Numerical simulation of Sector Bond log and improved cement bond image

Abstract

The two principal functions of a primary cement job are to provide support for the casing and to provide hydraulic isolation between zones. A poor cement job may cause many issues during the well production. Therefore, cement bond evaluation is very important in well completion. The Sector Bond log (SBL) has been widely used for cement bond evaluation for years. The SBL tool has eight pairs of directional transmitter-receivers, which are equally distributed in azimuth and used for identifying channels and channel azimuths. To better understand SBL, using a parallel 3D finite difference algorithm, we numerically simulated acoustic responses of the SBL under a variety of cement bond scenarios and investigated the sensitivity of the integral amplitudes to channel size and its azimuth. We further developed a new approach to image potential channels in cement annulus using the integral amplitudes. The comparisons between conventional SBL images and the reprocessed ones using the new approach showed significant improvement on both synthetic and field data.