- Home
- Conferences
- Conference Proceedings
- Conferences
Shiraz 2009 - 1st EAGE International Petroleum Conference and Exhibition
- Conference date: 04 May 2009 - 09 May 2009
- Location: Shiraz, Iran
- ISBN: 978-90-73781-65-8
- Published: 04 May 2009
1 - 50 of 140 results
-
-
EOR from Carbonates by Using Smart Water
Authors S. Strand, T. Austad and T. PuntervoldSeawater acts as an EOR-fluid, “Smart Water”, in chalk by improving the water wetness at high temperatures, T>90 °C. It has been verified that Ca2+, Mg2+, and SO42- are the active ions in the chemical mechanism for wettability alteration. In this paper, we have identified the chemical reactions involved and compared the reactivity of outcrop chalk and reservoir limestone cores. In general, and as expected, the active ions showed the same chemical reactions towards the chalk and limestone surface, but the reactivity of the limestone surface was significantly lower than that of the pure biogenic chalk surface. It is, however, expected that seawater can act as a “Smart Water” also for limestone at the right conditions.
-
-
-
Monitoring the Wettability of Oil Reservoir Rocks by AFM during Surfactant Treatment
Authors Omolbanin Seiedi, M. Rahbar, M. Nabipour, S. Ayatollahi and M. GhateiOil recovery from fractured, oil-wet/mixed-wet, carbonate reservoirs by waterflooding is hindered mostly because of the absence of water imbibitions into the matrix blocks. It is believed that the chemical treatments including surfactant flooding improve oil recovery efficiency by wettability alteration and interfacial tension (IFT) reduction. In this paper the effect of surfactants on the wettability of dolomite surfaces are studied. The Two different types of surfactants mainly a cationic (C16TAB) and a non-ionic surfactant (TritonX-100) were used to investigate the wettability alteration utilizing a novel technique of Dynamic contact angle measurement. The treated surfaces which show the most effective changed surfaces are then subjected to the AFM test. Results show that cationic surfactant can remove adsorbed compounds from the surface hence change the wettability. In the case of Non-ionic surfactant as it adsorbs on the surface however the wettability remains unchanged.
-
-
-
The Effect of Macroscopic Pore Structure Heterogeneities on the Recovery of Waterflood Residual Oil
Authors Rafat Parsaei and I. ChatzisGravity-Assisted Inert Gas Injection performance was investigated in heterogeneous packed model through a number of experiments for recovering waterflood residual oil. These heterogeneous media consisted of isolated regions of large pore-sizes, at the macroscopic scale, randomly distributed in small-size continuum. In such heterogeneous media the waterflood residual oil saturation is proportional to the volume fraction of heterogeneity. Experimental results of tertiary gravity drainage experiments have shown that the presence of large pore-size regions leads to the gas invading through such regions and thus improve the recovery of the large amount of residual oil.
-
-
-
Recovery Based Ranking Oil Reservoir for CO2 Miscible Injection
Authors F. Kamali, M. Talebian, M. Khosravi, A. Vahidi and E. RoayaeiThe use of CO2 for enhanced oil recovery of the Iranian oil reservoirs offers a unique opportunity to boost incremental oil recovery and reducing emissions of greenhouse gas through geological sequestration. In this paper, oil fields were screened and ranked for CO2 EOR suitability using new rapid and parametric method which can be applied to a large number of reservoirs with considering the technical feasibility of the EOR process and utilized eight essential reservoir properties: API gravity, oil saturation, ratio of reservoir pressure to minimum miscibility pressure (MMP), reservoir temperature, reservoir dip, net oil thickness, permeability and porosity via a developed program. By using this methodology, a systematic screening and ranking of all possible Iranian oil reservoirs was carried out. Evaluation and prediction of the efficiency of CO2 flooding technique were performed for candidate reservoirs by using an analytical method. In addition, a commercial stream-line type model was used to compare the results of this screening which clearly proves the pervious outcomes. Finally, best candidates were chosen by considering suitable distance from CO2 sources.
-
-
-
Miscible GOGD in Naturally Fractured Reservoirs
Authors M.L. Verlaan and P.B. BoerrigterOil recovery from naturally fractured reservoirs is difficult. Especially in the Middle East where carbonate rocks are oil or mixed-wet. In these reservoirs typical production mechanisms like viscous displacement and counter current imbibition will not work. Gas–oil gravity drainage (GOGD) is then the production mechanism of choice. However, gravity drainage with immiscible (equilibrium) gas could result in low oil rates and/or low ultimate recovery due to capillary hold-up. Miscible gas injection could have significant advantages in a GOGD situation. Miscibility might be achieved with for instance CO2, which has typically a low minimum miscibility pressure. When the injected gas is (first contact) miscible with the oil, density and viscosity will be reduced. Miscibility adds the advantages of single-phase flow and interfacial tension reduction, which further improves GOGD rates and ultimate recovery. This paper evaluates the impact of first contact miscible gravity drainage on oil recovery and discusses the main modelling aspects. The key parameters were identified to be matrix block width over height ratio and vertical heterogeneity. First contact miscible gas injection benefits mainly from IFT reduction and has its application in heterogeneous reservoirs with large capillary hold up and re-imbibition effects.
-
-
-
Study of Thermally Assisted Gas Oil Gravity Drainage in One of Iranian Fractured Reservoirs
Authors Y. Mahmoodi, R. Kharrat and A. HashemiNaturally fractured reservoirs hold well over 100 billion barrels of heavy oil worldwide. For conventional reservoirs containing heavy oil, steam injection is the most widely used thermal recovery method. In heavy oil fractured reservoirs,steam injection is a challenging problem; however it is a potentially effective improved oil recovery method. In naturally fractured reservoirs containing gas filled vertical fractures, gas oil gravity drainage (isothermal gas oil gravity drainage) is an important recovery mechanism. In dipping fractured reservoirs with high fracture permeability, it may be possible to use steam to accelerate isothermal gas oil gravity drainage. This technique is a new and novel EOR technique known as Thermally (Steam) Assisted Gas Oil Gravity Drainage (TAGOGD (SAGOGD)). This study investigates the feasibility of steam injection and conducting TAGOGD technique in a highly fractured reservoir containing heavy oil in Iran. All data for this study are based on Kuh-e-Mund reservoir which is a highly fractured symmetrical anticline located in the southeastern part of Bushehr in the coast of Persian Gulf. The results of this study showed that this technique could improve oil recovery factor for this field.
