摘要
深层天然气是重要的埋藏深度大,地层年代老,经过多期构造运动与油气运移充注,天然气成因及成藏过程十分复杂,对深层天然气资源的成因及成藏规律认识不清,将制约深层天然气资源的高效开发。文章以地震、测井、录井、岩心、分析化验及生产动态资料为基础,利用碳同位素分析的手段,开展了车镇凹陷西北带下古生界深层天然气特征研究,明确了天然气碳同位素分析的原理、测试流程及关键地质参数,揭示了研究区深层天然气藏的形成原因,梳理了天然气藏的成藏模式及产量差异性主控因素。研究表明:研究区碳同位素δ_(13)C_(1)介于-47.41‰~-34.67‰,δ_(13)C_(2)介于-18.57‰~-16.21‰,δ_(13)C_(3)介于-20.71‰~-17.93‰,依据天然气成因类型综合鉴别标准及判定图版,属于煤成气,以δ_(13)C_(1)计算的Ro值高于烃源岩实测值,推算气源来自比深层天然气储集层埋藏略深的相邻断块。研究区上古生界煤系烃源岩与下古生界碳酸盐岩储层在垂向上有100~200 m的深度差距,当毗邻正断层的断距大于100~200 m时,处于正断层上升盘的下部碳酸盐岩储层抬升至上古生界煤系烃源岩高度或之上,使烃源岩与储集层的主体基本对接,深层天然气通过断层运移充注之后富集程度高。以上研究成果和认识为研究区天然气进一步的高效开发提供了理论支撑和技术依据。
Deep natural gas is an important resource with a large burial depth,old geological age,and multiple stages of tectonic movement and oil and gas migration and injection.The genesis and accumulation process of natural gas are very complex,and the unclear understanding of the genesis and accumulation rules of deep natural gas resources will restrict the efficient development of deep natural gas resources.Based on seismic,well logging,logging,core analysis,laboratory testing,and production dynamic data,this article uses carbon isotope analysis to study the characteristics of deep natural gas in the Lower Paleozoic in the northwest zone of the Chezhen Depression.It clarifies the principles,testing processes,and key geological parameters of natural gas carbon isotope analysis,reveals the reasons for the formation of deep natural gas reservoirs in the study area,and sorts out the formation modes and main controlling factors of production differences in natural gas reservoirs.Research shows that the carbon isotopeδ_(13)C_(1)in the study area ranges from-47.41‰~-34.67‰,δ_(13)C_(2)is between-1857‰~-16.21‰,δ_(13)C_(3)is between-20.71‰~-17.93‰,according to the comprehensive identification criteria and judgment chart of natural gas genesis types,it belongs to coal formed gas.The Ro value calculated based onδ_(13)C_(1)is higher than the measured value of the source rock,and it is estimated that the gas source comes from adjacent fault blocks buried slightly deeper than the deep natural gas reservoir.There is a depth difference of 100-200 m in the vertical direction between the Upper Paleozoic coal bearing source rocks and the Lower Paleozoic carbonate reservoirs in the research area.When the fault displacement adjacent to the normal fault is greater than 100-200 m,the lower carbonate reservoirs located on the rising plate of the normal fault are lifted to the height of or above the Upper Paleozoic coal bearing source rocks,which basically connects the main body of the source rocks and reservoirs.The enrichment degree of deep natural gas is high after migration and injection through the fault.The above research results and understanding provide theoretical support and technical basis for further efficient development of natural gas in the study area.
作者
李永臣
LI Yongchen(PetroChina Coalbed Methane Company Limited,Beijing 100028,China)
出处
《钻采工艺》
北大核心
2025年第3期197-203,共7页
Drilling & Production Technology
关键词
深层天然气
车镇凹陷西北带
碳同位素分析
天然气成因
deep natural gas
northwest zone of Chezhen depression
carbon isotope analysis
origin of natural gas
