The Effective Reservoir Evaluation Of Tight Sandstone Of Yanchang Formation In Honghe 92 Production Field Of Honghe Oilfield

The development of tight sandstone reservoir is controlled by many factors and the reservoir quality difference mechanism is complicated.Sedimentation,diagenesis and fractures developping under the regional tectonic stress comprehensively control reservoir evaluation and the distribution of effective reservoir,which will influence area selection of oil reservoir exploitation.This paper takes Chang 8₁²,the main production layer in Honghe 92 production field of Honghe oilfield,as the research object.Based on analysis test data including casting thin section,SEM and conventional mercury injection,core observation,logging curves and seismic attribute analysis to study on reservoir basic characteristics and planar distribution,discuss the influence of sedimentation and diagenesis on reservoir quality,reveal the development rules and controlling factors of fractures at different scales,elucidate reservoir quality difference mechanism.Finally,based on basic reservoir characteristics,diagenesis types and fracture development rules,a Comprehensive Reservoir Evaluation Standard of Chang 8₁² in Honghe 92 production field is established to divide the plane distribution range of effective reservoir and provide guidance for reservoir production.Chang 8₁² reservoir in Honghe 92 production field is dominated by braided delta front deposition.The lithology is underwater distributary channels feldspathic lithic fine sandstone with medium compositional maturity and texture maturity.The reservoir space is mainly intergranular dissolved pore and residual intergranular pore with complicated pore and throat texture.The reservoir has reached middle diagenetic stage A.Compaction and cementation is the direct factor of sandstone tightness.The chlorite coatings protect the primary pore from compaction to some extent.The dissolution makes great contributions to improve the reservoir quality and secondary solution pores become favorable reserving space.The development of NEE Trend fault and fracture developed zone is controlled by NE-SW trend tectonic stress associated with the Yanshan tectonic events,which improves the reservoir permeability and is the superior factor contributing to high production in this area.Effective reservoir is controlled by many geological considerations,including sedimentary microfacies,reservoir quality,pore and throat texture,diagenetic reservoir facies types and the development rules of fracture.Effective reservoir occurs as lenses in the muti-cutting place of the distributary channels in the northern part of the study area with superior original sedimentary fabric.The effective reservoir has also experienced constructive diagenesis and fracture system is well developed.