-
-
-
Surfactant Induced Solubilization and Transfer Resistance in Gas-Water and Gas-Oil Systems
Authors R Farajzadeh, A. Banaei, J. Kinkela, T. deLoos, S. Rudolph, R. Krastev, J. Bruining and P.L.J. ZithaTypically, conventional reservoir simulators underestimate the recovery factor of heavy oil reservoirs under solution gas drive. We hypothesize that natural surfactants in oil (e.g. asphaltenes) cause this phenomenon in two ways: 1) by hindering the mass transfer rate of gas molecules through the gas-oil interface and 2) by enhancing the solubility of gas in the heavy oil. We investigate effect of surfactants on mass transfer rate of gas through gas-water interface and on the solubility of gas in oil. In bulk experiments, we observe that the addition of sodium dodecyl sulfate (SDS) does not influence the gas transfer rate while in the presence of a porous medium the growth of gas bubbles becomes increasingly difficult with increasing SDS concentration, which indicates that the interaction of the grain with fluids is an essential element in bubble growth in porous media. The effect a non-ionic surfactant on the solubility of methane in n-dodecane is also examined. The bubble point pressures of the gas+oil+surfactant system are determined experimentally.It is found that the bubble point pressures of the system decrease with increasing surfactant concentration, i.e., the surfactant enhances the solubility of methane in the oil.
-
-
-
A CT Scan Study of Foam Flooding in Porous Media
Authors M. Simjoo, M. Mahamoodi Nick, R. Farajzadeh, S.A. Mirhaj and P.L.J. ZithaFoam is widely used in oil and gas recovery operations as a mobility control and profile correction agent. A brief list of foam applications includes acid diversion during matrix stimulation, gas blocking and enhanced oil recovery. This paper aims to study the dynamics of foam flooding assisted liquid displacement in a porous media. We report core-flood experiments performed using Bentheimer sandstone and N2 foam with the aid of X-ray computed tomography. A detailed description of CT images and quantification of local fluid saturation revealed that foam is formed in-situ and giving a mobility control. Furthermore, oil can be produced by a liquid slug induced by this strong immiscible foam front.
-
-
-
A Petroleum system study in the Persian Gulf
More LessAbstract A comprehensive geochemical study and research on crude oil samples from different producing oil field in the Persian Gulf resulted in preparation of the first phase of Atlas of Iranian oils which is unique in its own kind. Detailed measurements on oil physical properties included determining of API gravity, viscosity, pour point, sulfur content, Ni/V and stable carbon isotope 13C. Complementary geochemical analyses such as SARA tests, Gas Chromatography and Gas Chromatography and Mass Spectrometry were carried out for the purpose of oil to oil correlation and in order to identify characteristic biomarkers of organic origin, depositional environment, thermal maturity and geologic age. Based on physical and chemical properties and characteristic geochemical fossils, three major petroleum systems with respective oil families were recognized in the Iranian offshore of the Persian Gulf. Most oils produced from Aboozar, Dorood, Foroozan (1 and 3) and Reshadat fields were sourced from Paleozoic petroleum system. Oils encountered in Nowrooz, Hendijan 3, Bahregansar 1and 2, Salman 2and 3 and Reshadat 2 fields are assigned to Jurassic petroleum system. Oils produced from fields including Hendijan 1and 2, Foroozan 2, Salman1, SirriA and C are sourced from Cretaceous petroleum system. Keywords: Petroleum system, Persian Gulf, Atlas of Iranian Oils
-
-
-
Origin of Transfer Faults in the Fars Folded Belt, Zagros Mountains
Authors M. Sepehr, S.F. Mirhashemi and M. YavariTransfer Fault describes a broad category of structures that accommodate lateral variations of deformation. They form in various scales and in different tectonic setting. In the southeastern part of the Zagros Fold-Thrust Belt of Iran number of transfer faults, ranging from a few to tens of Kilometers has been identified. These transfer faults in which all accommodate the lateral variation of shortening as a result of continental collision along the northeastern margin of Arabian Plate interpreted as oblique/lateral ramps and have various modes of origin. The development of these fault zones in the sedimentary cover, their relation to the inherited and active basement faults and their importance in the hydrocarbon exploration is discussed. Based on evidences presented in this paper we have argued that probably most of the transfer faults in the Fras Folded Belt are not basement origin as was suggested previously.
-
-
-
Fold-diapir Interactions and the Building of the South Fars Fold and Thrust Belt
Authors JP Callot, S. Jahani, J. Letouzey and D. Frizon de LamotteThe southeastern Zagros is situated at the eastern tip of the Zagros system, close to the Makran accretionary prism and Oman Mountains. This orogenic system results from the ongoing collision between the Arabian and Central-Iran plates. In this context, the main features of the studied area are; (i) the existence of numerous emerged or buried salt diapirs, made up of Late Precambrian Hormuz salt moving since the early Paleozoic, and (ii) the irregular along-strike shape of the collision-related detachment folds, with frequent apparent bending, change in width and structural association with salt diapirs which express the control of deformation by the pre-existing salt structures.
-
-
-
Salt Activity and Halokinesis in the Zagros Fold-thrust Belt and Persian Gulf (Iran)
Authors S. Jahani, D. Frizon de Lamotte and J. LetouzeyAt eastern tip of the Zagros fold thrust belt (ZFTB) and Persian Gulf numerous salt diapirs emerged which originated from pre-Cambrian–early Cambrian Hormuz salt layer. We show that almost all the diapirs were already active prior to Zagros folding either as emergent diapirs forming islands or as buried domes initiated at as early as the Lower Paleozoic. They have been reactivated by subsequent sedimentary supply, tectonic events and surface erosion. A quite continuous halokinesis exists since the early Paleozoic, i.e. just after the deposition of the Hormuz salt, up to the present. In fact, each salt diapir shows individual evolution depending of their position in the system. Abundance of emergent salt diapirs and presence of recycled Hormuz debris mostly in the Miocene in the onshore suggest that during the Zagros folding nearly all salt diapirs has been emerged.
