Identification and Applications of Micro to Macroscale Shale Lithofacies

Area of Science:

• Geosciences
• Petroleum Engineering
• Sedimentology

Background:

• Systematic evaluation of shale gas reservoirs is crucial for exploration and development.
• Previous experimental analyses for shale gas reservoirs are often overly simplified.
• Need for an integrated approach combining geological and engineering methods.

Purpose of the Study:

• To develop and validate an integrated geological and engineering method for shale gas reservoir evaluation.
• To establish a lithofacies division system and identification technology for micro to macroscale analysis.
• To improve the accuracy and efficiency of shale gas exploration and development.

Main Methods:

• Developed a lithofacies classification system based on lithology, total organic carbon (TOC), and brittle mineral content.
• Applied sequence and thin layer interfaces to longitudinally divide organic matter-rich shales into 7 lithofacies.
• Created marine shale lithofacies identification technologies using conventional logging, image logging, and logging summarization.

Main Results:

• Successfully classified shale lithofacies in the Upper Ordovician Wufeng to Lower Silurian Longmaxi Formations.
• Identified organic carbon-rich, high-silicon lithofacies as the most favorable for shale gas reservoirs.
• Demonstrated successful application of the lithofacies technology in the Fuling gas field and other Sichuan Basin areas.

Conclusions:

• The integrated lithofacies method provides a comprehensive approach to shale gas reservoir evaluation.
• The developed lithofacies identification technologies are efficient and applicable for field site applications.
• This method enhances shale formation comparison, horizontal well drilling analysis, and fracturing stage assessment.