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Mishrif Formation
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
DOI:10.24996/ijs.2018.59.1A.16
ISSN: 0067-2904
Formation Evaluation by using Well Logging of Mishrif Formation in the
Noor Oil Field, , Southeast Iraq
Ali M. Hasan Altameemi*, Aiad Alzaidy
Department of Geology, College of Science, University of Baghdad, Baghdad, Iraq.
Abstract
Mishrif Formation regards one of the most important reservoirs in Iraq.Well
logging represents one of the most important tool in the formation evaluation.
According to the Petrophysical properties that have been gotten from well logging,
Mishrif Formation in terms of reservoirs units, consist of several reservoirs
units..Major reservoirs units divided into three reservoir units,MA,MB&MC. Each
of these major units divided into minor reservoirs units
(MB11,MB12,MC2&MC3).MB major reservoir units represent the best reservoir
unit.These reservoirs units separated by cap rocks(mainly tight
limestone)(CR1,CR2,CR3,CR4,CR5,CR6,and CR7).CPI were demonstrated for all
wells.Hydrocarbon saturation vs. water saturation have been determined for each
units.In addition, the types porosity and moveable vs.residual oil were calculated.
Keywords: Petrophysical properties, , Mishrif Formation .Noor Oil Field.
التقييم المكمني بأستخدام الجس البئري لتكوين المشرف في حقل النور النفطي جنوب شرق العراق
أياد علي حسين الزيدي،*علي محمد حسن التميمي
. العراق، بغداد، جامعة بغداد، كلية العلوم، قسم علم االرض
الخالصة
الجس البئري يعتبر. يعتبرتكوين المشرف واحدا من اهم المكامن النفطية في العراق والشرق االوسط
، من خالل دراسة الخواص البتروفيزيائية المستحصلة لهذا التكوين. واحدا من اهم ادوات التقييم المكمني
الوحدات المكمنية الرئيسة في. تكوين المشرف في مصطلح الخواص المكمنية يتكون من عدة وحدات مكمنية
) كل واحدة من هذه الوحدات المكمنيةMA ,MB ,MC ( تكوين المشرف قسمت الى ثالث وحدات مكمنية
.)MB11,MB12,MC2&MC3 ( قسمت الى وحدات ثانوية
الوحدات المكمنية مفصولة عن. ( تعتبر من أحسن الوحدات المكمنيةMB (الوحدة المكمنية الرئيسة
تم. (CR1,CR2,CR3,CR4,CR5,CR6,and CR7)بعضها بصخور صماء تتكون من الحجر الجيري
تم حساب انواع.بناء منحنيات تفسيرات الجس البئري وتم تحديد نطاق التشبع النفطي والمائي لكل وحدة مكمنية
.المسامية وتحديد النفط المتحرك من النفط المتبقي
Introduction
Petrophysical interpretation is essential for understanding subsurface reservoir rocks[1].
Subsurface characterization requires physical measurements that made from well logging. Well
Logging is a process of recording a details for the geological formations have penetrated by borehole.
Well logging represents as an integrated process in the measuring the reservoir .The log depends on
the samples taken from the subsurface or measurements made by physical instruments lowered into
________________________________
*Email: alialtamimi82@gmail.com
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
the hole. Formation evaluation in this study based on the well logging. Subdivision of reservoirs
depends on several Petrophysical properties ( porosity, permeability, mineralogy, water and fluid
saturation).
The Study Area
Noor oil field is located about 15 km NE of the Missan governorate, southern Iraq. Noor structure
field consist of anticlinal fold with general trend axis NW-SE. Figure-1
Figure1- Location map of the study area
Definition of Mishrif Formation
One of the most important reservoirs in the middle east is the Mishrif
Formation[2],[3],[4],and[5].The Mishfrif formation make up about 30% of the total oil in Iraqi
reserves[6].During the Cretaceous period within the secondary sedimentary cycle Cenomanian-Early
Turonian the Mishrif formation was deposited.
Data and Methods
Petrophysical properties have been studied from 8 boreholes in Noor Oil Field(No-1,No-2,….. No-
8). There are several steps are required before the process of interpretation of well logging. First,
processes of the digitization. Second, stage of correction because well logging is indirect
measurements that are influenced by the effects of environment (for example, mud circulation and
mud properties). In this study there are different logs were used including (Gamma-
Ray,Density,Sonic,Resisitivity,and Neutron logs. Interactive petrophysics(IP) and Techlog software
were used to integrated in formation evaluation.
Environmental Correction
Environmental corrections are necessary for compensate the differences between the actual
condition in borehole and the calibration of the test pit tool. All these corrections should be done with
all logs (Gamma ray, Density, Neutron and Resistivity logs) according to the Schlumberger's
environmental correction. In this study, IP software was used to apply these corrections. After
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
complete all the previous corrections and calculation of borehole temperature, invasion corrections
should be made.
Invasion corrections
The resistivity log measures apparent resistivity. It's represent a resistivity of isotropic,
homogeneous medium. If the measurement conditions will be known, the apparent resistivity
represents a true resistivity.This step were done by correction of Rt to LLDC and Rxo to
MSFL.Figure-2
Scale : 1 : 1200 No-4
DB : (-1) DEPTH (3282.M - 3554.95M) 02/08/2017 19:13
1 2 3 4
DEPTH Temp (C) RT (ohm.m) RXO (ohm.m)
(M) 10. 100. 0.2 2000. 0.2 200.
LLDC (ohm.m) MSFLC (ohm.m)
0.2 2000. 0.2 200.
3300
3400
3500
1 2 3 4
DEPTH Temp (C) RT (ohm.m) RXO (ohm.m)
(M) 10. 100. 0.2 2000. 0.2 200.
LLDC (ohm.m) MSFLC (ohm.m)
0.2 2000. 0.2 200.
Figure 2-Invasion corrections and temperature Formation(Rt to LLDC and Rxo to MFSL) in No-4.
Determination of water resistivity
Formation water resistivity have to be known in order to calculation water saturation Sw.This
method focused on strong salinity contrasts between formation water and the mud filtrate in specific
conditions in thick-clean sand with well defines shale volume[1].Figure-3.
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Petrophysical parameters:
1-Determination of clay volume (Vsh)
One of the most important logs is used to determine clay volume from Gamma Ray(GR).This type
of logs measures the natural radioactivity in clay. In order to determine the clay volume in formation,
formula will be used from[7]. Figure-3.
IGR=
IGR= gamma ray index
GRlog=gamma ray reading of formation
GRmin= minimum gamma ray
GR max= maximum gamma ray
In this study, because the formation regards as an old rocks, the equation in [8]and [9] were used.
Vsh=0.33×(
Vsh= 0.33× (
Scale : 1 : 1200 No-4
DB : (-1) DEPTH (3282.M - 3554.95M) 14/10/2017 12:24
1 2 3 4 5
DEPTH GR (gAPI) VCLGR (Dec) Rw SP (ohm.m)
Clay Volu
(M) 0. 50. 0. 1. 0.01 1.
Top Mishrif
3300
MA
CR1
MB11
CR2
3400
MB12
CR3
MB21
3500
MC1 CR5MB22CR4
CR6
1 2 3 4 5
DEPTH GR (gAPI) VCLGR (Dec) Rw SP (ohm.m)
Clay Volu
(M) 0. 50. 0. 1. 0.01 1.
Figure 3-Vsh calculation from GR log and Rw in No-4.
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Porosity
Rock porosity can be calculated from the combination of neutron-density logs. Density log
representa as a porosity log that measures the electron density of the formation[10]. In order to get
accuracy results, density and neutron logs must be corrected for the shaliness .Corrections were made
according to the following formula relationships:
For density porosity log according to the [11]
øDCorrection=Ød-(Vsh×øDsh) (3)
For neutron porosity log according to [12]
øNcorrection=ØN-(Vsh×øNsh) (4)
Where,
Vsh: represents the shale volume.
ØN: represents neutron porosity in shale formation
Total porosity can be calculated form the following formula [9]
Øt) = (ØN+ØD) (5)
Effective porosity: the amount of pores that are interconnected[13].Effective of porosity can be
calculated from the following formula:
Øeff=Øtotal×(1-vsh)[14] (6)
Primary and secondary porosity
Primary porosity represents the pore space sediments that are deposited at or during the same time
of deposition[15].Secondary porosity is the term triggered on the pore space sediment that are formed
after deposition due to diagenetic processes[16]. Sonic log was used to determine primary porosity
according to the following formula[17 ]
ØS= (Δlog-Δtma)/Δtfl-Δtma) (7)
Where:
Øs=porosity derived from sonic log
Δtma=interval transit time in the matrix.
Δlog=interval transit time in the fluid in the formation.
Δtfl= interval transit time in the fluid.
Presence of hydrocarbon lead to the increase in Δt, therefore,[18] suggested the following formula in
order to denied hydrocarbon effect.Secondary porosity was computed by the difference between total
porosity and the primary porosity was derived from Sonic log.
Ø=ØS×0.7……….gas (8)
S×0.9……….oilØ=Ø
There is another step to avoid shale effect from sonic log:
ØScoreection= ØS -(Vsh-ØSch) (9)
Finally, the index of secondary porosity (SPI) can be calculated according to the following
formula[11]
SPI= (Øt-ØScorrection). (10)
Water Saturation
Water saturation for reservoirs in uninvaded zone is calculated by the Archie formula [13]
[ ] (11)
Where the water saturation in flash zone can be calculated according the following formula [13]
Sw= [ ] (12)
Where:
Sw: water saturation of the uninvaded zone(Archie method).
