This paper gives an analysis of Wuerhe oil reservoir in block-8 and discusses the effectsof Sedimentary facies, reservoir texture, diagenetic compaction and epigenesis on the petrophysical properties and the oil saturation of this low permeable reservoir. The alluvial-flood fan depositional facies and structural elements give controls on the oil and gas distribution; "multi-mixtures" texture makes the petrophysical properties worse; the diagenetic compaction and epigenesis cause authigenic minerals to be vertically distributed zones and horizontally in belts. A low permeability, fine throat and double-porosity reservoirdominated by secondary porosity is formed. Thedata of conventional core analysis, special core analysis, well-testing, and their isopack maps are used to evaluate the reservoir in eachzone and each belt. The development pattern ofthis type of oil reservoir is discussed with these parameters together with those data from the production tests.
The lower Wuerhe oil reservoir of upper Permian in block No. 8 of Karamay oilfield, is located on the monocline of K-W overthrust zone along the N-W margin of Zhunger Basin, it is bounded by No. 202 paleo-uplift in its west andby Mahu depression in its south, being a monocline controlled by "A" type faults formed by an intersection of the K-W fault and No. 202, No. 256 faults. It dips to the southeast at an angle of 3-14° with an average depth of burial of 2900 m, and is a conglomeratic reservoir of alluvial-talus mixed facies with a thickness of 111-815 meters. From the bottom to the top the seven members, , are overlapped on Carboniferous-Permian andesite with a mean effective thickness of 58 m, an effective porosity of 9.0% and an effective permeability of 2.15 md., are the major oil-bearing zones and the , being the next. The reservoir pressure is 348.5 atm. and saturation pressure is 296 atm. The original GOR is158 m3/m3, and the formation temperature is 67°C. The reservoirviscosity of the oil is low, averaged 0.7 cp. Salinity of formation water is 30 g/l and is in the type of CaCI2, NaHCO3, or Na2SO4(see Tables).
Poor depositional facies, strong diagenic compaction, complicated reservoir matrix texture and intense epigenesis have resulted in the characteristics of a fine throat and low porosity, very low permeability double porosity conglomeratic reservoir which is dominated by secondary porosity.