Reservoir Description And Prediction Of HZ19 Block In Huizhou Depression

Huizhou depression is a very important zone of hydrocarbon accumulation and distribution in the South China Sea Basin, which is located in the middle part of Zhu I depression. Research papers focus on the Midwest of Huizhou depression. Three oil fields are developed in the study area-HZ19-1/2/3, and the major pay formations are Zhuhai Formation and the lower part of the Zhujiang Formation. Structural trap is the main kind of trap, but the accuracy of the structure and estimation of reserves is badly affected by reservoir lateral heterogeneity. Study on reservoir genesis and distribution characteristics is the key to calculation of reserves and potential development.Analysis on depositional systems and facies reveals that the study area processed a sedimentary environmental evolution of tidal-dominated delta, tide coast to beach shore. Because of Dongsha uplife’s resisting, transgression entered into Huizhou depression from southwest in the early Zhuhai sedimentary period and this area was dominated by tidal current. Palaeodelta sediment was reformed into tidal-delta sediment. With the strengthening of transgression, gradually evolved into tidal environment. During the sedimentary period between late Zhuhai and early Zhujiang, transgression gradually expanded, southeast Dongsha uplift was flooded and the study area evolved into open beach shore environment.The study strata contains two third-order sequences. Six fourth-order cycles are identified in Zhuhai formation and two in the lower part of Zhujiang formation. Based on a small amount of core and logging data, 3D seismic data, with the guide of tidal and siliciclastic shore deposition models, using seismic sedimentology analysis methods, stratigraphic slice and impedance inversion technology to study sedimentary facies distribution in the fourth-order cycle stratigraphic framework. Reservoir classification based on the reservoir characteristics, diagenesis and property analysis provides a reliable basis for prediction.This paper finished oil sand correlation and sand body distribution in the fourth-order cycle. HZ19 block reservoir is mainly faulted anticline and fault-lithologic. Combination of structural and other reservoir-forming conditions, the favorable exploration zones and potential targets are predicted. It is considered that faulted anticline traps may develop in the downthrow side in the south part of the study area and fault-lithologic traps may develop in the intertidal channel and tidal sandy flat sand associated with fault in the north.