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Unconventional oil and gas resources require petrophysical logs to answer the question “How to optimize the geological and engineering sweet spots?”. Therefore the establishment of key well with comprehensive descriptions of lithology, reservoir property, hydrocarbon bearing property, electronic well log responses, source rock property, brittleness, and in situ stress magnitude and direction is important for exploration and production of unconventional hydrocarbon resources. Cores, thin section, scanning electron microscopy (SEM) and comprehensive well log suits are used to build a key well of the Permian Lucaogou Formation, Jimusar Sag of Junggar Basin. The results show that there are mainly three types of lithologies including siltstone, mudstone, and dolostone. Lithologies can be predicted using the combination of conventional well and image logs. The pore spaces consist of interparticle pores, intragranular dissolution pores, and micropores. Nuclear Magnetic Resonance (NMR) T2 components longer than 1.7 ms are superposed as effective porosity. Permeability is calculated using the Coates model from NMR T2 spectra. The ratio of T2 components >7.0 ms to the T2 components >0.3 ms is used to calculate oil saturation. TOC is calculated using ΔlogR method. Brittleness index is calculated using Poisson‐ Young's method, and brittleness index ranges from 13.42%–70.53%. In situ stress direction is determined, and in situ stress magnitudes (Maximum horizontal stress SHmax, Minimum horizontal stress Shmin, Vertical stress Sv) are calculated using density and sonic logs. The strike‐slip stress type (SHmax>Sv>Shmin) is encountered. The key well which comprehensively includes the above seven properties is established. Then geological and engineering (geomechanical) sweet spots are optimized from the key well by fully analyzing lithology, reservoir property, oil bearing potential, in situ stress magnitude and brittleness. The results are hoped to support engineers' and geologists' decisions for exploitation of unconventional hydrocarbon resources.

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