1. Overview of Seismic Interpretation
Lecture 9
Overview of Seismic Interpretation
SLIDE 1
This slide introduces seismic interpretation
It gives an outline of the next several units
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L 9 – Overview Interpretation

2. From Lecture 1 Exploration’s Task Identify Opportunities Capture
Prime Areas
Identify
Opportunities
From Lecture 1
Acquire
Seismic Data
Process
Seismic Data
Drill
Wildcats
Interpret
Seismic Data
Assess
Prospects
Failure
Success
Confirmation
Well
SLIDE 2
We talked about this simply flowchart for exploration in Lecture 1
We want to focus in on the box outlined in magenta – how we interpret seismic data
Uneconomic
Success
To Development
Or Production
Drop
Prospect
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L 9 – Overview Interpretation

3. Remainder of this Course
Seismic Interpretation and Beyond …
Develop a Geologic Framework
Apply the Geologic Framework to Prospecting (Exploration)
Given our time constraints, we will only be able to look at a subset of the concepts, procedures and tools that geologist and geophysicists use in the exploration phase of the oil & gas industry
SLIDE 3
There are two major tasks in the interpretation & analysis of the seismic data
First we need to develop a geologic framework
As you will see, this is the identification and mapping of the main faults and the main stratigraphic horizons
Once we have developed the geologic framework, in exploration we want to examine the HC system components:
Where are potential reservoirs, traps, seals, mature source rocks, and HC migration pathways?
Then where would we drill to make a new discovery?
For development and production, we also want to develop a geologic framework (if it does not exist or does not have the level of detail that we need)
Then we can consider where to drill a development well – to answer a question on the spatial distribution of fluids and reservoir rock properties
Or we can consider where to drill a production well (a producer or injector) to increase HC production from the field
Courtesy of ExxonMobil
L 9 – Overview Interpretation

4. of these basic elements
Workflow: Overview
1. Geologic Framework
We can subdivide the exploration work process from seismic interpretation forward into 4 major elements
Modules provide
some details on each
of these basic elements
2. Data Analysis
3. Prospect Elements
SLIDE 4
Here is the basic workflow for seismic interpretation & beyond
First, we need to develop a geologic framework; major faults and stratigraphic packages (depositional sequences)
Then we need to analyze all the key packages – where are potential reservoirs, source rocks, etc.
Next we have to identify prospects – places where all the HC system elements look favorable & we are willing to propose a drill site to management
Finally we have to access the prospect – what type and volume of HC do we expect & what is the chance of success or risk
4. Prospect Assessment
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L 9 – Overview Interpretation

5. Geologic Framework Structural Interpretation
Using all available data (wells, seismic, outcrop, regional studies, gravity, magnetics, etc.) build a framework of present-day structure and stratigraphy
Structural Interpretation
Faults & Folds
Subsidence & Uplift
Structural Trends
Structural Features
Stratigraphic Interpretation
Unconformities
Stratal Packages
Environments / Facies / Lithologies
Ages
SLIDE 5
A bit more about the geologic framework
We want to use all the available data ……….
We have to perform a structural analysis – identify & map faults ……
We also need a stratigraphic interpretation – map unconformities ……
Although we teach these two components separately, an experienced seismic interpreter will work structure & stratigraphy simultaneously
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L 9 – Overview Interpretation

6. SLIDE 6
Module 10 focuses on structural interpretation
We will look at different types of faults (extensional, compressional, strike-slip)
We’ll also talk a little about diapiric structues – caused by mobile salt or shale
A major product is structure maps that indicate the morphology (highs, lows, fault traces) on each of our mapped horizons

7. Applying the Framework for Prospecting
Data Analysis
Present-day conditions - How things are now
Basin reconstruction - How things evolved
Prospect Elements
Individual elements: Source, Migration, Reservoir, Trap, Seal
Favorable juxtaposition of all elements
Prospect Assessment
Likely HC volumes in the success case
Risking - How likely is the success case?
SLIDE 7
The geologic framework allows us to proceed with the next steps:
Analyze the data to get both present-day conditions and information on how the basin evolved
Examine the prospect elements to find potential new drill locations (exploration)
Assess the prospect (exploration) in terms of the type of HC, the quantity of HC, and the risk associated with the proposed well location
Courtesy of ExxonMobil
L 9 – Overview Interpretation

8. The Alpha and Beta Prospects
For Modules 12 through 14, we use two hypothetical leads: Alpha and Beta. Should we propose that we drill either or both?
Alpha
Beta
Sea Water
Overburden
Seal
Reservoir
SLIDE 8
For modules 12 and beyond, we will use two hypothetical prospects: Alpha and Beta
This cross-section shows a potential reservoir, source and seal with two fault-bounded anticlines
The business question is whether we should drill either or both (in which order)
We’ll look at how we would address this question
Source
Basement
Courtesy of ExxonMobil
L 9 – Overview Interpretation