Seismic interpretation

PG7 SEISMIC INTERPRETATION DOSSIER - TEAM 10

TEACHER: LAURENCE BOVE

MADE BY: JESUS LOPEZ C.I: V-13.207.104 FRANCISCO QUINTERO C.I: V-12.357.150

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INDEX
I Geological framework and petroleum system…………………………… Synthetic table………………………………………………………………... Pag. 03 Pag. 05

Presentation of the different objectives on Alwyn North………………….. Pag. 00 II Principle and methodology of welltying………………………………….. Pag. 06 Objective of well tying and data needed………………………………..…... Pag. 06 Seismic character of the three (3) reference horizons and reliability between wells………………………………………………….. Pag. 11 III Alwyn North project…………………………………………………………. Pag. 12 Inlines, Crosslines and time slices…………………………………………… Pag. 12 Time mapping………………………………………………………………….. Pag. 13 IV F3 project: Strategy in workstationinterpretation………………...…….. Pag. 16 Identification of the reference horizons and faults…………………………. Pag. 16 Geological context……………………………………………………………… Pag. 16 Griding method…………………………………………………………………. Pag. 17 Stratigraphic interpretation……………………………………………………. Pag. 20 Use of Coherency Attribute…………………………………………………… Pag. 23 V Conclusions………………………………………………………………….. Pag. 24Recommendations……………………………………………………………... Pag. 24

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I GEOLOGICAL FRAMEWORK AND PETROLEUM SYSTEM Despite Old Red Lacustrine Shales and Coal & Carbonaceous Shales deposited during Paleozoic and Carboniferous respectively are considered source rock, Kimmeridge Clays are the objective in this report due to its prolific potential in the interest area. Kimmeridge Clay as a source rock can be recognized in logs due to the hot shale presented. The type ofkerogen found in Kimmeridge Clay is Type II which generated a considerable quantity of oil-prone. Assuming a TOC 1%, (which based on only the quantity of organic matter) is considered poor. The figure 1 shows the quantity of oil generated by this clay reflecting its potentiality and interest. What concern to its maturation, despite it is believed being buried below 3200 m, this depth is incorrect inF3 block due to uplifting process and erosion where it is about 2500 m. Moreover, variation of geothermal with time, and with depth in the sedimentary section is a complex function temporally fluctuating heat flow having as result non linear geothermal gradients in Alwyn field with a rapid rise in temperature below the overpressure zone. Table 1 shows timing generation (which occur in Paleocene)and approximate maturity with respect to oil generation having an average geothermal gradient of 30 C/Km. In regards to reservoir rock, Stafjord (Triassic-Early Jurassic) and Brent (Mid Jurassic) Formation can be considered as the main reservoirs for both F3 Block and Alwyn area. However, F3 Block counts with another reservoir Zechstein Platten from Permian and mainly constituted by Dolomites. BothStafjord and Brent represent the beginning of retrograding in the basin due to the transitional environment from continental (alluvial fans, braided and meandering system) in Stafjord to transitional (Deltaic) in Brent. What concern to petrophysical characteristic they have a porosity 12,5 -14%(Stafjord) and 15 – 20%(Brent); and average permeability of 80 mD and 100mD (max 10D) respectively.Fault blocks in Alwyn area are strongly aligned south-west –north-east parallel to Caledonian structural grain. This geometrical framework is resulting of relationship 30 C/Km.
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Figure 1.- Generation curve for oil and gas from type II kerogen and TOC 1% in North Sea

Table 1.- timing of generation from the Upper Jurassic of the North Sea as deduce from subsidence curves. Maturity with respectto oil generation is shown using an average geothermal gradient of 30celcius degrees.

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ALWYN BLOCK
PETROLEUM SYSTEM SOURCE ROCK

PALEOZOIC

CARBONIFEROUS

PERMIAN EARLY

TRIASSIC MID

LATE

EARLY

JURASSIC MID

RESERVOIR

Old red lacustrine Coal & Carbonaceous Shale Shales Marine Shale Scottish Oil Shale Old red SST Barren Red SST...