Ibrahim M Al-Goba¹, Rami A Kamal¹, Ahmed Q Hameda¹

(1) Saudi Aramco, Dhahran, Saudi Arabia

ABSTRACT: A New Technique to Predictively Map Occurrences of Abnormally High Permeabilities in the Arab D Reservoir, Ghawar, Saudi Arabia

Parts of the Arab D reservoir across Ghawar Field are plagued by premature, erratic and unpredictable injected water encroachment due to the existence of abnormally high permeability pathways. When it occurs, this irregular sweep plays havoc with reservoir performance simulation history matching. In 1997 a project was launched at Saudi Aramco to create super permeability (Super k) risk assessment maps (RAMs). These are maps that predict the probability of encountering Super k. A special technique was developed to create these RAMs.

Across a large area in central Ghawar, 226 wells were chosen for the project. Intervals where super k occurrence was documented by reservoir engineering were carefully identified and QCed. The occurrence of Super k was considered as a modelling attribute in itself. A simple binary coding system was used. At six-inch intervals, all super k occurrences were coded as 1. All other depths were coded as 0. Advanced stochastic modelling software was then used to create and laterally distribute super k facies for each of the resultant 220 layers.

The super k facies distribution patterns were then validated against cases where unexpected watering out occurred in updip producers. These RAMs are a major breakthrough in our ability to predict areas of potential super k. Efforts will continue to upgrade these maps using other geological and geophysical data.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado