Density-Log Porosity
Compute a reservoir rock's porosity from the density log, φ = (ρma − ρb)/(ρma − ρf), where ρma is the matrix (mineral) density, ρb the bulk density read by the log and ρf the pore-fluid density. It is one of the most used petrophysical methods to estimate porosity in wells, since the bulk density drops as the pore volume (filled by less dense fluid) increases. Enter the matrix, bulk (log) and fluid densities.
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Porosidade por perfil de densidade
O perfil de densidade é uma das principais ferramentas para medir porosidade num poço. Uma fonte radioativa emite raios gama que interagem com os elétrons da rocha; quanto mais densa a rocha, mais raios são espalhados, e o detector lê uma densidade total (ρb) menor de fótons retornando. A porosidade sai de φ = (ρma − ρb)/(ρma − ρf): a rocha real (ρb) é uma mistura da matriz sólida (ρma, ~2,65 para arenito, ~2,71 para calcário) com o fluido nos poros (ρf, ~1,0 para água, menos para óleo/gás). Quanto mais poros (preenchidos por fluido leve), mais a densidade total cai abaixo da matriz — e essa queda mede diretamente a porosidade. Combinado com o perfil neutrônico, ajuda ainda a identificar o tipo de fluido e a litologia. Informe as densidades da matriz, do perfil e do fluido.
Related Tools
Water Saturation (Archie)
Compute a reservoir's water saturation (Sw) by Archie's equation (with a=1, m=2, n=2), Sw = √(Rw/(φ²·Rt)), from the formation-water resistivity (Rw), the rock's true resistivity (Rt) and the porosity (φ). It is the fundamental petrophysics equation: it relates the resistivity measured by electric logs to the fraction of pores filled with water — and, by complement (1−Sw), with hydrocarbons. Enter Rw, Rt and the porosity.
Reservoir Net Pay
Compute a reservoir's net pay (net productive thickness) by multiplying the gross interval thickness by the net-to-gross ratio (N/G), the fraction of rock with enough porosity and permeability to produce. Shale layers, tight rock or water zones are discounted. The net pay, not the total thickness, is what enters the oil and gas volume calculations. Enter the gross thickness and the net-to-gross ratio.
Sintering Relative Density
Compute the relative density of a sintered body, RD = (bulk density/theoretical density)·100%, the fraction of the maximum density (of the fully dense, pore-free material) the piece reached. It is the central measure of the degree of sintering: advanced ceramics aim for RD above 99% (almost pore-free) for maximum strength and properties. The residual porosity is 100% − RD. Enter the bulk (sintered) density and the theoretical density.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.