马朗凹陷条湖组含沉积有机质凝灰岩致密油成储-成藏机理

发布时间：2018-07-09 18:39

  本文选题：凝灰岩 + 致密油　； 参考：《中国石油大学(北京)》2016年博士论文

【摘要】：三塘湖盆地马朗凹陷二叠系条湖组凝灰岩油藏的发现,为我们认识凝灰岩致密油藏成藏机理提供了一个很好的机会,这套凝灰岩储层的特殊性在于它是火山灰降落在湖盆水体中形成的,本身含有一定的沉积有机质。本文通过这套凝灰岩有机地球化学特征、储层岩石学特征、物性特征、孔隙结构特征和润湿性等方面的研究,结合地质条件综合分析,明确了条湖组凝灰岩的分布规律、储层形成机理、致密油藏石油充注机理和成藏主控因素,建立了成藏模式。条湖组凝灰岩可以分为玻屑凝灰岩、晶屑玻屑凝灰岩、泥质凝灰岩和硅化凝灰岩四种岩石类型。玻屑凝灰岩平面上主要分布在中远火山口带,垂向上主要分布在凝灰岩段的中-下部;晶屑玻屑凝灰岩平面上主要分布在近火山口带,垂向上也主要分布在凝灰岩段的中-下部,且多与玻屑凝灰岩互层;泥质凝灰岩平面上主要分布在远火山口带,垂向上主要分布在凝灰岩段的上部;硅化凝灰岩分布在凝灰岩段的底部。凝灰岩的岩石类型受距离火山活动带远近的影响,其厚度分布受火山活动带和沉积古地形共同控制,火山活动带两侧的沉积洼地是凝灰岩分布的主要部位。条湖组凝灰岩储层具有中高孔低渗的特征,其中玻屑凝灰岩物性最好,原始火山灰玻璃质的脱玻化作用是微观孔隙形成的主要原因。凝灰岩中含有的原始沉积有机质演化过程中形成的有机酸有利于火山灰脱玻化作用的进行。凝灰岩孔隙度的演化有一定的规律,主要受原始物质组成和埋深的影响,同深度条件下玻屑凝灰岩的孔隙度大于晶屑玻屑凝灰岩,但都具有随深度增大孔隙度先减小后增大的特点,埋深大于3000m,玻屑凝灰岩仍保持高孔隙度的趋势。条湖组凝灰岩孔隙演化可以划分为正常压实减孔阶段、脱玻化增孔阶段和增孔后演化阶段三个阶段,分别发生在白垩纪早期之前、白垩纪石油充注之前以及白垩纪末之后。凝灰岩致密油藏的原油主要来自下伏芦草沟组二段烃源岩,属于源储分离型的致密油藏。凝灰岩中沉积有机质生成原油的极性组分优先吸附在孔隙表面,使得岩石润湿性为偏亲油,加之凝灰岩孔喉比小,从而导致油驱水启动压力梯度较小,这是远源的凝灰岩致密储层内石油能够得以高效充注成藏的主要原因。凝灰岩内致密油的成藏与富集主要受控于凝灰岩储层质量、岩石润湿性和芦二段良好的排烃条件及断-缝输导体系,因而,提出“自源润湿、它源成藏、断-缝输导、多点充注、有效凝灰岩储层大面积富集”的成藏模式。
[Abstract]:The discovery of tuff reservoirs in the Permian Tiaohu formation in Marang depression of Santanghu Basin provides a good opportunity for us to understand the reservoir formation mechanism of dense tuff reservoirs. The particularity of this set of tuff reservoir is that it is formed by falling of volcanic ash in the lake basin water body and contains certain sedimentary organic matter. By studying the organic geochemistry, petrology, physical properties, pore structure and wettability of tuff, combined with the comprehensive analysis of geological conditions, the distribution law of tuff in Tianhu formation is determined. Reservoir forming model was established by reservoir formation mechanism, oil filling mechanism and main controlling factors of reservoir formation. The tuff of Tianhu formation can be divided into four types: glassy tuff, crystalline tuff, argillaceous tuff and silicified tuff. The glassy tuff plane is mainly distributed in the middle to lower part of the tuff section, and the vertical direction is mainly distributed in the middle and lower part of the tuff section, while the crystal chrysotile tuff plane is mainly distributed in the near crater zone. The vertical tuff is mainly distributed in the middle and lower part of the tuff section and interbedded with the glassy tuff, the plaster tuff is mainly distributed in the far crater zone and the vertical upward in the upper part of the tuff section. Silicified tuff is distributed at the bottom of the tuff section. The rock type of tuff is influenced by the distance from volcanic active zone and its thickness distribution is controlled by volcanic active zone and sedimentary paleotopography. The depositional depression on both sides of volcanic active zone is the main part of tuff distribution. The tuff reservoir of Tianhu formation has the characteristics of medium high porosity and low permeability, among which the vitreous tuff has the best physical properties, and the devitrification of the original pozzolanic glass is the main reason for the formation of micro pores. The organic acids formed during the evolution of the original sedimentary organic matter contained in tuff are conducive to the devitrification of volcanic ash. The evolution of tuff porosity has a certain regularity, which is mainly affected by the composition of the original material and the depth of burying. At the same depth, the porosity of the vitreous tuff is larger than that of the crystalline tuff. However, the porosity decreases first and then increases with the increase of depth, and the buried depth is more than 3000m, and the glassy tuff still keeps high porosity. The pore evolution of tuff in Tianhu formation can be divided into three stages: normal compaction and pore reduction stage, devitalized pore increasing stage and post-pore increasing evolution stage, which occurred before the early Cretaceous, before the Cretaceous oil filling and after the Cretaceous. The crude oil of dense tuff reservoir mainly comes from the source rock of the second member of Lower Fuluchaogou formation, which belongs to the tight reservoir of source reservoir and separation type. The polar components of the crude oil generated by sedimentary organic matter in tuff are preferentially adsorbed on the pore surface, which makes the wettability of the rock to be oil lipophilic, and the pore throat ratio of tuff is small, which leads to the small starting pressure gradient of oil flooding. This is the main reason that the oil in the dense tuff reservoir can be efficiently filled and formed. The accumulation and accumulation of dense oil in tuff are mainly controlled by the quality of tuff reservoir, the wettability of rock, the good hydrocarbon expulsion condition of Lu2 member and the system of fault-fracture transport. Multi-point filling and large-area enrichment of effective tuff reservoirs "reservoir formation model.
【学位授予单位】：中国石油大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P618.13

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