Case Study: Woodford Shale Source Rock Characterization by Geochemical and SEM Evaluation in a Horizontal Well
The benefits to hydrocarbon exploration from geochemical and scanning electron microscope (SEM) analyses have been known for many years. Yet the advent of smaller, cheaper and more specialized equipment is now providing the ability to make highly precise and critical measurements during the drilling process rather than having to wait for weeks or even months to obtain the results. When this data is coupled with standard surface logging techniques of gas and formation analysis, they provide valuable information about the reservoir that will help with current production of the subject well and future development planning.
For this case study, several instruments were used in a mobile laboratory during the drilling of a Woodford horizontal well on cutting samples taken at regular intervals, including:
Gas Chromatography Isotope Ratio (GCIR) II for Gas Isotopes (proprietary),
Niton X-Ray Fluorescence (XRF), and
Hitachi TM–3030 SEM.
The Rock Eval pyrolysis provided data on producible hydrocarbons, thermal maturity and total organic content in each sample. The GCIR II analyzed the gas isotopes from both isotubes and isojars yielding data on C1, C2, and C3 isotopes. These data provided insight into permeability, porosity, and provided information on hydrocarbon compartmentalization and differentiation from oil based mud (OBM). XRF analysis was able to quantify the elemental composition of the cutting samples, providing an understanding of the best locations to fracture based on silica content, changes in mineral composition, and an indication of total organic carbon (TOC). Petrographic analysis was done using the SEM. This instrument gave direct observation of both microstructures and available pore space. In turn this data gave corroboration to the previous geochemical and elemental analysis.
AAPG Datapages/Search and Discovery Article #90219 © 2015 GCAGS, Houston, Texas, September 20-22, 2015