Challenges and Countermeasures for Deep-Marine Oil and Gas Reservoir Prediction and Hydrocarbon Detection—Taking the S1 Structure of the Deep Water Area in the Southwest of the Pearl River Mouth Basin as an Example

Abstract

In the past fifteen years, LW3-1, LW3-2, LS17-2 and other medium-large gas fields have been successively discovered in the deep water area of the South China Sea, demonstrating the good exploration potential. The degree of exploration is still low and the resource potential is huge. This paper takes the S1 play study in the deep water area of the southwestern Pearl River Mouth Basin in the South China Sea as an example. Against the background of no well and seven 2D seismic lines with a length of 63 km in the study area, the rock physics of LW-X in the LiWan Sag with a similar structural background in the immediate area Starting with physical analysis, the feasibility of acoustic impedance identification of gas-bearing sandstones was determined. At the same time, the well-seismic AVO forward modeling was used to determine the type of AVO gas anomaly in the study area, that is, the third type of AVO anomaly appears at 5% low gas content. At the time of over 15% high gas content, it is the fourth type of AVO anomaly, and finally formed a combination of methods of mutual verification by post-stack acoustic impedance inversion combined with pre-stack AVO analysis, and carried out reservoir prediction and hydrocarbon detection in deep-water areas. The thickness of the gas-bearing sand bodies in the S1 play is about 30.68 m, the closing height is 238 m, and the trap area is about 48 km2. The preliminary calculation of the geological reserves of the gas play is 511.33 × 108 m3, which has the exploration scale of medium-sized gas reservoirs. The area provides the basis for the next exploration and deployment.KeywordsDeep water areaZhuhai FormationAcoustic impedance inversionScalar Poisson’s ratio reflectanceAVO inversion