Cost-Effective Reservoir Characterization from Advanced Surface Logging Technologies in Unconventional Reservoirs

摘要

Unconventional reservoirs can have significant vertical and horizontal heterogeneity in the formation. It is important to understand these spatial changes, whether they are mineralogical or structural. Open natural fractures contribute significantly to production in these reservoirs. The challenge is how to accurately identify the open natural fractures to help optimize completion strategy and improve production. In this paper we show how advanced surface mud logging techniques help identify open natural fractures and structural faults from detection of light gases like helium and methane while drilling. These techniques are validated by correlating with new generation oil-based image logs. In recent years, significant improvements are seen in surface logging techniques from analyzing mud gas and drill cuttings. These improvements have led to new sophisticated methodologies to petrophysically and geochemically characterize the reservoir rocks and the production fluids. Early characterization of these reservoir properties adds significant value in optimizing drilling and designing completions. Sophisticated surface logging technologies can now provide a more cost-effective solution to reservoir characterization when compared to running more expensive downhole logging tools. Correlating the reservoir rock properties from geochemical composition of the rock to evaluate heterogeneity along the lateral length is achieved using advanced mud-gas evaluation methods. Which include net mud gas measurement, stable carbon isotopic ratios, and elemental spectroscopy using the X-Ray Fluorescence (XRF) technique. Besides the primary aspect of fracture identification other measurements like identifying drill bit metamorphism by detecting alkene hydrocarbons in drilling fluid can help optimize the drilling performance and prevent drill bit failures.