A Study On Pore Structure Of Chang6Reservoir In Fuhuang Area

This article studies the macro and micro sedimentary facies, diagenesis features, andpetrology characteristics of the Chang6reservoir in Fuhuang area, systematically analyzesthe micro pore structure through methods including cast thin section, SEM photograph andmercury injection. The focus of this study is to address the effect of the type, size anddistribution of pores, apertures and tubes, sedimentology and diagenesis to the pore structurein the Chang6reservoir in Fuhuang area.The Chang6reservoir in Fuhuang area is described as mid-fan subface, Hackberry face.Three types of microfacies, turbidity channel, middle turbidity channel and mid-fan transitionzone are developed in this area. Sandstone types are mainly feldspar sandstones, which arefine-grained; moderate to poor sorted, subangular to angular in shape with strongheterogeneity. The heterogeneity of fillings is caused by carbonations cement and claycement. Diagenesis compaction, cementation and dissolution are observed in the study area.According to the standard of diagenesis stages, the Chang6reservoir in Fuhuang Area is atthe A episode of middle diagenesis.The study area is dominated with residue intergranular pore and feldspar dissolutionpore. Interfacies pores are rare. Pore combinations are classified as residual intergranular,intergranular-dissolution, dissolution-micropore, and micropore types. Throats are present aspoints, pipes and flakes or bowed flakes. Narrow-neck throats are rear. The matrix showspoor pore connectivity. Throat coordination numbers are fairly low, which mainly range from2~3. In summary, the pore structure in study area shows strong heterogeneity. Additionally,through the correlation analysis of the physical property and characteristic parameter gainedby mercury injection experiment, the reservoirs are divided into I (fine), II (moderate fine),III (moderate) and IV (poor) four categories.Conclusions drawn through the integrated analysis of factors influencing the porestructure in Chang6reservoir in Fuhuang area are: the distribution and development of porestructure in reservoirs depend on the composition maturity,structure maturity,sedimentarystructure and micro-sedimentary facies. Diagenesis has various effects on pore structures:compaction and cementation increases the micro-heterogeneity and pore structure complexityof reservoir, while dissolution can decrease the detour of throats, and therefore improve pore structure. In the main time, the composition and proportion of fillings are also important indetermining the micro-pore structures in reservoirs.