2015. "Introduction", Microbial Carbonates in Space and Time: Implications for Global Exploration and Production, D. W. J. Bosence, K. A. Gibbons, D. P. Le Heron, W. A. Morgan, T. Pritchard, B. A. Vining
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Microbial carbonates (microbialites) are remarkable sedimentary deposits for four good reasons: they have the longest geological range of any type of biogenic limestones; they form in the greatest range of different sedimentary environments; they oxygenated the Earth’s atmosphere; and they produce and store large volumes of hydrocarbons. However, they are amongst the most intractable of sedimentary rocks to study, as, being formed by the action or influence of microbes, they do not always preserve direct, or diagenetically robust, evidence for their mode of formation.
Despite this, the scientific study of microbial carbonates has seen a significant renaissance in recent years, largely because of their importance as petroleum reservoirs, in both the Proterozoic of the Salt Basin of Oman and, more recently, the discoveries in the Lower Cretaceous pre-salt, Santos Basin, offshore Brazil (Figs 1 & 2). Here, production from the pre-salt reservoirs surpassed 500 000 BOPD in June 2014, and the Basin was estimated to have over 50 billion barrels STOIP (Formigli 2014). However, these are in deep-water sites, hundreds of kilometers offshore, hosted in poorly understood carbonate facies and with no nearby outcrop analogues.
Many research programmes by academia and the petroleum industry have been spawned in recent years to investigate possible analogues and to further our understanding of these intractable rocks and their complex pore systems. The results from some of this work are contained in this volume together with the first series of scientific papers on the remarkable pre-salt plays of Brazil.
This Special Publication provides significant contributions at a pivotal time in our understanding of microbial carbonates, when their economic importance has become established and the results of many research programmes are coming to fruition.
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Microbial carbonates (microbialites) are remarkable sedimentary deposits. They have the longest geological range of any type of biogenic limestones, form in the greatest range of different sedimentary environments, oxygenated the Earth’s atmosphere and produce and, furthermore, store large volumes of hydrocarbons. This Special Publication provides significant contributions at a pivotal time in our understanding of microbial carbonates when their economic importance has become established and the results of many research programmes are coming to fruition.
It is the first book to focus on the economic aspects of microbialites and in particular the giant pre-salt discoveries offshore Brazil. The volume contains papers on the processes involved in the formation of both ancient and modern microbialites and the diversity of style in microbial carbonate build-ups. Structures and fabrics from both marine and non-marine settings are discussed from throughout the geological record.