-
-
-
Neogene Sequence of Folding in the NW Zagros Fold Belt Dating Non-marine Foreland Growth Strata
More LessThree magnetostratigraphic sections across the Pusht-e Kuh Arc in NW Zagros and Izeh Zone constrain the ages of syntectonic foreland deposits as well as the timing of folding. These sections are located in the front of the Pusht-e Kuh Arc in the Changuleh growth syncline, in the centre of the arc in the Afrineh growth syncline and in the hinterland along the footwall of the High Zagros Fault. The ages for folding onset are well constrained in Changuleh at 7.65 Ma and in Afrineh at 11.8 Ma. In Chaman Goli growth syncline the age of initial folding could be as old as 13.5 Ma that fits with even older ages (early Miocene) along the footwall of the Main Zagros Thrust. Folding propagated towards the foreland during at least 20 My, which implies an older age and a longer duration than previously assumed.
-
-
-
Field Evidence for a Major Early Paleogene Folding Phase Across the Zagros Simple Folded Zone (Lurestan Province, Iran)
Authors E. J.-P. Blanc, J. Verges, P. Gillespie, E. Casciello, H. Emami, T. Egebjerg, M.H.G. Ghoodarzi, M. Valinejad, S. Homke, D. Hunt and I. SharpWe report here the presence of fold growth strata in lower Paleogene beds across Lurestan. Those are associated with a compressional phase much older than the typical Zagros folding which affected the eastern side of the Simple folded zone 12 Ma ago (Emami, 2008) and spread to the mountain front, on the western edge of the Simple Folded Zone around 8 Ma ago (Homke et al., 2006) with the deposition of Agha Jari-Bakhtyari and Quaternary sediments. Early folding accounts there for up to half of the total shortening measured in cross section and corresponds to a shortening of around 10%.
-
-
-
Development and Folding of the NW Zagros Foreland Basin, Lurestan Povince, SW Iran
Authors S. Homke, E. Saura, J. Serra-Kiel, G. Bernaola, D. Hunt, I.R. Sharp, J. Verges, E. Blanc, E. Casciello and M.H. Hasan GoodarziIt is crucial for exploration in fold-and-thrust belts to get robust understanding of foreland basin evolution and deformation, in order to constrain the timing of hydrocarbon generation, migration and trap formation. Although it is widely accepted that the main phase of deformation in the Zagros belt occurred in the Miocene and Pliocene, recent field studies have demonstrated that folding started in the NW Zagros (Lurestan Province) as early as the Late Cretaceous and Paleocene. The objective of this work is to constrain the timing of the development and folding of the NW Zagros foreland basin, on the base of accurate dating of the Amiran, Taleh Zang and Kashkan syntectonic foreland formations at different places through Lurestan Province. A multidisciplinary approach has been used, combining benthic foraminifera biostratigraphy, calcareous nannoplankton biostratigraphy, palynostratigraphy and strontium isotope stratigraphy. Dating results show that the Amiran-Kashkan clastic wedge prograded south-eastward in the NW Zagros foreland basin between the late Cretaceous and the early Eocene. The dating of associated syn-depositional folding structures permits to establish that an early folding of the NW Zagros foreland basin progressed south-westward during the same period.
-
-
-
Style and Age of Deformation in the Northwest Persian Gulf
Authors B. Soleimany and F. SabatThe study area is located in the foreland of the Zagros (Persian Gulf) where important oil and gas fields are present. Data consist of two orthogonal sets of 2D seismic sections. Both NNE-SSW folds (Arabian trend) and NW-SE folds (Zagros trend) are documented. These folds formed during two folding stages: the older one Late Cretaceous in age and the younger one Plio-Quaternary. Older folds formed according to the Arabian trend. During the younger folding stage older folds has been reactivated and tightened, and some of the new folds also with Arabian trend formed on top of them. This occurs in front of the advancing Zagros trend folds front.
-
-
-
Quantification of Stress and Strain Using Calcite Twins and Anisotropy of Physical Rock Properties in a Folded/Fractured Reservoir
Authors K. Amrouch, O. Lacombe, J.M. Daniel, P. Robion, J.P. Callot and N. BellahsenThe description of folded/fractured reservoirs requires the understanding of mechanical behaviour of rocks during deformation. In folds, at the decametric scale, deformation is accommodated by flexural slip, faulting and formation of macroscopic fracture sets. The role of LPS has been recognized for years using magnetic fabric analysis which shows that in siliciclastic deposits the deformation is mainly accommodated by pretilting strain. This paper thus combines analyses of calcite twins, Anisotropy of Magnetic Susceptibility and Anisotropy of P-wave Velocity, together with petrological study to investigate the relationship between fold development and stress/strain. The results are compared to already available and newly collected mesoscale fracture and fault slip data. The Sheep Mountain anticline was chosen as a natural laboratory.Our results show a good agreement between calcite twinning and anisotropy of rocks properties, and with macroscopic fracturing on the other hand. Our study points toward a better description of deformation mechanisms of folded strata. A major result is the consistency of the record of deformation at microscopic and macroscopic scales, emphasizing that core scale data can be relevant to fold-scale structuring. This study yields important constraints for forthcoming modeling of stress distribution during fold development.
-
-
-
3D Fold Pattern Formation: a FEM Study
Authors D.W. Schmid, M. Dabrowski and M. KrotkiewskiThe numerical study of three dimensional (3D) fold patterns formation in randomly perturbed layers requires large resolutions. We have developed BILAMIN, a geometry fitted mesh implementation of the finite element method for incompressible Stokes flow that is capable of solving such systems. We use BILAMIN in a case study of fold pattern evolution. Folds are ubiquitous in nature, and contain both mechanical and kinematic information that can be deciphered with appropriate tools. Our results show that there is a relationship between fold aspect ratio and in-plane loading conditions. We propose that this finding can be used to determine the complete parameter set potentially contained in the geometry of three dimensional folds: mechanical properties of natural rocks, maximum strain, and relative strength of the in-plane far-field load components. Furthermore, we show how folds in 3D amplify and that there is a second deformation mode, besides continuous amplification, where compression leads to a lateral rearrangement of blocks of folds. Finally, we demonstrate that the textbook prediction of egg carton shaped dome and basin structures resulting from folding instabilities in constriction is largely oversimplified. The fold patterns resulting in this setting are curved, elongated folds with random orientation.
