Study On The Crevice Unit Of Ordovician Carbonate Reservoir In The Middle Slope

This paper focus on the on the ordovician carbonate fractured-vuggy reservoir in the central slope of Lungu oil field, and study the characteristics and the distribution of carbonate fractured-vuggy units in ordovician carbonate reservoir by chromatographic fingerprint of crude oil and reservoir in petroleum geology, combining with geological, well logging, seismic data and reservoir engineering data reservoir geology, and obtained the following conclusions:1、The main reservoir is the YingShan formation of middle and lower Ordovician carbonate in the central slope belt of Lungu oil field. Lithology of Ordovician carbonate reservoir include micritic limestone, followed by granular limestone. The Ordovician carbonate reservoir matrix is belong to low porosity and low permeability reservoir.The main reservoir space include karst caves,denudation vugs, pores and cracks.The heterogeneity of the reservoir is very strong.2、the development and distribution of Ordovician carbonate reservoirs in middle slope of Lungu oil field was controled by karst geomorphology and later changes, faulting. In vertically, The development of the cave is gradually reduced with increasing distance from the unconformity, the most favorable area is within40m under the unconformity; on the plane, the development of karst caves is controled by karst geomorphology, fault and ancient water systems, the cave reservoir in Lungu7wellblock is better than Lungu2wellblock, the plane distribution is relatively concentrated, the cave reservoir in Lungu2wellblock is relatively dispersed, but large cave reservoirs can be developing near the fault.3、It is divided six multiple well fractured-vuggy units in the central slope belt of Lungu oil field by using crude oil chromatographic fingerprint technology and the oil well production performance.4、According to occurrence form of oil and gas in the fracture-vug units, it can be divided into three types:Single gas-oil vug, Single gas-oil-water vug, Multiple combinations of gas-oil-water vug.