Diagenesis and Favorable Diagenetic Facies of the Chang 6 Reservoir in Heshui Area,Ordos Basin

The Chang 6 sandstone reservoir in Heshui area,Ordos Basin,is manily composed of feldspathic litharenite sandstone and litharenite.It is of typical low porosity and low permeability reservoir with average porosity of 8.68% and average permeability of 0.15×10-3 μm2.The reservoir has experienced compaction,cementation,metasomasis and dissolution,and is now in the late diagenetic phase A.On the base of diagenesis research,it sets up the single well diagenetic facies by many ways of core observation,cast section,SEM and the logging analysis.Then the paper analyses areal distribution graph of diagenetic facies.The braided river delta front sandbody in the study area can be divided into 4 diagenetic facies belts,including compaction,carbonate cementation,chlorite film residual pore and chlorite film residual pore-feldspar corrosion.The advantaged reservoir is distributed at the latter two facies belts.The oil production of well in the adwantage belt is more than 10 t/d according to the test oil data.