A 3-D view of the Eagle Ford: Some operators believe “linking the results of well tests to attributes derived from the seismic will provide operators with a far more reliable predictive capability in any shale play.” Graphic courtesy of Galen Treadgold
Once it became clear that natural gas prices likely will remain dismal for some time, many companies working the shale gas plays recognized they had best punch up their production by adding some respectably-priced oil and liquids-rich gas.
How better than to get in on the ground floor of shale oil plays.
For those playing the dry-gas Haynesville shale play concentrated in north Louisiana and a part of east Texas, it was only a short romp to move into the Cretaceous Eagle Ford shale in south Texas. This shale is known for sourcing hydrocarbons to Austin Chalk fields and others, including the magnificent East Texas field.
Veteran Haynesville shale operator Petrohawk established a foothold in the Eagle Ford shale early-on when it drilled the discovery well in LaSalle County in the fall of 2008 in what would be dubbed Hawkville Field. The horizontal well flowed the 7.6 MMcf and 250 barrels of condensate per day from the shale.
The now-burgeoning play is a mix of players. Along with the smaller companies, the majors have begun jumping into domestic shale plays, including the Eagle Ford. For example, both ExxonMobil and ConocoPhillips bagged large acreage positions in the play fairly early.
A Need for 3-D Data
A key issue for the exploration companies centers on determining exactly where to lease and how to optimize drilling plans for optimal gas and oil recovery.
Conventional subsurface data, such as wireline logs, cores and cuttings are not widely available to many of the companies exploring the play, according to Galen Treadgold, vice president at Weinman GeoScience, a division of Global Geophysical.
Consequently, many explorers lack in-depth knowledge of the play’s regional aspects.
Modern seismic data and interpretation techniques are a must-have to wrap your arms around this play.
“Newly acquired 3-D data sets provide a continuous characterization of the subsurface, highlighting drilling hazards (faults) and also offering the potential to identify intervals having better reservoir quality,” Treadgold said.
“Extracting rock properties from the seismic should be the goal of any processing and interpretation effort,” he emphasized.
“Linking the results of well tests to attributes derived from the seismic will provide operators with a far more reliable predictive capability in any shale play.”
Weinman has been working diligently on a study addressing Eagle Ford shale prospecting with 3-D seismic data.
They have plenty of data to work with, given that Global has multiple crews shooting multi-client data across the play.
“Ultimately, we’ll be looking at three to six thousand square miles of 3-D in the play,” Treadgold said. “We’ll be integrating that with microseismic fracture monitoring and are working with companies to plan a large buried array across the Eagle Ford to do fracture monitoring and processing of that data for integration into our 3-D analysis.
“Others are acquiring seismic data in the Eagle Ford,” he added, “but they’re not doing the next phase of the work, which is the interpretation, the inversion and the microseismic.”
The seismic data used by Weinman are being acquired in full azimuth fashion, and some processing has been completed.
“A lot of variability in the geology is coming out in the seismic, and that’s the key” Treadgold said. “We have graphics that help illustrate the amount of variability in the section and the importance of using seismic to understand it and to hi-grade and direct drilling activities.”
Eagle Ford is not the be-all/end-all here. This petroleum-rich province has multiple targets – conventional and unconventional.
“Serendipity will win the day, and there will be plenty of opportunities beyond the shale that these high resolution 3-Ds will help us identify and exploit,” Treadgold noted. “Wells have been drilled here for years, and coarser 3-Ds have allowed for basic exploration.
“Now with newer data sets, there can be a more quantitative exploration effort focused both on conventional and unconventional opportunities,” he emphasized.
“It’s an exciting moment.”