Reservoir characteristics of thick sandstone and micro-anisotropy of delta front micro-facies:A case study of Chang 6 reservoir in Wucangbu area

Based on data obtained from cast slice, mercury injection test, SEM, physical properties, and oil/water micro-displacement experiment, the authors made a thorough study of the petrological characteristics, porosity and permeability characteristics, pore structure characteristics, diagenesis and micro-anisotropy of Chang 6 reservoir in Wucangbu area, and analyzed the main influ-encing factors. The results show that the sedimentary environment of the Chang 6 thick sandstones reservoir is a delta front derived from the provenance in the northeast. In addition, the reservoir is characterized by medium compositional maturity and high textual maturity. The reservoir space includes residual intergranular pores, intergranular emposieu and intragranular emposieu. The sedimentary micro-facies and diagenesis constitute the main factors controlling the reservoir properties. The diagenetic period affecting reservoir development is stage A of middle diagenesis. The middle compaction, clay film cementation, residual intergranular pore diagenesis facies with weaker compaction and the secondary dissolution pore diagenesis facies are favorable diagenetic facies belts for reservoir development. Four oil displacement types are distinguished by studying reservoir microscopic heterogeneity, and the microscopic pore structures can more really reflect the reservoir's essential characteristics than the macroscopically physical properties.