DE-NT0005664

Goal
The goal of this project is to test the suitability of Alkaline-Surfactant-Polymer (ASP) flood technology as an enhanced oil recovery technique for increasing oil production from the two most productive reservoirs in the Lawrence Field of Lawrence County in the Illinois Basin. The ultimate objective of this project is to expand the employment of ASP flood technology from small, limited pilots in the Bridgeport and Cypress sandstones to the remainder of the Lawrence Field.

Performers
Illinois State Geological Survey (ISGS), , Champaign, IL 61820
Rex Energy Corporation, Bridgeport, IL 62417

Background
The Lawrence Field has produced in excess of 410 million barrels of oil since 1906 utilizing both primary and secondary recovery (water flood) methods. The field currently produces with a less than two percent oil cut and, like many mature fields in the United States, is approaching its economic limit. This is despite the fact that Lawrence Field contains a significant volume of potentially recoverable oil. ASP flood technology offers some promise for recovering this remaining oil.

ASP flood test laboratory results have demonstrated that an estimated 130 million barrels of oil could potentially be extracted by employing ASP flood technology in the reservoirs of the Lawrence Field. However, ASP flooding is an untested technology in the Illinois Basin. This project presents an exceptional opportunity to perform and document field testing of this unconventional recovery technique in two of Illinois? most prolific reservoirs, the Lawrence Field-located Bridgeport and Cypress sandstones. Rex Energy has committed time, money, and materials to this effort.

Most of the unrecovered oil in the Lawrence Field is contained in Pennsylvanian Age Bridgeport sandstones and Mississippian Age Cypress sandstones. These reservoirs are highly complex and compartmentalized. Detailed reservoir characterization/simulation modeling, including the development of 3-D geologic and stochastic models of target areas in the field, is needed to identify areas with the best potential for recovery of remaining reserves. This remaining volume includes all unswept compartments and bypassed oil. The reservoir modeling will be completed as a prerequisite for the design of efficient ASP flood patterns.

This three-year project is designed to compile, interpret, and analyze the data required to conduct reservoir characterization, accounting for the geological complexities inherent to the Bridgeport and Cypress sandstones.

Impact
Recent coreflood tests utilizing ASP flood technology have produced conservative incremental oil recovery estimates of 10?15 percent of original oil-in-place (OOIP). The Lawrence Field Cypress and Bridgeport reservoirs possess a potential volume of 130 million bbls of oil at a recovery of 13 percent OOIP. Successful extraction of this existing domestic oil would replace some reliance on overseas sources, providing a concrete benefit derived from the ASP flood technology research.

The successful application of this technology to other national reservoirs could lead to significantly increased domestic oil production. The remaining OOIP in the United States residing in similar sandstone reservoirs is estimated at 30 billion bbls of oil, with nine individual sedimentary basins containing one billion bbls or more (Nelson, et al., 1984). Recovery of this sizable quantity of oil should be the goal for the application of ASP flood technology in sandstone reservoirs. Assuming that a conservative 1/6 of these reservoirs are suitable for ASP flood extraction and that this method can recover 20 percent of the remaining OOIP, the incremental oil recovery potential is one billion bbls of oil.

Accomplishments
A presentation of the Lawrence Field ASP project was made in association with an AAPG Training Course on modern fluvial and coastal environments on the Brazos River in South Texas. These environments are modern analogs to the deposition environments in the Pennsylvanian Bridgeport and Mississippian Cypress formations in the Lawrence Field. The course was held September 8?9, 2011, on the Brazos River and in Houston, Texas.

Data from the 25 largest Cypress fields and the 25 largest Pennsylvanian fields in Illinois have been collected and formatted into tables for the assessment of ASP flood technology in this region. Further assessment of basins within the United States with potential ASP application is nearing completion.

The project is fully staffed with three geologists and one GIS/database specialist devoted full-time to completing contract tasks. Regular meetings have been conducted with Rex Energy representatives to coordinate the ISGS project and ensure that project tasks are on target.

Reservoir characterization of pilot areas for Bridgeport and Cypress Sandstone reservoirs has been completed. An expansion area of approximately 5.5 square miles has been established for reservoir characterization. Research with emphasis on understanding the complex relationship of depositional environment and facies variation within a rapidly altering sequence stratigraphic framework and how this relates to reservoir compartmentalization and flow unit modeling has progressed considerably in the third quarter of 2011, particularly within the Pennsylvanian reservoir section. Petrographic analyses, with emphasis on the characteristics that positively and negatively affect the reservoir properties of the separate reservoir facies, have been defined. Over 800 feet of core samples from 15 separate wells have been photographed and described in the expansion area. Additional core has recently been obtained from Rex Energy that, when incorporated into the research, has enhanced the understanding of the complex stratigraphic relationships within the Bridgeport sandstone reservoirs of the expansion area.