Rw: resisitivity of formation at formation temperature.
Rt: true resistivity of formation.
Ø= porosity
Sxo= water saturation of the formation in the flushed zone.
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Rmf:resistivity of mud filterate.
A=tortuosity factor
m=cementation exponent
n=saturation exponent assumed to be 2.0
Two values Sw and Sxo are used to estimate the saturation in residual hydrocarbon (shr) and the
movable hydrocarbon (shm) according to the following equation[9]
Shr=1-Sxo (13)
Shm=1-Sw (14)
Bulk volume water (BVW)
The product of a formation's water saturation (Sw) and it's porosity (ø) is the bulk volume of
water[9]
Where, the bulk volume of water can be computed in the flushed zone using the following
formula[19].
BVW= Sw× øe (15)
BVSXO=SXO× øe (16)
Where:
BVW: bulk volume of water in uninvided zone.
BVSXO=bulk volume of water in flushed zone.
Determination of lithology and Mineralogy
1-NPHI and RHOB cross ploting
Neutron and density logd where used to determine the lithology by using the separation of the
curves visually or plotting the two values on special graphs[11].Figure-4.
Figure 4-The NPHI and ROHB cross plot in No-3.
2-Matrix Identification Determination (MID )plot
Identification and secondary porosity can be obtained by using Matrix identification (MID) plot.
Three types of data should be available to obtain this type of plot,the these data are, total porosity øt,
an apparent matrix transit time Δt mma, finally, apparent grain density αmaa are required[14].Figure-5
ρmma=
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Where:
mma:apparent density matrix.ρ
Δtmma:apparent transit time in rock matrix.
Øta:apparent total resistivity.
Figure 5-MID plot in No-3.
3-M-N cross plot
M-N cross plot can be detected the mineralogy of the formation. This type of cross-plot requires a
sonic with neutron and density logs.M-N values are essentially independent of matrix porosity
(sucrosic and intergranular )[13].
Figure 6-M-N cross plot in No-3.
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Net –Gross ratio
Net pay refers to the thickness of porous, interval permeable zone with commercial quantity of
hydrocarbon.Net to- gross is a expression ratio of the thickness of net pay to the total pay thickness.
This ratio is an important ratio in reservoirs volumetric calculation[20].Determination the net pay
requires three important values. These values are, porosity, water saturation, and permeability to
reservoir fluids.Net-gross ratio is a function of the quality of the limestone as potential reservoirs in
Mishrif Formation.Figure-7
Scale : 1 : 1000 No-4
DB : (-1) DEPTH (3282.M - 3554.95M) 14/10/2017 12:37
1 2 GammaRay Porosity Water Saturation Clay Volume
DEPTH GR (gAPI) PHIE (m3/m3) SWT (dec) VWCL (Dec)
Cutoffs
(M) 0. 150. 0.5 0. 1. 0. 0. 1.
Reservoir Flag Reservoir Flag Reservoir Flag
Pay Flag Pay Flag Pay Flag
Top Mishrif
3300
MA
CR1
3350
MB11
CR2
3400
MB12
CR3
3450
MB21
3500
CR5MB22 CR4
MC1
CR6
3550
1 2 GammaRay Porosity Water Saturation Clay Volume
DEPTH GR (gAPI) PHIE (m3/m3) SWT (dec) VWCL (Dec)
Cutoffs
(M) 0. 150. 0.5 0. 1. 0. 0. 1.
Reservoir Flag Reservoir Flag Reservoir Flag
Pay Flag Pay Flag Pay Flag
Figure 7-Net –Gross ratio cross plot in No-4.
Determination of Archie's parameters(m,n and a) using Pickett plot
Archie's parameters(m,n,and a) were determined by using pickett plot.This type of plot based on
the true resisitivty (Rt) is a function of water saturation,porosity and cementation
exponent(m)[9].Figure-8
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Figure 8-Archie's parameters(m,n and a) using Pickett plot.
Computer processes interpretation
These processes are valuable in order to Petrophysical analysis more easier.These processes were
used for;1)Division the units of Formation into reservoirs and non-reservoirs(cap rocks);2) comparison
of the reservoirs units according to the Petrophysical properties for each unit.Finally,these processes
represent the last step in terms of petrophysical properties.Figures-(9, 10)
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Figure 9-CPI for No-3.
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
Figure 10-CPI for No.5.
Discussion and Results
1. Porosity: poor to-fair primary porosity in the reservoir unit MA acoording to the classification of
porosity[21].MB1&MB21 show relatively higher porosity than other reservoirs units.
2. Hydrocarbon saturation vs. water saturation shows that Hydrocarbon saturation in the MA is
varying from poor to moderately comparison with water saturation in the same reservoir unit.While,
the hydrocarbon saturation values increased especially in the Nr5,7,&8.
