--> Abstract: Water Saturations in a Wilcox Shaly Reservoir Sandstone, Fordoche Field, Point Coupee Parish, Louisiana, by C. R. Berg and R. R. Berg; #90950 (1996).

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Abstract: Water Saturations in a Wilcox Shaly Reservoir Sandstone, Fordoche Field, Point Coupee Parish, Louisiana

Charles R. Berg, Robert R. Berg

A new equation has been derived for calculation of water saturations in shaly reservoir sandstones. The equation is based on effective medium theory (EMT) and has been used successfully on a wide range of clayey, low-resistivity reservoirs. A further, independent test of saturations calculated by the equation was made for a deep Wilcox shaly reservoir at a depth of 13,176 ft (4016 m) in Fordoche field. The reservoir (W8) has a low, average resistivity of about 2.5 ohm-m and an estimated 18% clay as compared to an average resistivity of 1.5 ohm-m in an underlying water-saturated sandstone (W-10) of similar clay content. For the reservoir, calculated water saturations are in the range of 35 to 50%, increasing downward, and suggest that the shaly sandstone should produce wat r-free oil. For the underlying wet sandstone, the calculated water saturations range from 55 to 75% and confirm that only water should be produced. Other shaly sand equations generally give water saturations in excess of 50% for the reservoir. Water saturations calculated by the EMT equation agree well with other parameters for sandstones: reported production, core, analysis, and synthetic capillary pressures. The reservoir (W8) had an initial potential of 213 bbl of oil per day, confirming water-free oil production which could have been predicted by the EMT equation.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas