Characteristics and Main Controlling Factors of Chang-6 Reservoir of Triassic Yanchang Formation in Dalugou Area,Ordos Basin

Based on outcrop observation,core description,geophysical logging interpration and other test datum,the petrologic characteristic,pore structure and the physical properties of Chang-6 reservoir of Yanchang formation in the Dalugou exploration area are studied.The result shows that: the Chang-6 reservoir of Yanchang formation in this area is feldspar sandstone with low porosity and permeability;the sandstones can be compositionally classified as immature and high structural maturity;the pores of the reservoir are mostly intergranular pores,intraparticle dissolution pores and moldic pores or relic moldic pores;the characteristics of the pore structure are minor pores and microcrystals;the reservoir is formed by interaction among original terrestrial composition,sedimentary facies and diagenesis;the structure and amount of original terrestrial composition are direct factors leading to good physical property;sedimentary facies is the basic factor that controls the final distribution and space characteristics of reservoir;submerged distributary channels in delta fronts are the favorable sedimentary environment for the formation and development of reservoir;diagenesis plays!cardinal role in the quality of reservoir,compaction and cementation mainly led to the tight reservoir and poor physical property, while dissolution makes the reservoir become good.