Study On The Reservoir Of Lower Silurian Shiniulan Formation In Fenggang 2 Block In Northern Of Guizhou

Natural gas plays an important role in the country's energy structure.Guizhou Province is relatively poor in oil and gas resources.The northern of Guizhou province is close to the edge of the Sichuan Basin and which is a key area for natural gas exploration in the future.A few days ago,Anye 1 well in Zheng'an County acquired the industrial natural gas flow for the first time in the Shiniulan Formation.This is the first time that this layer has been discovered in China,and it also pointing out a new direction for natural gas exploration in Guizhou Province.In this paper,based on the Fenggang 2 block,through the results of previous studies,combined with field work and indoor analysis,we started with the aspects of sedimentary facies,diagenetic lease,physical properties of reservoirs,interpretation of well logs,and comparison of adjacent blocks.The research and evaluation of the Shinulan Formation reservoir are conducted to clarify the influencing factors of the Shinulan Formation reservoir.The types of sedimentary facies in the Shiniulan Formation of the study area mainly include the carbonate platform facies,platform margin slop facies,and the shelf facies.Among them,the reservoir is mainly developed in the nodular limestone of the platform margin slop facies,where the fractures were developed.The micritic limestone and the argillaceous limestone of the shallow water shelf facies are relatively dense and the reservoirs are not developed.The Shiniulan Formation in the study area experienced four tectonic evolution stages: isogenetic rock,early diagenesis,late diagenesis,and epigenetic rocks.The main types of diagenesis are compaction and pressure dissolution,cementation,fracture,filling,dissolution and dolomitization.Among them,the role of dolomitization is related to the deep-seated depositional environment.It develops and fills in the erosion cracks,which has little effect on the reservoir reconstruction.The intragranular dissolved pores and intergranular dissolved pores formed by dissolution are the main reservoir spaces for reservoir development,but the intense filling and cementation at the later stage of the diagenesis process results in further reduction of the porosity of reservoirs and reservoirs.Space is further reduced.The diagenesis has a great influence on the development of the Shiniulan Formation reservoir in this area.The Shiniulan Formation reservoir in the study area has a low porosity and permeability,the average porosity is 1.18%,most of the porosity is less than 2%,and the average permeability of the reservoir is 0.002771 md,which is a dense type reservoir.The fractures and dissolution holes were the storage space,but the fractures play an important role in the storage space.The development of reservoirs is mainly affected by sedimentary facies,diagenesis,and the degree of development of fractures.The development and filling of fractures have a greater impact on reservoirs.According to the analysis of well logging data of Yongfeng 3 well,the log curves of the Shinulan Formation reservoir are characterized by high resistivity,high natural gamma,low neutron porosity,low time difference,high density,and well diameter.relatively stable.Reservoir types are mainly Type III and Type IV reservoirs.The fractures and dissolution holes are the storage space.And as the development of the fractures,which let the fracturs become the main storage space.