Editing Thomas Gold (section)

===A test: Drilling deep into granite===
[[File:Siljan WorldWind.jpg|thumb|right|[[Sweden]]'s [[Lake Siljan]] is a large lake created from an eroded impact crater, the [[Siljan Ring]], that was formed by a [[impact event|meteorite impact]] about 370 million years ago. It was at this lake that Gold proposed as the most likely place to test the hypothesis on the origin of petroleum because it was one of the few places in the world where the [[granite]] basement rock was cracked sufficiently to allow oil to seep up from great depth.]]
Gold began testing his abiogenic petroleum theory in 1986. With the backing of a group of investors, [[Vattenfall]] and the [[Gas Research Institute]], drilling of a deep [[borehole]] – named Gravberg-1 – commenced into the [[bedrock]] near [[Lake Siljan]] in [[Sweden]]. This was the site of a large [[meteor crater]], which would have "opened channels deep enough for the methane to migrate upward" and formed deposits in [[Caprock#Petroleum|caprock]] just a few miles beneath the surface.<ref>{{citation|last=Sullivan|first=Walter|title=Swedish Search for Methane Tests Radical Theory of Fuels|date=July 6, 1986|work=[[The New York Times]]}}.</ref><ref>{{cite journal |last1=Dye |first1=Lee |title=Sweden to Test Theory That Earth Has Unlimited Supply of Oil, Gas |journal=Los Angeles Times |date=15 December 1985 |url=https://www.latimes.com/archives/la-xpm-1985-12-15-fi-661-story.html}}</ref> He estimated that the [[Fracture (geology)|fractures]] near Lake Siljan reached down nearly 40 kilometers into the earth.<ref name="Shiry">{{citation|last=Shiry|first=John|title=Gold Drills For Gas In 'The Basement': Weird science?|work=[[Financial Post]]|date=May 30, 1991}}.</ref>

In 1987, approximately {{convert|900|oilbbl}} of [[drilling fluid|drilling lubricant]] disappeared nearly {{convert|20000|ft|m|lk=on}} into the ground, leading Gold to believe that the lubricant had fallen into a methane reservoir.<ref>{{citation|last=Sullivan|first=Walter|title=Natural Gas Well Is Believed Found|date=March 22, 1987|work=[[The New York Times]]}}.</ref> Soon after, the team brought up nearly 100 liters of black oily sludge to the surface. Gold claimed that the sludge contained both oil and remnants of [[archaebacteria]]. He argued that "it suggests there is an enormous sphere of life, of biology, at deeper levels in the ground than we have had any knowledge of previously" and that this evidence would "destroy the orthodox argument that since oil contains biological molecules, oil reserves must have derived from biological material".

The announcement of Gold's findings was met with mixed reactions, ranging from "furious incredulity" to "deep skepticism".<ref>{{citation|last=Hodgkinson|first=Neville|title=Sludge at core of earth boosts deep oil theory|work=[[The Sunday Times]]|date=June 12, 1988}}.</ref> Geochemist Geoffrey P. Glasby speculated that the sludge could have been formed from the [[Fischer–Tropsch process]], a [[catalyst|catalyzed]] [[chemistry|chemical reaction]] in which [[syngas|synthesis gas]], a mixture of [[carbon monoxide]] and [[hydrogen]], is converted into liquid [[hydrocarbon]]s.<ref name="Glasby-2008" /> Critics also dismissed Gold's archaebacteria finding, stating that "since micro-organisms cannot survive at such depth, the bacteria prove that the well has been contaminated from the surface".<ref name="Cole-1996" /> Geochemist Paul Philp analyzed the sludge and concluded that he could not differentiate between the samples of sludge and [[petroleum seep|oil seep]] found in sedimentary [[shale]] rocks near the surface. He reasoned that oil had migrated from the shale down to the granite deep in the ground.<ref name="Aldhous">{{citation|last=Aldhous|first=Peter|title=Black Gold Causes a Stir|date=1991|journal=[[Nature (journal)|Nature]]|volume=353|issue=593|page=55|issn=0028-0836|doi=10.1038/353593a0|bibcode = 1991Natur.353..593A |doi-access=free}}.</ref> Gold disputed Philp's finding, believing that the oil and gas could have just as easily migrated up to the surface: "They would have it that the oil and gas we found down there was from the five feet of sediments on the top – had seeped all the way down six kilometres down into the granite. I mean, such complete absurdity: you can imagine sitting there with five feet of soil and six kilometres underneath of dense granitic rock, and that methane produced up there has crawled all the way down in preference to water. Absolute nonsense."<ref name="Cole-1996" />

In light of the controversy surrounding the sludge and possible drill contamination, Gold abandoned the project at Gravberg-1, calling it a "complete fiasco", and redesigned the experiment by replacing his oil-based drilling lubricant with a water-based one.<ref name="Cole-1996" />

The drill hit oil in the spring of 1989, but only collected about {{convert|80|oilbbl}}. Gold stated, "It was not coming up at a rate at which you could sell it, but it showed there was oil down there." The drill then ran into technical problems and was stopped at a depth of 6.8 kilometers. The hole was closed, but a second hole was opened for drilling closer to the "center of the impact ring where there was even less sedimentary rock". By October 1991, the drill hit oil at a depth of 3.8 kilometers, but many skeptics remained unconvinced of the site's prospects.<ref name="Shiry"/><ref>{{citation|last=Haliechuk|first=Rick|title=Scientist says our bedrock contains vast oil reserves|date=February 14, 1992|work=[[Toronto Star]]}}.</ref> Geologist John R. Castaño concluded that there was insufficient evidence of the mantle as the hydrocarbon source and that it was unlikely that the Siljan site could be used as a commercial gas field.<ref>{{citation|last=Castaño|first=John R.|date=1993|title= Prospects for commercial abiogenic gas production: Implications from the Siljan Ring area, Sweden.|journal=U.S. Geological Survey Professional Paper|issue=1570|pages=133–154}}.</ref> In 2019, a study of gases and secondary carbonate minerals revealed that long-term microbial methanogenesis has occurred in situ deep within the fracture system of the crater (for at least 80 million years) and with an obvious spatial link to seep oils of surficial sedimentary origin,<ref>{{Cite journal|last1=Drake|first1=Henrik|last2=Roberts|first2=Nick M. W.|last3=Heim|first3=Christine|last4=Whitehouse|first4=Martin J.|last5=Siljeström|first5=Sandra|last6=Kooijman|first6=Ellen|last7=Broman|first7=Curt|last8=Ivarsson|first8=Magnus|last9=Åström|first9=Mats E.|date=2019-10-18|title=Timing and origin of natural gas accumulation in the Siljan impact structure, Sweden|journal=Nature Communications|language=en|volume=10|issue=1|pages=4736|doi=10.1038/s41467-019-12728-y|pmid=31628335|pmc=6802084|bibcode=2019NatCo..10.4736D|issn=2041-1723}}</ref> at odds with Gold's theories of deep abiotic gas migration.

Gold's later views on the drilling results can be found in chapter 6, "The Siljan Experiment," of his 1998 book.<ref name="DHB-1998" /> Another section of the book titled "The Upwelling Theory of Coal Formation" presents another argument in favor of the abiogenic model that he had not presented in an earlier paper. Similarly, he also presents arguments pertaining to the origin of diamonds and that microbial processes are the cause of mineral concentrations at depth.<ref name="DHB-1998" />