Apparatus and methods for measuring formation characteristics

摘要

Abstract An apparatus can measure characteristics of a formation surrounding a borehole. The apparatus comprises a tool body including a neutron measurement section including a neutron 5 source and a neutron detector arrangement spaced in an axial direction from the neutron source; and a density measurement section including a gamma ray source and a gamma ray detector arrangement spaced in an axial direction from the gamma ray source. The neutron measurement 10 section and the density measurement section are positioned in the tool body so that the sections overlap in the axial direction and are azimuthally spaced apart in the tool body. The tool body also includes shielding to block a direct signal path from the neutron source to the gamma ray detector 15 arrangement and to block a direct signal path from the gamma ray source to the neutron detector arrangement. 2340139_1 (GHMattere) 14/07/10 38 34 40 36 32ig16e11 22 38 2 2 8 24 30 Figure 1 Figure 2 2340139 1 (GHMar~ters) 14/07/10