Changbei field, as one of the largest onshore sedimentary basin in China, is situated at North Shaanxi Province, Ordos basin. The main tight gas reservoir deposits in the Upper Paleozoic, Lower Permian Shanxi clastic Formation (P1S2). The combination of 2km long single and dual-lateral barefoot horizontal wells is successfully used to drill from surface location "clusters" into the lower Permian Shanxi (P1S2) Formation to maximize the gas production. Several key geological uncertainties which control the optimal landing of the 12¼" well trajectory and placement of the 8 ½" hole in the reservoir along with the delivery of the 2 km horizontal well length have been identified: 1. Top reservoir prognosis, 2. Reservoir thickness prediction and 3. Spatial distribution of unstable carbonaceous claystone bodies within and along marginal reservoir areas. And relevant improvement plans that have been put in place to mitigate the operation challenges had been analyzed.

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