Reservoir Evaluation Of The Sinian Dengying Formation In The Gaoshi Ladder-Moxi Area In Central Sichuan

Reservoir evaluationhas important significance for oil and gas exploration of Dengying Formation in the Gaoshiti-Moxi area.Based on the drilling,geology,core,outcrop,logging,testing and seismic data,a systematic research of stratigraphic characteristics,sedimentary characteristics,reservoir characteristics and distribution,has been carried out,reservoir evaluation standard is established.It mainly achieved the following results and understanding:(1)According to the latest standard of Sinian layered,It can be divided into two series,Upper Permian is Dengying Formation,lower Cretaceous is Doushantuo Formation.Dengy:ing Formation is divided into four sections,withthe thickness of 700m,the second and fourth Member are above 230m,which the transverse stability is poor,the first and third Member are below 100m,which the distribution is relatively stable.(2)Dengying Formationis the carbonate platform sedimentary facies and shelf facies.Specifically.Member 1 is carbonate platform facies restricted platform subfacies lagoon facies and sedimentary facies;Member 2 is the limitations of Taiwan and phase particles beach,lagoon,algae beach sedimentary microfacies;Member 3 is Mixed shelf shallow shelf facies and deep shelf facies;Member 4is the limitations of Taiwan and phase lagoon,grain bank,algal bank microfacies.(3)It is mainly lithologic reservoir grain dolomite,algal dolomite and particle dolomite;the reservoir space is mainly karst cave and pore,fracture secondly,The reservoir has the characteristics of low porosity and low permeability for weighted average porosity is less than 5%,permeability is lower than 1mD,the reservoir type is fracture pore type.(4)The second and fourth Member reservoir are much develop.Member 4 is 100m?180m,the thinnest is about 50m;Member 2 is 40?100m,the thinnest below 20m.The reservoir is the most developed in the west of Gaoshiti-Moxi area,which is distributed from the north to the south.(5)Based on the FMI and resistivity logging,the reservoir validity is established.Member 4 is mainly type ?,accounting for the total thickness,which is from 90.8%to 100%;Member 2 is mainly type III,which is from 88.0%to 100%.