-
-
-
Multilayer Properties Revealed by Anticline Distribution, the Case of the SE Pusht-E Kuh Arc (Lurestan)
Authors E. Casciello, J. Vergés, E. Saura, G. Casini, N. Fernández, E. Blanc, S. Homke and D.W. HuntFolding in the south-eastern Lurestan Province was analysed by measuring anticline’s wavelength and axial-length and by comparing the fold distribution with the available paleofacies maps. It was found that the large variability of the measured parameters occurs in relation with facies changes within the Cretaceous Bangestan Group, which acts as the competent carbonate unit that governs buckling in this region. The Oligocene-Miocene Shahbazan-Asmari unit folds harmonically with the Bangestan Group, except in the areas where the Paleogene deposits interposed between the two units exceed 1300m of thickness. In these areas the Shahbazan-Asmari carbonate displays short wavelength folds that indicate a complete decoupling from the underlying folds of the Bangestan Group. It is suggested that this decoupling occurs because the summed thickness of the incompetent units separating the Shahbazan-Asmari from the Bangestan Group exceeds the extension of the effective zone of contact strain of the Bangestan Group folds.
-
-
-
Disharmonic Folding (Related to Different Mechanical Behaviour of Rock Formations) of Lurestan Region in the Zagros Fol
Authors A. Farzipour Saein, A. Yassaghi, S. Sherkati and H. KoyiThree main decollement units whithin the sedimentary pile of the Lurestan region were distingushed based on the field observation, seismic data and dipmeter logs from drilled wells. The effect of these decollement units on folding style was studied based on the constructed balanced regional cross section.
-
-
-
Uplift in Sedimentary Basins Revisited - New Insights from the Voring Basin, Norwegian Sea
Authors L. Rupke, D.W. Schmid, S.M. Schmalholz and Y.Y. PodladchikovMany sedimentary basins show subsidence pattern that cannot be explained by uniform stretching models. In fact, uplift, or reduced subsidence, appears to be common during basin evolution. In this study we review the causes and consequences of different uplift mechanisms. Using a two-dimensional basin model we explore how differential thinning, mineral phase transitions, and magmatic underplating affect the structural and thermal evolutions of sedimentary basins. The paper is divided into two parts: the first part explores the characteristics of different uplift mechanisms, while the second part shows the results of a reconstruction case study. The case study focuses on the structural and thermal evolution of the Gjallar Ridge, a structural high in the Norwegian Sea that was uplifted to sealevel during the last rifting phase. The key findings are: (i) all discussed uplift mechanisms show characteristic structural and thermal evolutions that can potentially be used to discriminate between them, (ii) mineral phase transitions can enhance mantle thinning induced uplift, (iii) uplift of the Gjallar Ridge is explainable by different scenarios but phase transitions and differential thinning appear the most likely, and (iv) integrated basin modeling is key for discriminating between different uplift scenarios.
-
-
-
Early Foreland Basin Depositional Evolution in NW Zagros from Latest Cretaceous to the Early Eocene
Authors E. Saura, J.C. Embry, J. Vergés, S. Homke, D.W. Hunt, E. Casciello, N. Fernández, G. Casini, J. Serra-Kiel and G. BernaolaWe present an analysis of the evolution of the eastern Lurestan arc after own detailed paleobathymetric and thickness maps, based on paleofacies analysis and dating of our own field stratigraphic logs and existing borehole data. Integration of these maps in a geomodel was used to generate step-by-step subsidence maps, which illustrate a south-westward migration of the basin depocenter. However, WNW-ESE trending, relatively uplifted areas can also be recognised in the internals parts of the basin, which fit the location of the main anticlines of the area. These uplifted areas migrate to the SW and we interpret them as recording an early folding stage, spanning at least from the Maastrichtian to the early Eocene.
-
-
-
Kopet-Dagh Basin Evolution During Middle-late Jurassic
Authors M.A. Kavoosi, M. Sepehr and S. SherkatiIn this paper with the help of latest available data including field, well and seismic data, palaeoenvironments and depositional sequences of Kashafrud, Chaman Bid and Mozduran formations constructed in order to determine the basin evolution of the Kopet-Dagh during Middle-Late Jurassic. Our study reveals that wedge-shaped sedimentary units, onlap surfaces, high sedimentation rate along with deepening- and fining-upward, assign extensional regime as the result of rifting during Middle Jurassic. The sequence of initial rapid continental stretching during the Middle Jurassic, followed by slower and thermally driven subsidence in the Late Jurassic. Tectonosedimentary evolution of the Kopet-Dagh Basin during Middle-Late Jurassic has a great interest for the future exploration and production in this rich but poorly understood hydrocarbon province.
-
-
-
Origin of Gaseous Hydrocarbons of the Outer Carpathians and Palaeozoic-Mesozoic Basement in Southeastern Poland
By M.J. KotarbaNatural gases accumulated both in the Polish Outer (Flysch) Carpathians and the Palaeozoic-Mesozoic basement are genetically related to thermogenic and microbial processes. Thermogenic gaseous hydrocarbons accumulated in the Dukla and Silesian units were generated from Type-II and -II/III kerogen of the Menilite Shales. Thermogenic gaseous hydrocarbons accumulated in the Sub-Silesian Unit migrated from the Silesian Unit. Natural gases accumulated in traps within the Middle Devonian, Lower Carboniferous and Upper Jurassic strata of the Palaeozoic-Mesozoic basement were mainly generated during thermogenic processes and only sporadically during microbial processes. The themogenic gases accumulated within Palaeozoic complex were generated from Type-II kerogen of the Ordovician-Silurian strata and gases accumulated within Mesozoic complex from Type-III (II/III) kerogen of the Middle Jurassic strata. In some traps within the Dukla and Silesian units of the Outer Carpathians and Palaeozoic-Mesozoic basement had already been formed and sealed as early as the initial, microbial transformation stage of the source rocks. These traps were successively supplied with thermogenic gaseous and liquid hydrocarbons generated from the same source organic matter at successively higher maturation stage.
-
-
-
Acoustic Emission Associated with the Formation of Sets of Fractures in a Sandstone
Authors M.S. King and W.S. PettittA laboratory ployaxial loading system has been employed to study acoustic emission (AE) associated with the failure of a sandstone specimen. The minor principal stress is maintained at a low level, while the two other principal stresses are raised until failure takes place. The AE events associated with the formation of micro-cracks, and resulting through-going fractures, are located precisely by an array of AE sensors in each of the loading platens. The mechanisms indicate tensile failure during initial fracture failure, but shear failure as the fractures approache the platens.
-
-
-
Seismic Facies Analysis Based on K-means Clustering Algorithm Using 3D Seismic Attributes
Authors H. Sabeti and A. JavaherianIn seismic interpretation, clustering seismic data can be used to extract more information about structures and geology of underground units. In this paper, an efficient clustering method called k-means clustering algorithm is utilized to categorize seismic facies based on seismic attributes. By a given k value (i.e. the number of clusters), k-means clustering algorithm uses an iterative algorithm that minimizes the sum of distances from each sample to its cluster centroid over all clusters. This algorithm moves samples between clusters until the sum cannot be decreased further. The result is a set of clusters that are as compact and well-separated as possible. By applying this method over a synthetic seismic cube it is concluded that lateral changes in layer boundaries are detectable. In the case of real data, in order to increase the information needed for clustering, eight seismic attributes were calculated using Paradigm software. By applying k-means clustering algorithm to real dataset, it is shown that more seismic facies appears by increasing the k value and this leads to extract useful information about underground beddings.
-
-
-
3D Pore Pressure Prediction Using Seismic Data in an Oil Field in SW Iran
Authors P. Hadian, E. Nosrat and M.R. TorabiThe pore pressure prediction method based on seismic velocity field is a common method for constructing a 3-D pore pressure cube. In this study, the resolution of stacking velocity was improved using sonic logs and a geostatistical calibration method. In this calibration procedure, the differences between velocity derived from sonic logs and stacking velocity were calculated and, then, the calibration parameters were obtained. These parameters were interpolated in the velocity grids. Effective pressures were calculated using the measured pore pressures and the calculated overburden pressures at well locations. The coefficients of Bowers equation were calculated using well data. Using the Bowers equation the calibrated stacking velocity cube was converted to the effective pressure cube. The pore pressure cube was constructed by computing the differences between the overburden pressure cube and the effective pressure cube. Finally the predicted pore pressure cube was calibrated with regard to the measured pore pressures at well locations. In the area of study, the stacking velocity was improved and, then, the pore pressure cube was made accordingly. The predicted pressures show good agreement with regard to the measured pressures at well locations.
-
-
-
A New Technology for Enhanced Hydrocarbon Production
Authors I.G. Kerimov and S.I. KerimovOur Technology has an aim of equal influence on medium in order to save oil deposit, increase oil production and recovery and minimize negative effects from outside impacts. This Technology is capable resolving these problems successfully and with the high rate result.
-
-
-
Determination of Bin Size and Migration Aperture in 3D Seismic Survey Design for AHWAZ Oil Field
Authors E. Pegah, B. F. Aghaei, A. Javaherian and D. NowrooziIn oil exploration, because of anisotropy of the earth, velocity of the waves in horizontal and vertical directions are not uniform; but we can apply the assumption with good accuracy in exploration procedure that in a layer, velocity changing is limited as a result of slow variation in density and elastic properties of the layers in this horizontal directions. In general, variation of above parameters in horizontal directions is very slowly than vertical directions. For this reason often divide acquisition area to smaller areas and ignore horizontal variations and apply same vertical velocity distribution in any sub-areas. Conventional formula for Bin size and migration aperture is based on constant velocity assumptions. In this paper calculation of Bin size and migration aperture for AHWAZ oil field is carried out base on linear model between velocity and depth. On the other hand Bin size and migration aperture have the firstorder effects on acquisition and processing cost, thus method of this paper steer to optimize and reduce the cost of acquisition.
-
-
-
Direct Detection of Hydrocarbon by Matching Pursuit Decomposition in One of the Reservoirs of South West Iran
Authors M. Radad, A. Javaherian, B. N. Araabi and M.R. TorabiSpectral decomposition has many applications in processing and interpretation of seismic data. In present, there are several methods for spectral decomposition. Each of spectral decomposition methods is useful for a special application, but it has been proved that matching pursuit decomposition has more efficiency in various cases. In the present work, the performance of matching pursuit decomposition was compared with STFT and CWT methods in improving the resolution of thin beds and studying the tuning effect on synthetic data. Moreover, efficiency of MPD method has been shown to detect hydrocarbon directly in oil Bearing sandstone reservoir at south west area of Iran.
-
-
-
Estimation of Well Log Data by Conjunctive Use of Seismic and Petrophysical Data (Hendijan Oil Field, Iran)
More LessWell logs are of the important tools for reservoir characterization. Parameters such as porosity, volume of shale, water saturation, permeability, lithology and production zones could be computed from processing and interpreting of well logs. Such information is obtained from petrophysical logs. Considering coverage and continuity of seismic data, log estimation in each location of reservoir by using seismic data, not only before the drilling but also after it will be applied and invaluable. So that using the predicted wells log from seismic data, reservoir evaluation and assessment over the seismic data coverage is possible. In this research, a formulation is established between well log data including sonic and density logs and their corresponding seismic attributes using neural networks in Hendijan oil field, Persian Gulf. For this purpose, optimal input seismic attributes were obtained using a forward stepwise regression. The results show a good agreement between measured and neural network predicted data at test wells. So, the estimated well logs could be used for reservoir parameters evaluation and reducing risks of future exploration and field’s development. Also such predicted well logs enable us to gain more vital parameter about a reservoir.
