Energy consumption is increasing, while production from conventional reservoirs is declining. The unconventional resources, including shale oil/gas, tight oil/gas, coalbed methane and natural gas hydrates are gradually playing a more important role in offsetting this shortage. Due to the low porosity and ultra-low permeability of unconventional reservoirs, more challenging and different solutions are required to characterize, optimize and manage reservoirs. Advanced evaluation theories and development techniques have been well established and tested in laboratories and fields in the past decade. Hydraulic fracturing, micro/nano scale pore characterization, fracture reservoir modeling and sweet-spot prediction are proposed to promote global unconventional oil and gas development. The powerful machine learning algorithm and models also help solve problems in reservoir characterization due to the availability of high-performance computational resources in recent years.

Despite the recent advances and techniques, unsolved problems with reservoir characterization and development remains. Some drilling wells still have no economic production even though hydraulic fracturing is conducted in the production layer. The complex rock-fluid interactions lead to significant heterogeneity of the pore-crack network. The relatively short production span observed in unconventional reservoirs also increases the uncertainty of hydrocarbon production. Hence, more novel solutions are required to optimize drilling and completion, and improving recovery efficiency should combine geological and engineering methods. Geological factors control the fundamental properties of hydrocarbon reservoirs, while the engineering approaches are closely related to the drilling practice and development results.

This Special Issue aims to cover the recent pressing challenges and inspiring advances in reservoir characterization, optimization and management from geological and engineering aspects. We sincerely invite prospective authors to submit high-quality original articles or reviews regarding how to promote unconventional oil/gas development, especially by integrating geological and engineering theories and methodologies.

Potential topics include but are not limited to the following:

• Sedimentary environment and genesis mechanism of fine-grained rocks
• New advances of reservoir geochemistry
• Pore evolution and structure of reservoirs
• Hydrocarbon generation and enrichment
• Physical properties, occurrence and mobility of oil/gas
• Oil and gas exploration in onshore and offshore areas
• Drilling, completion, hydraulic fracturing, and related reservoir damage and stimulation
• Characterization of natural fractures and hydraulic fractures
• Fluid flow behavior in the matrix and fracture
• Enhanced oil/gas recovery through physical and chemical methods
• Prediction of oil/gas production rate