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Study of Viability of Previous HitSeismicNext Hit Imaging for Site Selection and Monitoring of CO2 Sequestration in Illinois Thin Coal Seams*

By

Iraj A. Salehi1, Sherif I. Gowelly1, and Samih I. Batarseh1

 

Search and Discovery Article #80004 (2006)

Posted October 16, 2006

 

*Oral presentation at AAPG Annual Convention, Houston, Texas, April 9-12, 2006.

 

Click to view presentation in PDF format (~3.9 mb).

Click to view presentation (with accompanying Notes) in PDF format (~2.2 mb).

 

1Gas Technology Institute, Des Plaines, IL ([email protected])

 

Abstract 

In this paper, we present results of a series of field and laboratory experiments aimed at determination of Previous HitseismicNext Hit resolution relative to thin Illinois coal seams and study of viability of time-lapsed Previous HitseismicNext Hit imaging (4-D Previous HitseismicNext Hit) for monitoring the position of the injected carbon dioxide front during CO2 sequestration process, or desorbed methane in the case of coalbed methane production. The project was a cooperative effort between Illinois Clean Coal Institute (ICCI) and Gas Technology Institute (GTI) with valuable technical contribution and logistical support from Illinois State Geological Survey (ISGS).

 

Illinois coal seams are shallow and thin with the thickness rarely exceeding 10 feet. To investigate viability of Previous HitseismicNext Hit technology relative to imaging of Illinois coal seams a series of Previous HitseismicNext Hit data acquisitions including surface Previous HitseismicNext Hit, vertical Previous HitseismicNext Hit profiling, and crosswell Previous HitseismicNext Hit imaging carried out at the ISGS pilot site in Southern Illinois. Results were encouraging in that the data proved that thin coal seams can be reliably mapped by properly designed Previous HitseismicNext Hit surveys.

 

Our second objective was to verify viability of 4-D Previous HitseismicNext Hit as a monitoring tool for the potential CO2 sequestration projects in coal seams of Illinois. In pursuing this objective, a number of elaborate laboratory measurements of acoustic velocity in gas and water saturated coal samples were carried out. Results of these measurements showed that the magnitude of velocity change resulting from addition of a gas phase into water saturated coal samples is large enough to render the time-lapsed Previous HitseismicNext Hit technique useful for monitoring the position of injected or evolved gas fronts.

 

Selected Figures

 

Location map of four Previous HitseismicNext Hit lines and wells used in crosswell survey, White County, Illinois.

Final processed broadband Previous HitseismicNext Hit sections (NW-SE and NE-SW lines), shown on location map.

Crosswell Previous HitseismicNext Hit imaging: final crosswell reflection image.

Decrease in P wave velocity resulting from introduction of a gas phase into the water-saturated coal.

Summary of results of Previous HitseismicNext Hit surveys. Coal seams can be clearly identified on well logs from wells Hon 3 and Hon 9. Each vertical band is for a range of frequencies that increases to the right; i.e., low frequency band on the left (10-50 Hz) and high frequency band (100-1200 Hz) on the right. The upper part of the figure exhibits the Previous HitseismicNext Hit response of individual seams before velocity reduction, and the lower part shows the response after 20% velocity reduction. Note that changes in the Previous HitseismicTop response resulting from injection of carbon dioxide or evolution of coalbed methane can only be observed at frequencies in the 100-800 Hz and 100-1200 Hz bandwidths (area within the blue rectangles).