专利名称：A method and apparatus for measuring well
characteristics and formation properties
发明人：Wijeyesekera, Nihal I.,Scott, Hugh D.申请号：EP98401960.4申请日：19980731公开号：EP0895097B1公开日：20061004
摘要：The present invention provides for method and an apparatus for determiningthe porosity of a geological formation surrounding a cased well. The method furthercomprises of generating neutron pulses that release neutrons into an area adjacent thewell, from a neutron source. Neutrons are sensed and a plurality of neutron detectorcount rates is acquired using at least two neutron source to neutron detector spacings. Atiming measurement is acquired at one of the spacings to measure a first depth ofinvestigation. A ratio of the neutron detector count rates is acquired to measure a seconddepth of investigation. An apparent porosity is calculated using the timing measurementsand the ratios of neutron count rates. The effect of a well casing on the calculatedapparent porosity is determined in response to at least one of the ratio of neutrondetector count rates and the timing measurement. A cement annulus is computed basedon the ratios of neutron count rates and the timing measurement. A formation porosity iscalculated by performing a correction to the apparent porosity for the casing and thecement annulus.
申请人：SCHLUMBERGER LTD A NETHERLAND,SCHLUMBERGER TECHNOLOGYBV,SCHLUMBERGER HOLDINGS
地址：US,NL,VG
国籍：US,NL,VG
代理机构：Hagel, Francis
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