陆相页岩油储层可动油含量测井评价方法——以苏北盆地古近系阜宁组二段页岩油为例

Well-log-based assessment of movable oil content in lacustrine shale oil reservoirs:A case study of the 2nd member of the Paleogene Funing Formation,Subei Basin

近年来中国东部陆相盆地页岩油勘探开发取得重大进展,但制约页岩油产能评价的关键因素是油可动性。研究苏北盆地页岩油提出了二维核磁共振法和常规测井法2种测井评价页岩可动油含量的方法。建立了二维核磁共振测量纵向弛豫时间(T1)-横向弛豫时间(T2)可动油识别图版,评价吸附油及束缚水等流体类型,通过游离烃含量(S1)与沉积环境、沉积构造的关系及测井响应的关联性,分析常规测井电阻率及声波时差对游离烃含量、有机质含量响应灵敏度,建立了游离烃含量测井定量评价模型。提出了测井资料评价游离烃含量的方法,计算可动油饱和度及含油量。咸化环境和纹层状构造有利于有机质成烃和运移,游离烃含量高。

Recent years have witnessed significant progress in the exploration and exploitation of shale oil in continental basins in East China.However,the assessment of shale oil productivity is largely hindered by the evaluation of oil mobility.By investigating the shale oil in the Subei Basin,we propose two well-log-based methods for assessing the movable oil content in shales:the two-dimensional nuclear magnetic resonance(2D NMR)method and the conventional logging.An identification plot for movable oil is thereby established using the 2D NMR-derived longitudinal and transverse relaxation time(T1 and T2,respectively),acting to assess fluid types like adsorbed oil and irreducible water.By exploring the relationships of free hydrocarbon content(S1)with sedimentary environments and structures,along with the correlation between S1 and logging responses,we analyze the response sensitivities of conventional well-log-derived resistivity and sonic interval transit time to S1 and organic matter content,and establish a well-log-based quantitative assessment model for S1.Furthermore,a method for assessing S1 using log data is developed to calculate both movable oil saturation and oil content.The results reveal that saline environments and lamellar structures promote hydrocarbon generation and migration from organic matter,resulting in high S1.