STRUCTURE-CORRECTION METHOD WITH SEISMIC DATA AND ITS APPLICATION TO IGNEOUS ROCK AREAS

Cenozoic igneous rocks are widely and unevenly distributed in the BZ Oilfield of the Bohai Sea. The underground structure of igneous rocks varies with depth. It is not able to correctly describe the underground structure by the conventional time-depth conversion method with seismic data, and as the result it will increase the risk and uncertainty in hydrocarbon exploration and development. In this paper, a new method for structure correction is proposed specifically for igneous rock areas. Firstly, the impact of igneous rock is studied by means of numerical simulation method so as to establish the relationship between the igneous rock thickness and the time span to be corrected. Secondly, the total thickness of igneous rocks is calculated using the interval velocity constrained inversion, then the time-correction for seismic events is obtained. Finally, time-depth relationship is adopted to eliminate the effects of igneous rock, and get more accurate structural maps by time-depth conversion. The drilling results show that this method can effectively improve the precision of structural mapping and may provide strong technical support for the first time to carry out the oilfield evaluation under the Cenozoic igneous rocks in the Bohai Sea.