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Oil More Plentiful Than Previously Thought

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    NHNE News List Current Members: 732 Subscribe/unsubscribe/archive info at the bottom of this message. ... Thanks to Roleigh Martin. ... OIL FIELDS FREE REFILL
    Message 1 of 1 , Apr 27 12:18 AM
      NHNE News List
      Current Members: 732
      Subscribe/unsubscribe/archive info at the bottom of this message.


      Thanks to Roleigh Martin.


      By Robert Cooke
      April 16, 2002


      Deep underwater, and deeper underground, scientists see surprising hints
      that gas and oil deposits can be replenished, filling up again, sometimes

      Although it sounds too good to be true, increasing evidence from the Gulf of
      Mexico suggests that some old oil fields are being refilled by petroleum
      surging up from deep below, scientists report. That may mean that current
      estimates of oil and gas abundance are far too low.

      Recent measurements in a major oil field show "that the fluids were changing
      over time; that very light oil and gas were being injected from below, even
      as the producing [oil pumping] was going on," said chemical oceanographer
      Mahlon "Chuck" Kennicutt. "They are refilling as we speak. But whether this
      is a worldwide phenomenon, we don't know."

      Also not known, Kennicutt said, is whether the injection of new oil from
      deeper strata is of any economic significance, whether there will be enough
      to be exploitable. The discovery was unexpected, and it is still "somewhat
      controversial" within the oil industry.

      Kennicutt, a faculty member at Texas A&M University, said it is now clear
      that gas and oil are coming into the known reservoirs very rapidly in terms
      of geologic time. The inflow of new gas, and some oil, has been detectable
      in as little as three to 10 years. In the past, it was not suspected that
      oil fields can refill because it was assumed the oil formed in place, or
      nearby, rather than far below.

      According to marine geologist Harry Roberts, at Louisiana State University,
      "petroleum geologists don't accept it as a general phenomenon because it
      doesn't happen in most reservoirs. But in this case, it does seem to be
      happening. You have a very leaky fault system that does allow it [petroleum]
      to migrate in. It's directly connected to an oil and gas generating system
      at great depth."

      What the scientists suspect is that very old petroleum - formed tens of
      millions of years ago - has continued migrating up into reservoirs that oil
      companies have been exploiting for years. But no one had expected that
      depleted oil fields might refill themselves.

      Now, if it is found that gas and oil are coming up in significant amounts,
      and if the same is occurring in oil fields around the globe, then a lot more
      fuel than anyone expected could become available eventually. It hints that
      the world may not, in fact, be running out of petroleum.

      "No one has been more astonished by the potential implications of our work
      than myself," said analytic chemist Jean Whelan, at the Woods Hole
      Oceanographic Institution, in Massachusetts. "There already appears to be a
      large body of evidence consistent with ...oil and gas generation and
      migration on very short time scales in many areas globally," she wrote in
      the journal Sea Technology.

      "Almost equally surprising," she added, is that "there seem to be no
      compelling arguments refuting the existence of these rapid, dynamic
      migration processes."

      The first sketchy evidence of this emerged in 1984, when Kennicutt and
      colleagues from Texas A&M University were in the Gulf of Mexico trying to
      understand a phenomenon called "seeps," areas on the seafloor where
      sometimes large amounts of oil and gas escape through natural fissures.

      "Our first discovery was with trawls. We knew it was an area of massive
      seepage, and we expected that the oil seeps would poison everything around"
      the site. But they found just the opposite.

      "On the first trawl, we brought up over two tons of stuff. We had a tough
      time getting the nets back on board because they were so full" of very
      odd-looking seafloor creatures, Kennicutt said. "They were long strawlike
      things that turned out to be tube worms.

      "The clams were the first thing I noticed," he added. "They were pretty big,
      like the size of your hand, and it was obvious they had red blood inside,
      which is unusual. And these long tubes -- 3, 4 and 5 feet long -- we didn't
      know what they were, but they started bleeding red fluid, too. We didn't
      know what to make of it."

      The biologists they consulted did know what to make of it. "The experts
      immediately recognized them as chemo-synthetic communities," creatures that
      get their energy from hydrocarbons -- oil and gas -- rather than from
      ordinary foods. So these animals are very much like, but still different
      from, recently discovered creatures living near very hot seafloor vent sites
      in the Pacific, Atlantic and other oceans.

      The difference, Kennicutt said, is that the animals living around cold seeps
      live on methane and oil, while the creatures growing near hot water vents
      exploit sulfur compounds in the hot water.

      The discovery of abundant life where scientists expected a deserted seafloor
      also suggested that the seeps are a long-duration phenomenon. Indeed, the
      clams are thought to be about 100 years old, and the tube worms may live as
      long as 600 years, or more, Kennicutt said.

      The surprises kept pouring in as the researchers explored further and in
      more detail using research submarines. In some areas, the
      methane-metabolizing organisms even build up structures that resemble coral

      It has long been known by geologists and oil industry workers that seeps
      exist. In Southern California, for example, there are seeps near Santa
      Barbara, at a geologic feature called Coal Oil Point. And, Roberts said,
      it's clear that "the Gulf of Mexico leaks like a sieve. You can't take a
      submarine dive without running into an oil or gas seep. And on a calm day,
      you can't take a boat ride without seeing gigantic oil slicks" on the sea

      Roberts added that natural seepage in places like the Gulf of Mexico "far
      exceeds anything that gets spilled" by oil tankers and other sources.

      "The results of this have been a big surprise for me," said Whelan. "I never
      would have expected that the gas is moving up so quickly and what a huge
      effect it has on the whole system."

