1、Chapter Two Petroleum GeologyGeology(地质学)is a natural science.With it men can discover all kinds of useful minerals.Geology studies the earth.But of the three spheres,the atmosphere(大气圈),the hydrosphere(水圈)and the lithosphere(岩石圈),it only directly studies the lithosphere.Petroleum geology(石油地质学)is t
2、he application of geology(the study of rocks)to the exploration for and production of oil and gas.第1页Before further study four terms must be understood:Porosity(空隙度),Permeability(渗透率),saturation(饱和)and Darcys law(达西定率),Porosity is a percentage of holes or voids in the rock,and controls how much flui
3、d the rock can hold.Primary or original porosity(原生空隙度)is created as the rock is deposited.Secondary porosity(次生空隙度)is the pore space that is gained or lost as the rock buried.Two process may increase the secondary porosity(solution溶解作用 and fracturing断裂作用);while other two may decrease secondary poro
4、sity(cementation胶结作用 and compaction压实作用)第2页Permeability(渗透率)is a measure of the ease with which a fluid can flow through the rocks.If the pore are interconnected(相互连接),the fluids can flow from pore to pore through the rock.Permeability is measured in units of millidarcies(md)(毫达西).The greater the pe
5、rmeability,in millidarcies,the easier it is for the fluids to flow through the rock.第3页Saturation(饱和)(饱和)The fraction or percentage of the pore volume occupied by a specific fluid(e.g.,oil,gas,water,etc.).Is an important figure in calculating the potential reserve(潜在储量)the higher the saturation,the
6、more oil the formation(地层)holds第4页PermeabilityPermeabilityDarcys law(达西定律)describes the rate of flow of fluids through rocks.It states that the rate of flow depends on the permeability(渗透率)of the rock times the difference in fluid pressure from one side of the rock to the other(pressure gradient压差)d
7、ivided by the fluid viscosity(粘稠度).Q=rate of flowK=permeability(p1-p2)=pressure drop across the sampleA=cross-sectional area of the sampleL=length of the sampleu=viscosity of the fluid第5页Petroleum Geology4.The Essential Conditions of Formation of Oil Reservoir(油藏)2.Petroleum Migration(运移)and Accumul
8、ation(聚集)in Reservoirs3.Traps(圈闭)of Petroleum1.Generation(生成)of Petroleum第6页1.Generation of petroleuma.Geological requirement Sediments are deposited along with organic matter at the rate that is rapid enough before the organic matter being destroyed by decay.b.Oxygen-free condition organic matter-k
9、erogenpetroleumc.Temperature In an average sedimentary basin,oil generation starts starts at 50 degree C,peaks at 90 degree C,and ends at 170 degree C.d.Time:millions of years ago.第7页2.Petroleum Migrates and Accumulates in ReservoirsPrimary Petroleum Migration:Petroleum is squeezed out of source bed
10、s(烃原岩层)and is accepted by a receiver bed(运载岩层).Underlining principles for Primary migration:thermal expansion of the hydrocarbons,Porosity and permeability,pressure,properties of fluid第8页Secondary Petroleum Migration Once within the receiver bed,petroleum travels upward and laterally with in the rec
11、eiver bed until a suitable geologic deformity(地质变形)(trap)is reached or until the petroleum can find an exit(出口)from the receiver bed.Gas is separated and goes up to form a gas cap.Underlining principles for secondary migration:thermal energy,water drive,capillary pressure,oil is lighter than water,g
