Sweet Spots Identification: Geological and Engineering Integrated Shale Gas: A Case Study of Shale Gas Ahnet Basin Algeria

Abstract

Shale was initially regarded mainly as a source rock, but it is now recognized as both a source and reservoir. This shift has led to increased investigation into its geological properties. Extracting oil and gas from low-permeability shale formations is made possible by horizontal drilling, maximizing wellbore-rock contact, and hydraulic fracturing, which enhances permeability. The identification of sweet spot involves considering factors like source rock richness, natural fractures, core analysis, well-log data, and gas data to strategically position wellbores for optimal productivity. This paper aims to locate the sweet spot at the Ahnet Shale Gas Field by applying a comprehensive methodology, proving its accuracy in identifying geological and engineering sweet spots. Geological factors included organic matter quantity, maturity, composition, clay type, and reservoir characteristics. Engineering assessment considered rock mechanics and brittleness index, forming a robust evaluation system. Three significant sweet spot zones were pinpointed based on well-logging and geological data. The geochemical analysis emphasized high-quality Silurian shale rich in type II marine organic matter. Fluid characterization through chromatographic analysis and mechanical properties assessment reinforced the methodology's efficacy, aiding optimal shale gas exploration site selection.