Constant producing pressure semi-analytical solutions have been developed for decline curve analysis of hydraulically fractured wells with finite or infinite conductivity in dual-porosity systems. The solutions have led to the identification of the following flow periods:

  1. A linear flow period characterized by a straight line with a 0.5 slope in a log-log crossplot of qD vs. tD. This occurs in the case of an infinite conductivity vertical fracture. If the fracture has finite conductivity, the early straight line has a slope equal to 0.25.

  2. A transition period due to flow from the matrix into the fractures.

  3. A pseudo radial flow period toward the hydraulic fracture.

  4. A pseudo steady state flow period when the outer boundaries of the reservoir are reached.

It is concluded that recognition of these flow periods can lead to calculation of fracture permeability, hydraulic fracture half-length, distance between natural fractures, and the parameters omega and lambda.

Type curves have been developed to facilitate reservoir characterization. Their use is illustrated with an example.

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