Patent RU-2199010-C2 (RU)
Title: Method and device for measurement of well characteristics and properties of formations
Inventor: VIDZHEJESEKERA NIKHAL I
IPC: G01V5/10
Filed: 1998-07-30
Granted: 2003-02-20
Abstract: FIELD: measurement of porosity of formations. SUBSTANCE: method includes production of neutron pulses which liberate neutron energy into the first region and geological formation surrounding the first region. Neutrons are registered and multitude of velocities of neutron detectors counting is obtained with use of at least two neutron sources in places of neutron detectors location. The results of measurements of time relationships are obtained in one of places of location for measurement of the first depth of research object. The first ratio of velocities of neutron detectors counting is obtained for measurement of the second depth of object under research. Apparent porosity is calculated with use of at least one of measurements of time relationships and ratio of velocities of neutron counting. Influence of the first region on calculated apparent porosity is determined in response to at least one of ratio of velocities of neutron detectors counting and measurement of time relationships. Formation porosity is calculated with the help of correction of apparent porosity during definite action of the first region. The other version of method realization provides for liberation of neutron energy into region adjacent to well, determination of influence of well casing pipe on calculated apparent porosity, calculation of cement ring parameters on basis of at least one of ratios of velocities of neutron counting and measurement of time relationship. Invention also covers device having body, neutron source located in body and adapted for neutron liberation to region adjacent to well; means for production of neutron pulses by means of neutron source; the first pickup of epithermal neutrons located in body and arranged separately from neutron source; means for gathering of distant velocities of neutron counting with the help of the first pickup of epithermal neutrons; the second pickup of epithermal neutrons located in body between neutron source and the first pickup of epithermal neutrons; means for gathering of near velocity of neutron counting with the help of the second pickup of epithermal neutrons; the third pickup of epithermal neutrons located in body between the first and second pickups of epithermal neutrons; means for gathering matrix velocity of neutrons counting by means of the third pickup of epithermal neutrons; means for reception of electric signals from the first, second and third pickups indicating number of neutrons detected by pickups; means for gathering data of measurement of time relationships at least from one near neutron pickup, matrix neutron pickup and distant neutron pickup; means for gathering of at least one ratio of near velocity of neutron counting to matrix velocity of neutron counting, and ratio of near velocity of neutron counting to distant velocity of neutron counting; means for calculation of porosity of region adjacent to well. The other version of device provides means for registration of neutrons and obtaining of many velocities of counting of neutron detectors using at least two neutron sources. EFFECT: higher accuracy of measurements of formation porosity. 26 cl, 8 dwg