EPS-109 Earth Resources and the Environment
Lab 3: Petroleum Prospecting with Seismic Data
Week of 2/13, 2011
The goal of this lab is to familiarize you with seismic reflection data, which is regularly used in
the oil industry for petroleum exploration. You will be interpreting an excellent data set from an
active exploration area in West Africa.
As explained during lecture, you will be interpreting 2-D reflection seismic data, using PC-based
seismic interpretation software (The Kingdom Suite from Seismic Micro-Technology). This
software allows you to display digital seismic data and interpret horizons, faults, and other
geologic structures.
The Lab:
You are now an exploration geologist/geophysicist working for a multinational oil company and
are in charge of evaluating the potential of a structure that has been imaged in the subsurface.
You must map at least two different geologic stratigraphic units (horizons), and a fault that is
present in the area. Your objectives are to map the structure, and calculate the potential oil
reserves that could exist in the targeted reservoirs. To do this, you must interpret two horizons in
all of the seismic lines in order to generate a structural contour map.
Most seismic data is usually presented with the vertical scale in time, making it necessary to
convert the interpretations to depth in order to calculate potential reserves. In our case, all the
seismic lines have been converted to depth for your convenience. (Remember: The vertical scale
you are looking at in the seismic profiles is given in meters).
Getting Started:
Directions on how to use The Kingdom Suite are on the Kingdom Suite Notes handout. Most
importantly, we need you to open the original, uninterpreted data and save a new session with
your name that you will edit during the lab.
Go to Project  Session  Open Session. Select C:\EPS_109\Lab3\lab3_ndelta\original.s85
and hit OK. TKS will ask if you want to close existing windows. Select Yes.
Go to Project  Session  Save Session As. Type your name and press Save. All your work on
the project will be saved under your session.
Locate seismic line 330 in the basemap and display it. Look for shot point (s.p.) 940 on the
seismic profile. The following list shows the absolute depths of the 2 horizons you must interpret
along s.p. 940:
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
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Horizon A = 3.250 km
Horizon B = 3.520 km
Fault A = 4.500 km
Interpret the 2 horizons and the fault on all seismic lines using the methodology provided during
lecture. You do not need to correlate across the second fault to the north (to the right as displayed
on screen) and where the seismic images get messy towards the edges of the basemap.
Horizons A and B have been displaced by the fault. To determine where they are on the other
side of the fault, we will use a method called looping and tying. After you have picked Horizons
A and B to the edge of the faults on line 330, you will want to open line 132 which trends along
the strike of the fault. A red line will appear on the view of line 132, showing you where it
intersects line 330. Small circles will show the locations you have picked for Horizons A and B.
From these circles, pick Horizons A and B on line 132. You can now extend your interpretation
of the horizons to adjacent lines, using this same approach. You will eventually be able to loop
your interpretation around to the other side of the fault on line 330, showing you the original
depth of the horizons and the offset across the fault.
Answer the following questions:
1. Is this reservoir a stratigraphic or structural trap?
2. What type of geologic structure is present in the area?
3. Is the fault that you interpreted a reverse fault or a normal fault?
4. Create contour maps of Horizons “A” and “B.”
5. You need to calculate the area(s) of closure of your structure(s). Which horizon do you need
to calculate this for? Why? Draw a schematic cross-section of the two horizons and show
where the oil is actually trapped. Draw the fault too. We will assume that the fault seals – is
this always true?
6. Calculate the area of closure of your structure(s). To do this, you will need to create a
polygon as described in the attached KingdomSuite notes. When you are done, print out
copies of your contour maps showing the polygons and attach them to your lab.
7. Calculate the potential reserves that could be present in the structure(s) using the information
given below.
Area =
Reserves =
For the oil reserves calculation, we will use the following equation:
Reserves = (Area * Thickness * Porosity * Oil Saturation * recovery factor) / Volume factor
Note: use fractions for the Porosity, Oil saturation and recovery factor values during your
calculations.
Assume the following:
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Porosity = 0.25 (25 %).
Oil saturation = 0.5 (50 %). This number tells you the water cut.
Recovery factor = 0.3 (30 %). How much oil you could actually extract.
Volume factor = 1.6 (1.6 barrels in the subsurface are equivalent to 1 barrel of oil in the
surface).
Estimate the thickness of your mapped reservoir unit, measuring the distance between
horizons A and B and multiply by 0.5 (because only 50 % of the actual thickness is suitable
as a reservoir = Net Pay).
8. Calculate the value of the oil in the structure(s), using the spot price of West Texas
Intermediate crude oil today ($84.81/barrel) and the price on July 11, 2008 ($147.27/barrel),
shortly after concerns about Iranian missile tests. Note that there are ~6.29 oil barrels per
cubic meter.
9. To get the oil out of the structure(s), you need to drill a well (one per structure). On average,
a well in the Niger delta costs $50,000,000. How much money can you expect to make on
these structure(s) today? How much if you could sell at July 2008’s price? What other costs
would you need to take into account to make this more accurate?
10. What uncertainties are there in your interpretations, and how would they impact your
estimate of reserves in this reservoir?
11. Your manager has asked you to propose a well location to drill this prospect. Using the
attached shot point map, where would you locate your well and why? Draw a schematic
cross-section again (like the one above) and mark the location of your well on the crosssection as well as on the basemap below.