Abstract: Detailed reservoir description is a method of integrated reservoir study,with the purpose of researching structure,configuration of geobody,lithology,describing distribution of reservoir and fluid condition,detailed geology model has been provided for improving recovery and economical development of oil fields.In this paper,taking A oilfield which is located in Pearl River Mouth basin of South China Sea as an example,focusing on complicated geological characterization of reef reservoir,introducing a method of integrated study under the guidance of geology pattern which is based on fundamental geology study,using seismic,log and geological data,has been applied to the characterization of depositional facies,reservoir heterogeneity,reservoir inversion and fracture distribution to build detailed geology model which can provide necessary,credible geological recognition for oilfield development project and evaluation.