الفهرس 
REGIONAL GEOLOGICAL SETTINGOnly 14 pages are availabe for public view
Abstract
The Belayim Marine Oil Field is located in the central part of the Gulf of Suez between latitudes 28˚ 34’ 45’’ and 28˚ 38’ 32’’ N and longitudes 33˚ 05’ 17’’ and 33˚ 10’ 38’’ E in the eastern side of the Gulf of Suez, 165 km southeast of the Suez City.
The main purposes of this study are to analysis the well logs data for evaluation the petrophysical parameters of the interested reservoirs (Nubia, Rudies, Kareem and Belayim Formations). Then, build a 3D structural model of the Belayim Marine Oil Field by studying the subsurface geologic structural features through picking and identification of the horizon tops on seismic sections of the interested horizons (Nubia, Thebes, Rudies, Kareem, Belayim, South Gharib and Zeit Formations), use Allan’s diagram method for fault seal analysis to indicate the seal and leak areas of the major NW-SE normal fault dissecting the studied reservoirs. Finally, identify new prospect locations over the main reservoir in the study area.
The used data in the present study include:
1) Twenty seismic lines cover the study area.
2) Well logs data for five wells distributed in the area which comprises (composite logs, gamma ray logs, resistivity logs, density logs, neutron logs and sonic logs).
The stratigraphic units in the Gulf of Suez range in age from Precambrian to Holocene and have been divided into three major sequences relative to the Miocene rifting event: Post-rift units (Post-Miocene sediments), Syn-rift units (Miocene sediments) and Pre-rift units (Pre-Miocene sediments).
The Gulf of Suez is subdivided into three tectonic dip provinces These are from north to south: The northern dip province where the fault blocks dip towards the SW direction, The central dip province where the fault blocks dip towards the NE direction, and the southern dip province where the fault blocks dip towards the SW direction.
The three provinces are separated by two north-northeast and south-southwest major accommodation faults or hinge zones. Each province has its own structural and stratigraphic history. The northern hinge zone called the Galala-Zenima hinge zone, this hinge zone separates the northern province of the Gulf of Suez, from the central province. The southern hinge zone called the Morgan hinge zone, which separates the central and southern provinces.
The well logs data analysis has been done for five wells in the study area using Techlog 2015 Schlumberger’s Software. The procedure includes the determination of formation temperature and water resistivity (Rw). The volume of shale (Vsh) was calculated by using gamma ray log as a single indicator and Neutron-Density log as a double indicator. Also, the total and effective porosity (Φeff) was calculated by Sonic, Density and Neutron logs.
The determination of water saturation (Sw) and hydrocarbon saturation (Sh) were carried out for both clean and shaly zones. Archie equation was applied in clean formations, while Indonesia method was used in shaly formations.
The horizontal distribution of hydrocarbon occurrences was studied and explained through a number of Iso-parametric maps such as volume of shale maps, effective porosity maps, water saturation maps, and hydrocarbon saturations maps for Nubia, Rudies, Kareem, and Belayim Formations. Then, the lithology was determined graphically by using Neutron-Density crossplots and M-N crossplots for the interested formations, and analytically by litho-saturation crossplots.
The litho-saturation crossplots present the vertical distribution of hydrocarbon occurrences and the main lithology of the interested reservoirs. These crossplots were applied for the five available wells.
For Nubia Formation, it consists mainly of sandstone and streaks of shale, it has a good effective porosity values range from 12 % to 18 %, and low hydrocarbon saturation ranges from 3 % to 12%.
For Rudies Formation, it mainly consists of shale and sandstone with some contents of limestone, it has average effective porosity values range from 5 % to 15 %, high hydrocarbon saturation values reach to 75 %, and net pay thickness reach to 47 m in (BM-85) well and 60 m in (BM-72) well.
For Kareem Formation, it mainly consists of shale with some streaks of sandstone, it has average effective porosity values range from 3 % to 16 %, and low hydrocarbon saturation.
For Belayim Formation, it subdivided into four members (Hamam Faraun, Feiran, Sidri, and Baba members). Hamam Faraun and Sidri Members consist mainly of sandstone with streaks of shale, while Feiran and Baba Members consist mainly of salt and anhydrite. Hamam Faraun Member has average effective porosity ranges from 10 % to 14 %, and hydrocarbon saturation reaches to 40 %. Sidri Member has average effective porosity ranges from 10 % to 20 % and hydrocarbon saturation reaches to 55%.
Seismic data interpretation was carried out using twenty seismic lines (10 Inline and 10 Crossline) cover the study area and check shots data of the available wells, which used in well-to-seismic tie to identify the formation tops on the seismic section. Interpretation was carried out by picking the fault sticks on all the seismic sections. Then, picking and looping the reflection horizons of the interested seven formation tops (Nubia, Thebes, Rudies, Kareem, Belayim, South Gharib, and Zeit Formations) over all the vertical seismic sections using manual tracking technique according to reflection character of each horizon.
