基于低场核磁共振技术和多重分形理论的高阶煤样孔裂隙分维特征
Study on pore and fracture heterogeneity of high rank coal samples based on NMR technology and multi-fractal theories
祝汉京 1张军建2
作者信息
- 1. 河南能源永煤公司 新桥煤矿,河南 商丘 476600
- 2. 山东科技大学 地球科学与工程学院,山东 青岛 266590
- 折叠
摘要
结合沁水盆地中高阶煤样品NMR饱和及离心T2 谱分布曲线,将中高阶煤样划分为三种类型.分析了单重分形和多重分形模型对中高阶煤样孔径分布定量表征的适用性,并综合孔隙结构和储层物性参数揭示了孔隙分形特征.表明A类样品T2 值在1～1000 ms之间,饱和T2 谱分布呈"单峰态",以大孔隙发育为主,物性条件较好.B类样品T2 值主要为 0.1～300 ms,T2 谱呈对称状"三峰态",束缚水饱和度相对较高,平均孔隙度和渗透率均小于A类.C和D类样品T2 值分别为0.01～200 和0.01～10 ms之间,饱和T2 谱分布均呈"单峰态",孔渗结构最差.单重分维值与孔隙度、T2 cutoff 等物性参数具有良好的线性关系,主要适用于微孔相对发育的B、C和D型样品.同时,多重分形参数与单重分形参数间具有良好的负相关关系.受计算原理的差异性影响,小孔和大孔是影响单重分形参数变化的关键孔径,而介孔孔隙分布是影响多重分形参数变化的关键孔径.
Abstract
Based on the NMR saturation and centrifugal T2 spectrum distribution curves of high rank coal samples in Qinshui Basin,coal samples were divided into three types.Applicability of single fractal and multifractal models to the quantitative characterization of pore size distribution of middle and high-order coal samples was analyzed,and the pore fractal characteristics were revealed by integrating pore structure and reservoir physical parameters.The results show that the T2 value of class A samples is between 1～1000 ms,and saturated T2 spectrum distribution shows a"single peak",which is dominated by the development of macro-pores,with good physical conditions.The T2 value of class B samples is mainly 0.1～300 ms,the irreducible water saturation is relatively high,the pore development is relatively small under the influence of compaction,and the average porosity and permeability are less than that of class A.The T2values of C and D samples are between 0.01～200 and 0.01～10 ms,respectively.The saturated T2 spectrum distribution shows"single peak state",and the pore permeability structure is the worst.The single fractal dimension has a good linear relationship with porosity,T2 cut off and other physical parameters.Meanwhile,there is a good negative correlation between multifractal parameters and single fractal parameters.Small and large pores are the key pore sizes affecting the change of single fractal parameters,while mesoporous pore distribution is the key pore size affecting the change of multifractal parameters.
关键词
煤储层/孔裂隙/分形特征/分布非均质性Key words
coal reservoirs/pore-fracture/fractal dimension/pore size distribution heterogeneity引用本文复制引用
出版年
2024
NETL
NSTL
万方数据