Robert C. Ransom

Table of Retrievable Contents:

A CLARIFYING CONCEPT OF ARCHIE'S RESISTIVITY RELATIONSHIPS AND PARAMETERS.

A MODEL AND DISCUSSION

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SUMMARY OF EQUATIONS

TABLE 1

 EQUATION NUMBER PURPOSE Equation No. (1a) for Rwe 1 / Rwe = ( ϕe / ϕt ) 1 /Rw + (ϕne /ϕt ) 1 / Rwb Equation for Rwe for 100% water saturated environment. Involves two waters. Converts single-water to dual-water method. Equation No. (1b) for Rwe 1 / Rwe = ( ( Sweϕe ) / (Swtϕt ) ) 1 /Rw + (ϕne / ( Swtϕt ) ) 1 / Rwb Equation for Rwe for ≤ 100% water saturated environment. Involves two waters. Converts single-water to dual-water method. Equation No. (1c) for a a = Rwe / Rw For the a coefficient. Shows the conversion from Rw to Rwe. Equation No. (2a) for R0 R0 corrected = Ft Rwe For R0 in 100% water saturated rock. Equation No. (2b) for Rt Rt calculated = Ft Rwe For Rt calculated in ≤ 100% water saturated environment. Equation No. (3a) for Ft Ft = 1.0 / (Swtϕt ) m2 = 1.0 / (ϕt m1 ) For Ft conversion from oil-bearing environment to 100% water saturated environment. Equation No. (3b) for Ft Ft = 1.0 / ( Swtϕt ) m2 For universal Ft in ≤ 100% water saturated environment. Equation No. (3c) ( Swtϕt ) m2 = ( Swt ) n ( ϕt ) m1 Exponent equivalence equation. Equation No. (3d) r ohms = ( ( L / A ) m / m2 ) ( R ohms m2 / m ) Converts resisitance to resistivity and converse. Equation No. (4a) for Rt Rt measured = ( 1.0 / ( (Swtϕt ) m2 ) ) aRw = ( 1.0/( (Swtϕt ) m2 ) ) Rwe Calculates Rt while using single-exponent m2 saturation method. Equation No. (4b) for Swt Swt n= ( 1.0 / ( ϕt m1 ) ) ( Rwe / Rt measured ) Dual-water Archie equation using two exponents, m and n, from the triangle CDG of the model. Equation No. (4c) for Swt Swtn = R0 corrected /Rt = (Ft Rwz )/( Ft Rwa ) = Rwz / Rwa Water saturation equation from Figure 4, utilizing graphic determination of Rz . Equation No. (4d) for Swt Swtm2 = (1.0 / ( ϕt m2 ) ) (Rwe /Rt measured ) Dual-water saturation equation using equivalent single exponent method from triangle AEG of the model. Equation No. (5a) for m m = ( log R0 - log Rw ) / (log1 - log ϕe ) Evaluation of m from raw data from triangle ABC of the model. Equation No. (5b) for m m = (log R0 corrected -log Rwe)/( log1 - log ϕt) Evaluation of m from corrected data. Equation No. (6) for Swe Swe = 1.0 - ( ϕt / ϕe ) ( 1.0 - Swt ) Calculation of water saturation in effective pore space. Equation No. (4b) solved for exponent n n = ( log Rt - log R0 ) / ( log1 - log Swt ) Calculation of exponent n in both water-wet and oil-wet environments. Equation No. (4d) solved for exponent m2 m2 = ( log Rt - log Rwe ) / ( log1 - log Swtϕt ) Calculation of exponent m2 in both water-wet and oil-wet environments.