# Analysis of Hydrocarbon Enrichment in Tight Sandstone Reservoirs in the Eastern Baiyun Depression
## 4 Basic Characteristics of Paleogene Reservoir Formation Elements in the Eastern Baiyun Depression
### Development Characteristics of Reservoir and Cap Combination  
The Yunli uplift and Yundong low uplift have developed a few favorable nose-shaped structural belts, which are located in the east wing of the main depression of Baiyun and have developed a number of secondary depressions around them and have rich hydrocarbon source potential. As long as effective reservoir and cap combinations can be implemented and located on favorable oil and gas migration paths, related traps with exploration potential can be formed. Through the oil and gas display revealed by the existing drilling and lithology combination analysis, the advantageous oil and gas migration and accumulation range (the area circled by the dotted line) in the eastern Baiyun area can be preliminarily defined, that is, the advantageous accumulation driving range (Figure 7).  
The western side of the Yunli low uplift and the western side of the Yundong low bulge in the eastern part of Baiyun are adjacent to the east side of the main depression of Baiyun and the related source rocks of the secondary depression and are on the favorable path of oil and gas transport, and the transport distance is relatively close, so they belong to the advantageous source transport and accumulation path and have high hydrocarbon migration and accumulation potential. Through the analysis of the relevant cross-well seismic profile, the seismic facies characteristics of the sand-oil-rich lithologic assemblage are mainly medium-strong amplitude-to-intermittent reflection, while those of the mud-rich lithologic assemblage in the eastern Baiyun area are mainly medium-weak amplitude-to-continuous reflection.  
The LGH-8 well site showed mud-rich deposits and, occasionally, thin sand bodies developed deposits. At the LGH-7 well location, the lower Wenchang Formation develops a large set of sandstone, the upper Wenchang-Zhuhai Formation develops a thick mudstone and mud-sand combination, the sand body is relatively thin, and the upper Wenchang Formation can be seen as an oil layer. At the LGH-4 well location, there is a large set of sand conglomerates in the lower Wenchang Formation, but no oil and gas show. The well LGH-9 developed large sections of mudstone in the T70-T80 period, abnormal gas measurement in the Enping Formation period, and overpressure accumulation in the Lower Wenchang period. The well WXD-5 shows oil formation in both the Enping Formation and Wen3 Member. The Enping Formation is well developed, while the Wen 3 Member is poorly developed.  
In summary, the relevant drilling results in the eastern Baiyun area reveal the following: (1) The Lower Wenchang developed thick sand conglomerate (LGH-4 and LGH-7), but there was no oil and gas display--high-quality sand bodies near hydrocarbon sources or favorable transport high locations should be sought. (2) The Upper Wenchang-Enping Formation: thin sand formation (WXD-5 and LGH-7)--thick and high-quality reservoir sand bodies should be implemented within the effective range of reservoir formation drive. Therefore, the most restricted oil and gas exploration in the eastern Baiyun area is the lack of high-quality sandstone reservoirs located in the favorable accumulation driving zone, which is also the focus of this study.  
5 Optimal Selection and Main Distribution of Favorable Trap Targets in the Eastern Baiyun Depression