Reservoir characteristics and diagenesis of the Cambrian dolomite in Tarim basin

The Cambrian dolomite reservoir is one of the most important potential fields for petroleum exploration in Tarim basin.The main objectives of this paper are to investigate the reservoir features and diagenesis of the Cambrian dolomite in Tarim basin,based on the analysis of the core,thin-section,SEM,C-O-Sr isotope and petrophysical properties.The results show that the porosity types of the Cambrian dolomite reservoir are mainly composed of intercrystalline solution pore,vug and fracture.It is rare for reservoir that only consists of intercrystalline porosity.The petrophysical properties of the reservoirs are associated with the dolomite types,and the reservoir quality of very fine to fine-crystalline dolomite is the best of all dolomites.The main constructive digenesis include shallow burial dolomitization,contemporaneous dissolution,karstification and hydrothermal dissolution;the destructive digenesis contain cementation,over-dolomitization,calcite and other authigenic minerals void-filling.The late diagenetic dissolution including karstification and hydrothermal corrosion plays an important role for the formation of dolomite reservoir,due to the over-dolomitization leading to the decreasing of intercrystalline pores in the Cambrian dolomite reservoirs.