The oil reservoir of the Neogene Guantao Formation Ⅲ oil group (N1gⅢ) in the C oilfield in the Bohai Sea area is a thick massive braided river deposit. The oilfield is developed by horizontal wells driven by natural energy. The spatial distribu
tion of a single genetic sand body and its seepage barrier revealed by the fine characterization of reservoir architecture units of different levels is the key to improve the oilfield development. Based on the data conditions of sparse well patterns in the oilfield, the seismic response analysis of braided river reservoir architecture units and boundaries of different levels is carried out by using 3D seismic frequency division RGB fusion technology. Under the calibration of fine interpretation of horizontal wells, the fine characterization of braided river reservoir architecture units of N1gⅢ in oilfield C is realized. The research reveals that the N1gⅢ of oilfield C mainly develops two types of level 4 architecture units: braided bar and braided channel. The optimized 30 Hz, 45 Hz and 65 Hz frequency dividers for frequency-fused can effectively reveal the thickness variation and boundary response of different architecture units. In the frequency-fused seismic attribute, the braided bar is mainly bright red, the braided channel is represented by relatively dim green and blue strips, the sand body is represented by the splicing style of braided bar-braided channel- braided bar laterally, and the braided channel surrounds the braided bar in a “narrow strip” on the plane. Braided bar is the main type of level 4 reservoir architecture unit, mainly medium coarse sandstone with good physical properties. It is distributed in an NEE-SWW direction on the plane. The width and length of a single level 4 braided bar architecture unit is 1500~2000 m and 2000~3500 m respectively. The braided channel lithology changes greatly and the reservoir physical properties are poorer. The level 4 reservoir architecture unit is 100~300 m wide. It is a narrow strip on the plane to divide the braided bars and become a seepage barrier between different braided bars. The characterization of braided river reservoir architecture units based on frequency-fused seismic attribute overcomes the shortcomings of insufficient sedimentary feature information displayed by a single frequency band and single color, and improves the ability to extract geological bodies and detect boundaries. It has certain advantages for the prediction of out of limit reservoirs, and systematically couples the relationship between lithology, thickness and architecture. The combination of frequency-fused seismic attribute and horizontal well information is an effective means to realize the fine characterization of braided river reservoir architecture of offshore sparse well patterns, and provides a direct geological basis for the optimization of comprehensive oilfield adjustment schemes.
侯东梅, 郭敬民, 全洪慧, 张墨, 张文童. 基于分频RGB融合技术和水平井信息的辫状河储层构型研究—以C油田馆陶组为例. 石 油科学通报, 2022, 01: 1-11 HOU Dongmei, GUO Jingmin, QUAN Honghui, ZHANG Mo, ZHANG Wentong. Research into braided river reservoir architecture based on frequency-fused seismic attribute and horizontal wells — A case study of the Guantao Formation of C oilfield. Petroleum Science Bulletin, 2022, 01: 1-11