Page 70 - The Petroleum System From Source to Trap

3. Petroleum Systems of the World Involving Upper Jurassic Source Rocks 63
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(11) EGRET·HIBERNIA(') PETROLEUM SYSTEM Table 3.3. Present Geography of Upper Jurassic
100 150 100 70 '"' sO 40 30 20 I I 10 I I I Source Rocks
MESOZOIC I CENOZOIC · -----ro SCALE
1R !JURASSIC I CRETACWJS I TERTIARY ouu. PETROLEUM Mature Source Rock
L I' " I L I E I L I P<LEol WCENE I OLIG I MIOCENE I pp SYSTEII EVENTS
I
!;;� SOURCE ROCK Area BOE (%) Area (%) Volume (%)
RESERVOIR ROCK
Interior 80 70 56
SEAL ROCK
- � T ? \ , :l. · :�;c OVERBURDEN ROCK Coastal 20 30 44
TRAP FORJ.IATION
GEt-�EI\._"{I�\Gfi�1101'1�CCU� .. l\(l
PRESERVATION
t CRITICAL MOMENT
Table 3.4. Plate Tectonic Location of Upper Jurassic
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(12) VERRJL CANYON·MIC MAC( I) PETROLEUM SYSTEM Source Rocksa
"
200 150 100 70 60 50 30 20 10
MESOZOIC j CENOZOIC SCALE Mature Source Rock
lljJURASSIC CRETACEOUS j TERTIARY !Quu PETROLEUM
l I ' I M. I L ' I l I PALEO I EOCENE I OliG I "'OGENE jpp SYSTEM EVENTS Terrane BOE {%) Area {%) Volume {%)
(
n;:01 m SOURCE ROCK Craton 58 (9) 21 (10) 38 1 8 )
� IIR �H I �I fl RESERVOIR ROCK Hercynian 23 (45) 49 (70) 42 (57)
u u SEAL ROCK
(
OVERBURDEN ROCK Caledonian 18 (44) 26 1 6 ) 1 8 (20)
G F . " � "" TRAP FORMATION Pacific 1 (2) 1 (3) 2 (4)
GE."EI'IJ�'fl."11�(;cu��J,."TIO
PRESERVATION •Numbers in parentheses exclude the Hanifa-Arab(!) ard Bazhenov-Neocoian(!)
t CRITICAL MOMENT
supergiant petroleum systems.
(13) OBERMALII·BADENIAN(I) PETROLEUM SYSTEM
or through the cap rocks. The supergiant and giant
petroleum systems to be compared are ( 1 ) the
Hanifa-Arab(!) system located in the Arabian-Iranian
basin; (2) the Bazhenov-Neocomian(!) system in the
West Siberia basin; (3) the Kimmeridgian hot
shale--Brent(!) system in the northwest European shelf;
and (4) the Smackover-Tamman(!) in the Gulf of Mexico
province (Table 3.2).
The prolific nature of these petroleum systems is
(14) FLAMINGO·PLOVER(.) PETROLEUM SYSTEM related to where the high percentage of the system's BOE
is trapped relative to the active source rock. Here the
reservoir rocks are immediately sealed by either an espe­
cially efficient cap rock or else the source and the seal for
the oil are the same rock (e.g., Hith anhydrite in the
Hanifa-Arab system and the Kimmeridgian hot shales in
the Kimmeridgian hot shale--Brent system). Conversely,
petroleum systems that include poor seals have about
80% of the BOE in reservoir rocks well above the active
source rocks. When oil leaks upward to overlying
Figure 3.6. ( c ontinued) reservoir rocks and structural sequences, it results in a
less efficient or prolific petroleum system (e.g., Gulf of
Mexico and West Siberian basin) (Table 3.7).
type II and III kerogens and coal as source rocks than do
low paleolatitudes. Most of the Upper Jurassic rift-sag Plumbing and Dynamic Events
cycles developed along paleolongitudinal north-south
lineations often underlain by either the Caledonian or Using the distribution and volume of conventionally
Hercynian orogenic-accretionary prisms present in recoverable BOE, several observations can be made
Laurasia and in and along the Pangea break-up rifts of about petroleum systems with Upper Jurassic source
Gondwana (Atlantic and Indian ocean margins). rocks (Figure 3.6). Most of the reservoir rocks are Jurassic
(63%) in age followed by Cretaceous (33%) and Tertiary
Proximity of Source, Reservoir , and (3%), and their lithologies are more likely to be carbonate
Seal Rocks (60%) rather than siliciclastic sandstone (40%). The onset
of oil generation is usually Late Cretaceous-early
In the four largest petroleum systems, the recovery Tertiary (76%), as opposed to Late Jurassic-Early Creta­
efficiency is directly related to the proximity of the Upper ceous (17%) or late Tertiary (7%). Most trap growth
Jurassic source rocks to the charged reservoir rocks and occurred before the onset of oil generation (90%) as
traps, and indirectly to the leakage of petroleum around compared to during (5%) and after (5%) oil generation.