12、as is the lightest.第9页A single accumulation is referred to as a pool or a reservoir.A field consists of one or more reservoirs.Oil reservoirs are often used term in the petroleum industry,and the deposits(油气沉积)are more often like piles of sand or porous rock that have been saturated with oil.Accumul
13、ation of PetroleumIts guiding principle is this:oil and gas move through permeable beds until they reach a position in which the energy available is insufficient to move it further-or it dissipates at the surface.Such leakage at the surface(called“seeps”(油苗)or“seepages”)have guided exploration activ
14、ities to important accumulations,and at least they indicate that conditions for petroleum generation and migration exist.第10页After petroleum generated,petroleum compounds originated both in the sands and muds and the rock compaction squeezed them from these source beds into pore spaces of the layers
15、 of sands and carbonated where deposits of oil and gas are located today.Being lighter than the adjacent(邻近)water,the oil and gas floated upward through the tiny tortuous(弯弯曲曲)pore channels(孔隙通道)in the sand.The oil and gas tend to rise and will eventually reach the surface of the earth and be dissip
16、ated(消散)unless they encounter a barrier stops the upward migration.Such a barrier produces a trap.储集层是指能够储存和渗滤油气岩层,它必须含有储存空间(孔隙性)和储存空间一定连通性(渗透性)。储集层中能够阻止油气向前继续运移,并在其中贮存聚集起来一个场所,称为圈闭或储油气圈闭。第11页3.Traps of PetroleumGeologists have classified petroleum traps into three types:structural traps(结构圈闭),strat
17、igraphic trap(地层圈闭)and depositional trap(lithologic trap)(岩性圈闭)Structural traps are traps that are formed because of a deformation in the rock layer that contains the hydrocarbons.Two common examples of structural traps are fault and anticlines.第12页The anticlinal trap(背斜圈闭)is the simplest and common
18、est form of petroleum accumulation.A porous and permeable reservoir rock must be sealed above by a fine-grained(质地细密),relatively impermeable bed such as clay,shale,or salt.The surface is the form of a dome(拱行)or elliptical(椭圆)dome forms a closed space in which the oil or gas,being less dense than wa
19、ter,accumulates.Within the reservoir,oil lies on water,and the interface between them is known as the“oil/water contact”(油水界面).If gas occurs associated with the oil,it forms a gas cap.第13页Fault traps(断层圈闭)are also common.There must be a porous and permeable reservoir rock that is sealed above by a f
20、ine-grained,relatively impermeable bed.But the real trap is provided by the fault,which prevents further updip migration either by the fine-grained material in the fault itself or by the bringing of a fine-grained relatively impermeable bed on the other side of the fault to the position that truncat
21、es the reservoir.第14页Stratigraphic traps(地层圈闭)comprise an interesting variety of accumulations in which the trapping mechanism,as the name suggests,is from stratigrahphic rather than structural causes.In these,the essential features remain a porous and permeable reservoir rock sealed by a fine-grain
22、ed relatively impermeable rock,but the configuration(形状)of this to form a trap arises from the particular sedimentary process and nature of the resulting sediments.第15页depositional trap(lithologic trap)(岩性圈闭)refers to the trap surrounded by impermeable rocks such as granite(花岗岩)(花岗岩).第16页4.The Essen
