Using diagenetic facies to analyze heterogeneous reservoir of Donghe sandstone of east slope of Lunnan,Tarim Basin

Based on the study of diagenetic facies,the heterogeneous reservoir of Donghe sandstone of the east slope of Lunnan in Tarim Basin is subdivided into six diagenetic facies.The compact and non-compact cemented carbonate facies,which are widespread and regularly developed,damage the reservoir performance in the eogenetic stage and make it become a strongly heterogeneous reservoir.Generated from the partial solution,non-compact cement carbonate-weak solution facies,remaining primary porosity-weak solution facies and remaining primary porosity-solution facies are the results of the improved reservoir performance in the late diagenesis.Comprehensive studies show that the diagenetic facies and reservoir types have good corresponding relations.The type Ⅴ non-reservoirs are composed of the compact cement facies of carbonate;the type Ⅳ reservoirs are composed of the non-compact cement facies of carbonate;the type Ⅲ poor reservoirs are mainly composed of the non-compact cement-weak solution facies of carbonate and secondarily composed of the primary porosity facies;the type Ⅱ medium reservoirs are mainly composed of the remaining primary porosity-weak solution facies and secondarily composed of the non-compact cement facies-weak solution facies of carbonate;the type Ⅰ fine reservoirs are mainly composed of the remaining primary porosity-solution facies.According to the facies' distribution and structural features,it is predicted that the fine reservoir of type Ⅰ is mainly located along the pinchout boundary of the research area,and the main trap type is structured-iagenetic.The medium reservoir of type Ⅱ is mainly located in the north slope region of Well Quema 1-Well Cao 3,and the main trap type is diagenetic.