Research On Reservoir Characteristics Of 1-3 Sand Set Of The Third Member Of Guantao Formation In Dalujia Area

With the theoretical basis of sedimentology, subsurface geology of oil and gas fields, and the methods of"cycle-thickness correlation"and"isobath time quautum contrast", the division and correlation of fine strata and monosandbodies are fulfilled by using the data related to cores, grading analysis, well logging and its comprehensive interpretation results. In this paper, the 1-3 sand set of the third member of guantao formation is divided into 3 fine strata: Ng3~1, Ng3~2 and Ng3~3, which can also be subdivided into several monosandbodies respectively (8 monosandbodies in all). Based on the fine stratigraphic framework, the sedimentary microfacies in Dalujia area are analysed. According to the analyses, the sedimentary facies of this area consist of alluvial fan facies and braided river facies. There are 8 types of sedimentary microfaies in the mid-fan subfacies, which are channel filling of the braided river of the mid-fan subfacies, channel bar, levee, overbank, sheet sandstone, sand dune, low-lying land among the channels and alluvial fan plain. And there are 5 types of sedimentary microfacies in the braided river facies, which are channel filling of braided river, overbank, low-lying land among the channels, flood plain and obsolescence fluvial. Meanwhile, the models of the 2 sedimentary facies are set up. And then, the reservoir heterogeneity is researched from the aspects of inter-layer, intra-layer, plane and microscale by using the data related to cores, ordinary rock thin slices, photos of scanning electron microscope and the capillary pressure curve. Finally, the reservoirs are classificated and evaluated. The classification and evaluation results demonstrate that there are 4 types of reservoir in this area that are named classⅠ～Ⅳ. 3~2 and 3~3 monosandbodies whose porosity and permeability are the best belong to the classⅠreservoir, 3~1 monosandbody belongs to the classⅡreservoir, 1~1 and 1~3 monosandbodies belong to theⅢclass reservoir, and 1~2, 2~1, 2~2 monosandbodies whose porosity and permeability are much poorer than the 3 classes mentioned above belong to the classⅣreservoir.