| Baiyun sag is located in the northern continental slope deep water area of the South China Sea, belonging to Zhu?depression in Pearl River Mouth Basin. The study region with the area about 4000 km2 is located in the south of Baiyun sag in this paper. The research sequence(ZHSB6) is located in the upper part of the Zhuhai formation. On the basis of the explained sequence interface, we encrypted interfaces to 1×1grid and repeated revising,it is in order to extract the RMS amplitude attribute.According to the data of 5 Wells in work area and combining the waveform analysis, the sand-body is divided into three categories: type?with the speed is less than the mudstone, is very good in sorting and rounded and has no impurity, such as channel sandstone, mouth bar sandstone, sheet sandstone and so on, which is good oil-gas reservoir in deep water exploration and the focus sandstone of this paper; type?sandstone is basically the same speed with mudstone; type?sandstone is greater than the mudstone.To make synthetical record of 5 wells and adjust them by waveform analysis and speed analysis. In this way, match the amplitude and waveform of synthetic seismogram with well seismic record and make lithology histogram. Combining with logging data and comprehensive histogram of sedimentary facies made by GR curve, it has lithology and physical properties show obviously. Single well sedimentary facies analysis results show that in W18 well, the lithology is mainly argillaceous limestone and mudstone above SB21 interface; it shows the low-frequency and weak amplitude in seismic profiles. Between SB23.8 and ZHSB6 interface, there is mainly mudstone, coarse sandstone, fine sandstone and argillaceous siltstone, sandstone is relatively pure, shale content reduces downward. In W13-2 well, the lithology is mainly mudstone, with a small amount of mud argillaceous siltstone and silly mudstone. The main sedimentary environment is outer continental shelf parfacies, with stable hydrodynamic conditions and shortage sedimentary material supply, it shows the low-frequency and weak amplitude in seismic profiles.By combining seismic line, waveform analysis and single well sedimentary facies analysis results, we effectively convert seismic facies to sedimentary facies, and then study paleocurrent direction. There are 2 main water systems from north-west to east-south in the ZHSB6 sequence. The lithology in W35 well is mainly mudstone and has thin layer of silty mudstone shale, the mudstone is pure as a whole. The sandstone content is increasing near MFS18.5 interface. The GR value is higher, it is delta front subfacies depositional environment, that displayed on the seismic section for low frequency weak amplitude characteristics. The W16 is located in the middle of the study area. The lithology is mainly mudstone between SB21 and SB23.8 interface. GR curve for finger, it is the outer continental shelf subfacies depositional environment with stable hydrodynamic conditions and scarce sedimentary material supply shortage. On the seismic section, it appears as weak low-frequency amplitude characteristics.To extract RMS amplitude attribute of ZHSB6 sequence and combine waveform analysis, we analyze the different colors on the RMS attribute and portray sand-body. And then, we analyze sedimentary system in order to better display the sedimentary body skeleton formation distribution and horizontal distribution pattern through sand-body extension explanation. It forms the sedimentary environment of the delta plain, the land and sea in delta front and slope fan in the internal sequence. |
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