Multiple Linear Regression Approach For The Permeability Calculation From Well Logs: A Case Study in Nahr Umr Formation - Subba Oil Field, Iraq

The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. Nahr Umr reservoir in Subba oil field is a heterogeneous clastic reservoir. The calculations of the permeability was based on rock types delineation from well logs data. The methods that have been used for the rock types classification are; the rock-quality-index (RQI), flow-zone-indicator (FZI), and Discrete-rock-typing (DRT). It has been recognized that excellent permeability-porosity relationships were obtained after conventional core data are grouped according to their rock types. Conventional core data analysis were first used to define the rock types for the cored intervals, the data analysis from 7 plugs taken from 7 wells in Subba oil field were used for this purpose. The wireline log measurements at the cored depths were extracted, normalized, and subsequently analyzed together with the calculated rock types. The resulted mathematical model can be used to predict the rock type in cored intervals and in uncored wells through (DRT) prediction. This allows the generation of a synthetic rock type log for all wells. The permeability model is constructed as a function of a number of wire line measurement?logs data (sonic, gamma ray, neutron porosity, deep indication, spontaneous potential, bulk density, porosity, and shale volume). The wells that chosen to apply this procedure that contains core data, and logs-data together. These wells cover a wide range area of the Subba field. The permeability function contains 9-parameters, the values of these parameters are calculated by employing multiple linear regression for each rock type. High correlation coefficients were obtained for all resulted equations used for calculated permeability compared to the core permeability, the resulted equations enable to calculate permeability in non-cored intervals in all wells for each rock type.