In this paper, we present a new method for analyzing a multi-layered, commingled reservoir with unequal initial layer pressures. The main objective is to provide techniques and methodology to determine the individual layer permeabilities, porosities and skin factors from the pre-production well test data. The layer information obtained early in the life of the reservoir is very important for planing production schedule and economic decisions concerning the future of the wells. This pre-production well test is carried early in the life of the reservoir, during the period after perforation but before any surface production and is caused by crossflow in the wellbore only.
The results of this study provide a useful foundation for the design of a new pre-production well test procedure that ensures that the individual layer properties are measured adequately and early in the life of th6 reservoir when they are most needed.
The pre-production well test requires no production on surface. Thus, the environmental impact caused by flaring oil or gas during a conventional well test is alleviated.