This paper presents a discussion and interpretation of a variety of transient pressure responses observed in nine flow and buildup surveys performed in horizontal wells in the Sole Pit area fields Barque and Clipper. Horizontal well pressure transient flow regimes and signatures associated with heterogeneous reservoirs are observed in the survey log-log pressure derivatives. The signatures show considerable variability and emphasize the strongly heterogeneous nature of the reservoirs. Rapidly declining transmissibilities in the vicinity of the wellbore are observed in two surveys, while other survey log-log derivative responses suggest a dual-porosity characteristic followed by horizontal well intermediate-time linear flow. Pressure transient testing contributes to an understanding of the reservoir behavior by revealing essential characteristics of a flow model that can describe flow in the heterogeneous, fractured sandstone.