“…A number of downhole sources have been developed that are capable of carrying out high-fidelity production surveys (Gustaysson et al, 1986;Hardee et al,1987;Baria et al, 1988;Harris, 1988), and a number of reconstruction algorithms have been proposed (Dines and Lytle, 1979;Mason, 1981;Pratt and Worthington, 1988;Bregman et al, 1989;Pratt et al, 1993). In spite of the conceptual attraction of the crosshole technique, often the resolution of the images has been less than hoped for, prompting recent researchers to try to explain the limitations of the reconstruction algorithms (Williamson, 1991;Williamson and Worthington, 1993;Rector and Washbourne, 1994).…”