ECS-研究成果-Matrix density and Porosity-阅读笔记4

title: "ECS-研究成果-阅读笔记4"

Matrix density and Porosity

  • Paper:Application Of Nuclear Spectroscopy Logs To The Derivation Of Formation Matrix Density
  • PaperAuthors:Susan L. Herron ,Michael M. Herron (Schlumberger Doll Research)
  • Document ID:SPWLA-2000-JJ *Source:SPWLA 41st Annual Logging Symposium, 4-7 June, Dallas, Texas
  • Publication Date:2000
  • Publisher:Society of Petrophysicists and Well-Log Analysts
  • Language:English
  • Copyright:2000. Society of Petrophysicists & Well Log Analysts

Formation matrix properties, such as matrix density, can be estimated from the elemental concentrations available from modern, openhole, nuclear spectroscopy logging techniques. Although this estimation is similar to that of mineral-based interpretation frequently practiced today, it can preempt the a priori selection of minerals by solving for matrix properties directly from the elements. This simple approachgreatly enhances the ability to perform wellsite interpretations in both simple and complex formations.The interpretation for the matrix density is derived from a comprehensive database containing hundreds of core samples analyzed for both mineralogy and chemistry. The chemical analysis includes not only the major elements, but also the minor and trace elements that significantly influence wireline log responses. These data are used to forward model the matrix which is then solved as a linear combination of four elements (silicon, calcium, iron, sulfur) that are measured by prompt neutron capture spectroscopy. Comparisons are shown between measured and derived matrix density along with statistical measures of goodness of fit. Although in many cases the errors could be reduced by local optimization, the overall agreement is quite good.Although matrix density is empirically derived, the rationale is straightforward. For example, in sandstone, matrix density is approximately equal to that of quartz and feldspar, and it increases as the concentration of calcium- and iron-bearing minerals increases. Therefore calcium and iron heavily influence matrix density. The feldspar minerals are less dense than quartz and are not well sensed by the elements Si, Ca, Fe, and S. Therefore, separate algorithms are presented for non-arkosic, sub-arkosic, and arkosic environments.


  • 骨架密度:Matrix density
  • 体积密度:Bulk density

有的地方好像把Bulk density也叫做块密度,把Matrix density叫住真密度??


Denbulk × Vbulk = Denmatrix × Vmatrix +Denfluid × Vfluid


Vbulk = VMatrix + V_fluid

而Vfluid也就是Vbulk × Porosity

即:Vbulk = (1 - Porosity) × Vbulk +Porosity × V_bulk


Porosity=(Denmatrix - Denbulk)/(Denmatrix -Denfluid)




  • 2620+227Ca+1990Fe+4.9Si+1190S

Mineral:1/Denmatrix = Σ(Mi/Den_i)


  • M_i——第i种矿物的含量

  • Den_i——第i种矿物的密度



  • 黄铁矿 5.01
  • 磁铁矿 5.26
  • 石英 2.65
  • 斜长石 2.61-2.75
  • 方解石 2.71
  • 铁白云石 2.97
  • 硬石膏 2.9-3.0
  • 石 膏 2.3-2.37
  • 重晶石 4.3
  • 钙芒硝 2.75-2.85
  • 浊沸石 2.25-2.36
  • 粘土矿物
  • 天青石 3.97-4
  • 辉 石 3.2-3.4
  • 菱镁矿 2.9-3.1
  • 白云石 2.85
  • 钾长石 2.54-2.57



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