This paper adopts and improves the existing workflows for integrated production data analysis. Clarkson (2013) presented an integrated production data analysis workflow through incorporating existing models and methodologies. Despite great achievements, some additional improvements are required to address the complexities associated with reservoir/fluid properties in shale plays. Some of the improvements are as follows. A new iterative algorithm is introduced toward integrated evaluation, prediction, and optimization of production in shale plays; the production contribution from unstimulated parts of the matrix (outside SRV) is considered; a new multi-phase productivity index is proposed; a new mechanistic formulation is presented to describe Dynamic-Drainage-Volume (DDV) for both early transient linear flow and late compound-linear flow regime; a new pressure-saturation relation is established through relating fluid properties to production history. Moreover, geomechanics effects are coupled into material-balance model by introducing the pressure-dependent rock and fluid properties. The optimization of fracture and well spacing is achieved in Niobrara shale oil.