3. Moveable vs.residual oil in general, the MB reservoir unit shows higher moveable oil comparios
with the other units especially in No-5.Taking in consideration the less amounts of clay in the MB.
4. Cap Rock(CR):There are several non-reservoirs units(cap rocks) were recognized based on the
reading of GR,resisitivity,RHOB,NPHI, and DT logs.These rocks composed mainly from compacted
limestone.
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Altameemi and Alzaidy Iraqi Journal of Science, 2018, Vol. 59, No.1A, pp: 144-155
5. From RHOB-NPHI cross plot,Mishrif Formation composed mainly from Limestone and some
dolomite.
6. M-N cross plot shows the mineralogy of the Mishrif Formation composed mainly form calcite and
dolomite.
Conclusion
1- From Petrophysical properties, Mishrif Formation consist of several reservoirs units separated by
impermeable cap rocks zones.The main reservoirs units are (MA&MB).
2- Petrophysical parameters have been studied inNoor oil field, shows ,that MB is the main reservoir
unit.
3- lithological cross plot analysis, RHOB vs. PHIN, indicates the Mishrif Formation consist mainly
limestone with some dolomite.
4- M-N cross plot indicate the mineralogical of limestone in Mishrif Formation is mainly calcite with
less amounts of dolomite.
References
1. Cannon, S. 2016. Petrophysics: A Practical Guide: John Wiley & Sons, Ltd Registered, 209 p.
2. Al-Khersan, H. 1975. Depositional environments and geological history of the Mishrif Formation
in southern Iraq. 9th Arab Petroleum Congress, Dubai. Paper no. 121 (B-3), pp. 1-18.
3. Reulet, J. 1982. Carbonate reservoir in a marine shelf sequence, Mishrif Formation, Cretaceous of
the Middle East. In: A. Reekman and G.M. Friedman (Eds), Exploration for carbonate platform
reservoirs. Elf Aquitaine. John Wiley and Sons. New York,pp. 165-173.
4. Burchette, T.P. 1993. Mishrif Formation (Cenomanian-Turonian) southern Arabian Gulf,
carbonate platform growth along a cratonic basin margin. In: J.A. Simo, R. Scott and J.P. Masse
(Eds), Cretaceous Carbonate Platforms. AAPG Memoir, 56: 185-199.
5. Alsharhan, A.S., Nairn, A.E.M. 1997. Sedimentary basins and petroleum geology of the Middle
East. Elsevier, Amsterdam, 843 p.
6. Al-Sakini, J. 1992. Summary of petroleum geology of Iraq and the Middle East. Northern
Petroleum Company, Kirkuk, Iraq. 179 p (in Arabic).
7. Schlumberger,1974. Log Interpretationmanual/ principles,Vol.,I, Housten,Schlumberger well
services Inc.,112p. -Larinov, V., 1969.Borehole Radiometry, Moscow,U.S.S.R., Nedra
8. Larinov, V. 1969. Borehole Radiometry, Moscow,U.S.S.R., Nedra,238p.
9. Asquith,G.B. and Krygowski, D. 2004. Basic Well Log Analysis, 2nd Edition:AAPG Method in
Exploration Series 16. Published by the American Association of Peteroleum Geologists
Tulsa,Oklahoma, 244p.
10. Hughes, 1999. Petroleum Geology,Houston,Texas,Baker Hughes,245p.
11. Schlumberger. 1997. Log interpretation charts. Schlumberger Wireline and Testing, Housten,
198p.
12. Debrandes R. 1985. Encyclopedia of well logging.
13. Asquith, G. and Gibson, C. 1982. Basic well log analysis for geologists: methods in Exploration
series,AAPG,216 p.
14. Schlumberger,1998. Log interpretation principles/Application,Seventh edition,Texas,226p.
15. Halliburton, Energy Service, 2001. Basic Petroleum Geology and log Analysis:
Houston,Texas,Halliburton Company,80p.
16. Bowen, D, G. 2003. Formation Evaluation and Petrophysics,Core Laboratories, Jakarta,
Indonesia,273p.
17. Willie MRJ,Gregory AR,Grander GHF 1958. An experimental investigation of the factors
affecting elastic wavevelocities in porous media. Geophysics, 23: 459-493.
18. Hilchie DW 1978. Applied open hole log interpretation. D.W. Hilchie, INC., Colorado,309 p.
19. Schlumberger,1984. Log interpretation charts. Schlumberger,106 p.-
20. Katz. AJ,Thompson AH 1986. Quantitative prediction of permeability in porous rocks. Physical
review, B 34: 879-881.
21. Leverson LA 1972. Geology of Petroleum 2nd ed.Freeman , W.H and company, Pub,San
Francisco, 724p.
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