Rapid calculation of gravity anomalies based on residual node densities and its GPU implementation

Gravity forward modeling is an important part of three dimensional physical property inversion; however, its time-consuming nature restricts its practical application. Several authors have made efforts to develop this procedure and have achieved some success. This paper proposes a new simple and fast approach for computing gravity anomalies at arbitrary points. In our method, the subsurface is divided into a 3D array of rectangular prismatic blocks, each with a constant density. Then the block density model is transformed into a residual node density model. Finally, gravity anomalies at survey points are calculated using the new residual node density-based forward formula. This method is implemented on a CPU-GPU heterogeneous architecture with the CUDA FORTRAN language and achieves more than four times acceleration compared to the classical method in the same computational environment and two orders of magnitude acceleration compared to one CPU processor on synthetic random density model tests.