What's new in exploration

Mar. 2002 Vol. 223 No. 3  What's New in Exploration

Perry A. Fischer,  Engineering Editor

New mass-extinction mechanism. It is not only difficult to find consensus on exactly how many mass extinction events have occurred in Earth’s history, but even more difficult to determine their causes. Besides meteorites, the most widely accepted causes of mass extinction include glaciation, volcanism and the formation / glaciation of the mega-continents Gondwana and Pangea.

New research was presented in January at the American Astronomical Society meeting supporting the idea that a lesser-known extinction – the Pliocene-Pleistocene boundary 2 million years ago – was caused by cosmic rays from a nearby supernova (a massive exploding star). Narcisco Benítez at John Hopkins University in Baltimore, Maryland, and Jesús Maíz Appellániz of the Space Telescope Science Institute in Virginia traced the motion of a cluster of young, short-lived stars formed from the debris of about 20 supernovae that have exploded over the last 20 million years. The cluster, called the Scorpius-Centaurus OB association, passed within 130 light-years of Earth about two million years ago.

This correlates with the Pliocene-Pleistocene extinction and evidence found by German researchers in 1999 of a very rare isotope of iron, ⁶⁰Fe, in cores taken from the seafloor. Because it has a half-life of 1.5 million years, ⁶⁰Fe is rare in the solar system. The finding suggests that the iron was fallout from a nearby supernova. Donald Clayton, an astronomer at Clemson University, says the story appears consistent: "The amount of ⁶⁰Fe found in the seafloor deposits is about what you might expect from a supernova going off about 100 light-years away."

Geologist Luann Becker of the University of California, Santa Barbara, agrees that a supernova is a plausible, but unproven, candidate for the marine extinction. She notes that supernova dust isn’t the only type of iron-rich space debris to pelt Earth. Analyzing more samples of ocean sediment to pinpoint the amount and timing of the ⁶⁰Fe excess could provide a more rigorous test of the supernova model, Becker adds.

Benítez says that high-energy cosmic rays caused by particles from a supernova 100 to 130 light-years from Earth would generate enough ions in the Earth’s atmosphere to oxidize the ozone layer. He estimates that the ozone-layer damage could last between 100 and 1,000 years – long enough to wipe out susceptible species on Earth. Their research will be presented in an upcoming issue of Physical Review Letters. 

Alaska’s 5-Year Leasing Program. The state unveiled its 20-sale, area-wide leasing program for state oil and gas acreage in February. The plans call for offering all available state land in the next five years by holding five sales each in the Cook Inlet, Beaufort Sea, North Slope and North Slope Foothills areas. Cook Inlet and North Slope Foothills sales would be held in May and the North Slope and Beaufort Sea sales in October.

In 2001, Alaska leased 334 tracts in four sales for $26.5 million in bonus bids. Since 1998, when the program began, the state has leased over 3 million acres and taken in over $91 million in bonus bids The successful program and the aggressive schedule laid out is in response to industry interest for exploration in Alaska. The schedule provides for public input during the fall and winter months, when most people have more time.

This year is forecast to be the first year in more than a decade that North Slope oil production will increase, as production ramps up from the BP-operated Northstar project and because of new discoveries and new activity in the National Petroleum Reserve-Alaska. Northstar production is the first oil produced from the federal offshore OCS.

Marathon hits Alaskan gas. A significant natural gas discovery was made on the company’s Ninilchik Prospect on Kenai Peninsula, about 35 mi south of Kenai, Alaska. The discovery well, Grassim Oskolkoff 1, was drilled to 11,600-ft TD and encountered several gas-bearing sands. One sand – a 39-ft interval at 9,822 ft – tested 11.2 MMcfd. with an FTP of 1,565 psia.

Marathon estimates 90 Bcfg of gross proven recoverable reserves on the structure. Three additional wells completed on the structure await testing, and additional drilling is planned to delineate the structure. Marathon is operator with a 60% working interest, while Unocal holds 40%.

In the last five years, Marathon has drilled six successful gas-exploration wells in Cook Inlet. Marathon expects further field development in anticipation of first gas sales in late 2003. A new gas transmission line, the Kenai Kachemak Pipeline (KKPL), plans to deliver gas to existing Cook Inlet infrastructure for local market consumption. Design and permitting for KKPL, a venture between Marathon and Unocal Alaska, is currently in progress.

McMoRan strikes gas. The Mound Point 2 exploratory well was perforated between 18,558 and 18,600 ft MD and flowed at rates between 10 and 20 MMcfd. Located on Louisiana State Lease 340, the well initially flowed water-free; however, the cement job appears to have broken down and allowed water to communicate into the wellbore.

The well has been shut in and will be squeeze-cemented and retested. The well was drilled by Parker Drilling’s inland barge rig, PD 76-B. James R. Moffett, co-chairman of McMoRan, said, "This well is significant because it validates our exploration concept for the Mound Point area, where we predicted that deep gas-productive Miocene sands underlie shallow production in the Mound Point area, which is one of the largest geologic structures in the shallow waters offshore Louisiana and has produced about 3 Tcfg from sands above 12,000 ft. Immediately below these shallow sands, the deeper Miocene sands known as the Robulus L and Operculinoides / Gyroidina, have been sparsely drilled. McMoRan currently has exploration rights in 60,000 acres in the Mound Point area, with the opportunity to earn rights in an additional 20,000 acres in an adjacent prospect area."

Moffett continued, "In addition to the 50-foot interval at 18,558 ft, the well encountered a laminated-sand section at 16,890 to 17,275 ft, which, from log calculations, could also contain hydrocarbons." McMoRan has a 30.4% interest; ChevronTexaco has a 43.0% interest; Samedan has a 25% interest; and an unnamed individual owns the remaining interest.

Comments? Write: fischerp@gulfpub.com