李琪琪, 徐尚. 海陆过渡相页岩储层研究现状与展望[J]. 地质通报, 2022, 41(8): 1417-1429. DOI: 10.12097/j.issn.1671-2552.2022.08.009
    引用本文: 李琪琪, 徐尚. 海陆过渡相页岩储层研究现状与展望[J]. 地质通报, 2022, 41(8): 1417-1429. DOI: 10.12097/j.issn.1671-2552.2022.08.009
    LI Qiqi, XU Shang. Research status and prospects of marine-continental transitional shale reservoirs[J]. Geological Bulletin of China, 2022, 41(8): 1417-1429. DOI: 10.12097/j.issn.1671-2552.2022.08.009
    Citation: LI Qiqi, XU Shang. Research status and prospects of marine-continental transitional shale reservoirs[J]. Geological Bulletin of China, 2022, 41(8): 1417-1429. DOI: 10.12097/j.issn.1671-2552.2022.08.009

    海陆过渡相页岩储层研究现状与展望

    Research status and prospects of marine-continental transitional shale reservoirs

    • 摘要: 中国广泛分布石炭系—二叠系海陆过渡相富有机质页岩,开发利用其中赋存的页岩气对于缓解巨大的能源和环境压力具有重要意义。从沉积环境、地球化学、矿物学、岩石物理学等方面概述了不同区域、不同层位代表性海陆过渡相页岩的关键属性,并与典型海相和陆相页岩进行了对比和总结。结果表明,对于过渡相富有机质页岩,三角洲体系中的沼泽相及障壁-潟湖体系中的潟湖和沼泽相具备更优越的页岩气成藏条件。过渡相页岩与煤层、砂岩层频繁互层,岩相垂向上变化极其复杂,意味着其具有高度的非均质性。同时,TOC含量垂向变化较大,高低值交互出现,平均TOC含量总体高于海相和陆相页岩,表明其巨大的页岩气勘探开发潜力。海陆过渡相页岩有机质类型以Ⅲ型为主,Ⅱ型为辅,腐殖质显微组分约占70%,热演化程度普遍处于成熟—高成熟阶段,少数达到过成熟,总体介于陆相和海相页岩之间。过渡相页岩粘土含量较高,给压裂开发带来了较大的挑战。储集空间以粒间孔和粒内孔为主,有机质中可能普遍存在大量的不可见有机孔,但受有机质类型及成熟度的影响,它们理论上不是过渡相页岩的主要孔隙类型。高的粘土含量可能导致海陆过渡相页岩最低的孔隙度及较低的渗透率。海陆过渡相页岩的甲烷吸附能力分布范围较大,存在甲烷吸附能力较强的页岩,可能是受煤层的影响。目前,海陆过渡相页岩气储层的研究已经取得了很多重要的研究成果,但资源评价方法的不完善、“甜点”识别与预测技术不成熟、优势成藏环境研究不深入及“多气共采”可行性不确定,仍然是当前过渡相页岩气勘探开发面临的主要问题。

       

      Abstract: The Carboniferous-Permian transitional organic-rich shales are widely distributed in China, and the development of shale gas in them is of great significance to alleviate the huge energy and environmental pressure.The key properties of representative transitional shales in different regions and layers are summarized from the aspects of sedimentary environments, geochemistry, mineralogy, and petrophysics, and compared with typical marine and continental shales.The results show that for the transitional shales, the swamp facies in the delta system and the lagoon and swamp facies in the barrier-lagoon system have superior conditions for shale gas accumulation.The transitional shales are frequently interbedded with coal and sandstone layers, and the vertical change of lithofacies is extremely complex, implying that they are highly heterogeneous.At the same time, the vertical variation of TOC content is large, and the average TOC content is generally higher than that of marine and continental shales, which means that it has great potential for shale gas exploration and development.The organic matter type of marine-continental transitional shales are mainly Type Ⅲ, supplemented by Type Ⅱ, humic maceral accounts for about 70%.The degree of thermal evolution is generally in the stage of maturity to high maturity, with a few reaching over-maturity, and generally between continental and marine shales.The high clay mineral content of transitional shales poses a great challenge to fracturing development.The reservoir space is dominated by intergranular pores and intragranular pores, and a large number of invisible organic matter pores prevalent in organic matter, but they are not theoretically the dominant pore type in transitional shales due to the type and maturity of the organic matter.High clay content may result in the lowest porosity and low permeability of marine-continental transitional shales.The methane adsorption capacity of transition shales are distributed in a wide range, and there are shales with strong methane adsorption capacity, which may be influenced by coal seams.At present, many important research results have been achieved in the study of marine-continental transitional shale gas reservoirs.However, the imperfection of resource evaluation methods, the immaturity of "sweet spot" recognition and prediction technology, the lack of in-depth study on favorable reservoir formation environment, and the uncertainty of the feasibility of the co-mining of various unconventional natural gas resources are the main problems in the exploration and development of transitional shale gas.

       

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