察、薄片鉴定,结合阴极发光分析、碳、氧、锶同位素分析、稀土元素分析和流体包裹体测试等地球化学手段,探讨顺南地区中-下奥陶统岩溶储层基本特征、成因机制和发育分布规律。结果表明:(1)塔中顺南地区中-下奥陶统岩溶储层主要发育在微晶灰岩中,颗粒灰岩、白云岩和藻粘结灰岩中发育较少;储集空间类型以溶蚀孔洞和岩溶洞穴为主,其次是未充填裂缝空间;岩溶储层总厚度较大,储层类型主要有岩溶缝孔洞型和岩溶洞穴型两类,其中岩溶缝孔洞型储层占绝大多数(92.4%),岩溶洞穴型储层占比较少(7.6%);分布层位上,岩溶储层在一间房组最为发育,其次是鹰山组下段,在鹰山组上段发育最少。(2)首次在塔中顺南地区中-下奥陶统碳酸盐岩中识别出两期大气水岩溶作用,分别是加里东中期第Ⅰ幕大气水岩溶作用和海西早期大气水岩溶作用。加里东中期第Ⅰ幕大气水岩溶作用缝洞方解石中富含单相水溶液包裹体,δ13C值为正,δ18O值较高,成岩流体落于中晚奥陶世这一时期海水δ18O值的下方,锶同位素和稀土元素分析结果与奥陶系一间房组正常海相灰岩值相近,略贫稀土元素;海西早期大气水岩溶作用构造-风化裂缝方解石δ13C值为负,δ18O值特偏负,较一间房组正常海相灰岩锶同位素分析结果值偏高,稀土元素富集。(3)加里东中期第Ⅰ幕岩溶作用受不整合面控制,台地边缘低部位岩溶缝洞充填破坏严重,储集意义有限;台地内部高部位岩溶缝洞可以有效保存,具有一定的储集意义。加里东构造运动中期第Ⅰ幕岩溶储层具有纵向上发育深度较为稳定,靠近台地内部方向更为发育的趋势。(4)海西早期岩溶作用主要受断裂控制,岩溶缝洞经历多期充填后,还有大量的剩余空间,是研究区内中-下奥陶统岩溶储层形成的主要机制,具有重要意义。顺南地区东南部主要遵循沿断裂渗透岩溶模式,岩溶储层平面上主要沿断裂分布,断裂拉分段更为发育,纵向上距不整合面深度大,发育层位具有跳跃性;顺南地区西北部主要遵循断裂诱导模式和沿断裂渗透岩溶模式,岩溶储层发育分布特征较为复杂,平面上可不沿断裂分布,纵向上,可在深部顺层发育分布,也可跳跃分布。
[Abstract]:Karst reservoir is one of the important reservoir types in middle and lower Ordovician in Shunnan area of Tazhong. By means of core observation, thin section identification, cathodoluminescence analysis, carbon, oxygen, strontium isotope analysis, rare earth element analysis and fluid inclusion testing, the basic characteristics of middle and lower Ordovician karst reservoirs in Shunnan area are discussed. Genetic mechanism and developmental distribution. The results are as follows: (1) the karst reservoirs of the Middle and Lower Ordovician in the Shunnan area of Tazhong are mainly developed in microcrystalline limestone, while the granular limestone, dolomite and algal bonded limestone are less developed; The main types of reservoir space are corrosion cavity and karst cave, followed by unfilled crack space. The total thickness of karst reservoir is large, the reservoir types are mainly karst fracture porosity type and karst cave type, among which karst fracture hole type reservoir accounts for most (92.4%), and karst cave type reservoir accounts for less (7.6%). The karst reservoir is the most developed in Yijianfang formation, followed by the Yingshan formation and the least developed in the upper member of Yingshan formation. (2) the two stages of atmospheric water karstification have been identified for the first time in the middle and lower Ordovician carbonate rocks in the middle and lower Ordovician area of Tazhong. They are the karstification of atmospheric water in the middle Caledonian stage I and the early Hercynian atmospheric water karstification. In the first act of Caledonian, the calcite is rich in single-phase aqueous solution inclusions, the 未 ~ (13) C value is positive, the 未 ~ (18) O value is higher, and the diagenetic fluid falls below the 未 ~ (18) O value of seawater during the middle and late Ordovician period. The results of strontium isotope and rare earth element analysis are similar to those of the normal marine limestone of the Yijianfang formation of Ordovician, and are slightly poor in rare earth elements. In early Hercynian atmospheric water karstification, the 未 13C value of structure-weathering fracture calcite is negative, and the 未 18O value is especially negative, which is higher than that of normal marine limestone isotopic analysis of Yijianfang formation. REE enrichment. (3) Karst in the middle Caledonian first act is controlled by unconformities, and the filling of karst fractures and cavities in the lower part of the platform edge is seriously damaged, and the reservoir significance is limited; The karst fractures and cavities in the high part of the platform can be effectively preserved and have certain reservoir significance. In the middle period of Caledonian tectonic movement, the karst reservoir in the first episode of Caledonian tectonic movement has a tendency of relatively stable longitudinal development depth and more development near the interior of the platform. (4) the early Hercynian karstification is mainly controlled by faults, and the karst fractures and cavities are filled for several periods. There is also a large amount of residual space, which is the main mechanism of the formation of karst reservoirs in the Middle and Lower Ordovician in the study area, which is of great significance. The southeastern part of Shunnan area mainly follows the model of permeable karst along the fault, the karst reservoir mainly distributes along the fault plane, the faulting segment is more developed, the depth of the vertical unconformity surface is large, and the developmental horizon is jumping. The northwestern Shunan area mainly follows the fault-induced model and the percolation karst model along the fault. The characteristics of karst reservoir development and distribution are complicated, and the distribution of karst reservoir can not be distributed along the fault plane, but vertically, it can be distributed in the deep layer or jump distribution.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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