EROSION THICKNESS RESTORATION BY MASS BALANCE METHOD: A CASE STUDY IN DONGYING FORMATION, NANPU SAG

The restoration of erosion strata thickness, as a precondition of burial history and thermal history inversion, is a very important work in basin simulation. Mass balance method is used to restore the strata erosion thickness through stratigraphic physical property obtained from drilling, well logging and seismic data. Firstly, the contact relationship of adjacent formations is judged by the physical property difference. A layer with a thickness of H and same lithology is put at the top of the eroding formation to balance the physical property difference. Therefore, the erosion strata thickness can be obtained by mass balance method. According to the computer program based on mass balance method, the calculation process of erosion strata thickness becomes more and more accurate and efficient. In this paper, according to mass balance method, the erosion strata thickness of Dongying Formation of Nanpu Sag has been calculated, which are 486m, 466m, 573m and 634m in Well G35, Well G62, Well L4 and Well L14 respectively. Simulation result indicates that it is feasible and effective to restore the erosion strata thickness using the mass balance method. Compared with traditional methods, the physical properties data needed by mass balance method are more accessible, so it is applicable to calculate the stratigraphic erosion amount in various exploration stages.