Complex reservoir geometries can influence the results obtained from transient production decline analysis. For tight gas reservoirs it is common to observe limited drainage areas and linear flow geometries. In some cases these results are inconsistent with the expected geological structural and depositional character of the reservoir. Complex reservoir geometries and flow conditions such as liquid loading can contribute to this phenomenon. Numerical simulation cases will be used to generate the control data sets to demonstrate these effects. This paper will show the effects of complicated reservoir flow conditions on the results obtained from production analysis.

Production analysis is commonly performed in tight gas reservoirs as the analytical technique can be used to quantify reservoir flow capacity, gas in-place, and reservoir geometry (both area and aspect ratio). The results have been used to estimate the effective drainage area, infer completion efficiency and evaluate potential infill drilling spacing for tight gas reservoirs. Complex reservoir cases considered in the paper include stress dependent permeability in both single and dual porosity reservoirs, radial composite systems, and multi-layered reservoirs. From a completion point of view the paper presents the effects of fracture clean-up, fracture damage over time, and the effects of liquid loading on transient production behavior.

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