The Study Of Reservoir Characteristics And Residual Oil Distribution Law About Chang6₂Formation Of Easten Area Of Shuanghe In Yongning Oilfield

This paper takes Chang62formation of eastern part of Shuanghe area at Yongning oil field as its main interest of study. The petroleum development contradiction gradually emerges as the much kinds aspects such poor reservoir property, much serious heterogeneity of various scales, complex pore structure, apparous natural performance decline, serious pressure drop, upsurging rate of water content, complex water flooding feature et al. As for the these problems above, the object of deciphering distribution rule of the residual oil for providing rational oilfield development with referencial values are achieved after a serious analysis of reservoir fundamental characteristics, the calculation of both geological reservers by volumetric method and remaining recoverable reservers, based on the data from various experiments available such as SEM, cast thin section, X diffraction to dynamic performance analysis. Finally, the following understandings are made:Chang62of study area develops the delta front subfaces with steady stratrum thickness and simple stratrum structure. The lithic is fine grain arkosic sandstone with high content of interstitial matter, poor texture maturity, strong diagenesis and heterogeneity of various scales. The pore mianly consists of intergranular, feldspar and debris dissolved pore, which contacts each other at angles and lines mainly leading to poor connectivity.After the conformation of net thickness standard (Φ≥9%, K≥0.2×10-3μm2, Δt≥220μs/m, Rt≥18Ω.m, Ro≥31%), reserver recalculation by volumetric method announces Chang62reservoir with ample geological reservers (940.31×104t) and lavish residual recoverable reservers around231.29×104t, which especially lies in the layer Chang622(geological reservers about671.92×104t and residual recoverable reservers around188.14×104t).The decline law of productivity presents as the following status:apparent productivity decline at the initial stage of production, poor surfacial water flooding effect, relatively large discrepancy of water washing degree among various layers, poor rationality of well arranging pattern, stable ascending ratio of cumulative injection-production, stratrum energy still being deficit.Analysis of flow zone classification is taken out into4kinds:E、G、M、P, among which G、M mainly account and E、P account less. The residual oil of interlayers is distributed mainly affected by sandstone rythem type and permeability variation. The distribution of residual oil of interlayers is influenced by interlayer heterogeneity, which results in apparent interlayer interference、low producing degree、relative large residual recoverable reservers、 high producing value. Planar distribution of residual oil is mainly dominated by the combination of micro-structure, sedimentary microfaces and injection-production arrangement, among which sedimentary microfaces controls obviously. Under the middle-low hydratation, E, G flow unit is rich with residual oil and M type is secondary, while worstly P flow unit has poor producing economic value.Under micro pore scale, the residual oil of Chang62formation mainly results from the combination of variation, size, distribution isotrope, connectivity of pore and throat and rock wettability. Displacing mainly consist of three types:stable, fingering, mesh, which forms residual oil correspondingly presenting film, flow-over often mostly, cut-off, pore-edge, pore-angle.