الاطاريح
2023
PHD "Using 3D seismic attributes analysis to estimate structure and properties of the reservoir in Chia Surkh field – Kalar, Kurdistan Region, Iraq"
2023-11-02
The study area lies to the east of Kalar City within the Sulaimani Government of the
Kurdistan Region, Iraq. Utilizing a 3D cube Seismic dataset covering an expanse of 75 square
kilometers, the investigation sought to unveil subsurface geologic structures. These seismic
data were sourced from the Pet Oil Company, authorized by the Ministry of Natural
Resources (MNR) of the Kurdistan region-Iraq (KRI). The study involved the use of 40 inline
sections-oriented NE-SW and 30 crosslines sections-oriented NW-SE. This approach revealed
the presence of elongated NW-SE linear features, with one predominant feature extending
throughout the entirety of the surveyed region. Within this framework, seven reflectors were
identified and marked. To further refine subsurface geology interpretation, a synthetic
seismogram was created by integrating 3D seismic data and check shot data from well CS-11.
The combination of well data and seismic data facilitated the identification of distinct
horizons, encompassing Fatha unit 1, Fatha unit 2, Fatha unit 3, Fatha unit 4, Jeribe, Dhiban,
and Euphrates Formations. These horizons were correlated and linked to the seismic data
through the application of Petrel Schlumberger 2017 software. Through the deployment of 3D
Two-Way time maps, the study depicted reflections from the aforementioned horizons, along
with the presence of three reverse faults: F1, F2, and F3. Notably, the seven reflectors
clustered in close proximity exhibited undulation patterns corresponding to an anticline
structure aligned along a NW-SE axis. Among the faults, F1, extending across the study area,
shared a parallel disposition with the smaller F2 and F3 faults, which also exhibited reverse
characteristics. However, F3's dip direction contrasted with that of F1 and F2. After
converting time-to-depth, seven depth maps were generated. Notably, the first four maps
spotlighted a prominent NW-SE anticline structure that dominated the study area over a
distance of 10 kilometers. The varying tilt of these structures was observable along their
length, with the northeastern limbs demonstrating a less pronounced tilt (45°) than the steeper
southwestern side (50°). Within this geological context, two distinct faults emerged. F1,
spanning the study area over 10 kilometers, paralleled the major anticline trend. On the other
hand, F2 extended 2 kilometers, aligning parallel to F1 and potentially contributing to
localized deformation patterns. The seismic depth maps underscored the intricate nature of the
region's structural features, prompting a call for expanded exploration to refine subsurface
geology interpretation and detect potential hydrocarbon reservoirs. Incorporating the seismic
depth maps of Dhiban, Jeribe, and Euphrates, the study highlighted the presence of two
observable domes, with the larger situated in the southeast and the smaller in the northwest.
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Significantly, the contour lines on the domes' northeastern sides displayed a shallower incline
in contrast to the steeper dips on the southwestern side. While F1's identification within these
formations was limited due to its constrained vertical and horizontal extension, F2 was
consistently identified, extending 2 kilometers in the NW-SE direction. It's conceivable that
F2 contributed to localized changes in the area's deformation pattern, contributing to the
overall complexity of its deformation history. geological evolution can be attributed to ancient
tectonic forces originating from the northeast. Seismic attribute analysis played a pivotal role
in deciphering these structural complexities, spotlighting their significance in terms of
hydrocarbon exploration and production. The study employed seismic attributes including
variance edge, curvature, root mean square, envelope, and sweetness. These attributes
unveiled a major NW-SE trending anticline, a major fault, and two parallel minor faults.
Envelope and sweetness attributes highlighted bright spots within Fatha, Dhiban, Jeribe, and
Euphrates Formations, suggestive of hydrocarbon presence. Using 3D seismic data
interpretation, a geomodel for the Chia Surkh oil reservoir established a structural framework.
The model accurately captured essential features, aiding precise property estimation. TWT
grids of reflectors and the 3D seismic volume were input for constructing the static model
using Petrel software. Porosity modeling, pivotal in oil and gas industry, yielded six models
indicating porosity variations (0-49%) due to lithological diversity. Notably, a major NW-SE
trending anticline aligned with Zagros series tectonic trend, spanning 10 km by 7.5 km. A
major fault with 150m displacement, 10 km length, extending beyond study area, and two
parallel minor faults (displacements 40-70m, lengths 1.25-3 km) were observed. Seismic
attributes confirmed these features. Attributes like envelope and sweetness indicated bright
spots across formations, implying hydrocarbon presence. Detected geological features -
anticline, carbonate rocks, gypsum, anhydrite as cap rocks, and bright spots as Direct
Hydrocarbon Indicators (DHI’s) - suggest oil trap reservoir presence in multiple formations.
Structural features - major anticline, three parallel reverse faults - formed during Alpine
Orogeny in Early Miocene. Study area’s geological structure suggests oil prospectively, with
anticline as trap, evaporites as seal, limestone as reservoir. Notably, major fault intersecting
anticline near crest could lead to hydrocarbon escape, though interbedded claystone may
retain some hydrocarbons. Geomodel elucidates study area as anticline oil trap with
geological formations as reservoir.
2010
M.Sc. thesis : Simulation of Gravity Data in Western Nainawa Area
2010-08-11
Abstract:
The study area lies in the northern part of Iraq in the western part of
Nainawa governorate. It is surrounded by Tigris River to the east,
Mashuradagh anticline to the north, Sinjar anticline and Baaj area to the west
and Al- Gayara region to the south, The study area locates within the foothill
subzone including Mosul block consisting of secondary blocks which was
suggested by a stratigraphic correlation based on deep oil exploration wells.
The Bouguer gravity map covered the study area reflects a gravity high
which its centre locates near Atshan anticlinal structure. The previous gravity
high extends over many anticlinal structured surfaces Allan, Shaikh -Ibrahim,
Sasan, Ishkaft, Gusair, Ain-Zalah, Butma, Rafan, Atshan, Nwaigit, Qlaian,
Adayia and Najma. Twenty-three gravity traverses were chosen. (T1-T8) with
NW-SE direction and the others (T10-T24) with NE-SW.
The present study conducted simulation of gravity data with different
computer techniques taken in to consideration the previous studies. The
calibrated gravity field was chosen visually and upward continually avoiding
both the personal bias and the pure mathematic. Mosul block reflects a huge
mass of 120 Km length and 60 Km width which is divided into a southern
block with Zagrosian trend and a northern Taurosian trend by a strike-slip
fault might explaining why the anticlines changing their axes orientations
from NW-SE to the southern one with E-W on the northern.
The gavity anomally of Mosul block reflects density vaiation between
basement rocks and the sedimentary cover.
On the other hand, the study explained subsidiary block faults
surrounding and within Mosul block which extends in role to deep depths.
This conclusions leads to the large importance of the study area due to
presence of hydrocarbon resources in sedimentary basins as a result of
tectonic activities during the geological eras.
الرجوع