Performances of Openhole Completed and Cased Horizontal/Undulating Wells in Thin-Bedded, Tight Sand Gas Reservoirs

摘要

With the recent advancements in drilling technology, drillingundulating wells, which specifically target various zones in areservoir, has become a rather routine application. Inaccordance, drilling engineers are able to steer the well tocoincide with pre-established sinusoidal trajectories. Thisadvancement in drilling practices calls for the enhancement ofour understanding of the production characteristics ofundulating wells. This paper provides an in-depth comparativeanalysis of production performances of open-hole completedand cased horizontal/sinusoidal wells.Horizontal wells offer great advantages in thin-layered,tight sand gas reservoirs as they increase the productivitythrough a larger contact area with formations. In this study, acomprehensive performance comparison of open-hole vs.perforated horizontal wells in thin, tight sand gas reservoirs ispresented. This is accomplished using a 3-D, single-phaseflow model, which is capable of accommodating vertical,horizontal, undulating, perforated, and fractured wells. Effectsof drilling damage and crushed zones are considered in thesimulations. The parametric study presented in this paperincludes various phase angles, shot densities, perforationlengths, and number of fractures. Additionally, the studyconsiders effects of uneven perforation lengths on thetopology of the flow fields generated around the perforations.The flow performance comparison is further extended toundulating wells in thin-layered, tight sand gas reservoirs withshale streaks. In the presence of shale streaks, it is observedthat undulating wells, which penetrate individual isolatedlayers, perform more effectively than horizontal wells.