East Baghdad Oil Field Research Articles

Development of East Baghdad Oil Field By Clusters of Horizontal Wells

There are varieties of reasons lead for drilling horizontal wells rather than verticals. Increasing the recovery of oil, especially from thin or tight reservoir permeability is the most important parameter.
 East Baghdad oil field considered as a giant field with approximately more than 1billion barrel of a proved reserves accompanying recently to low production rate problems in many of the existing wells.
 It is important to say that presence of of horizontal wells in East Baghdad field especially by converting some of already drilled wells by re-entry drilling horizontal sections may provide one of best solutions for the primary development stage in East Baghdad field which may be followed by drilling new horizontal wells or using multilateral wells.
 Advance software (Well Test/FAST) has been used to convert the production data for the already drilled vertical wells to horizontals to simulate the productivity. It can be concluded that no measurements available for the ratio of anisotropy (Kv/Kh); in East Baghdad Oil Field therefore, the wells productivity has been estimated using wide range of anisotropy ratios that will help the field operator to determine exactly wells productivity. Moreover, it helps to recommend the effectiveness of applying hydraulic fracturing in improving horizontal well productivity.
 The results show that it could be used well EB-32 as a re-entry horizontal well with an optimum section length of 1500-2000ft wich give the best production rate. The same result could be stated for EB-10 with somewhat higher productivity than EB-32.

Structural and Stratigraphic Study of Hartha Formation in the East Baghdad Oil Field, Central of Iraq.

Three-dimensional seismic reflection study was conducted for the EasternBaghdad oil field which is located in the middle part of Iraq within Al-Madaaenprovince that belong to Baghdad governarate, South of Diyala River , this fieldincludes two southern parts (S1 and S2), the study area was about 781.905 km 2 forthe upper Cretaceous age, synthetic seismogram was generated from data of EB-5and EB-1 wells. Saadi reflector was picked and identified to determine the HarthaFormation. The seismic sections and time slice maps confirmed that the upperCretaceous age was affected by faults and the indicators of faults ended withinHartha Formation and continue to the deeper formations with increasing intensity.The attribute section was applied on time slice and shows that the area was affectedby normal fault parallel to the structure of the field trends (NW-SE). Time, velocityand depth maps of Hartha reflector depending on data from wells (EB-1, EB-2, EB-6, EB-30, EB-52, EB-54) the maps show the structural picture of East Baghdadstructural nose opened toward NW and trending (NW-SE) that confirmed by 3Dvolume which prepared for the studied area. DHI was identified as flat spot, dimspot and sag , when applying attributes like (instantaneous phase and InstantaneousFrequency) has been proved the absence of hydrocarbons in EB-15 well on otherhand found in adjacent wells such as EB-2 and EB-5 because of facies changes andnot structural change. A scaling facies change was identified at (inline 40910 andinline 47960) , Mound (inline 48310), as well as the work of the Isochron map,which was used to find Isopach and a suitable site for drilling wells.

Assessments of oil characterization, source affinities, and hydrocarbon dynamic of East Baghdad oil fields, Central Iraq

Bulk properties, stable carbon isotopes, whole crude Gas-Chromatography and oil mode ratios of sterane and terpanes data of analyzed samples of oil from the Cretaceous Formation reservoirs of East Baghdad oil field are from five producing wells (EB21, EB68, EB92, EB5 and EB31) from reservoirs of Zubair, Khasib, and Tanuma Formations. They are discussed with aids of characters, hopane, tricyclic terpane, isotopic δC13 saturate, aromatics, and pristine-phytane diagrams. The analized oil have indicated light and medium oil in the Zubair reservoirs and heavy oil for the Khasib and Tannuma oil, with about 15% asphalt and porpherine range of 16.7–35.1 Ni and 68–117 ppm, giant reservoirs. The oil source environment and lithology are of marine algal type II and deltaic type II/III that are non biodegraded deposited in anoxic environments of carbonate and shale. Source maturation at the time of the oil generation, aided by pristine-phytane and Tmax equivalent from MDR (Methyldibenzothiophene ratio) diagrams, are showing mature with Tmax 430–435 °C while source age assessment are taken from δC13 (%) and the calculated C28/C29 sterane ratio to be of Middle and Upper Jurassic as well as Lower Cretaceous age that could be correlated mainly with the Chia Gara and Zubair Formations as well as the Middle Jurassic Sargelu Formation source rocks for oil that are accumulated in the reservoirs of Zubair, Khasib and Tannumah Formations.Source rocks are mainly Upper Jurassic-Lower Cretaceous Chia Gara Formation with contribution from the Middle Jurassic Sargelu and Lower Cretaceous Zubair Formations. The richness of the source rocks, mostly due to shale rich in TOC, and the type of kerogen is mixed type II/III and type III. The formations have good petroleum potentiality (PP) and the OM reaches the Early of hydrocarbon generation. Oil, and gas are the most probable product, and the generated hydrocarbons can be expelled at this level of thermal maturity which is confirmed by petromod software basin modeling to suggest migration and accumulation during the Upper Cretaceous time.Hydrocarbon dynamic in East Baghdad Oil Field are performed using seismic section, logs and porosities. Model assessments of the hydrocarbon generation, migration paths and accumulation sites as well as places of enriched oil are used to assess reservoir location and suggestion for drilling sites.

