Decreasing Uncertainty of Joint Gravity and Seismic Inversion by Constraining Initial Models with Well and TEM Data
A. Cygal, J. Pilch, A. Pasternacki, M. Stefaniuk, T. Maćkowski and J. Wazny
Event name: 79th EAGE Conference and Exhibition 2017
Session: Near Surface : Joint Inversion, Integration, Environmental and Engineering
Publication date: 12 June 2017
Info: Extended abstract, PDF ( 1.87Mb )
Price: € 20
Several geophysical surveys were conducted along 6-km-long testing line in order to obtain an accurate shallow distribution of P-wave velocity for static corrections calculations. The near-surface geology of the study area (Puławy Trough, SE Poland) consisted of horizontal, undisturbed Jurassic and Cretaceous sediments unconfornably overlaid by Quaternary unconsolidated cover. Gravity and seismic joint inversion (GJI) was applied to obtain detailed velocity fields, however, while developing a workflow, a problem concerning high sensitivity of the inversion results to initial models was encountered. It was concluded that for the proper imaging of the characteristic lithological stratification and groundwater conditions of the analyzed medium, it is reasonable to supplement the standard methodology (GJI) by additional geophysical technique, in this case TEM. Resistivity models of the subsurface derived from TEM data inversion were subsequently geologically interpreted in reference to the neighbouring well. Once the models interpretability was confirmed, some advanced statistical analyses comprising well log data were carried out in order to establish velocity-resistivity estimates. Eventually, new initial models for GJI were prepared from well-calibrated resistivity data conversion. Updated values of static corrections brought a remarkable improvement in seismic imaging, emphasizing the necessity of independent geophysical and geological data integration.