Gamma-gamma density measurements: basic response and environmental corrections

The basic response of a gamma-gamma density logging tool and the environmental corrections to that response have been determined. This has been accomplished through the use of test formation data and Monte Carlo modeling. The basic response has been determined for formation densities of 1.6 g/cm³ to 3.1 g/cm³. Environmental corrections have been obtained for a full range of borehole conditions. Mudcake corrections in light mud, barite mud, and hematite mud have been obtained for simulated mudcake thicknesses of up to 0.75 in. Borehole size corrections have been obtained for mudcake thicknesses of up to 0.75 in. Borehole size corrections have been obtained for air-filled, water-filled, and mud-filled boreholes with diameters from 6 to 14 in. The response and corrections have been verified downhole through extensive comparisons with core and gravinometer data