      Although the oil industry hasn't shown great enthusiasm for the idea --
      arguing that the upward migration is too slow and too uncommon to do much
      good -- the search for new oil and gas supplies already has been affected,
      Whelan and Kennicutt said. Now, companies scan the sea surface for signs of
      oil slicks that might point to new deposits.

      "People are using airplane surveys for the slicks and are doing water column
      fluorescence measurements looking for the oil," Whelan said. "They're
      looking for the sources of the seeps and trying to hook that into the
      seismic evidence" normally used in searching for buried oil.

      Similar research on known oil basins in the North Sea is also under way, and
      "that oil is very interesting. There are absolutely marvelous pictures of
      coral reefs which formed from seepage [of gas] from North Sea reservoirs,"
      Whelan said.

      Analysis of the ancient oil that seems to be coming up from deep below in
      the Gulf of Mexico suggests that the flow of new oil "is coming from deeper,
      hotter [sediment] formations" and is not simply a lateral inflow from the
      old deposits that surround existing oil fields, she said. The chemical
      composition of the migrating oil also indicates it is being driven upward
      and is being altered by highly pressurized gases squeezing up from below.

      This upwelling phenomenon, Whelan noted, fits into a classic analysis of the
      world's oil and gas done years ago by geochemist-geologist John Hunt. He
      suggested that less than 1 percent of the oil that is generated at depth
      ever makes it into exploitable reservoirs. About 40 percent of the oil and
      gas remains hidden, spread out in the tiny pores and fissures of deep
      sedimentary rock formations.

      And "the remaining 60 percent," Whelan said, "leaks upward and out of the
      sediment" via the numerous seeps that occur globally.

      Also, the idea that dynamic migration of oil and gas is occurring implies
      that new supplies "are not only charging some reservoirs at the present
      time, but that a huge fraction of total oil and gas must be episodically or
      continuously bypassing reservoirs completely and seeping from surface
      sediments on a relatively large scale," Whelan explained.

      So far, measurements involving biological and geological analysis, plus
      satellite images, "show widespread and pervasive leakage over the entire
      northern slope of the Gulf of Mexico," she added.

      "For example, Ian MacDonald at Texas A&M has published some remarkable
      satellite photographs of oil slicks which go for miles in the Gulf of Mexico
      in areas where no oil production is occurring." Before this research in oil
      basins began, she added, "changes in reservoired oils were not suspected, so
      no reliable data exists on how widespread the phenomenon might be in the
      Gulf Coast or elsewhere."

      The researchers, especially the Texas team, have been working on this
      subject for almost 15 years in collaboration with oil industry experts and
      various university scientists. Their first focus was on the zone called
      South Eugene Island block 330, which is 150 miles south of New Orleans. It
      is known as one of the most productive oil and gas fields in the world. The
      block lies in water more than 300 feet deep.

      As a test, the researchers attempted to drill down into a known fault zone
      that was thought to be a natural conduit for new petroleum. The drilling was
      paid for by the U.S. Department of Energy.

      Whelan recalled that as the drill dug deeper and deeper, the project seemed
      to be succeeding, but then it abruptly ended in failure. "We were able to
      produce only a small amount of oil before the fault closed, like a giant
      straw," probably because reducing the pressure there allowed the fissure to

      In addition to the drilling effort and the inspection of seeps, Whelan and
      her colleagues reported that three-dimensional seismic profiles of the
      underground reservoirs commonly show giant gas plumes coming from depth and
      disrupting sediments all the way to the surface.

      This also shows that in an area west of the South Eugene Island area, a
      giant gas plume originates from beneath salt about 15,000 feet down and then
      disrupts the sediment layers all the way to the surface. The surface
      expression of this plume is very large -- about 1,500 feet in diameter. One
      surprise, Whelan said, was that the gas plume seems to exist outside of
      faults, the ground fractures, which at present are the main targets of oil

      It is suspected that the process of upward migration of petroleum is driven
      by natural gas that is being continually produced both by deeply buried
      bacteria and from oil being broken down in the deeper, hotter layers of
      sediment. The pressures and heat at great depth are thought to be increasing
      because the ground is sinking -- subsiding -- as a result of new sediments
      piling up on top. The site is part of the huge delta formed over thousands
      of years by the southward flow of the massive Mississippi River. Like other
      major deltas, the Mississippi's outflow structure is continually being built
      from sands, muds and silts washed off the continent.

      Analysis of the oil being driven into the reservoirs suggests they were
      created during the so-called Jurassic and Early Cretaceous periods (100
      million to 150 million years ago), even before the existing basin itself was
      formed. This means the source rock is buried and remains invisible to
      seismic imaging beneath layers of salt.

      In studying so-called biomarkers in the oil, Whelan said, it was concluded
      that the oil is closely related to other very old oils, implying that it
      "was probably generated very early and then remained trapped at depth until
      recently." And, she added, other analyses "show that this oil must have
      remained trapped at depths and temperatures much greater than those of the
      present-day producing reservoirs."

      At great depth, where the heat and pressure are high enough, she explained,
      methane is produced by oil being "cracked," and production of gas "is able
      to cause sufficient pressure to periodically open the fracture system
      [faults] and allow upward fluid flow of methane, with entrapment of oil in
      its path."

      Oil and Water

      The underground sediments of a zone called South Eugene Island Block 330,150
      miles south of New Orleans, is one of the world's most productive oil and
      gas fields. It lies more than 300 feet deep in the Gulf of Mexico.

      Buried salt layers gradually creep upward to form tall "salt domes, " which
      can trap gas and oil coming up from deep below.


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