三塘湖盆地条湖组火山湖相沉凝灰岩致密油形成条件与富集因素

Geological Conditions and Enrichment Factors of Tuff's Tight Oil in Volcanic Lake Facies,Tiaohu Formation of Santanghu Basin

基于地震、录测井、试采等资料,开展火山喷发期次、火山机构、储集层沉积环境、岩石学特征、孔喉结构特征和成藏富集研究。结果表明,条湖组沉积时期具多期次火山喷发,火山机构叠置;储集层具火山口湖相、火山堰塞湖相及远火山口的湖相沉积特点;有利储集体岩性为中酸性玻屑沉凝灰岩,脱玻化微孔和晶屑溶蚀微孔为主要储集空间。认为烃源岩的有效配置及持续充注、盆地稳定的构造背景和浅水湖盆环境、火山湖相发育规模、中酸性火山灰和空降成因沉积方式、后期脱玻化和溶蚀作用、沟通条湖组储集体的断缝疏导体系,共同控制着油藏的富集及成藏规模。

As a new type of tight oil reservoir, tuff has been achieved a breakthrough in the Tiaohu formation of Permian oil and gas exploration of Santanghu basin, research on accumulation and its distribution mechanism is still facing many technical difficulties. Taking P2 t2 as an Example,Based on the data analysis of seismic, logging and production test, carry out the volcano eruption period, volcano mechanism, reservoir sedimentary environment, lithological characteristics,pore structure characteristics and enrichment factors.The results show that there are many volcanic eruptions and volcanic structures in the sedimentary period of P_2t, the reservoirs has sedimentary characteristics of the volcanic crater lake facies, volcanic barrier lakes and far volcanic crater, the favorable reservoir lithology is acidic vitric tuff, devitrification and fines dissolve microporous is the main reservoir space. It is concluded that the effective configuration and continuous filling of the source rock, stable tectonic background and the environment shallow lake basin, the scale of the volcanic lake facies, the deposition method of the acidic volcanic ash and the airborne deposition methods, causes of late devitrification and dissolution,the fault-crack system＇s communication, controling the enrichment and accumulation scale.