are two schools of scientific thought when it comes to gas hydrates
—one views them as a nuisance, and one sees them as a potential
or hate them, there's no ignoring them. Gas hydrates are garnering
much attention among geoscientists hoping to better understand their
the U.S. Department of Energy and the petroleum industry have joined
forces to study gas hydrate accumulations in the Gulf of Mexico.
(See related story, November 2003 Explorer).
in the project is the Minerals Management Service, which will have
to approve the drilling plan, environment report and application
for a permit to drill any deep stratigraphic hydrate test well.)
there is a major challenge facing the DOE Gulf of Mexico Joint Industry
Project (JIP), dealing with the development of protocols and laboratory
tests for acquisition, processing and interpretation of seismic
data to image gas hydrate zones.
is only slowing, not stopping, the research.
parameters and survey design of exploration 3-D seismic are not
optimal for shallow sediments where gas hydrates are found and do
not allow accurate characterization of naturally occurring hydrates,
according to Michael A. Smith, operation geologist for the deepwater
Gulf of Mexico with the Minerals Management Service.
years ago a Senate bill funding a $50 million, five-year research
effort on gas hydrates was passed, and at that time the DOE sent
out requests for proposals to study gas hydrates in the Gulf of
Mexico and the arctic regions of Alaska, according to Smith.
three main goals for the research—to develop technology, to characterize
the gas hydrates and understand the hazards, particularly in regard
to seafloor stability, and develop safe and efficient drilling and
coring protocols," he said.
put together a proposal that was accepted by DOE—a 42-month,
$13.2 million investigation funded 80 percent by the DOE.
held a workshop in 2000 to determine industry interest in the research
venture, and seven other companies have joined them to date: ConocoPhillips,
Halliburton, Japan National Oil Co., MMS, Reliance Industries, Schlumberger
is a multi-phase, multi-year project, and its goals include:
and implementing a research and technology plan to assist characterization
of sediments containing naturally occurring hydrates in deepwater
in the Gulf of Mexico.
and understanding potential safety hazards associated with drilling
wells and running pipelines through sediments containing gas hydrates.
a database of existing seismic, core, log, thermo physical and
biogeochemical data to identify current hydrate containing sites
in deepwater Gulf of Mexico.
existing knowledge to choose several sites in the deepwater Gulf
of Mexico for field tests.
and executing a drilling and sample collection field testing program
to collect data and obtain cores to characterize the hydrate containing
sediments in the Gulf of Mexico.
existing data and data collected during the project to develop
wellbore and seafloor stability models pertinent to hydrate containing
sediments in the Gulf of Mexico.
phase, concluded last year, was devoted to data collection, analysis,
model development and generating protocols to detect and characterize
the hydrate containing sediments. The results will be used to plan
and execute phase II's drilling, sampling and data collection field
of the recently begun phase II is to drill and core up to a dozen
or more 1,000- to 2,000-foot test wells through bedded hydrate deposits,
probably starting in April.
comprises three technical teams—a gas hydrates characterization
team, a seafloor stability team led by Smith and a drilling and
has hosted a workshop to identify the critical issues in each area,
and several contracts have been awarded to fill the knowledge gaps
identified in those meetings," Smith said.
team awarded Georgia Tech a contract to study the effects of the
thermal history and gas hydrate properties. A wellbore stability
project was awarded to a division of Schlumberger and a critical
research contract was awarded to WesternGeco to study the potential
of seismic for gas hydrates detection.
study is particularly important, because a successful detection
method is critical to any meaningful research on gas hydrates. The
firm is currently completing its project at several prospective
chief geoscientist with WesternGeco's seismic reservoir division,
is heading the team studying seismic detection of gas hydrates.
He said he first became interested in gas hydrates after conducting
a literature survey a couple of years ago.
there are two camps in the United States concerning gas hydrates:
camp is interested in identifying gas hydrates because they feel
there is a great deal of natural gas trapped in the hydrates that
can be exploited to meet our energy demands.
other camp is interested in avoiding gas hydrates when establishing
infrastructure because of presumed seafloor instability associated
"However, I view
both camps as an opportunity," Dutta said, "because either way
it is important to identify the gas hydrates, and seismic is
the key detection technology. The deepwater Gulf of Mexico is
the ideal location to test how useful seismic can be in detecting
, quantifying and mapping gas hydrates, since the entire area
is covered by 3-D seismic data."
and Smith presented papers on seismic prediction of gas hydrates
at the AAPG international conference in Barcelona, and both will
be speaking at the upcoming AAPG annual meeting in Dallas.
that the first key challenge for the research team was to find if
there were, in fact, subsurface gas hydrates in the Gulf of Mexico.
exception of one or two anecdotal incidences of bottom simulating
reflectors, there have been no direct seismic signatures of gas
hydrates like in other parts of the world, even though the deepwater
Gulf is the right environment for gas hydrates," he said.
critical element for the study was, if seismic or some other technology
could prove the existence of gas hydrates, then could we quantify
focused on the extensive seismic data covering zones where people
believed gas hydrates might exist. To make seismic data a useful
remote sensing tool for gas hydrates, Dutta and his group had to
determine which models needed to be developed and how the seismic
data should be conditioned.
techniques typical for oil and gas detection focus on deeper targets
and, therefore, were not useful in detecting gas hydrates that are
found at relatively shallow depths," he said. "So the first step
was to develop a new processing technique that keyed on the shallow
depths completely ignored in the original processing phase."
As a result,
the team "began to see hints of bottom simulating reflectors that
were never identified in the past."
at the Keathley Canyon and Atwater Valley locations was evidence
of a bottom simulating reflector.
mounds are known at the seabed near both sites, and gas is percolating
up through those mounds, creating a good environment for gas hydrates
interpretation picked up deeply steeping events in the deepwater
environment, and we see gas hydrates cross-cutting the sedimentary
strata," he said. "The rock physics models seem to be working well
at Keathley Canyon, so we are getting some concentration estimates."
else they "think we found" this summer is a second layer of gas
hydrates that was not visible on conventional seismic—it became
visible following the seismic inversion.
turns out to be definitive, it will be the first paleo bottom simulating
reflector in our seismic data.
to Smith the first drilling leg of the JIP will get under way this
spring. The plan calls for at least 12 holes about 10 inches in
diameter at six sites. The log data and additional wireline logs
will give scientists a better picture of where to collect core samples
in a twin hole.
would like to include an estimate of total gas hydrate resources
on all four coasts in the next national oil and gas assessment in
2005," Smith said. "To reach that goal this JIP research is critical."