Pulsed neutrons help engineers collect data from underground wells.
Pulsed neutron tools are used in oilfields to locate oil, gas, water and possibly hydrocarbon reserves. According to well-diggers NPS International, oil workers primarily use pulsed neutron tools in cased-hole types of wells, which the Schlumberger company defines as an oil well that has an inner casing or liner whose job it is to protect the well from outside fluids, pressure and other factors which could influence the well's stability.
General Use
The most popular use for pulsed neutron tools, according to NPS International, is to measure water saturation in hydrocarbon reservoirs. Oil field engineers once had difficulty measuring the salinity of water found in hydrocarbon reservoirs, but can now do so easily because of advances in pulsed neutron technology and the resultant data. Pulsed neutron tools can also monitor how a particular well changes over its lifetime, which reports data such as the location of any remaining hydrocarbon reserves and of any remaining oil or water, as well as the presence of coal or other potentially useful mineral. Pulsed neutron tools can also gauge the porosity of rocks and dirt surrounding a well, as well as fractions in shale or clay, saturation of hydrocarbon and any gaseous saturation. Pulsed neutron tools can also provide data to combat some environmental problems.
Technical Applications
According to Patent Docs, a pulsed neutron tool can use two or more gamma ray detectors to provide a mineralogical and/or elemental image of a particular well. This image may be used in reservoir navigation and in furthering the understanding of the geology of the prospect, including what minerals oilfield engineers could find in it. Baker Hughes Incorporated, who registered a patent for a pulsed neutron tool with Patent Docs, list nearly 30 functions for their pulsed neutron tool, including the ability to read a larger data set than other well-monitoring devices. Geo-Prakla, a group which has also studied pulsed neutron tools, uses gamma rays to bombard potential mineral formations and report measurements such as an analysis of existing elements, thermal decay times, mineral porosity and a production analysis which could help reservoir engineers locate oil, detect water-flood fronts and hone production operations.
Scholarly Speculations
A study published by the Society of Petroleum Engineers posits a reevaluation of data sets provided by pulsed neutron tools. The study claims that weighted, inelastic ratio interpretation is more reliable than the traditional responses used to identify and characterize hydrocarbon deposits. The study's new algorithm for interpreting gamma ray behavior is, the authors claim, more reliable because it does not allow the data to decay before it is available to engineers. Essentially, treating gamma rays as inelastic is more representative of their nature and therefore provides petroleum engineers with the best framework by which to gauge the data collected by the gamma rays from their pulsed neutron tools.
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