23、tial Conditions of Formation of Oil ReservoirOil reservoirs are the deposits which are more often like piles of sand or porous rock that have been saturated with oil.In order to have a gas or oil deposit in any area,three subsurface conditions must be met.第17页First,there must be a subsurface source
24、rock that generated the gas or oil at some time in the geologic past.Oil Source BedOil Source Bed生油岩生油岩生油岩生油岩按照有机成因学说,大量微体生物遗骸与泥砂或碳酸质沉淀物埋藏在地按照有机成因学说,大量微体生物遗骸与泥砂或碳酸质沉淀物埋藏在地按照有机成因学说,大量微体生物遗骸与泥砂或碳酸质沉淀物埋藏在地按照有机成因学说,大量微体生物遗骸与泥砂或碳酸质沉淀物埋藏在地下,经过长时期物理化学作用,形成富含有机质岩石,其中生物遗骸转化为下,经过长时期物理化学作用,形成富含有机质岩石,其中生物遗骸转化为下
25、,经过长时期物理化学作用,形成富含有机质岩石,其中生物遗骸转化为下,经过长时期物理化学作用,形成富含有机质岩石,其中生物遗骸转化为石油。这种岩石称为生油岩。石油。这种岩石称为生油岩。石油。这种岩石称为生油岩。石油。这种岩石称为生油岩。Second,there must be a separate subsurface reservoir rock that holds the gas or oil.Oil Reservoir BedOil Reservoir Bed储集层储集层储集层储集层 是指能够储存和渗滤油气岩层,它必须含有储存空间是指能够储存和渗滤油气岩层,它必须含有储存空间是指能够储存
26、和渗滤油气岩层,它必须含有储存空间是指能够储存和渗滤油气岩层,它必须含有储存空间(孔隙性孔隙性孔隙性孔隙性)和储存空和储存空和储存空和储存空间一定连通性间一定连通性间一定连通性间一定连通性(渗透性渗透性渗透性渗透性)。储集层中能够阻止油气向前继续运移,并在其中贮。储集层中能够阻止油气向前继续运移,并在其中贮。储集层中能够阻止油气向前继续运移,并在其中贮。储集层中能够阻止油气向前继续运移,并在其中贮存聚集起来一个场所,称为圈闭或储油气圈闭。存聚集起来一个场所,称为圈闭或储油气圈闭。存聚集起来一个场所,称为圈闭或储油气圈闭。存聚集起来一个场所,称为圈闭或储油气圈闭。第18页Third,there
27、must be a trap or high point on the reservoir rock that concentrates the gas or oil Cap Rock,Seal RockCap Rock,Seal Rock盖层盖层盖层盖层 为了不使储集层中油气逸散掉,在储集层上方需要有一套致密、为了不使储集层中油气逸散掉,在储集层上方需要有一套致密、为了不使储集层中油气逸散掉,在储集层上方需要有一套致密、为了不使储集层中油气逸散掉,在储集层上方需要有一套致密、不渗透地层把储集层中油气保护起来。这种致密不渗透保护层就叫做盖不渗透地层把储集层中油气保护起来。这种致密不渗透保护层就
28、叫做盖不渗透地层把储集层中油气保护起来。这种致密不渗透保护层就叫做盖不渗透地层把储集层中油气保护起来。这种致密不渗透保护层就叫做盖层,适合做盖层岩石有页岩、泥岩、盐岩、石膏等。致密泥灰岩和石灰层,适合做盖层岩石有页岩、泥岩、盐岩、石膏等。致密泥灰岩和石灰层,适合做盖层岩石有页岩、泥岩、盐岩、石膏等。致密泥灰岩和石灰层,适合做盖层岩石有页岩、泥岩、盐岩、石膏等。致密泥灰岩和石灰岩有时也能够充作盖层。岩有时也能够充作盖层。岩有时也能够充作盖层。岩有时也能够充作盖层。第19页Petroleum Reservoir are the deposits which are more often like
29、piles of sand or porous rock that have been saturated with oil.油气藏圈闭内储集了相当多油气,就称为油气藏。Petroleum field may contains one or more petroleum reservoirs.油气田在地质意义上,油气田是一定(连续)产油面积内各油气藏总称。该产油面积是受单一或各种地质原因控制地质单位。Petroleum Zone:areas underlain by mature source rocks with another name generative depressions.油气聚
30、集带是油气聚集条件相同、位置邻近一系列油气藏或油气田总和。它含有明确地质边界区,形成年产原油430万吨和天然气3.8亿立方米生产能力。Petroleum Generative Basin:that contains one or more petroleum generative depressions.含油气盆地在地质历史上某一时期沉降区,接收同一时期沉积物,有统一边界,其中可形成并储集油气地质单元,称做含油气盆地。第20页Review:Key words:Geology(地质学)Petroleum geology(石油地质学)Porosity(空隙度),Permeability(渗透率),
31、Saturation(饱和)Darcys law(达西定率)Generation(生成)Reservoir(储集岩)(油藏)Migration(运移)Accumulation(聚集)Traps(圈闭)第21页source rock(烃原岩,产油岩)“seeps”or“seepages”(油苗)deposits(油气沉积)structural traps(结构圈闭)stratigraphic trap(地层圈闭)depositional trap(lithologic trap)(岩性圈闭)the anticlinal trap(背斜圈闭)fault traps(断层圈闭)oil/water c
32、ontact”(油水界面)petroleum reservoir(油气藏)petroleum field(油气田)petroleum zone(油气聚集带)petroleum generative basin(含油气盆地)第22页Questions for reviewing 1.What is geology?What is petroleum geology?2.What is Darcys law?3.How many types of traps according to geologists,what are they?4.What are the two common examples of structural traps?5.What are the essential conditions of formation of oil reservoir?6.What is a petroleum reservoir?第23页