油藏物理学英文油藏物理学 (6).ppt

Hydrocarbon Phase Behavior and Vapor-Liquid Equilibrium in Reservoirs(油气藏油气藏烃类的相的相态和汽液平衡和汽液平衡)Terminology:Phase behavior:相相态Phase diagram:相相图Bubble point：泡点：泡点Dew point：露点：露点Critical ponit：临界点界点Phase envelope：相：相包包络线Two phase region：两相区：两相区Quality lines:等液量等液量线Cricondentherm:临界凝析温度界凝析温度Cricondenbar:临界凝析界凝析压力力Locus：轨迹迹Curve：曲：曲线Shrinkage：压缩Volatile：挥发性性的的Condensate gas：凝析气：凝析气Depletion：衰竭，降：衰竭，降低低 Retrograde gas condensate:反凝析油反凝析油Separator：分离器：分离器Equilibrium ratio：平衡比平衡比 3、The characteristic of multi-component hydrocarbon system 多多组分体系的相分体系的相态特征特征 Three phase regions:liquid region,vapor region,two phase regionThree points:cricondenbar,critical point,cricondenthermThree lines:bubble point curve,dew point curve,quality linesTwo iso-regions:isothermal decompression retrograde region(等温降压反凝析区等温降压反凝析区),isobaric cooling retrograde region(等压降温反凝析区等压降温反凝析区)PT diagram1）The key points:Critical point(临界点)：intersection of bubble point curve and dew point curve.The Pc is the maximum pressure above which no gas can be formed regardless of temperature(cricondenbar),The Tc is defined as the maximum temperature above which liquid cannot be formed regardless of pressure(Cricondentherm).isothermal decompression retrograde region(等温降等温降压反凝反凝析区析区)isobaric cooling retrograde region(等等压降温反凝析区降温反凝析区)isothermal decompression retrograde region(等温反凝析等温反凝析区区)2）The particular:4、Reservoir classificationGasCondensate gasBlack oilVolatile oil Oil reservoirsIf the reservoir temperature T is less than the critical temperature Tc of the reservoir fluid,the reservoir is classified as an oil reservoir.Gas reservoirsIf the reservoir temperature is greater than the critical temperature of the hydrocarbon fluid,the reservoir is considered a gas reservoir.5、Oil reservoirs1.Under-saturated oil reservoir.2.Saturated oil reservoir.3.Gas-cap reservoir.1）Phase diagram of ordinary black oil reservoirs(low shrinkage oil)常规黑油油藏（低收缩油藏）相图常规黑油油藏（低收缩油藏）相图 The quality lines are closely spaced near the dew-point curve,The gas oil ratio is generally lower than 90 m3/m3,and the relative density is higher than 0.876.The color of this type of oil is generally black or dark brown.The dash line simulates the path of pressure and temperature variation from wellbore to surface.Oil accounts for about 85%at the condition of separator.The phase diagram of volatile oil reservoir is similar to that of black oil.But the quality lines are close together near the bubble-point and are more widely spaced at lower pressures.The relative density is lower than 0.78,and gas oil ratio is lower than 1800 m3/m3Oil accounts for about 65%at the condition of separator2)Phase diagram of light oil reservoir(high shrinkage)轻质油藏（高收油藏（高收缩油藏）相油藏）相图6、Gas reservoirsOn the basis of their phase diagrams and the prevailing reservoir conditions,natural gases can be classified into four categories:-Retrograde gas-condensate -Near-critical gas-condensate -Wet gas -Dry gas The initial reservoir pressure is higher than critical pressure,but its temperature is between critical temperature and cricondenthermThe gas oil ratio of condensate gas reservoir could reach 12600 m3/m3.The relative density of condensate oil could reach 0.74.The color is light and transparent.liquid accounts for about 25%under the condition of surface separator.The produced liquid is called as condensate oil1）Phase diagram of retrograde condensate gas reservoir反凝析气藏相反凝析气藏相图 2）Phase diagram of near critical gas condensate reservoir近近临界凝析气藏相界凝析气藏相图The initial reservoir temperature is near the critical temperatureAll the quality lines converge at the critical point,a rapid liquid buildup will immediately occur below the dew point as the pressure is reduced to point 2.The reservoir temperature is above the cricondentherm of the hydrocarbon mixture,and it will always keep gas status when pressure decreases from point 1 to point 2.It will be in two phase region under separator condition,therefore,there will be some light oil in separator.The relative density of light oil is lower than 0.78,and the surface gas oil ratio is lower than 18000 m3/m3.3)Phase diagram of wet gas reservoir(湿气气藏相湿气气藏相图)The natural gas with high methane content(70 98）is referred as dry gas.The reservoir temperature and separator temperature are outside two phase region.There is no liquid released in underground and surface condition.The gas oil ratio is higher than 18,000 m3/m3.4)Phase diagram of dry gas reservoir(干气气藏相干气气藏相图)