Current Status (June 2012)
Rex Energy is currently executing two pilot ASP floods in the Lawrence Field, the Middagh flood (initiated in August 2010 and is now yielding positive results), and the Perkins flood (currently in the brine injection pre-flush stage) to be followed by ASP injection in the fourth quarter 2011. An additional Bridgeport Sandstone ASP flood on the Griggs lease offsets these two floods and is in the development stage. The three floods are in the north half of Section 32-T4N-R12W in Lawrence County, Illinois. Rex Energy is interested in expanding their enhanced oil recovery efforts in the area surrounding these three floods. The Illinois State Geological Survey (ISGS) continues to conduct reservoir characterization studies of the Pennsylvanian Bridgeport Sandstones and Cypress Sandstones in an expansion area of approximately 5.5 miles around the present floods, in accordance with Rex Energy?s expansion plan.

Characterization-flow units
The project team is continuing flow unit characterization by integrating depositional environment and facies analysis within a very complex stratigraphic framework and, in particular, the Pennsylvanian Bridgeport zones, and is expanding to some extent past the general expansion area in order to better understand and refine the geology of the area that Rex Energy is targeting for development.

Several more Bridgeport B cores from areas outside the expansion area have been located. They are presently being studied because they are particularly useful for the geological model interpretation within the Bridgeport B development area, which contains very few cores from this interval.

Rex Energy has expressed an interest in coring two wells in late 2011 or early 2012 in the Bridgeport B expansion area that should be key data points for defining deposition environments and, therefore, flow unit characteristics.

Reservoir Simulation
A viscous injection black oil reservoir simulation using our established geocellular models developed within the present ASP flood areas is scheduled for early 2012. A UTCHEM simulation will be developed based on the outcome of this modeling, which may be coordinated with Rex Energy. The inclusion of the ASP results from the current floods should make this simulation modeling more valid and practical. Because reservoirs in the Bridgeport and Cypress sandstones are highly complex and compartmentalized, the application of geocelular and simulation modeling may assist in the identification of potential unswept or poorly swept reservoirs and aid in the design of effective flood development.

Petrography
Petrographic analysis including thin section, SEM, and XRD with emphasis on the characteristics that positively and negatively affect the reservoir properties of the separate reservoir facies are scheduled to continue into 2012. This research is defining pore, pore throat, grain size, compaction, and clay mineral relationships. Diagenetic minerals, organic components and their relative time of emplacement with resulting depositional and flow unit implications are also being analyzed. Petrographic research of reservoir and non-reservoir facies is an integral aspect of reservoir characterization and successful flood design.

Web Access and Technology Transfer
Website development is in progress with access scheduled before the end of 2012. Information will be uploaded throughout the term of the contract and final reporting. The site will incorporate presentations, papers, cross-sections, maps, core and petrographic images, research results, and research data.

Publications
The research group is working to acquire information regarding the success of the three section 32 expansion area floods. The Middagh lease is starting to pressure up and oil cuts are increasing. The offsetting Perkins lease to the west (the second flood) is in the initial stage of flooding. The brine injection pre-flush was initiated in August 2011. The Griggs lease (the eastern offset to the Middagh flood and the third flood) is still being prepared for flooding. Researchers will work with Rex Energy to acquire development and results data pertinent to the success of these floods. The data, if and when it is acquired from Rex Energy, will be used to publish a paper with SPE or AAPG. A publication through the Illinois State Geological Survey describing our research and results can be an alternative should Rex Energy keep their development and results proprietary.

A presentation entitled, ?Alkaline-Surfactant-Polymer Flood Application for Enhanced Oil Recovery has Potential for Significant Recovery of Remaining Reserves in the Mature Lawrence Field, Illinois? is scheduled for the AAPG national meeting in Long Beach, California, April 22?25, 2012.

Project Start: September 22, 2008
Project End: September 21, 2012

DOE Contribution: $1,460,717
Performer Contribution: $410,664

Contact Information:
NETL ? ?Sinisha (Jay) Jikich (Sinisha.Jikich@netl.doe.gov or 304-285-4320
Illinois State Geological Survey - John Grube (grube@isgs.uiuc.edu or 217-244-1716)
If you are unable to reach the above personnel, please contact the content manager.

Publications

Beverly Seyler, John Grube, Bryan G. Huff, Curt S. Blakley, and Philip Johanek, 2009, Reservoir Characterization of the Mississippian Cypress Sandstone at Lawrence Field, Illinois, Program with abstracts 2009 Eastern Section American Association of Petroleum Geologists p. 50

John P. Grube, James Damico and Beverly Seyler, 2009, Enhanced Oil Recovery and CO2 Sequestration Potential of Chesterian (Mississippian) Sandstones in the Illinois Basin in Program with abstracts 2009 Eastern Section American Association of Petroleum Geologists p. 38