1. 1. INTRODUCTION
Geology is the science that deals with the history and structure of the earth and its life forms, especially as
recorded in the rock record. A basic understanding of its concepts and processes is essential in the petroleum
industry, for it is used to predict where oil accumulations might occur. It is the job of the petroleum
geologist to use his/her knowledge to reconstruct the geologic history of an area to determine whether the
formations are likely to contain petroleum reservoirs. It is also the job of the geologist to determine whether
the recovery and production of these hydrocarbons will be commercially profitable.
The physical characteristics of a reservoir, how petroleum originated and in what type of rock, what types of
fluids exist in the reservoir, how hydrocarbons become trapped, and basic well log analysis are some of the
concepts vital to the production and recovery efforts of any exploration or energy service company.
2. INTRODUCTION TO GEOLOGICAL MAP
Subsurface geological maps are perhaps the most important vehicle used to explore for un discovered
hydrocarbons and to develop proved hydrocarbon reservoir. However, aspect of petroleum exploration and
exploration .as afield developed from its initial discovery a large volume of well log seismic and production
data are obtained with these data the accuracy of the subsurface interpretation is improved through time.
2.1. STURCTURE CONTOUR MAP:
A structure contour is the trace of a horizontal line on a surface (e.g., on a formation
top or a fault). The dip direction of the surface is perpendicular to the contour lines and the dip amount is
proportional to the spacing between the contours. Structure contours provide an effective method for
representing the three-dimensional form of a surface in two dimensions.
2.2. ISOPACH MAPS:
An isopach map is used to show thickness trends from measurements at isolated points. An isopach map can
be interpreted as a paleotopographic map if the upper surface of the unit was close to horizontal at the end of
deposition. If the paleotopography was controlled by structure, then it can be considered to be a
paleostructure map. The thickness variations represent the structure at the base of the unit as it was at the
end of deposition of the unit. The trend of increased thickness down the center of the map in could imply a
filled paleovalle.
2. 3. WELL LOCATION MAP:
Well location map determines the coordinates (X-Y) in the field by using the given data in table (1-1):
Table (1-1)
Well X Y Top (m) Bottom (m) Net Pay
B-123 812065.6325 640147.5096 1130 1250 120
B-122 811933.8902 640904.2146 1195 1275 80
B-124 812038.9021 640632.1839 1158.5 1229.4 70.9
B-125 811949.1647 640848.659 1090 1178 88
B-126 812048.4487 641337.1648 1344 1409 65
B-127 810719.5704 642651.341 1247.96 1335.96 88
B-128 811828.8783 641009.5785 1038.76 1109.69 70.93
B-129 812008.3532 640718.3908 1062.5 1108.5 46
Figure (1-1)
4. Original oil in place calculation from isopach map:
From pay (isopach) maps:
Table (1-2)
The trapezoid volume formula:
If ratio
𝐴𝑛+1
𝐴𝑛
˃0.5 used the trapezoid volume formula
Δvb = h/2 (An+An+1)
The pyramidal volume formula:
If ratio
𝐴𝑛+1
𝐴𝑛
˂0.5 used the pyramidal formula:
√𝐴𝑛𝐴𝑛+1)
+
n+1
+A
n
= h/3 (A
b
v
Δ
Number of
zone
Contour
Value
Thikns (m) Area (m) Ratio (A1/A2) Method Δv (m3)
A0 110 5 3353898.69 0
A1 105 5 3322367.2 1.00949067 T 16690665
A2 100 5 3170364.82 1.047944759 T 16231830
A3 95 5 2968126.18 1.068136808 T 15346227
A4 90 5 2751715.68 1.078645659 T 14299605
A5 85 5 2385777.8 1.153383053 T 12843734
A6 80 5 1640670.66 1.454147901 T 10066121
A7 75 5 919410.321 1.784481451 T 6400202.5
A8 70 5 281769.893 3.262982818 T 3002950.5
A9 65 5 17212.2246 16.37033561 T 747455.29
A10 60 5 9579.675 1.796744107 T 66979.749
A11 55 5 3510.07068 2.729197183 T 32724.364
A12 50 5 116.10184 30.23268777 T 9065.4313
A13 45 0.75908646 0 0 290.2546
5. ————————————————
Grid Volume Computations
————————————————
Sun Dec 25 10:28:03 2022
Upper Surface
Grid File Name: D:PROJECTNew foldernew bottom.grd
Grid Size: 100 rows x 54 columns
X Minimum: 810719.5704
X Maximum: 812065.6325
X Spacing: 25.397398113207
Y Minimum: 640147.5095
Y Maximum: 642651.341
Y Spacing: 25.291227272727
Z Minimum: 1140
Z Maximum: 1260
Lower Surface
Grid File Name: D:PROJECTNew foldernew top.grd
Grid Size: 100 rows x 54 columns
X Minimum: 810719.5704
X Maximum: 812065.6325
X Spacing: 25.397398113207
Y Minimum: 640147.5095
Y Maximum: 642651.341
Y Spacing: 25.291227272727
Z Minimum: 1140
Z Maximum: 1260
Volumes
Z Scale Factor: 1
6. Total Volumes by:
Trapezoidal Rule: 95841444.032121
Simpson's Rule: 95845267.974932
Simpson's 3/8 Rule: 95849666.866233
Cut & Fill Volumes
Positive Volume [Cut]: 95846498.948877
Negative Volume [Fill]: 0
Net Volume [Cut-Fill]: 95846498.948877
Areas
Planar Areas
Positive Planar Area [Cut]: 3370312.6869361
Negative Planar Area [Fill]: 0
NoData Planar Area: 0
Total Planar Area: 3370312.6869361
Surface Areas
Positive Surface Area [Cut]: 3418498.085525
Negative Surface Area [Fill]: 0
