Abstract:
The main target layer of Bohai B Oilfield is the Dongying Formation, which is 50-80 meters away from the bottom of the overlying Guantao Formation. There are one or more sets of high-speed, high-density and limited-distributed conglomerates developing at the bottom of the Guantao Formation, they cause energy loss, weaken the seismic response of the underlying reservoir and seriously affect the identification of the true range of the reservoir. For this reason, in this paper, starting with the theory of seismic wave propagation, firstly, we analyze the reflection and transmission loss effects of conglomerate-induced energy. Secondly, based on the forward simulation, the degree of energy loss caused by the conglomerate is analyzed, which is the same cumulative thickness. With more layers of conglomerate come greater losses. Based on the forward simulation results and the well-earthquake combination, we describe the plane distribution range of the three seismic phases, which are single set of conglomerates, multiple sets of conglomerate and non-conglomerate rock. Furthermore, combined with seismic attributes, we perform quantitative analysis on the plane distribution range of the energy loss of the reservoir. Then we extract the energy compensation factors of different seismic phases, and propose the phase-controlled energy compensation method for corresponding amplitude compensation. That is, the energy loss caused by single set of conglomerate is mainly compensated by reflection coefficients while the energy loss caused by multiple sets of conglomerate is mainly compensated by transmission coefficients repeatedly. Finally, we quantitatively eliminate the energy shielding influence of the overlying Guantao formation conglomerate on the underlying Dongying formation reservoir, portray the true plane range of the reservoir, and obtain drilling success, which fully proves the validity of this research and realizes accurate prediction of potential area.