-
-
-
Seismic Velocity – Reservoir Permeability Relations within Hydraulic Units in an Oil Field Southwest Iran
Authors M. Emami Niri and A. MisaghiEstablishing a relation between permeability and velocity has met with little success so far. Different types of uncertainties usually make this relationship not very straightforward. Categorizing the pore systems in different hydraulic units may reduce the uncertainties. This study tries to improve characterization of a carbonate reservoir with complex pore systems which is located in southwest of Iran. A combination of classification methods was used to build a robust determination of Hydraulic Units using porosity and permeability values. Then the concept of grouping porosity and permeability data according to their FZI (Flow Zone Indicator) values were tested. It was shown that such relation can be extended to seismic parameters to create strong correlation between velocity and permeability. Strong correlation between P and S waves' velocity and permeability in this field was observed, i.e. the correlation coefficient for Vp-Permeability lies between 0.72-0.96 and for VS-Permeability lies between 0.62-9.98. Such a relation is invaluable as a prediction tool. We understood that by grouping rocks into hydraulic units, we can control and predict flow properties such as permeability via seismic velocity in this field.
-
-
-
Seismic Attribute Redundancy Reduction Using Statistical Feature Extraction Technique
Authors H. Hashemi Shahdani and A. JavaherianCombining seismic attributes and building a meta-attribute section is a useful stage for seismic object detection (fault, gas chimney and …), seismic facies analysis and many other applications. Many seismic attributes used in classification tasks are redundant, which yield a useless higher-dimensional feature space. In this paper, a criterion based on RDA with two sub-optimal forward and backward algorithms is presented to accomplish this problem. Then, classification based on four different MLP neural networks is done and the average error is plotted versus the ranked feature space. As a flexible method, the algorithm introduces dissimilar ranks as the training set changed by the user. This makes it possible to introduce several seismic attributes in input stage of the classification. Based on the proposed training set, the interpreter can find the most important seismic attributes for the classification.
-
-
-
Side View Seismic Location Method Helps Fracture Characterization in a Giant Fractured Carbonate Heavy Oil Field in Iran
Authors A. Shafiei, M.B. Dusseault and B. Samimi-SadehKuh-e-Mond heavy oil field is the largest onshore naturally fractured heavy oil carbonate field in Iran with a resource base of 6-10 Bb OOIP. The heavy oil is found in two formations with oil viscosities of 570-1160 cP in situ. Having a clear picture of the natural fracture fabric of the reservoir will help petroleum engineers and development geologists to determining orientation and flow characteristics of the dominant fracture sets in order to optimize production well placement. In this article, results from fractured media investigations using the Side View Seismic Location (SVSL) method are presented. The SVSL results indicate a transversely oriented zone of minimum values of open fracturing in the NW part of the field, which separates the field into two isolated blocks. The SE part is characterized by a high concentration of abnormally fractured zones and is considered to be the most promising area for primary field development. Based on this study a number of suitable locations for production well placement are proposed. Also, implementing proper down-hole operations in some of the existing wells are recommended to further assess the fabric and arrive at a development strategy.
-
-
-
Quantitative Seismic Attributes in a Fractured Reservoir
Authors S.M. Haghighi and E. AngererSeismic attributes provide critical information in characterising the heterogeneous fractured basement reservoir of the presented case study. Azimuthal anisotropy caused by open subseismic scale fracture networks is directly linked to the hydrocarbon production of existing wells. Further, acoustic impedance inversion shows the distribution of an additional, thin productive layer that was considered below seeismic resolution.
-
-
-
Application of Seismic Attributes for Identification of Gas Hydrate Bearing Zone and Free Gas Beneath it
Authors B. Hosseini Shoar, M. Sadiq Arabani and A. JavaherianGas hydrate is an ice like form of concentrated gas (>99% methane) and water found in the sediments of permafrost regions, marine continental margins and seafloor of deep sea at depths far shallower than conventional oil and gas. The first indicator of gas hydrate in deep sea is bottom simulating reflector (BSR). BSR approximately mimics sea-floor and cuts across reflection of statigraphic origin and have reverse polarity respect to seabed reflection. A second significant seismic characteristic of gas hydrate-cementation is called amplitude blanking. The presence of hydrate and free gas change the seismic properties of host sediments. Relative acoustic impedance and absorption quality factor attributes can be used for analyzing them. In this study, we have analyzed the gas hydrate indicators in 2-D seismic sections of deep sea sediments of Iran with seismic attributes.
-
-
-
Multiple Attenuation by F-X Parabolic Radon Transform
Authors V. Minaeian, A. Javaherian and A. MoslemiMultiples constitute one of the most troublesome forms of coherent noise in seismic exploration. Multiple reflections often destructively interfere with the primaries of interest. Therefore, suppressing multiples from reflection seismograms during processing stages is necessary. Radon transform is a robust tool for suppressing multiples from seismic data. The key idea in Radon based multiple attenuation is to map the CMP gather to a new domain where seismic reflections collapse to point-like events and, therefore, primaries and multiples are separable. The time invariant parabolic Radon transform is widely accepted for multiple suppression. The benefit of time invariance is that the computations can be performed in the frequency-space domain and so the computational costs are reduced. In this procedure, the first step is to replace hyperbolic events in offset domain with parabolas by applying NMO correction using velocities of primaries. In the next step, the data are transformed to the Radon domain by stacking amplitudes along parabolic trajectories. In this paper, a MATLAB coding for multiple attenuation using the parabolic Radon transform has been implemented and successfully applied on a synthetic model and a real data set. KEYWORDS: Radon transform, multiple attenuation, SNR enhancement, coherent noise
-
-
-
Rayleigh Wave Suppression in the RT Domain
Authors J. Jamali, M. Bagheri, M.A. Riahi and Z. FarajporAlways on seismic data record, reflection event will be masked with Ground_roll and observation of this event is not usually easy. Radial trace transform is a simple transform for mapping x-t gathered data into apparent velocity and travel time domain. The apparent frequency of Ground_roll will be changed completely in RT domain. With knowledge of this changes and the application of frequency filters in RT domain, these events can be attenuated. In this paper the result obtained from F-K method and RT method on one common shot gather acquired from oil field has been compared. The results showed that the RT filters is much better attenuate those events with respect to F-K method without much reducing amplitude spectrum.
