Doggers !!!!

By definition, Doggers are concretionary masses of calcareous sandstone or ironstone occurring in sedimentary rock. These are basically high dense, high resistible bodies often encountered by drillers. Geologist say, they are easily recognizable in the sedimentary rocks. As I first noticed it in a field trip in Northumberland, I first thought it as a mud volcano. well that's very much expected from a naive Geologist or a Geophysicist. But, what importance does it hold for a Geophysicist??

Well for a Geophysicist, it is important to note what kind of response these feature poses in log or seismic. On log it will occur as pretty high density, sonic spike. So, an expected high increase in impedance. So, you are expected to see a response in seismic. But, remember this is a very local feature. So, may not be resolvable on seismic scale and you might not see it in seismic. While doing a well to seismic tie, you will observe a strong booming reflector in well synthetics, but absolutely nothing in seismic. It could mislead us to think that, the booming event is either a noise or a real event not detected by seismic. Since this a local event encountered by a well, to achieve better well to seismic tie we could remove the effect of the doggers in the well logs (by editing logs) and then perform well to seismic tie. The tie will definitely improve...:)