Multilayer reservoirs are currently modeled as a single zone system by averaging the reservoir parameters associated with each reservoir zone. However, this type of modeling is rarely accurate because a single zone system does not account for the fact that each zone's pressure decreases independently. Pressure drop for each zone has an effect on the total output and would result in inter-flow and the premature depletion of one of the zones. Understanding reservoir performance requires a precise estimation of each layer's permeability and skin factor. The Multilayer Transient Analysis is a well-testing technique designed to determine formation properties in more than one layer, and its effectiveness over the past two decades has been demonstrated. In order to conduct MTA, a combination of rate profiles derived from production data and transient rate and pressure measurements at multiple surface rates is necessary. Numerous experimental and analytic approaches to calculating multilayer characteristics, performance, and flow behavior in multilayer systems have emerged. This technology was implemented at the Zubair oil field in southern Iraq. In the last four years, the number of wells producing under saturation pressure has been increased in the Zubair oil field, particularly for the Mishrif and Zubair reservoirs. In the design of secondary and tertiary recovery, the study of the reservoir in the form of an individual layer to determine the pressure, permeability, and damage of each layer with commingled formation is important. This research describes previously available methods, factors that affect Multilayer Transient Analysis an economic indicator of Multilayer Transient Analysis and a case study