-
-
-
Solving the Problem of Conflicting Dips in Common-Reflection-Surface (CRS) Stack
Authors M. Soleimani, I. Piruz, J. Mann and P. HubralCRS stack procedure is a data-driven imaging method which is independent of an explicit velocity model. The pragmatic search strategy for CRS attributes consists of three one-parameter searches. This implementation determines only one optimum stacking operator for each ZO sample to be simulated. Consequently, conflicting dip situations are not taken into account. In one of the efforts to overcome this problem, the strategy has been extended in order to take into account up to five conflicting dips at each sample. Here, we propose a strategy which considers all possible angles and, thus, accounts for all the conflicting dips that may exist at one sample. This strategy has some advantages that improve the continuity of reflection events as well as diffractions in the presence of conflicting dip situations. It also generally emphasizes diffraction events in the stacked section such that we may call it common-diffraction-surface stack. Here, we processed the Sigsbee 2A synthetic data and a real land data set with the new method. The stacked result of Sigsbee 2A and the results of the poststack depth migration of the real data also proved that the stacked section of the CDS stack is a suitable input for migration.
-
-
-
Using Singular Spectrum Analysis and Autoregressive Methods for Improvement of Temporal Resolution of Seismic Data
More LessOne of the goals of seismic processing is to improve the temporal resolution of seismic data. Seismic data usually have not enough temporal resolution because of band-limited nature of source signatures. In this paper we introduce a method in which we extrapolate deconvolved seismic spectrum for recovery of missed frequencies. The introduced method takes a certain part of both real and imaginary parts of the spectrum, where S/N is high compare to the rest of the spectrum, and extrapolates lower and higher portions of the spectrum using Singular Spectrum Analysis (SSA) and Autoregressive model. The selected part of spectrum is decomposed into some principal components. Each principal component has periodic pattern without trend, a narrow band frequency spectrum, and well defined characteristics to be extrapolated. After extrapolation of each principal component, the spectrum is reconstructed by combining the associated extrapolated principal components.
-
-
-
A Novel Drilling Fluid for Underbalanced Drilling
Authors E. Karimyan, H. Dashtian and K. ShahbaziInterest in underbalanced drilling is growing worldwide. UBD, when properly designed, eliminates problems associated with the invasion of particulate matter into the formation. However, experience has indicated it is difficult to maintain a condition of continuous underbalance pressure throughout the complete drilling operation, resulting in fluid losses to the formation due to no mudcake on the borehole wall and leading to possible significant damage. So, in this paper a new drilling fluid was developed. It contains a kind of nanomaterial particles called Carbonblack. It is currently the most widely used carbon nanomaterial. This is the first time which Carbon block particles are used as a drilling fluid. Insoluble Carbon black maintains its individual particle identity through high levels of pressure. Coated with lubricant, the ultra-fine particle size penetrates openings and scratches not normally penetrable with other solids in the drilling fluid system. When overbalanced situation is happening, the Carbonblack particles can bridge and form a thin plugging layer as soon as possible in the pores or fractures in the borehole wall. This plugging layer can stop further fluid invasion into the formation.
-
-
-
Underbalanced Drilling Technology, the Key for Solving Drilling Problems
Authors A. Shadravan, M. Khodadadian, K. Shahbazi and A. RoohiRS 12 well is the twelfth well in the 2 year underbalanced drilling project involving NIDC and Weatherford. NIDC supplied the UBD equipment and Weatherford supplied the UBD expertise to assist NIDC personnel on UBD techniques. National Iranian South Oil Company was the operating company whose oil wells were drilled under the contract between NIDC and Weatherford. RS 12 is a deviated well with the 9 5/8" casing shoe at 2,138 m and 7" liner shoe at 2,328 m and 5" liner shoe at 2824 m. The UBD interval will be from 2,905 m to TD of 3,250 m. Underbalanced conditions will be established by injecting nitrogen gas down the drill string along with native crude four objectives.
-
-
-
Underbalanced Drilling in Depleted Formation Achieves Great Success: A Case Study
Authors A. Shadravan, M. Khodadadian, A. Roohi and M. AmaniThe drilling technologies have evolved over the years. The prime reasons for the advancements in these technologies are the ever increasing demand for energy and the increase in ‘energy price’. Underbalanced drilling (UBD) is gaining popularity as a drilling methodology to overcome some of the problems encountered in conventional overbalanced drilling. UBD was initially adopted for resolving drilling problems; it is defined as a drilling operation where the pressure of the circulating drilling fluid is lower than the pore pressure of the target formation of interest. By far, it has also been proved that the advantages of underbalanced drilling are most evident in depleted reservoirs. Well Parsi 70 was the 3rd well of National Iranian Drilling Company (NIDC) UBD campaign in Parsi oil field. Well PR 70 is the first well that produced while drilling.
-
-
-
Wellbore Stability Analysis in UBD Wells of Iranian Fields
Authors S. Salehi, H. Emadi Baladehi, A. Mojdeh and R. Darvishi1. Severe lost circulation during overbalanced drilling condition is reported during drilling depleted carbonate fields in Iran, for this reason using the underbalanced drilling technique with proper wellbore stability analysis is recommended for drilling in these fields. 2. An elastoplastic model combined with a finite explicite code was used for mechanical wellbore stability analysis of underbalanced drilling technique in two depleted Iranian fields. Based on the results and compared with field data using elastoplastic models gives good predictions for wellbore stability in these fields. 3. A criterion based on size of yielded zone or NYZA (Normalized Yielded Zone Area), was used to assess stability condition. Based on the simulation results and for keeping UBD condition in most of the time the critical value of NYZA was adjusted to 1.20 instead of unity in Iranian carbonate fields. Choosing this critical value an ECD of 5.06-5.30 Lb/Gal was proposed for drilling the well in field A.