After full interpretation of the seismic sections by picking and identifying the faults and horizons, the time maps of the interested horizons were constructed. The fault polygons were interpreted for each horizon according to the intersection of the fault sticks and horizons that reflect the major structural trend in the study area. The average velocity maps of all the interested seven horizons were constructed according to the values of time and depth at each formation top, which extracted from the check shots data at every well. The depth maps were constructed through a depth conversion of the time values multiplied by the corresponding average velocity values for each horizon and divided by two; this produces depth values of the interested horizons.
The isochore maps were constructed for (Thebes, Rudies, Kareem, Belayim, South Gharib and Zeit Formations) by subtracting the depth values of each two sequential formations.
The depth maps on the top Nubia, Thebes, Rudies, Kareem and Belayim Formations show that the formations were dissected by several normal faults trending to NW-SE direction (Clysmic faults) with throw toward the SW and NE directions, and that there is another fault set trending ENE-WSE direction (cross faults).
The depth maps on the top South Gharib and Zeit Formations show that the structure at the top of them is a NW-SE doubly plunging anticline without any dissecting faults.
The 3D structural model of the Belayim Marine Oil Field was built by using the seismic horizon interpretation and seismic fault interpretation. This process includes the import of the interpreted stratigraphic horizons and faults to build the structural model. Using Petrel 2015 Schlumberger’s software the interpreted data have been integrated to build the final 3D structural model of the Belayim Marine Oil Field. The structural model starts from the top of Zeit down to the base of Nubia Formation.
The principal steps in creating a structural model are the boundary definition, the fault model, the pillar gridding and make horizons.
In the boundary definition step, we set up the area of interest and the grid resolution of the model.
The fault model was built by using the interpreted fault polygons over the interested formation tops and the interpreted fault sticks.
Three skeletons were created as a result of the pillar gridding of the Belayim Marine Oil Field model along the top, middle and bottom skeletons or hold on horizons and layers of structure model. These skeletons are the architecture of the structure model and will be used in making horizons and zones.
Seven interested seismic surfaces were utilized to make horizons process on the grid. To generate additional horizons using relative distance to existing horizons (for example, isochores) use the Make zones process. These two processes (Make horizons and Make zones) are used to create the geological zones within the model. It is expected that each zone will have similar petrophysical properties and can therefore be modeled using a single set of input data.
The 3D structural model of the Belayim Marine Oil Field indicate that the folding system plays a major role in the tectonic framework of the field. This fold system are dissected by several normal faults trending to NW-SE direction (Clysmic faults) thrown toward the SW and NE directions. There is another fault set trending ENE-WSE direction (cross faults). These sets of faults make together a horst block, two graben blocks and step-like faults. The top South Gharib and Zeit Formations show that they are affected by a NW-SE doubly plunging anticline without any dissecting faults and because they are composed mainly of evaporites (salt and anhydrite) they represent good seal rocks for underlying reservoir formations.
Petroleum system elements of the Belayim Marine Oil Field was studied. Several good quality source rocks have been identified in the field, it range in age from Carboniferous to Miocene, the primary source rocks mainly consist of limestones while the secondary source rocks mainly consist of shale. Belalyim Marine Oil Field contains several productive reservoirs, it can be subdivided into pre-rift reservoirs, the syn-rift reservoirs (The Miocene sandstone reservoirs).
Horizons of caprock beds (such as shales, evaporites, and dense limestones) are abundant throughout the stratigraphic column of the Belayim Marine Oil Field. The evaporites have provided the essential element for the preservation of oil accumulations. The Miocene clastic section, such as the Rudeis and Kareem Formations, can act as seals especially in areas where some shaly facies have developed.
The main trap types are due to faulting and related unconformities. In the Belayim Marine Oil Field, a three-way dip closure trap has formed as a hanging wall anticline. This trap is sealed vertically by mudstones or Miocene evaporates. The structures and lithologies furnished the condition for the primary migration of oil. Block faulting caused the juxtaposition of source and reservoir rocks and allowed the migration toward the latter.
The fault seal analysis was performed by using the Allan’s diagram method on three of the major faults (F-6, F-9 and F-10) in the Belayim Marine Oil Field to detect the seal and leak zones across these fault planes. Finally, the results of interpretation from the integrated geophysical methods propose new three potential locations (A, B, and C) for future exploration activities and drilling prospects in the field with respect to their structurally highs revealed from seismic structural interpretation and high hydrocarbon saturation, high porosity, low shale content revealed from petrophysical parameters evaluation of the Rudies Formation reservoir.