The Evaluation of Petro-physical and Geological Properties of the Southern Asmari Reservoir / Fauqi oil field Southeastern Iraq

: The wire line logs of five wells from Fauqi field are studied to delineate petrophysical properties, and also the shale volume and porosities are calculated and corrected from the effect of shale in this work. It is found that the formation of water resistivity is equal to 0.0145 Ω . m, which is calculated from the SP method (through the relationship between SSP and Rw). It is observed that the type of crude oil of the Asmari reservoir in Fauqia oil field is heavy. The Four units of oil reservoir within the Asmari Formation penetrated by the wells are delineated: A-B1-B2-C . The case study shows that the units (B1, B2) belongs to the formation of the upper Kirkuk, which is one of the main reservoir units producing oil in Asmari. of evaluation FQ6, FQ7, FQ15, FQ20, and FQ21. The petro-physics data of these are in Wire line logs obtained from these are resistivity, density, neutron porosity, sonic porosity, and gamma Ray log, as well as spontaneous potential.

No.24-(9) 2019 Journal of Petroleum Research & Studies (JPR&S) E4 There are nine formations of the Oligocene cycle, which belong to three sequence early (Palani, Sheikh Alas, Shurau) middle (Tarjil, Baba, Bajwan, Ibrahim) and late Oligocene age (Azkand and Anah) [13]. These Formations putted in one group called Kirkuk group. It was found in subsurface section in Kirkuk Province in north east of Iraq. These sequences have different environment from basin to reef and back reef facies. The Bellen's division modified from three cycle to two cycles: lower cycle including (Palani, Sheikh Alas, Shurau and Tarjil), whereas; an upper cycle including (Bajawan, Ibrahim and Anah , Azkand and Baba) formations.
Al Rawi and Al Din divided Asmari reservoir from above to bottom into some Formations as Jerebi/Euphrates, upper Kirkuk, Buzurgan member and lower and middle Kirkuk [4]. The thickness of reservoir in the study wells ranging between 385-438.5m. The boundaries of Asmari reservoir Formation have been determined based on the variation in the behavior of the different logs as follows: -1. Gamma ray log: gamma radiation log is gradually increased at the upper limits of the reservoir. The readings of gamma radiation log in the study wells are between 60-95 API. The highest reading recorded at Well FQ-7 reached API 95. While, the readings at the lower boundary of the reservoir were about 32 API at the rock formation, and 77 API at the well FQ-15, respectively..

Porosity logs:
it is represented by neutron, density and sonic log. It can be seen that there is a decrease in neutron log readings at the upper contact boundary of the Asmari reservoir, and the density log after recording readings up to 2.9 (anhydrite density) in the formation above the reservoir, the log readings reduced to 2.7 or higher in some wells, and this value represents the density of limestone or dolomitic limestone. For the sonic log, there was no significant change at the upper limit.  Rutba-Jazira zone 6+7 Stable Self.

1-Jeribe / Euphraties:
It represents the upper part of the Asmari reservoir, which is lied conformably underlain Fatha Formation (middle Miocene) as the cover rocks of the reservoir. The Euphrates and Jeribe are the most important reservoirs in Iraq. They contain oil and gas in more than 30 geological formations, but they show less importance than north (Jambur field) and the south in both Fauqi and Abu Gharb having18 API, with high sulfur content [20].
In this study, this formation insert under naming Jeribe /Euphraties due to the difficulty of these formations. Al-Daini pointed out that it was not possible to differentiate between the Euphrates and the Jeribe for in the subsurface sections [3].
The thickness of the Jeribe / Euphrates Formations in Fauqi field differs from the neighboring fields (Abu Gharb and Bazurgan), where the thickness is greater in Abu Gharb Field than in Bazrgan [17]. In this work, the thickness ranging from 24-31m. It is noted that the small thickness of the Jeribe /Eupherties formation because it is located far away from the sedimentation center during the sea regression [7].

2-Upper Kirkuk:
It is divided into five units: - x Unite B1: -the upper part of it consists of pure sandstone, whilst, the bottom consists of alternate sandstone with shale with interfere limestone layer. The sandstone part has reservoir characteristic at some wells.
x Unit B1-B2: -consists of limestone with thin layer of shale.
x Unit B2:-consists of pure sandstone.
x Unite B2-C: -consists of limestone with layer of shale.
The Units B1 and B2 are considered very important units reservoir in field.

3-Buzurgan Member:
It is basically consisted of sandstone alternate layer from shale, Bazurgan change horizontally and gradually into limestone particularly in north and south of

No.24-(9) 2019 Journal of Petroleum Research & Studies (JPR&S)
E8 field coexist shale with limestone, which is resulted a significant reduction in the permeability of the well of Fauqi field especially in the furthest north [18]. The sedimentation of this member reflects the existence of a source of classic material due to the tectonic activity in the source region, which provides a source of silicate and clay silica, indicating an increase in tectonic activity during the sedimentation of this member [5].