-
-
-
Integrated Modeling of the Crust and Mantle Structure in the Zagros Fold and Thrust Belt and the Mesopotamian Foredeep
Authors M. Fernandez, J. Vergés, I. Jiménez-Munt, J. Fullea, H. Zeyen, M. Pérez-Gusiñé and D. García-CastellanosThe Zagros mountains formed by collision between Arabian and Eurasian plates from Miocene times. The region is characterized by intermediate seismicity, a low mantle velocity, a deep foreland basin, and an irregularly folded sedimentary cover. Despite extensive acquisition of geophysical data major unknowns are related to i) the nature of the crustal deformation during collision and the resulting crustal structure; ii) the existence of a mantle root and the possible strain partitioning between crust and mantle lithosphere; and iii) the basement deflection caused by the building of the Zagros mountains and the associated deep geometry of the foreland basin. These items are addressed in two ways. An integrated approach, combining the use of gravity, geoid and absolute elevation allows us to infer the 3D regional crustal and lithospheric structure. The resolution of the gravity inverse problem for that lithospheric configuration allow us to separate the regional and local field components which, in turn, allows for a more detailed 2D lithospheric modelling along selected geotransects. These geotransects are constrained by existing seismic profiles, surface elevation, gravity and geoid data. The crustal and lithospheric structure is modelled by using a numerical code that simultaneously solves the geopotential, lithostatic, and heat transport equations.
-
-
-
Determinnig of Optimum the Length of Profile in Normalized Full Gradient Method
Authors H. Aghajani, A. Moradzadeh and H. ZengLength of profiles and number of stations for measuring gravity anomalies play an important role in the amount of cost for exploration projects. Also, length of profile relates to estimate of depth to anomalous bodies. Normalized full gradient (NFG) method applied to detect bodies is a special downward continuation of gravity anomaly. This method eliminates the perturbations which appeared during downward continuation when passing through mass depth. In this study, in order to determine the optimum length of profile for measuring gravity effects due to anomalous body, a horizontal cylinder with a known radius and depth have been used to produce synthetic anomalies to calculate NFG values on different profiles. The results show that the length of the profile and dimension of the area should be 13 times greater than the expected depth of the study to determine the depth of anomalous body with the least error.
-
-
-
A 3D Forward Method for Modeling Magnetic Anomalies Due to Tabular Bodies
Authors H. Jahandari and V. Ebrahimzadeh ArdestaniThis paper presents a new method for computing the magnetic anomaly due to a tabular dipping body, based on approximating a dipping prism by a large number of rectangular prisms. The magnetic anomaly due to this body would be the sum of anomalies resulted from all the small prisms. To test the efficiency of this approximation, we generate the 3-D synthetic anomaly due to a known dipping prism, perform a forward modeling scheme on these data using approximated models, and compare the resulted parameters with the known parameters of the dipping prism. In order to corrupt the synthetic data, we add pseudorandom noise with zero mean and standard deviation of 10% of the datum magnitude. To perform the forward modeling we use a FORTRAN program that inputs the ranges due to different parameters, calculates the anomaly for all possible conditions inside the ranges using the discretized body model, and chooses the best fit parameters. The remanent magnetization information, if available, can be incorporated into the modeling scheme. To show the practicality of this method, we apply the modeling on a real field magnetic data set from Zanjan province in the North-West of Iran.
-
-
-
Geostatistical Modeling of Radiometric Survey Data, Using Sequential Gaussian Simulation
By M. JamieA radiometric investigation has been done in Bandar-e-Abbas in the south of Iran. Geostatistical analysis, using WinGsLib, have been performed in order to model the anomaly distribution. As geostatistical estimators result more reliably in normal distributions, raw data were normalized by normal scores method. By drawing variograms in four major directions, the trend due to maximum anomaly concentration can be determined. The trend azimuth of 45 degrees shows hole-effect, indicating obvious cyclic-bedding with a hole effect signature which could be well interpreted by the rhyolit, gypsum sequential bedding. Because of geometrical anisotropy, the direction of maximum and minimum continuities must be defined. By drawing the 2D plot variogram map, these directions are shown to be 315 and 45 degrees respectively. Afterwards, the best theoretical model, here a spherical one, fits into these two directions. The map resulted from 100 Sequential Gaussian Simulations(SEG)was drawn. In order to reduce uncertainty resulting from simulations E-type map of 100 simulations was drawn. Also, by cross validation method, the estimation error histogram was drawn to assess geostatistical estimation accuracy. The cross-plot of estimated values versus true values shows the correlation coefficient of 82 percent which is desirable.
-
-
-
Integrated Rock Typing in Asmari Formation of Gachsaran Field
Authors V. De Groen, M. Fuchs and S.M. MirzadehAs part of an integrated reservoir modelling and simulation project, a rock-typing study has been performed on the carbonate Asmari Formation of Gachsaran Field (Iran). The current paper presents the challenges and results of integrating different disciplines in the definition of rock-types. Rock-types represent geological aspects such as stratigraphy, log facies and porosity, but their true added value is the dynamic characterization of facies and strong link with geology, which allows spatial distribution. This study has allowed definition of integrated rock-types representing geological facies and groups with similar dynamic rock properties, and identifying these from their log signature. As log data is much more abundant and presents a good spatial distribution over the field, this is the ideal means to refine the conceptual geological models (sedimentary environment, stratigraphy, diagenesis) and trace the extent of stratigraphic sequences. These subsequently allow propagating the rock-types away from the wells, and combined with the dynamic rock properties, allow simulation of these properties in a 3D reservoir model. The definition has resulted in a classification of 10 rock-types with a unique set of geological, log and dynamic properties along some 150 wells.
-
-
-
The Prediction of Permeability in a Carbonate Reservoir Using Adaptive Neurofuzzy Inference System
Authors Y. Beiraghdar, M. Nabi-Bidhendi and C. LucasIn this paper a new approach for the prediction of permeability from well logs is presented. It is based on adaptive neurofuzzy inference system (ANFIS) which is fuzzy inference system implemented in the framework of adaptive networks. A combination of back propagation and least-squares method referred to as hybrid learning method is applied to estimate membership function parameters of fuzzy inference system and learning purpose of ANFIS. The constructed model is optimized for the number of epochs to avoid overfitting and to provide maximum generalization by considering the error index of validation sets during training. To verify the effectiveness of the methodology, a case study in one of the carbonate reservoirs of Iran is carried out. Core and well-log data from two wells that are located in the center of the field provide the data for the learning task. Model validation of proposed ANFIS model is implemented by using core permeability and well-log data from a third well that is located on the corner of the field. Numerical simulation results show that the adaptive neurofuzzy inference system is capable for the prediction of permeability.
-