3D-VSP Design Acquisition for Monitoring In Situ Combustion. A Case Study: Llanos Basin Colombia

In order to monitoring the combustion in-situ in a field, we decide to use the 3D-VSP technique such that it could be repeated several times during the field development. The selection was based on (1) area target extension, (2) monitoring wells distribution, (3) thickness target affected by air injection and (4) vertical and horizontal resolution required. The goal of this work is select the parameters which allow both, right target illumination and repeatability. The 3D-VSP design strategy was analyzing the sensibility of the acquisition parameter and performs geophysical modeling by ray tracing. During sensibility analysis the source distribution (geometry) and the number and depth levels were perturbed. The depth level is a critical parameter for repeatability; because of the possible damage induced by combustion to the formation. Additionally, ray tracing was performed on the structural model to quantify the optimal source distribution and the optimal source density. Variability of parameters was evaluated as a function of the homogeneity coverage. Finally the optimized acquisition geometry includes results from sensibility analysis and geophysical modeling processes