4-Middle and lower Kirkuk
Middle and lower Kirkuk consist of limestone, sandstone, shale, sandy shale and shaly sand. This formation considers not important from reservoir in spite of rise porosity but this formation appear high water saturation and low hydrocarbon saturation. Figure

Data Collection and Methodology:
The data used for Asmari reservoir in the present study is obtained from Basrah oil company (BOC). Twenty-four oil wells have been drilling so far as. All of the wells do not have sufficient number of logs required for the petro-physics evaluation except 5 wells FQ6, FQ7, FQ15, FQ20, and FQ21. The petro-physics data of all these wells are available. Therefore, they have been chosen in this study. Wire line logs obtained from these wells are resistivity, density, neutron porosity, sonic porosity, and gamma Ray log, as well as spontaneous potential. The reservoir estimation generally needs three properties. The first one is the ability of the rock to contain liquids, while, the second one is the relative amount of fluids and the ability of liquids to pass through the rock to the well hole [15].These properties are intended porosity, water saturation and permeability that are addressed as follows:-Porosity (φ): It is an important petro-physical property in the reservoir rocks, wh1ich the oil or gas reserves is stored within the reservoirs. Porosity is the ratio between the size of the space in the rock and the total volume [11].
Water saturation (Sw): it is representing the ratio between the volumes of waterfilled voids to the total volume of rock spores as an important factor in reservoir assessment [26] can determine hydrocarbon saturation The volume of non-waterfilled spaces (the hydrocarbon saturation) can be determined by using the data of water saturation [21].
The presence of shale in a reservoir gives false values of water and porosity are derived from logs. These pseudo-values are not limited to sandstone but they are also found in limestone and dolomite. Hilchi (1987) suggested that in order for the shale to significantly affect the water saturation value derived from the log, the quantity of the shale should be higher than 10% to 50%, depending on the Fertl & Hammack equation [9].

Methodology:
x The data of well logs in the Asmari reservoir are taken for 5 wells are FQ6, FQ7, FQ15, FQ20 and FQ21according the specific methodology used in this work as shown below: 1-Study the petro-physics properties for these wells depending on resistivity, porosity, gamma ray log and spontaneous potential. x Manual cutting was used for the wells log, the cutting process included the calculation of Rt, GR, SP, ∆t, φ N , ρb, which were taken from the well logs, also the wells of the study and for each meter and then used Excel software for the purpose of calculating mathematical equations.
x Zoning and Point Selection: Zoning is of vital importance in the interpretation of well logs. The logs were split into potential reservoir zones and non-reservoir zones. Hydrocarbon bearing intervals were identified and differentiated based largely on the readings from the shallow and deep reading resistivity tools.
x Computing the Shale Volume from the Gamma Ray. This was derived from the gamma ray log first by determining the gamma ray index:
GR log =gamma ray reading of the formation.
GR min = minimum gamma ray reading (sand baseline); GR max = maximum gamma ray reading (shale baseline).
For the purpose of this research work, Larionov's volume of shale formula for tertiary rocks was used: sh = 0.083 (2 3.7 GR −1) sh : volume of shale and GR: gamma ray index. ) N cor= neutron porosity corrected from shale.
) N= Porosity derived from the neutron log.
x Computing the water resistivity R w ; this value is calculated by several ways, but in many cases the best value is easily obtained from the spontaneous potential curve. This value is recorded in clean formation (No-shale) and requires that the formation be clean, saturated, permeable and water-bearing [27]. The calculation of the R w method in the SP method depends on the relationship between SSP and R W :-For the purpose of calculation of the R w from SP log method, SP must specify the following: Base Shale line. SSP, which represents the maximum deviation of the SP curve in a clean, thick and water bearing layer.
Determine a temperature in the SSP area.
The formation temperature is determined by the following equation: -  After finding these parameters, the mathematical method is used to calculate the R w . that developed by Bateman & Konen (1997) [17]. The R w value of well FQ-15 was calculated in this way and found to be equal to 0.0145 Ω. m.
x Computing the Water Saturation. The presence of shale in a reservoir gives false values of water and porosity are derived from logs. These False values are not restricted to sandstone but are also found in limestone and dolomite. Hilchi (1987) suggested that in order for the shale to significantly affect the water saturation value derived from the log, the quantity of shale should be higher than 10% to 50%. Therefore, the Fertl & Hammack [9]

Conclusion and Results:
1-The result showed that the Asmari reservoir had a wide and rapid facial variation.
It consisted of a sequence of sand, carbonate and clay rocks reflecting a distinct tectonic activity during the period of Oligocene-Miocene, which are shown by the results of the logs interpretation where it was found that the high proportion of shale (V sh ) in the reservoir units.

2-
The result showed that the units (B1, B2) belonging to the formation of the upper Kirkuk is one of the main reservoir units producing oil in the reservoir of Asmari as compared to the unit (C).
3-The results of porosity logs analysis (sonic, neutron and density logs) showed that the predominant porosity are primary porosity and the secondary porosity formed very low proportion and nonexistent.

4-
The study showed that the residual oil in the reservoir units is larger than portable. This indicates that the oil of the Asmari reservoir in Fauqia field is heavy type, this also show from the behavior of the resistivity well log (R t and R xo behavior).