Abstract:

Changxing Formation reef-beach reservoir features are studied with core, thin section observation and logging explanation.It turns out that the main reservoir rocks are reef dolomites and reef limestone, and the reservoir space is mainly secondary pore with poor reservoir property.The reservoir types are mostly fracture-pore and pore-fracture with low-porosity and low-permeability.Changxing Formation has obvious electric response.The reef shows low gamma value, box-shaped resistivity and positive difference of deep & shallow double laterologging.The non-reef shows finger-like logging curve, low gamma, positive difference of laterologging, no significant fluctuation of three porosity log curve and its flow is affected by fissures.Relative change of sea level controls the scale of reef and beach, which gives a foundation of good reservoir.And the sedimentary setting determines the distribution of sedimentary facies which has effects on reservoir property.Uplifted side of rift trough and palaeogeomorphology highland dominate the distribution of reef and beach in the platform margin, which is the basis of the development of excellent reservoir facies belts.Moreover, dolomitization and solution promoted the property of reservoir and provided advantages for the formation of secondary pores.

Key words: Tieshan-Longhui, Changxing Formation, reservoir, reef, northeastern sichuan