Characteristics and main controlling factors of carbonate reservoirs in Qixia Formation,Longnvsi-Hechuan block,central Sichuan Basin
As a typical example of thin carbonate reservoirs with strong heterogeneity,the Middle Permian Qixia Formation gas reser-voir in the Longnvsi-Hechuan block of the central Sichuan Basin has the characteristics of low porosity and permeability.The uncer-tainty in the fine reservoir characterization only using static data restricts the well deployment,and rational and efficient development of the gas reservoir.The basic reservoir characteristics were clarified through the core,cutting,thin section and geophysical data.Subsequently,depending on the parameters of physical properties and pore structure,together with the geophysical response and pro-duction dynamic characteristics of the gas reservoir,a reservoir classification and evaluation system was established to delineate the distribution and development patterns of different types of reservoirs,and identify the main factors controlling reservoir development.The results show that,(ⅰ)the reservoir rocks in Qixia Formation are mainly composed of granular dolomites,granular limestones,and limy dolomites,and fractured-vuggy and vuggy reservoirs are most common;(ⅱ)according to the specific reservoir classification and evaluation system with the parameters of physical properties and pore structure as key indicators,the high-quality reservoirs in the study area are categorized as Type I and Ⅱ,with their spatial distribution characteristics determined;(ⅲ)five large-thickness zones are developed in the gas reservoir;the development of reservoirs in the upper submember of the second member of Qixia Formation are better than that in the lower part;high-quality reservoirs as thin beds are superimposed vertically and continuous horizontally,forming two development patterns of high-quality reservoirs,i.e.penecontemporaneous beach+karst,and penecontemporaneous beach+karst+fault;and(ⅳ)the pre-depositional paleogeomorphic slope is a favorable zone for beach development,the beach deposition controls the reservoir distribution,the karstification is a key driver for the formation of high-quality reservoirs,and the tectonism improves the storage and permeation capacity of the Qixia Formation;all these factors are conducive to the formation of high-quality reservoirs.
Sichuan BasinQixia FormationStrong heterogeneityCarbonate gas reservoirReservoir classificationMain controlling factor
万方数据
维普
