The Vacuum oil field was discovered in Lea County, New Mexico in 1929 on the northwest
shelf of the Permian basin. Vacuum cumulative production, primarily from the Permian age
Grayberg and San Andres dolomites, totals more than 600 MMBO and 800 BCF gas from
2400 wells at 4200 to 4800 feet.
Enhanced Recovery Project
A research project organized through the Colorado school of Mines, using multiple 3-D
seismic surveys and multiple geochemical surveys, evaluated both tools for tracking
hydrocarbon movements in an enhanced recovery project on the Vacuum oil field. Results
of the seismic portion of the project are available
here. The orange box shows the one
square mile area studied for this project. The structure, below, is the map generated from
the multiple 3D seismic surveys. The six CO2 injectors are shown along with two
established faults and two probable faults. This same structural map is overlaid on the
"net  change" geochemical survey maps below.
Stucture contour map based on the top of the San Andres. Interval, 100 feet. Roy Milks (1957) and the Roswell Geologic Society.
The first net change map shows a pronounced sweeping of hydrocarbon away from the
injectors and down  the structure both to the north and south. The hydrocarbons are
also moving away from the injectors to the east and west but they are moving towards
the highs.
Survey 1 Baseline 3/98
Survey 2 10/98
Survey 3 10/99
Net Change Iodine, Survey 1 to Survey 2
Net Change Iodine, Survey 1 to Survey 3
Lea County, New Mexico
Vacuum Oil Field
Survey 1 Baseline 3/98
Iodine Survey Results
The first survey, below (3/98), was before any CO2 injections and represents a baseline
to evaluate the next two surveys. The baseline iodine data indicated substantial
anomalies (remaining hydrocarbons) associated with this elderly Field. If we use the
baseline survey as a measure of subsurface hydrocarbons at each sample location then
other than analytical error the differences between the baseline and subsequent surveys
should be the net change in underlying hydrocarbons. If a reading goes lower the
hydrocarbons have moved away, if values increase hydrocarbons have moved to that
location. The "net change maps" should represent the subsurface hydrocarbon
movements responding to the CO2 injections.
The net change map for the baseline to the third survey is very similar to the first net
change map. The swept areas to the north have remained much the same, to the south
there are few increases south of the fault The areas around the injectors is largely
swept with the exception of the southwest injector with a very high value on a possible
fault. Most of the increases in  hydrocarbons are now on or very close to the structural
highs.
These surveys have established real time relationship between soil iodine and subsurface
hydrocarbons. Geochemical surveys should be a useful tool to monitor hydrocarbon
movements associated with CO2 enhanced recovery projects.  
GrayStone Exploration Labs, Inc.
GrayStone Exploration Labs, Inc.