Abstract

Several years ago, Mr. Tony Messenio chief log analyst with Atlantic-Richfield Company gave his log library to Texas Tech when he retired. Included in this library are numerous publications on “Old” [pre-1958] well log analysis. While reviewing these older publications to prepare my new well logging class entitled “Old” [Pre – 1958] Electric Logs [a Quick Review], I came across a publication by Tixier (1956) outlining a method he called MAXIMUM PRODUCIBLE OIL INDEX (Y). This method was designed to determine Mobile OOIP using only resistivity logs together with the formation water resistivity (Rw) and the resistivity of the mud filtrate (Rmf). Y = (Rmf/Rxo)∧0.5 – (Rw/Rt)∧0.5 where [Y] represents the amount of oil per unit volume which is displaced by mud filtrate (Tixier, 1956). With this method Mobile OOIP can be determine without knowledge of water saturation (Sw), Porosity (F), and Residual Oil Saturation (RHS).

In order to test the application of Maximum Producible Oil Index (Y) Mobile OOIP(stb) was calculated using standard volumetric calculations on two wells with modern logging suites, and compared with Mobile OOIP(stb) using the Maximum Producible Oil Index (Y) Method. The results are listed below:

Ordovician Gunton Dolostone Williston Basin

North Dakota [Salt Mud]

Drainage = 160acres (assumed) BOI = 1.2 (assumed)

Mobile OOIP(stb) = 1,018,884bo (Volumetric)

Mobile OOIP(stb) = 1,033,365bo (Maximum Producible Oil Index)

Cretaceous Glen Rose Limestone East Texas [Fresh Mud]

Drainage = 40acres (assumed) BOI = 1.2 (assumed)

Mobile OOIP(stb) = 208,949bo (Volumetric)

Mobile OOIP(stb) = 220,844bo (Maximum Producible Oil Index)

Next OOIP(stb) and OGIP(stb) were determined from two “Old” E – Logs using the Maximum Producible Oil Index Method. The results are listed below:

Permian Bone Springs Formation South East New Mexico [Salt Mud]

Drainage = 40acres (assumed) BOI = 1.2 (assumed)

Mobile OOIP(stb) = 87,905bo (Maximum Producible Oil Index)

Pennsylvanian Morrow Sandstone Oklahoma Panhandle [Fresh Mud]

Drainage = 640acres (assumed)

Mobile OGIP = 18.4bcf (Maximum Producible Oil Index)

The Maximum Producible Oil Index Method may very well provide a reliable way to determine Mobile OOIP with “Old” logging suites when working in studies of older fields.