Geo-Petro Services Company
P.O. Box: 3522
Abu Dhabi, UAE
30 March 2009
The Directors,
PI Oil Enterprises
P. O. Box: 123
Abu Dhabi, UAE
Dear Dr. Gabor Takcas and Dr. Thomas Stebuier,
Geo-Petro Services Company is writing to you to inform you about the attached seismic
interpretation report which consists of the latest outcomes for the seismic interpretation phase of
the Siri
field evaluation project. This report includes a comprehensive description of
methodology, results and recommendations.
The following tasks have been completed during the seismic interpretation phase:
Description of a geological formation that can probably contain oil & gas (hydrocarbons).
Calculating the Oil In Place (OIP) existence through the following procedures:
o Locating the oil field area
o Completing Two Way Travel Time (TWTT) map and time for contouring maps
o Calculating the thickness of the prospect area
o Determining the Formation Factor and the porosity
o Calculating the approximate OIP
Geo-Petro engineers' team has a confidence in the supplied information for this report to
meet the clients' specifications about the evaluation of the Siri prospect area.
We are looking forward to hearing from you. Your important comments and
clarifications for any point in this report will be appreciated.
Yours sincerely,
Geo-Petro Services Company
Petroleum Engineering & Petroleum Geosciences Departments-Petroleum Institute
Seismic interpretation report for the evaluation of the Siri prospect area
STEPS 251
Submitted to:
Directors of PI Oil Enterprises:
Dr. Gabor Taksas
Dr. Thomas Stebuier
Team Name:
Geo-Petro Services Company (GPSC)
Done by:
Hamed Mohamed Kamel
Fahad Al-Hashimi
Khaled Bani Hashem
Ahmed Al-Belooshi
Due: 30/3/2009
ID#: 920011849
ID#: 920010738
ID#: 920010771
ID#: 920011381
Contents
Excutive
Summary....................................................................................................................................IV
1.0 Introduction .......................................................................................................................... 4
Project overview ................................................................................................................ iv
Clarification of client’s needs ........................................... Error! Bookmark not defined.
Original client statement.............................................. Error! Bookmark not defined.
Objectives ..................................................................... Error! Bookmark not defined.
Constraints and Requirements. .................................... Error! Bookmark not defined.
Economic Analysis .......................................... Error! Bookmark not defined.
Environmental Impact ...................................... Error! Bookmark not defined.
Revised client statement.................................................... Error! Bookmark not defined.
Project management ................................................................. Error! Bookmark not defined.
Work breakdown .............................................................. Error! Bookmark not defined.
a Gantt chart &work compulsion Percentage. ............ Error! Bookmark not defined.
a linear responsibility chart ......................................... Error! Bookmark not defined.
problems we might face. & solutions ............................... Error! Bookmark not defined.
6.0 Recommendation ............................................................... Error! Bookmark not defined.
References ................................................................................ Error! Bookmark not defined.
Appendix .................................................................................. Error! Bookmark not defined.
List of Figure & Tables:
Figure 1: Geo-Petro Services Company team Logo ................ Error! Bookmark not defined.
Figure 2:Siri island location .................................................... Error! Bookmark not defined.
Figure 4: Gantt Chart . ............................................................. Error! Bookmark not defined.
Table 1: Budget Distribution ................................................... Error! Bookmark not defined.
Table 2: STEPS II course information ..................................... Error! Bookmark not defined.
Table 3:Team Members/Personal Information ........................ Error! Bookmark not defined.
Table 4: team member skill inventory ..................................... Error! Bookmark not defined.
Table 5: Linear Responsibility Chart ....................................... Error! Bookmark not defined.
table 6: Percent complete
matrix………………………………………………………………………………………………
…….
i. Executive Summary:
A comprehensive seismic interpretation report for the evaluation of the Siri field was
conducted in order to find out the existence of a geological formation that might hold a potential
quantity of hydrocarbon. After receiving an application form from the directors of the PI Oil
Enterprises, the Geo-Petro Services Company Conducted a seismic interpretation reports that
meets the clients' requirements. The report states whether to proceed with the exploration and the
development of the Siri field or not.
The included results in this report are based on the following interpretation:

Manual interpretation

Computer interpretation
The main results for our seismic interpretation are as following:

The geological structure is an anticline

The oil field area = 93.60 km2

The average thickness of the field

The volume of the field

The Original Oil In Place (OOIP)
= ………. m
= 14492299216.43 Barrels
= 2.46369*10^9 Barrels
According to our findings and results, Geo-Petro Team concluded that there is a potential
and economical amount of hydrocarbons in the Siri field structure. Therefore, it is recommended
that the Directors of PI Oil Enterprises permit our company to carry on with the exploration and
the development plans for the Siri field.
1.0
Introduction:
In response to the request of the PI Oil Enterprises, this report is written to show a full
evaluation of the seismic data of Siri field. The purpose of this report is to justify our
recommendation for the next step of the project.
The report will point up the steps that have been undertaken to generate a seismic
interpretation of Siri field. Also, it will cover a background about Siri prospect area and a seismic
interpretation which will be divided into manual (Hand) interpretation and computer (Software)
interpretation. Moreover, the report will include a calculation of the original oil in place (OOIP)
beside our recommendations.
2.0
Geological setting of the Siri area:
UAE is considered as one of the well-known countries in oil producing with a production
rate of 2.5 million barrels/day, the main sorts of geological structures that form the hydrocarbon
reservoirs in the UAE are anticlines and unconformities which formed in the Cretaceous and
Jurassic periods [1]. Furthermore, reservoirs in that area are made of carbonate rocks such as
limestone, dolomite, and anhydrite rocks. These types of rocks have the ability to make sufficient
reservoir rocks, where their porosity ranges between 20%-25%. According to [1] there are two
main source rocks for petroleum generation in the UAE foreland and one of them called Shilaif
Formation (Upper Albian − Cenomanian) which is the main source for the Mishrif and Simsima
reservoirs where the siri area consists of the Mishrif source rocks.
The Siri field is located northeast of Abu Dhabi as it’s shown in Figure (1); moreover it is
located between other existing hydrocarbon fields, which indicate that there is a great
opportunity to find hydrocarbons in this area [2].
Figure (1): Location of the Siri Field
Manual Interpretation
The purpose of the manual interpretation is to acquire a comprehensive background about
the seismic analysis and to discover the nature of the structure of the prospect area. This would
encourage us to proceed with further interpretation which is done by software program.
Contour Mapping
Several steps have been followed in order to conduct the manual analysis. First, our team
experts locate the shot points on the base map and produced a contour map. After contour map
was done, the team was able to describe the geological structure of the area. The main observed
structure was an anticline trap with south west and north east direction. The structure was found
to be steeper in the North West to south east directions. Then, the team determined the spill. The
spill point contour line was found to be at (1295ms) and it is converted to depth by dividing the
TWTT over two to get the arrival time and multiply it with the provided average velocity
(3800m/s) to get the depth which is 2460m
Volumetric Calculation
The extent of the oil is evaluated by first calculating the area bounded by the spill point and that
area was found to be 279.2Km^2. Then, the gross rock volume is calculated by multiplying the
area by the thickness of the layer.
Gross volume = area (279.2km^2* thickness (0.025km) = 7.43km^3.
After calculating the gross rock volume, we were able to determine the extent of the
hydrocarbons by simply using the following equation:
OOIP= (7758 std bbl/acre*ft)*63753acre * 82.3ft*0.2(* (1-0.15) = 7.50*109 bbl.
Where
7758 std bbl/acre*ft is the converging factor
63753 acre is the area (279.2km^2 /0.00404 = 69109 acre
82.3ft is the thickness (25m*3.33=82.3ft)
0.2 is the porosity percent
0.15 is water saturation percent
Computer Interpretation
After finishing the manual interpretation and with the encouraging results we have gone
to the next step which is the computer interpretation. We started to confirm our result by using
advanced computer program which will help us to get more information that was difficult in
manual interpretation and then to analyze it such as thickness of the reservoir. However, with the
data provided which is the 2D base map, porosity and the saturation of the reservoir, we
continued our interpretation using “Geographix program” within that we used “Geoatlas and
Seisvision modules” since they are widely used and give accurate results. However, the
Geographix program helped us to determine the location of the top and bottom horizon of our
reservoir while in the manual interpretation we only determined the top of our reservoir. Also, it
helped us to produce the thickness map and to calculate the area and the volume of the reservoir
so that we could calculate the amount of hydrocarbon in the reservoir. The steps that were
followed in the computer interpretation are:
1. Picking the top and bottom horizons
2. Correcting the Miss ties
3. Structural Analysis
4. Creating TWTT contour map.
5. Creating Depth map for the top and bottom of the Reservoir
6. Constructing a Thickness Map
7. Determining the oil emplacement (hydrocarbon quantity)

