PowerPoint Presentation

2. Concept & Use of Petroleum SystemsPresented by : LIM SOOK FUN & TANASKUMARDate : 25 /5/ 2015OUTLINE2Introduction to Petroleum G & GDefinitionPetroleum System ElementsTemporal & Spatial AspectsEvent ChartBasin, System, Play, Prospect

OIL & GAS LIFE CYCLE (RECAP)3

Appraisal Drilling: Drillingcarriedoutonceoilorgashasbeendiscoveredinordertoassesstheextentofthefield,the reserves,thepossiblerateofproduction,andthepropertiesoftheoilorgasIntroduction to Petroleum G & GPETROLEUM SYSTEM DEFINITIONA petroleum system encompasses a pod of active source rocks and all genetically related oil and gas accumulations. It includes all the geologic elements and processes that are essential if an oil and gas accumulation is to exist4Introduction to Petroleum G & GELEMENTSSource RockMigration PathwaysReservoir RockSeal Rock Trap*Overburden RockPROCESSESGeneration MigrationAccumulationPreservationMust be correctly placed in TIME & SPACEPETROLEUM SYSTEM ELEMENTS5Introduction to Petroleum G & G

PETROLEUM SYSTEM NAMING6

(Biggest accumulation)

TEMPORAL (TIME) ASPECTSA petroleum system has 3 important temporal aspects:

7Introduction to Petroleum G & GAGECRITICAL MOMENTPRESERVATION TIMETime required for the process of generation-migration-accumulation of hydrocarbons. Time that best depicts the generation-migration-accumulation of hydrocarbons in a petroleum system. Measured time begins immediately after the generation-migration-accumulation process occurs and extends to the present day. Petroleum systems are limited by time and space. Each system can be described in terms of its own unique temporal and spatial elements and processes.

A map and cross section drawn at the critical moment best show the geographic and stratigraphic extent of the system.

An incomplete/ just completed petroleum system lacks a preservation time.7SPATIAL (SPACE) ASPECTSGeographic extent: Determined at the critical moment; the line that encircles the active source rock, oil and gas seeps, shows and accumulations originating from the source rock

8Introduction to Petroleum G & G

MAPPetroleum systems are limited by time and space. Each system can be described in terms of its own unique temporal and spatial elements and processes.

Each petroleum system can be defined spatially by its geographic and stratigraphic extent.8SPATIAL (SPACE) ASPECTS

9Introduction to Petroleum G & G

Stratigraphic extent: Span of lithological units which encompasses the essential elements within the geographic extent of a petroleum system

CROSS SECTIONTo have a complete petroleum system, we need rocks that will form:

WHAT ROCKS WILL FORM A PETROLEUM SYSTEM?10Introduction to Petroleum G & GSource RocksReservoir RocksSealing RocksFrom which oil and gas will be generated; essentially rich with kerogenImpermeable rocks that will keep oil and gas within the reservoirPorous and permeable rocks in which oil and gas will accumulate over timeMigration Pathways11

HYDROCARBON TRAPS12Introduction to Petroleum G & GHYDROCARBON TRAPSSTRUCTURAL TRAPS13Introduction to Petroleum G & G

HYDROCARBON TRAPS14Introduction to Petroleum G & G

Pinch Out (Associated to Stream Channel)

Channel Trap

Unconformity (period of erosion and/or nondepositionSTRATIGRAPHIC TRAPSHYDROCARBON TRAPSCaused by upward movement of sediments that are LESS DENSE than those overlying themSaltClay

15Introduction to Petroleum G & G

Salt Dome Associated TrapsDIAPIRIC TRAPSHYDROCARBON TRAPS16Introduction to Petroleum G & G

Oil, attempting to escape to surface up a reservoir, is held against an unevenness of its upper surface by water flowing in the opposite direction. There is no structural or stratigraphic closure. Note that the oil-water contact is tilted down in the direction of water flow.

HYDRODYNAMIC TRAPSPETROLEUM SYSTEM PROCESSES17Introduction to Petroleum G & GPETROLEUM SYSTEM PROCESSES GENERATION: The process by which solid organic matter present in the source rocks is transformed into liquid or gaseous hydrocarbonsOil window : 60-120 degree CelsiusGas window: 120 180 degree CelsiusBurial Depth: 2.5 3km depending on the geothermal gradient and kerogen type18Introduction to Petroleum G & GGeneration 19

Metagenesis

PETROLEUM SYSTEM PROCESSES20Introduction to Petroleum G & G

MIGRATION:The process of petroleum migration is divided into 3 partsPrimary migration: Movement of hydrocarbons from source rock into the reservoir rock (expulsion)Secondary migration: Subsequent movement of hydrocarbons within the reservoir rock whereby the oil and gas has left the source rock and entered the reservoir rockTertiary migration: Occurs when the seal above the reservoir breaches; resulting in a probable petroleum seep to the surfacePETROLEUM SYSTEM PROCESSESACCUMULATION:Accumulations of petroleum occur in places where migrating fluids cannot escapeGas is lightest and accumulates above oil, which overlies waterNeed the right trap and seal rock to contain and accumulate the hydrocarbons

21Introduction to Petroleum G & G

PETROLEUM SYSTEM PROCESSESPRESERVATION:Hydrocarbons that are accumulated in the reservoir rocks are preserved in its state and are not subjected to tertiary migration of hydrocarbons22Introduction to Petroleum G & G

WHAT IS AN EVENT CHART?Shows the temporal (time) relation of the essential elements and processes of a petroleum system

Shows the preservation time & the critical moment for the system

Used to compare the times that the processes occurred with the times that the elements formed23Introduction to Petroleum G & GWHAT IS AN EVENT CHART?

24Introduction to Petroleum G & GCan be transformed into a risk chart to better evaluate a play or prospectMapping and dating the essential elements of a petroleum system are usually easier than mapping and determining the time over which the processes took place. 24PETROLEUM SYSTEM EVENTS CHART (Eg. Mandal-Ekofisk(!))Generation-migration-accumulation: 100Ma Present Day25Introduction to Petroleum G & G

Trap: During rift formationOverburden rock: Deposited after the rift formedSeal rock: Halite, shale, chalkSource rock: Deposited as the rift formedPeak generation: 30MaReservoir rocks: Late Cretaceous Early Paleogene

BASIN, SYSTEM, PLAY, PROSPECT PETROLEUM PROVINCE: An area where petroleum occurs in commercial quantitiesBasins (thick), uplifts (thin), and fold belts (folded) can be labelled petroleum provinces if they contain petroleum

SEDIMENTARY BASIN: A depression filled with sedimentary rocks. The presence of sedimentary rocks is proof that a basin existed.Essential elements of a petroleum system are deposited in sedimentary basinsIncludes: Basement rock, basin fill, traps, petroleum

26Introduction to Petroleum G & G PETROLEUM SYSTEM: Includes the pod of active source rock, the natural distribution network, and the genetically related discovered petroleum occurrences. Only includes the DISCOVERED petroleum occurrences

PLAY: Consists of one/ more geologically related prospects

PROSPECT: A potential trap that must be evaluated by drilling to determine whether it contains commercial quantities of petroleum

27Introduction to Petroleum G & GBASIN, SYSTEM, PLAY, PROSPECT

28Introduction to Petroleum G & GBASIN, SYSTEM, PLAY, PROSPECT