This paper presents a method to estimate induced fracture properties and reservoir geometry in multilayered gas reservoirs similar to the Travis Peak formation in East Texas. The Travis Peak is characterized by commingled production from small, high-permeability channel sands and blanket low permeability formations. Our specific objectives are to estimate fracture half-length, fracture conductivity, and area of the small, high-permeability layer in a two-layer reservoir system similar to the Travis Peak.

In this study, we developed constant rate drawdown type curves applicable for analyzing pressure buildup tests which follow production at constant bottomhole pressure. The results obtained from our type curves are used only as a starting point for a more rigorous numerical simulation (history-matching) study.

Our type curves assume the small, high permeability sand is a "channel" deposit, which is modeled with a 2×1 rectangle, whereas we assume the larger, lower permeability layer is a blanket-like deposit which can be modeled as a 160-acre square. A single vertical fracture of finite conductivity intercepts the wellbore and completely penetrates each layer, extending down the short side of the 2×1 rectangle.

Even though this paper presents a specific solution for a specific type of layered reservoir, it illustrates a general approach for analyzing other layered reservoirs with induced fractures and known geometry in the layers.

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