A method and apparatus for measuring well characte

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：EP05097A2公开日：19990203

专利附图：

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 the

well, 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 Limited (a Netherland Antilles corp.),SCHLUMBERGERTECHNOLOGY B.V.,SCHLUMBERGER HOLDINGS LIMITED

地址：having an office at: 277 Park Avenue New York, N.Y. 10172 US,Parkstraat 83-2514 JG The Hague NL,P.O. Box 71, Craigmuir Chambers Road Town, Tortola VG

国籍：US,NL,VG

代理机构：Hagel, Francis

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