Analytical treatment of neutron-density crossplot for shaly sand reservoirs

Abstract EN

-The neutron-density crossplot represents the basis for analyzing the shaly sand reservoir and coded as SARABAND program.

In this paper, a mathematical formulation for obtaining the volume fractions of the three types of shale (laminated, structural and dispersed) is established.

The computational sequence involving porosity (Φ) besides the total, laminated and dispersed water saturation calculation models.

The effect of light hydrocarbons is also incorporated.

The technique depends primarily on the neutron and density logs as shale indicators.

This can avoid the use of gamma ray log, hence the confuse with other radioactive elements.

The actual well log data representing the Abu Madi Formation, level III sands in East Baltim-1X and El-Qar’a-2 wells, in addition to the sands of Wakar Formation of Port Fouad marine-3 well were chosen for application.

The results obtained revealed a predominance of structural and laminated shales in case of level III sands of the Abu Madi Formation.

The simplified laminar water saturation model (SwL) is considered adequate.

Wakar sands in Port Fouad marine-3 well, according to the used technique, contain the three types of shale.

The total shale model for calculating the water saturation (SwT) is favorable in this case.

The production history and the Drill Stem Test (DST) data supported the results obtained and consequently confirmed the validity and accuracy of this technique.