Study On The Seismic Method For The Characterization Of The Reservoir Architecture Of The Shallow Delta In The South Of Bozhong 28-2

Reservoir architecture is one of the important factors to control the distribution of remaining oil in the high water cut period,and clarifying the type and characteristics of the reservoir architecture elements is an important means for finely characterizing the distribution of remaining oil and improving oil recovery.However,for offshore oil and gas reservoirs,due to the large well spacing,it is difficult to characterize the reservoir structure.This paper takes Bozhong 28-2 South Shallow Water Delta Reservoir as the research object,systematically studies the types and characteristics of reservoir architecture elements,and the technical methods of architecture characterization based on seismic data,revealing the different levels of reservoir structure in the study area The pattern of regular distribution.Through observation and analysis of core wells in the study area,combined with modern sediments in shallow water deltas,three types of sedimentary evolution models of the Bozhong 28-2 south shallow water delta were determined: transitional shallow water delta model developed by residual dams,branches with isolated branch channels Shallow shallow water delta model and continuous leafy sand body dominated by leafy shallow shallow water delta model.Under the guidance of the shallow water delta sedimentation model,six single underwater distributary channel architecture models are summarized: elevation difference type,thickness difference type,dam above river type,thick-thin-thick type,inter-channel dike type,inter-channel mud type.Through forward earthquake simulation,the seismic response characteristics of different architecture modes are revealed.The one-dimensional forward modeling has determined the lower limit of the thickness of seismic resolution at different frequencies.It is pointed out that when the main frequency of seismic data is 65 Hz and the recognition thickness is 8.5 meters,the composite sand body recognition accuracy is met,and the seismic reflection waveform characteristics of the composite sand body are obvious.Six architectures of single underwater distributary channels were selected to perform twodimensional seismic forward modeling at different frequencies,and the seismic response characteristics of different architectures were analyzed.The elevation difference type occurs at the sand body connection site and the seismic in-phase axis is misaligned;the thickness difference type stretches the seismic waveform at the sand body contact part and the energy is weakened;The reflection wave trough rises stepwise;the thick-thinthick seismic wave peak rises stepwise at the contact point of the sand body;the samephase axis of the inter-channel embankment-type seismic wave appears to rise first and then decrease,and the seismic energy is also weak;the inter-channel mud type Earthquake reflection is intermittent.On the basis of seismic attribute analysis,the root mean square attribute is optimized to establish a composite sand body thickness prediction model and determine the composite sand body boundary in the study area.Inside the composite sand body,through the analysis of seismic waveform characteristics,the boundary of a single underwater distributary channel was portrayed to realize the anatomy of different reservoir architectures in the study area.