Integrated Geologic Analysis From Two Marcellus Shale Science Wells in Northeastern West Virginia

Abstract

The Marcellus Shale Energy and Environment Laboratory (MSEEL) consists of four horizontal production wells, and two special purpose vertical science wells to better understand the detailed geology of the Lower Devonian organic-rich Marcellus Shale and other shallower shale units. All activities are in coordination with the Department of Energy and the operator Northeast Natural Energy. Understanding the vertical and lateral distribution of the shale lithofacies is critical to decipher the impact of depositional, diagenetic and geomechanical environments on hydrocarbon generation and production. Integrated geological and petrophysical characterization of the Marcellus and surrounding Onondaga through Mahantango units was performed using core, sidewall cores and well log data. Mineralogy and Total Organic Carbon (TOC) content were estimated using triple combo logs and advanced logging tools (e.g., spectral gamma, lithoscanner, and nuclear magnetic resonance) calibrated to core data (XRD and source-rock pyrolysis). A series of multi-mineralogical models were used to understand the petrophysical heterogeneities of the shale units. Based on the mineralogy and organic content the Devonian Marcellus-Mahantango interval is composed of six shale lithofacies. Integrated petrophysical analysis shows that three well developed organic mudstone facies are present in the Marcellus interval. Correlation of spectral gamma derived uranium content and organic carbon proportion indicates the highly organic mudstone (TOC> 7 weight percent) facies in the lowest part of the Marcellus Shale was deposited in a highly anoxic environment compared to overlying units. Bin porosities from the nuclear magnetic resonance log indicate that organic-rich mudstone facies contains pore sizes greater than 10 nanometers.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016