天然气工业2026，Vol.46Issue(2)：35-45,11.DOI:10.3787/j.issn.1000-0976.2026.02.004
基于核磁共振和高压压汞的孔喉半径确定方法
Method for determining pore-throat radius based on NMR and HPMI
摘要
Abstract
The conversion coefficient determines the accuracy of converting nuclear magnetic resonance(NMR)transverse relaxation time into pore-throat radius.To evaluate the applicability of different conversion methods,the linear correlation expression and power function expression for the conversion coefficient were compared,following the fundamental principles of NMR.Guided by the objective fact that the NMR pore-throat distribution encompasses the high-pressure mercury injection(HPMI)pore-throat distribution,three constraints were derived and then used to determine the upper and lower limits of the transverse relaxation time corresponding to the maximum and minimum HPMI pore-throat radii,respectively.Then,the range of conversion coefficient was defined,and a rationality evaluation chart for conversion results was constructed.Subsequently,a dual-eigenvalue method for calculating the conversion coefficient was proposed.Finally,the applicability of different conversion methods was evaluated,and corresponding correction methods were provided.The following results are obtained.First,the maximum pore-throat radius from HPMI and its corresponding upper limit of transverse relaxation time determine the lower limit of the conversion coefficient,while the minimum pore-throat radius from HPMI and its corresponding lower limit of the transverse relaxation time determine the upper limit of the conversion coefficient.Second,the dual-eigenvalue method takes the minimum and maximum HPMI pore-throat radii as eigenvalues,determines their corresponding approximate transverse relaxation times via the established constraints,and thereby calculates the conversion coefficient.Third,the dual-eigenvalue method yields a coincidence rate of 100%,and the cumulative saturation method also achieves 100%when curve shapes are similar.In contrast,the maximum eigenvalue method shows a coincidence rate of 80%when the maximum mercury injection saturation exceeds 40%.After correction,both the cumulative saturation method and the maximum eigenvalue method achieve 100%,without sensitivity to variations in maximum mercury injection saturation or curve shapes.The study concludes that the value range of the conversion coefficient,feasibility assessment templates,and dual-eigenvalue approach collectively address the challenges of inflexibility and inaccuracy in existing methods.The proposed correction technique,which enhances existing evaluation frameworks,provides reliable technical support and reference for the accurate evaluation of tight sandstone pore-throat structures.关键词
核磁共振/高压压汞/横向弛豫时间/孔喉半径/转换系数/合理性判断图版/双特征值法/致密砂岩Key words
NMR/HPMI/Transverse relaxation time/Pore-throat radius/Conversion coefficient/Rationality evaluation chart/Dual-eigenvalue method/Tight sandstone分类
能源科技引用本文复制引用
张磊,王香增,倪军,宋珈萱,王凯,乔向阳,张建锋,吴克柳..基于核磁共振和高压压汞的孔喉半径确定方法[J].天然气工业,2026,46(2):35-45,11.基金项目
国家自然科学基金项目"非常规储层纳米孔中水驱气动态润湿机理与传输特性"(编号:52174041)、陕西省创新能力支撑计划项目"致密砂岩储层气水微观渗流机理研究及应用"(编号:2024ZC-KJXX-132)、陕西省自然科学基础研究计划项目"多层合采气井全阶段产能劈分及预测研究"(编号:2025JC-YBMS-644). （编号:52174041）
