A 3D model of the Wathlingen salt dome in the Northwest German Basin from joint modeling of gravity, gravity gradient, and curvature

In the past few decades, numerous attempts have been made on modeling of salt tectonics and deciphering the geometry of salt domes, which is a key challenge in petroleum exploration. We have derived a 3D density model of the Wathlingen salt dome, situated in the southern part of the Northwest German Basin from joint modeling of reprocessed torsion balance measurements. Gravity, gravity gradients W (sub zx) and W (sub zy) , curvature derived from horizontal gravity gradients W (sub zy) , and horizontal directive tendency are jointly modeled to decipher the geometric structure of the salt dome. The model was constrained by geologic and borehole information. We found that the Wathlingen salt dome is a mushroom-structured salt body, which is 14-km long, 4-8-km wide extending up to approximately 4-km depth. The top mushroom structure of the salt is horizontally spread up to approximately 8 km. It would not have been possible to derive the complex 3D structure from modeling of gravity data alone.