Compaction and Migration of Hydrocarbons in East Baghdad Oil Field

An attempt is done to present a simple concept to combine the geochemical results with the concept of compaction- abnormality, reflecting a high variation in the porosity and internal pore pressure. The different compaction levels and the variation of the bulk volume may lead to the expulsion of fluids both hydrocarbon and interstitial H2O from high potential zones towards low potential zones, or in other words from low porosity towards high porosity areas. Furthermore, the both formations (Ratawi and Zubair) of lower Cretaceous age showing compaction trend as well as fluid expulsion current with a NW-SE trend of the primary hydrocarbon migration, while the sedimentary basin revealing a deepening towards the southern eastern part of the anticline structure. A change in thickness and the facieses of the rock packages is manifested. The horizontal porosity distribution of shales in Ratawi formation particularly in the upper part (15m thick) reveal differential compaction and such a mechanism is responsible for the kinetic of fluid and gas.

Petroleum geochemistry of oil samples from shallow boreholes at Sakran site, western Iraq

Findings of the oil source affinity for oil sample collected from shallow borehole already drilled for ground water purposes at the Sakran area, NE Haditha city, western Iraq, is performed in this study by biomarker studies with addition to the analysis of gravity map. Petroleum geochemistry study is carried out on oil sample. The terpane and sterane biomarker distributions, as well as the stable isotope values, are used for determining the validity of oil to correlate its source. The results showed that the oil belongs to the Jurassic age, with high sulfur content (2.75 %) and value of C28/C29 up to 0.75. The tricyclic terpanes values as well as hopanes indicated a source rock affinity of carbonates, whereas the pristine/phytane ratio indicated marine algal source of kerogen type II. All these information could confirm that the source rock affinity was the Sargelu Formation (Jurassic), in which their age’s equivalent to the source in East Baghdad Oil Field and Tikrit Oil Field, with a difference from the oil family near the Akkas field, located to the west of the area. Chemical analyses of water sample collected from the borehole showed the following results: TDS = 12,700 mg/l, EC = 215,900 μs/cm, pH = 6.8, DO = 28 mg/l, and temperature = 24 °C. Hydrochemical functions such as rNa/rCl (<1), (rNa–rCl)/rSO4 (<0) and rSO4/rCl (<1) indicate that the water is of marine origin, partially mixed with meteoric water. Analysis of the gravity map revealed two anomalous areas; the western one represents large anomaly with EW trend similar to the Anah graben to the north. The second one consists of many anomalies trending N–NW direction. The main local anomaly is identical with the seeps from the drilled borehole covering large area. The boundaries and trends of the main geological structures have been defined by gradient analysis procedure to the gravity data. The closed gravity anomalies with their large extensions reflect the importance of the results for further studies and promising area for oil reservoirs.

Khasib and Tannuma oil sources, East Baghdad oil field, Iraq

This work presents new insights of the generation, quality and migration pathways of the hydrocarbons in the East Baghdad Oil Field. The Khasib and Tannuma formations in East Baghdad are considered as oil reservoirs according to their high porosity (15–23%) and permeability (20–45 mD) in carbonate rocks. The hydrocarbons are trapped by structural anticline closure trending NW-SE. Gas chromatography analysis on these oil reservoirshave shown biomarkers of abundant ranges of n-alkanes of less than C22 (C17–C21) with C19 and C18 peaks. This suggests mainly liquid oil constituents of paraffinic hydrocarbons from marine algal source of restricted palaeoenvironments in the reservoir. The low non aromatic C15 + peaks are indicative for slight degradation and water washing. Oil biomarkers of Pr./Ph. = 0.85, C31/C30 < 1.0, location in triangle of C27–C29 sterane, C28/C29 of 0.6 sterane, Oleanane of 0.01 and CPI = 1.0, indicate an anoxic marine environment with carbonate deposits of Upper Jurassic to Early Cretaceous age. Four Miospores, seven Dinoflagellates and one Tasmanite species confirm affinity to the upper most Jurassic to Lower Cretaceous Chia Gara and Ratawi Formations.The recorded palynomorphs from the Khasib and Tannuma Formations are of light brown color of TAI = 2.8–3.0 and comparable to the mature palynomorphs that belong to the Chia Gara and the Lower part of Ratawi Formations. The Chia Gara Formation generated oil during Upper Cretaceous to Early Palaeogene and accumulated in structural traps of Cretaceous age, such as the Khasib and Tannuma reservoirs. The Chia Gara Formation generated and expelled high quantities of oil hydrocarbons according to their TOC wt% of 0.5–8.5 with S2 = 2.5–18.5 mg Hc/g Rock, high hydrogen index of the range 150–450 mg Hc/g Rock, good petroleum potential of 4.5–23.5 mg Hc/g Rock, mature (TAI = 2.8–3.0 and T max = 428–443C), kerogen type II and palynofacies parameters of up to 100% AOM (Amorphous Organic Matters). This includes algae deposits in a dysoxic–anoxic to suboxic–anoxic environment. Alternative plays are discussed according to the migration pathways.

