【研究目的】中国浅层-中深层页岩气勘探开发技术已经趋于成熟，深层页岩成为下一步勘探开发的重点，探明不同埋深条件下页岩的孔隙特征及其控制因素利于推动深层页岩的评优选区工作。【研究方法】本文基于核磁共振、场发射扫描电镜和X-射线衍射等实验分析手段，对比性评价了川南地区不同深度的龙马溪组页岩孔隙度、孔隙结构参数特征并进行影响因素分析。【研究结果】随着埋深的增加，总孔隙度呈现下降的趋势； 3000 m以浅、3000~3500 m和3500 m以深页岩孔隙度主体分别为4%~8%、3%~7%和3%~6%。不同埋深龙马溪组页岩孔隙类型与大小分布无显著差异，各深度段页岩均发育大量纳米级有机质孔隙、矿物粒间孔、粒内溶孔和微裂缝。【结论】高U/Th比和低Ti含量下形成的丰富有机质是深层页岩孔隙发育的关键因素；高硅质矿物含量和高地层压力系数对页岩储层孔隙起到了保护作用，减缓了上覆地层的压实作用，但埋深过大仍会导致页岩孔隙减少、孔隙度降低。
This paper is the result of oil and gas exploration engineering.
[Objective]With the maturity of exploration and development technology in shallow and medium-deep shale, deep shale has become a focus of next exploration and developmentin China. Clarifying the pore characteristics of shale under different burial depths and its controlling factors is conducive to promoting the selection and evaluation of deep shale gas.[Methods]Methods such as nuclear magnetic resonance, field emission scanning electron microscopy and X-ray diffraction were used to comparatively evaluate the porosity and pore structure of Longmaxi-Formation in southern Sichuan Basin, and its influencing factors were also discussed.[Results]With the increase of burial depth, the total porosity shows a downward trend, and the main porosity of shale below 3000 m, between 3000-3500 m and deeper than 3500 m are 4%-8%, 3%-7% and 3%-6%, respectively.There is no significant difference in pore types and size distribution of the Longmaxi Formation shale at different depths, and a large number of nano-scale organic pores, mineral intergranular pores, intragranular dissolved pores and micro-fractures are developed at different depth.[Conclusions]A large amount of organic matter formed at high U/Th ratio and low Ti content is the key factor for the development of deep shale pores. High siliceous mineral content and high formation pressure coefficient could protect pores of shale reservoirs and slow down compaction of its overlying strata. However, excessive burial depth wouldalso lead to a reduction of shale pores and porosity.
陈洋,唐洪明,廖纪佳,罗超,赵圣贤,郑马嘉,钟权. 基于埋深变化的川南龙马溪组页岩孔隙特征及控制因素分析[J]. 中国地质, 2022, 49(2): 472-484.
CHEN Yang, TANG Hongming, LIAO Jijia, LUO Chao, ZHAO Shengxian, ZHENG Majia, ZHONG Quan. Analysis of shale pore characteristics and controlling factors based on variation of buried depth in the Longmaxi Formation, Southern Sichuan Basin[J]. Geology in China, 2022, 49(2): 472-484(in Chinese with English abstract).