Geological characterization and modeling of the Cypress Sandstone at Noble Field, Southeastern Illinois

Abstract

The Mississippian Cypress Sandstone is a prolific oil producing horizon in the Illinois Basin, with production typically from NE-SW oriented tidal bars. However, a thick Cypress Sandstone fairway, deposited as part of an incised valley fill system that eroded the older Cypress tidal bars, lies in the central part of the Basin. The thick Cypress Sandstone can exceed 46 m and, in places, contains a relatively thin oil reservoir in the top. These oil reservoirs have low primary recovery due to excessive water coning and are an unproduced oil resource in the Basin, but recent horizontal drilling in these zones has had some success. Such reservoirs provide an economic incentive to mitigate greenhouse emissions via nonconventional carbon dioxide (CO₂) enhanced oil recovery (EOR) by storing more CO₂ compared to oil reservoirs conventionally flooded with CO₂.

Noble Field, discovered in 1937 in Richland County, Illinois, includes some of the Basin's most productive thick Cypress Sandstone reservoirs. Geophysical log correlation and mapping over more than 259 km² indicates a generally east-west trending sandstone body nearly 4.8 km wide and up to 52 m thick. The thick Cypress Sandstone at Noble Field has 15–19% porosity and permeability values that can exceed 1 Darcy with an oil column that can surpass 6 m. Sedimentary facies analysis of available core is being conducted to better understand the depositional environment and internal heterogeneity of the reservoir.

This presentation focuses on detailed geologic characterization of the Cypress Sandstone at Noble Field, leveraging a large and diverse dataset typical of Illinois Basin oil fields to evaluate potential economic CO₂-EOR and storage with aims to extrapolate findings to other areas of the Basin. Geologic characterization, in conjunction with digital porosity log data from over 130 wells, is being used to create a three-dimensional geocellular model that represents the internal architecture of the reservoir for use in reservoir simulations. Historical records are being used to establish the production history by lease to set the initial conditions of the model for hypothetical CO₂ injection scenarios. Preliminary results of detailed characterization and three-dimensional geocellular modeling at Noble Field will be presented.

AAPG Datapages/Search and Discovery Article #90218 © 2015 Eastern Section Meeting, Indianapolis, Indiana, September 20-22, 2015