ChapterTwoPetroleumGeologyBeforefurtherstudyfourtermsmustbeunderstood:Porosity（空隙度）,Permeability（渗透率）,saturation（饱和）andDarcy’slaw（达西定率）,Permeability（渗透率）isameasureoftheeasewithwhichafluidcanflowthroughtherocks.Iftheporeareinterconnected（相互连接）,thefluidscanflowfromporetoporethroughtherock.Permeabilityismeasuredinunitsofmillidarcies(md)（毫达西）.Thegreaterthepermeability,inmillidarcies,theeasieritisforthefluidstoflowthroughtherock.Saturation（饱和）Thefractionorpercentageoftheporevolumeoccupiedbyaspecificfluid(e.g.,oil,gas,water,etc.).Isanimportantfigureincalculatingthepotentialreserve（潜在储量）thehigherthesaturation,themoreoiltheformation（地层）holdsPermeabilityPetroleumGeology1.GenerationofpetroleumGeologicalrequirementSedimentsaredepositedalongwithorganicmatterattheratethatisrapidenoughbeforetheorganicmatterbeingdestroyedbydecay.Oxygen-freeconditionorganicmatter---kerogen—petroleumTemperatureInanaveragesedimentarybasin,oilgenerationstartsstartsat50degreeC,peaksat90degreeC,andendsat170degreeC.Time:millionsofyearsago.2.PetroleumMigratesandAccumulatesinReservoirsSecondaryPetroleumMigrationOncewithinthereceiverbed,petroleumtravelsupwardandlaterallywithinthereceiverbeduntilasuitablegeologicdeformity（地质变形）(trap)isreachedoruntilthepetroleumcanfindanexit（出口）fromthereceiverbed.Gasisseparatedandgoesuptoformagascap.Asingleaccumulationisreferredtoasapoolorareservoir.Afieldconsistsofoneormorereservoirs.Oilreservoirsareoftenusedterminthepetroleumindustry,andthedeposits（油气沉积）aremoreoftenlikepilesofsandorporousrockthathavebeensaturatedwithoil.Afterpetroleumgenerated,petroleumcompoundsoriginatedbothinthesandsandmudsandtherockcompactionsqueezedthemfromthesesourcebedsintoporespacesofthelayersofsandsandcarbonatedwheredepositsofoilandgasarelocatedtoday.Beinglighterthantheadjacent（邻近）water,theoilandgasfloatedupwardthroughthetinytortuous（弯弯曲曲）porechannels（孔隙通道）inthesand.Theoilandgastendtoriseandwilleventuallyreachthesurfaceoftheearthandbedissipated（消散）unlesstheyencounterabarrierstopstheupwardmigrat