Reservoir Evaluation Of Feixianguan Formation And Selection Of Favorable Exploration Areas In Huanglongchang North Block, Northeast Sichuan

The high-quality oolitic beach carbonate reservoirs developed in the Lower Triassic Feixianguan Formation in the northeastern Sichuan Basin have "four high" characteristics,namely high porosity,high permeability,large thickness,and high abundance.However,due to the wide variation of reservoir spatial distribution,the uneven thickness and the strong heterogeneity of the reservoir,it is difficult to explore and develop the gas field.Through the comprehensive study of the shoal reservoir in the Feixianguan Formation,not only its development characteristics and spatial distribution patterns can be revealed,but also the favorable exploration area for future exploration can be predicted.This paper is guided by the theories of sequence stratigraphy,sedimentary petrology,reservoir geology and petroleum development geology.Field profile,core description and slice analysis,logging data and production test data are taken in this paper.Based on the combination of macro and micro,geology and logging,the study of stratigraphic division and sedimentary facies is carried out in the study area,and the petrological characteristics,physical characteristics and reservoir space types of the reservoir are analyzed,and the spatial distribution laws of reservoirs are summarized,the main controlling factors for layer development are clarified.On this basis,the reservoir is classified and evaluated,and the next exploration favorable zone in the study area is predicted,which provides a useful geological basis for the next exploration and development work of the Feixianguan Formation gas reservoir in the study area.The following points were summarized through the study:(1)Based on the interpretation of well logging curves,lithologic characteristics,and thin section identification results,the Feixianguan Formation in this block can be re-determined to be a 1st member-to-4st member based on the interpretation of lithology.(2)Through the analysis of sedimentary facies,it is believed that the Feixianguan Formation in the study area is mainly in the mesa-facies zone,and the sedimentary facies in the study area is further subdivided into seven sub facies.(3)The main reservoir rocks of the Feixianguan formation in the study area are oolitic limestone and oolitic dolomite.The type of reservoir space in the eastern region of the study area is the residual intergranular pores and intergranular dissolved pores,dissolved pores and fractures in the western region.(4)The Feixianguan Formation is a typical facies-control reservoir,and reservoir development is controlled by the features of paleotopography,which is high in the east and low in the west.(5)Combining the evaluation criteria of reservoirs and the production status of oilfields,through the evaluation of single-well reservoirs and comparative analysis of wells and reservoirs,it is believed that the Huanglong 6-Huanglong 9 and its northeastern area should be favorable areas for the next exploration.