Data quality:
Before staring interpretation we had to examine the lines to evaluate their quality, and by quality
we mean that the lines provide a clear positions and the shape of the layers.
The lines provided were all nearly clear only for some lines the readings were not clear in small
areas that is the cause of the noisy surrounding during the collection of the data. As an example,
we have provided a seismic section with a poor quality reading ( fig (..) ).
Poor reading
due to noisy
surrounding
Fig (.) poor seismic map

Miss-ties and errors :
Miss-tie is the mismatch or shifts between two intersecting lines that can occur often in seismic
maps. The main causes of the shifts are using different datum points in the acquisitioning process
and highlighting wrong trough or peaks among the lines.
Miss-ties are an important subject that needs to be solved, because it will affect the accuracy of
the data negatively in:
i. Area of interest
ii. Thickness of potential reservoir
iii. Estimated OOIP
But with the help of the Geograpix software and to be more precise the seis-vision module has an
option to detect, compute and edit the shifts ( appendix v ). To give a clearer explanation of how
the program works, a table (xxx) and figure (x) are shown.
Table (x) mistie correction data
Line
1
Line
8
Before
Fig (x) Mistie correction between
line 1 and 8
Before correction
After correction
Miss-tie (ms)
-55.96
Miss-tie (ms)
0.14
After
Picking the top and bottom horizons
We started to pick the horizons of the Top Mishrif and bottom Mishrif of our reservoir.
Unlike the manual interpretation, we picked the exact location of the top and bottom horizons
with taking in the consideration that the top of the reservoir was the peak and the bottom of the
reservoir was the trough. Figure ( ) show the picked Top and bottom horizons of the reservoir.
Top
Mishrif
Bottom
Mishrif
Fig ( ), the top and bottom horizon of the reservoir
Structural Analysis
During the interpretation, we have observed some geological features which with reporting may
give a clearer inaccurate picture of the reservoir. Although that the anticline was shown in the
manual interpretation, it was shown clearly using the software in line 2 which may give an
indication of the present of hydrocarbon (fig..). Also, in line 8 we found an unconformity which
we think that it is an angular unconformity and it was
above our top and bottom horizons fig (..). However, in line 7 we found a reverse fault which
was formed due to a compression force.
Angular unconformity
Anticline
Fig ( ), Anticline found in Line 2
Fig ( ), Angular unconformity from Line 8
Fau
lt
Fig ( ), reverse fault from Line 7
Creating TWTT contour map.
After correcting all the miss ties we used GerGraphix to create TWTT contour map for
the top and bottom Mishrif which is needed to create the depth maps. This contour map shows
clearly the structure of the area and the boundary of the reservoir. Fig (...) and (...) shows the top
and bottom Mishrif contour map and the yellowish color represent the shallowest layer while the
purple color represent the deepest layer.
Fig (), Bottom contour map
Depth maps
Using Geoatlas software, the TWTT contour maps were converted into depth map
knowing that the velocity equal to 3500 m/s.
Depth = Velocity * Time
 Equation 1
Fig (), Depth map of the top
reservoir
Thickness Map
The thickness map was created using the Geoatlas software using the following equation.
Thickness= (Bottom of reservoir- Top of reservoir/2)*3500  equation 2.
Then we determined the area, volume and the thickness of the reservoir.
Area = 93.60 Square kilometers
Determining the oil emplacement
5.0 Conclusion and Recommendation:
Oil-Water contact
Fig (), Thickness map showing oil
water contact
To sum up, all sufficient geological and seismic information on the siri prospect area were
originated. Efficient information was interpreted using both manual (Hand) and computer
(Software) interpretation. Moreover, data contains the type of formation that appeared as an
anticline structure. While thickness, volume of the reservoir and necessary calculations were
conducted as follows:
Field area = ……… km2
Thickness of the field
Field Volume
= ……… m
= ………. km3
The Original Oil In Place (OOIP)
= ……….. m3 = ……… billion bbl
By analysing the information above, we are convinced that the anticline has high
potential of hydrocarbons. As a result, it is recommended to continue with the exploration and
the development phase of the siri prospect area.
6.0 References:
[1] Mohammed Y. Ali and A. B. Watts, “Subsidence history, gravity anomalies and flexure of the
United Arab Emirates (UAE) foreland basin”, Gulf PetroLink, Bahrain, GeoArabia, vol. 14, no.
2, 2009, p. 17-44
[2] B. Williams, “Interpretation Workflow”, “Chapter 4: Interpretation of 2-D seismic Data”
Exxon upstream research company, Huston, Texas, US, p. 41-55.