Cretaceous petroleum system of the Khasib and Tannuma oil reservoir, East Baghdad oil field, Iraq

Gas chromatography, palynomorph constituents, and maturation are analyzed for oil samples of the Campanian Khasib and Tannuma Formations in the wells of East Baghdad oil field for biomarker studies, while palynomorph constituents and their maturation, Rock Eval pyrolysis, total organic carbon (TOC) analysis are carried on for the Upper Jurassic and the Cretaceous Formations of core samples from the same wells for dating and evaluation of the source rocks. The gas chromatography of these oils have shown biomarkers of abundant ranges of n-alkanes of less than C22(C17–C21) with C19 and C18 peaks to suggest mainly liquid oil constituents of paraffinic hydrocarbons from marine algal source of restricted palaeoenvironments in the reservoir as well as low nonaromatic \( {\hbox{C}}_{15}^{+} \) peaks to indicate their slight degradation and water washing. Oil biomarkers of \( \Pr ./{\hbox{Ph}}{.} = {0}{.85,}{{\hbox{C}}_{31}}/{{\hbox{C}}_{30}} < 1.0 \), location is in the triangle of C27–C29 sterane, C28/C29 of 0.6 sterane, oleanane of 0.01, and CPI = 1.0, could indicate anoxic marine environment with carbonate deposition of Upper Jurassic–Early Cretaceous source. The recorded palynomorph constituents in this oil and associated water are four miospore, seven dinoflagellates, and one Tasmanite species that could confirm affinity to the Upper most Jurassic–Lower Cretaceous Chia Gara and Ratawi Formations. The recorded palynomorphs from the reservoir oil (Khasib and Tannuma Formations) are of light brown color of \( {\hbox{TAI}} = 2.8 - 3.0 \) and comparable to the mature palynomorphs that belong to Chia Gara and Lower part of Ratawi Formations. Chia Gara Formation had generated and expelled high quantity of oil hydrocarbons according their TOC weight percent of 0.5–8.5 with \({S_2} = 2.5 - 18.5\,{\hbox{mg}}\,{\hbox{Hc/g}}\;{\hbox{rock}} \), high hydrogen index of the range 150–450 mg Hc/g Rock, good petroleum potential of 4.5–23.5 mg Hc/g rock, mature (\( {\hbox{TAI}} = 2.8 - 3.0 \) and \( {\hbox{T}}\max = 428 - 443{\hbox{C}} \)), kerogen type II, and palynofacies parameters of up to 100 amorphous organic matters with algae deposited in dysoxic–anoxic to suboxic–anoxic basin, while the palynomorphs of the rocks of Khasib Formation are of amber yellow color of TAI = 2.0 with low TOC and hence not generated hydrocarbons. But, this last formation could be considered as oil reservoir only according their high porosity (15–23%) and permeability (20–45 mD) carbonate rocks with structural anticline closure trending NW-SE. That oil have generated and expelled during two phases; the first is during Early Palaeogene that accumulated in traps of the Cretaceous structural deformation, while the second is during Late Neogene’s.

Palynostratigraphy and palynofacies indications of depositional environments and source potential for hydrocarbons: the mid Cretaceous Nahr Umr and lower Mauddud formations, Iraq

Palynomorphs recovered from core and cuttings samples from five boreholes in the East Baghdad Oilfield indicate a mid Albian–early Cenomanian age-range for the Nahr Umr Formation and the lower part of the overlying Mauddud Formation. Two palynomorph zones and four types of palynofacies have been identified. The latter are interpreted to indicate delta-top swamp and marsh, silty–muddy deltaic, inner silty and carbonate-rich platform, and limestone-platform environments. The palynofacies of the two types of platform accumulations suggest that these are potential sources of biogenic methane and condensates, and may yield more liquid hydrocarbons in areas where the formations are at greater depths than within the region studied.

Revised Bean Performance Equation for East Baghdad Oil Wells

Summary A comparison of the existing correlations for the determination of multiphase fluid-flow performance through a wellhead choke is made. The comparison is based on statistical analysis with production data from 155 well tests, 20 of which are from the East Baghdad oil field. The comparison indicates the relative strengths and weaknesses of each correlation and should aid in the selection of a satisfactory correlation for different applications. No one method is found to be most accurate in all ranges of flow variables. The best overall comparison, however, is obtained with the Gilbert correlation that predicted measured production rates within an average error of 6.19%. This correlation is then revised in two forms to fit the observed data from the East Baghdad oil wells best.