四川盆地五峰组—龙马溪组页岩气富集特征与“建造—改造”评价思路  

Characterization of shale gas enrichment in the Wufeng-Longmaxi Formation in the Sichuan Basin and its evaluation of geological construction-transformation evolution sequence

作　　者：何治亮[1,2,3] 胡宗全[1,2,3] 聂海宽[1,2,3] 李双建[1,2,3] 许锦[1,2,3] 

机构地区：[1]页岩油气富集机理与有效开发国家重点实验室,北京100083 [2]中国石油化工集团公司页岩油气勘探开发重点实验室,北京100083 [3]中国石油化工股份有限公司石油勘探开发研究院,北京100083

出　　处：《天然气地球科学》2017年第5期724-733,共10页Natural Gas Geoscience

基　　金：国家重点基础研究发展计划("973")项目(编号:2014CB239100);国家自然科学基金项目(编号:U1663209;41202103)联合资助

摘　　要：四川盆地上奥陶统五峰组—下志留统龙马溪组页岩是中国目前页岩气勘探开发的重点层系之一,已发现了涪陵、威远、长宁和昭通等页岩气藏。通过页岩气藏的详细解剖,将五峰组—龙马溪组下部龙一段页岩气富集特征概括为"高、帅、富":"高"主要指页岩层系形成页岩气的原始物质基础条件优越,有机质类型好、丰度高、脆性矿物含量高、热演化程度适中;"帅"主要表现为构造变形较晚、变形强度较弱、变形方式与构造样式有利、抬升幅度以及现今埋深适中;"富"表现为含气量高、地层压力系数大、储层物性好、有利于储层规模改造、初始产量高、最终产出量大,开发难度相对较小,经济效益明显。优越的原始沉积条件与成岩过程(地质建造作用)与后期适度的构造变形改造与抬升剥蚀(地质改造作用)的有机组合,是页岩气的富集高产前提与关键。基于"建造"(生—储演化序列)的评价内容包括层序地层与沉积、生烃和储层孔隙形成3个方面内容,基于"改造"(储—保演化序列)的评价内容主要包括构造变形、储层裂缝形成和页岩气保存2个方面。"建造—改造"的评价思路就是沿着页岩气形成与保存的全过程,既分析页岩气形成的建造条件优劣,又评价构造改造方式、程度的正面、负面影响。基于这种评价思路所建立的各种评价要素的组合模型,更符合页岩气形成与富集规律,也能更有效地消除简单将各种要素不作区别地统一纳入评价体系所带来的偏差。Shale gas in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in the Sichuan Basin is one of the key strata being explored and developed in China, where shale gas reservoirs have been found in Fuling, Weiyuan, Changning and Zhaotong. Characteristics of shale gas enrichment in the formation shown by detailed profiling and analysis are summarized as ＂high, handsome and rich＂. ＂High＂ mainly refers to the high quality of original materials for the formation of shale with excellent key parameters, including the good type and high abundance of organic matters, high content of brittle minerals and moderate thermal evolution. ＂ Handsome＂ means late and weak deformation, favorable cteformation mode and structure,and appropriate uplift and current burial depth.＂Rich＂ includes high gas content, high formation pressure coefficient, good reservoir property, favorable reservoir scale transformation and high initial and final output, with relative ease of development and obvious economic benefit. For shale gas enrichment and high yield, it is important that the combination of shale was deposited and formed in excellent conditions （geological construction）,and then underwent appropriate tectonic deformation,uplift,and erosion （geological transformation）.Evaluation based on geological construction （evolution sequence from formation to the reservoir） includes sequence stratigraphy and sediment, hydrocarbon generation and formation of reservoir pores.Based on geological transformation （evolution sequence from the reservoir to preservation） ,the strata should be evaluated for structural deformation, the formation of reservoir fracture and preservation of shale gas. The evaluation of the ＂construction-transformation＂ sequence is to cover the whole process of shale gas formation and preservation. This way, both positive and negative effects of the formation-transformation sequence on shale gas are assessed.The evaluation models based on this strategy would be more accurate, re

关 键 词：页岩气 五峰组 龙马溪组 涪陵页岩气田 富集特征 地质建造 地质改造 四川盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]