Hasła / Terms beginning with N

Measures natural radioactivity of the rocks that emit small energy radiation from decay of naturally occurring radioactive isotopes of potassium, thorium and uranium decay chain.

Natural gas accumulations in conventional reservoirs are found in porous highly permeable rocks that are overlain by a layer of impervious rocks. Conventional gas is produced using a vertical well. Structural and stratigraphic conventional reservoirs are distinguished.

Natural gas produced from organic matter-rich fine grained claystones/mudstones called shales that tend to break into thin plates if subjected to stress. Natural continuous gas accumulations in claystones/mudstones that are simultaneously gas source, reservoir and sealing rocks. Shale gas chemistry is almost the same as that of conventional natural gas: it contains primarily methane (75 – 95%) and nitrogen, as well as occasionally trace amounts of ethane, propane, helium-group elements and carbon dioxide. As shale rocks are low permeable, gas production requires technologies that are more complex and advanced comparing to those used for extraction of conventional natural gas. Typically, shale gas accumulations are characterized by huge resources at a low recovery factor.

Natural gas in unconventional reservoirs occurs in poorly permeable rocks. In addition to vertical well, horizontal legs must be drilled and fractures induced in the rocks in order to enable controlled flow of gas to the borehole.

A generic term used to describe liquid products derived from extracted natural gas and generated at gas processing operations, including propane,  butane, ethane and other organic compounds.

Fossil fuel of organic origin, a mixture of volatile hydrocarbons, primarily methane gas (in excess of 90%), with an admixture of ethane, propane and butane.

Depending on chemistry, high-methane natural gas (which contains 95% of methane and ethane) and high-nitrogen natural gas (which contains up to 30% of heavy hydrocarbons, alongside methane and ethane) are distinguished. In addition, small amounts of nitrogen, carbon dioxide, hydrogen sulfide and helium may occur. It is a light, odourless and highly flammable gas. Natural gas deposits may be either gas-only reservoirs or associated with crude oil and hard coal deposits. Natural gas is produced from conventional reservoirs or from unconventional accumulations.

that term is used to describe both shale gas (i.e. gas present in organic matter-rich black shales) and tight gas (trapped in isolated rock pores, for example in sandstones or carbonate rocks with very low permeabilities).

A type of nuclear logs that are based on recording of neutrons dispersed by the formation to determine, among other things, porosity and chemistry of rocks. Hydrogen significantly slows down neutrons and trace elements present in the rock have an effect on their absorption.

Technically recoverable resources of which production is currently non-viable for technology, economic or environmental reasons

source: W. Mizerski, H. Sylwestrzak, Słownik geologiczny, Wydawnictwo Naukowe PWN, Warsaw 2002

Basic elements that are essential for survival of all living organisms. In marine ecosystems, they control primary production of the ocean by limiting phytoplankton growth. In the oceans, nitrogen (N), phosphorus (P) and iron (Fe) are the key limiting elements. If supplied in excessive quantities from the land with freshwater that is enriched in nutrients by human activities, the waters are eutrophicated and subject to algae and Cyanobacteria blooms.