The Study Of Reservoir And Flow Units Characteristics Of Chang-2₁in Yuanmao Region Wayaobao Field

As the experimental development region using waterflooding development since June2006, chang-21reservoir is the main production part in Yuanmao region WaYaobao field of Erdos basin in up Triassic series. Low porosity and low permeability makes chang-21reservoir comes with an highly initial yield, but also comes with serious development contradiction, such as rapid decline production and water out and water channeling in wells, which affect the yield in whole region. Due to the specific fluid characteristics in reservoir, this paper sets the reservoir and fluid unit as breakthrough point to analyse reservoir fluid characteristics in both microcosmic and macroscopical ways.this paper firstly studies the static characteristic, such as sedimentary affect, diagenesis, physical properties, heterogeneity and micro-pore structure and divide whole region into basic fluid units, then studies different fluid units based on dynamic development data and testing development data in according with fundamental geological data. The conclusions are presented as followed:1.The structure of chang-21is simple and sedimentary facie is delta plain facie, and most sandstone lies in distributary channel. The major rock type of the reservoir is mainly feldspar sandstone or feldspar-debris sandstone. Due to the strong diagenesis, the main space and chief pore types in reservoir are intergranular pores, feldspar soluble pore and widely-spread microfissure. Physical properties mostly affected by sedimentary effect and diagenesis.2.Due to the complicated micro-pore structure and pore sorting features, the pore assembly types mainly consist of medium-small pore and small-micro throat based on the study of casting film, electron microscope scanning,high pressure mercury and constant pressure mercury experiments.3.Sandstone in reservoir can be divided into three kinds of fluid units A, B, C based on the fundamental geological data. Type A has the best physical properties and lies in the center of distributary channel, coming with high initial production, rapidly decline production, increasing water saturation, serious water flood and high permeability area in sandstone, which makes adversely affects to reservoir. Compared with type A, type B has a relatively poor physical properties and lies in the edge of channel or nature levee, coming with relatively high initial production, rapidly decline production, steady increasing water saturation and high water injection amount. Type C has a poor physical properties and lies in distributary channel bay, coming with low initial production, steadily decline production, high injection pressure low amount of water injection and the change of water saturation is mild.4.Different development methods should be applied to enhance the development effect based on specific fluid units and wells.