Woodford-Oklahoma Shale

Reservoir Characterization and Production Properties

Currently, numerous oil and gas companies are directing their efforts toward the exploration and exploitation of the liquids maturity window of the Woodford Shale in Oklahoma. This play began in the Cano field area and has recently expanded to the South Central Oklahoma Oil Province (“SCOOP”). The play may also expand to the north to include the Woodford on both sides of the Nemaha Ridge. Exploration and exploitation of the Woodford is expect to continue for several years and there has not been a comprehensive regional study of the Woodford that links reservoir properties to well performance.

The Integrated Reservoir Solutions Division of Core Laboratories is proposing to interested companies participation in a multi-company (operators’ consortium), geo-engineering, regional study of the Woodford Shale in Oklahoma. This project consists of the characterization and evaluation of numerous conventional cores, rotary sidewall cores, and drill cutting samples taken from multiple wells targeting the Woodford Shale. Specifically, the prospective Woodford section will be analyzed for geological, geochemical, petrophysical, geomechanical, and production properties. These data will be integrated with well logs, stimulation designs, and production test information. This large and searchable database will provide operators with valuable information not only on their own wells, but also on other operator’s wells.

Each company joining the project will be required to contribute core material from two (2) wells for analysis, evaluation, and inclusion into the database. The cores must be through the Woodford section. It is anticipated that conventional cores from a minimum of twenty-five (25) wells will be included in the project. Each company may also contribute drill cuttings and/or rotary sidewall cores from one “reconnaissance” well.

The primary objective of this project is to provide operators with measured geological, geochemical, petrophysical, geomechanical, and production properties of the Woodford Shale in order to improve their formation evaluation and to optimize stimulation and production. Our work suggests that understanding the similarities and differences in the section on a regional basis is the key to successful exploration and exploitation. The resultant database will be an invaluable tool to operators in evaluating, comparing, and designing completion and stimulation methods. Specifically, the project objectives are as follows:

  • Geologically characterize the cored intervals in terms of depositional facies, environment of deposition, and rock types.
  • Characterize and classify the Woodford Shale in terms of lithology, mineralogy, clay content, clay types, and pore structure including macro- and micro-fractures.
  • Measure the various petrophysical properties such as porosity, permeability, grain density, and saturations (i.e. water saturation, gas saturation, oil saturation, hydrocarbon filled porosity and bound water).
  • Measure and characterize the organic content of the mudstones in terms of total organic content (TOC), Rock Eval pyrolysis, and vitrinite reflectance. Oil extracts from the core will also be analyzed for oil quality.
  • Measure the key geomechanical properties that are required for optimizing fracture designs and/or horizontal wells such as Young’s Modulus, Poisson’s Ratio, Bulk Modulus, horizontal stress, and proppant embedment.
  • Determine rock-fluid compatibility and fracture conductivity of proppant and fluid-carrier systems in support of hydraulic fracture stimulation.
  • Core-log calibration of open-hole logs for the development of petrophysical models to determine potential “pay” zones for stimulation.
  • Integrate the core data with well logs, fracture stimulation techniques, and production test results to aid companies in their evaluation and exploitation of the reservoirs.
  • Provide a regional assessment of the various reservoir attributes to aid in exploration and exploitation.
  • Develop relationships from the database to aid in evaluating and comparing the various rock properties.
  • Provide operators with a searchable database for reservoir properties that can be used as analogs to aid in the appraisal and exploitation of new areas as the play expands.