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78th EAGE Conference and Exhibition 2016
- Conference date: May 30, 2016 - June 2, 2016
- Location: Online
- Published: 30 May 2016
41 - 60 of 1034 results
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Infill Opportunities after 45 Years of Production from the L10 Central Gas Field, Dutch Sector of the Souther North Sea
Authors G. Daniau, J. Guyomard, H. de Haan and T. BenedictusSummaryIn 1969 the Placid Oil company made the first offshore gas discovery in the L10 block of the Dutch sector of the Southern North Sea. The asset now operated by ENGIE is producing gas from the Permian Rotliegend sandstone reservoir, located at a depth of about 4000m. After 40 years of production, ENGIE decided to acquire a new Pre Stack Depth migrated seismic. The aim was to benefit from a large continuous seismic dataset and apply the latest processing technology in order to unlock remaining potential of this asset. It was the starting point of a complete data review going from structural geology (field compartmentalization and fault seal analysis), to sedimentology (core description, well correlation), petrophysics (homogenize decades of well logs interpretations) and production data (formation pretest and material balance analysis). This work has resulted in de-risking several prospects and identifying new infill opportunities. The example of the L10 Central field review will illustrate this successful story.
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Reservoir Architecture Modelling for Geothermal Energy Production - Case Study of the Delft Sandstone Member, West Netherlands
More LessSummaryDeep-geothermal energy projects operate with a geothermal doublet comprising a hot-water produc-tion well and a cooled-down water injection well. Both wells target the same aquifer to maintain pressure support in the reservoir. The injection well ends at shallower depth than the production well to allow for gravity-driven cold-water front propagation. These conditions determine the doublet layout. A detailed knowledge of reservoir architecture and connectivity in the aquifer is required to assess the pressure communication between the wells, and to reduce the economic risk of these projects. A case study for a planned geothermal doublet research project in the Delft Sandstone Member (Valanginian, West Netherlands Basin) shows that the target comprises stacked sandstone interbedded with mudstone and lignite. Core, cutting, well-log and seismic analyses show that the sandstone formed by meandering rivers in a SE-NW elongated rift basin. The reservoir is subdivided in three units on the basis of variations in net-to-gross, log signature, lithofacies interpretation and stacking density. Unit 3 the best porosity and permeability values, is sand-prone and characterized by multi-storey and laterally-amalgamated meandering river sandstone bodies with minor mudstone floodplain intervals. Optimal placement of geothermal doublet is in the NW-SE trend of the fluvial pathway.
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Comparison of the Petrography and Petrophysical Parameters of Fontainebleau Sandstone - Measurements and Literature
Authors F.S Al Saadi, K.H. Wolf and C.K. KruijsdijkSummaryCharacterizing and understanding porous media is essential prior to standardized core-flow experiments, to investigate oil mobilization on a single-mineral porous medium with a limited permeability/porosity band width, and a homogenous pore- and grain-framework. Literature shows that one almost pure quartz horizon in the Fontainebleau sandstone meet these preconditions. Fresh samples were gathered from the “Gres de Fontainebleu and Cie” Quarry. Knowing the depositional environment and burial history, we measured and quantified spatial attributes of the matrix by CTS image analysis, associated stereological measurements, statistical 2D/3D reconstructions and petrophysical laboratory measurements. Permeability, porosity, capillarity, specific surface, pore framework and pore coordination number distribution were measured and compared with literature. This new database provides a comprehensive review on the Fontainebleau sandstone from micro-scale to meter scale for a porosity bandwidth of 0.05 - 0.11 and permeability bandwidth of 10 - 400 mD. The combined measurements, petrophysical and spatial properties support, are used for prediction, modeling and interpretation of comparative core-flow experiments meant for oil mobilization by chemical injections (surfactant & solvent), i.e. chemo-physical interaction of rock/fluids and multi-phase fluid/fluid adsorptions. Similarly, mapping the pore framework helps modelling the mobilization and transport of the oil from mm-scale to m-scale.
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Reservoir Quality within the Johan Castberg (Formerly Skrugard) Field in the South-Western Barents Sea
More LessSummaryThe Johan Castberg Field is located on the western margin of Loppa High in the south-western Barents Sea and comprises a reservoir in Lower-Middle Jurassic sandstones of Stø and Nordmela formations containing both oil and gas. Cored intervals, 15 samples (well 7220/5-1) and wells log data (7219/8-1, 7219/9-1, 7220/8-1 and 7220/7-1) have been used for petrophysical and petrographical study of sandstone reservoirs. Reservoir properties are preserved significantly due to uplifting and erosion of the entire region. Sandstone diagenesis is a function of burial rate, mineralogical composition and texture, climate, and hydrodynamic and geothermal gradients.
X-ray diffraction (XRD), Optical Microscopy, Scanning Electron Microscopy (SEM) and Core logging have been performed to investigate the depositional environment, clay mineralogy, role of sediments composition, facies distribution, and provenance of the reservoir sandstones. Petrographical study has been carried out to find the diagenetic clay and microquartz coatings, quartz cementation and its distribution in the sandstone reservoirs.
Lower-Middle Jurassic sandstones are moderate to well sorted, fine to medium grained and are mineralogical mature. Sandstones are deposited in prograding coastal regime whereas shale interval indicates regional transgressive pulses during deposition. The porosity and IGV values of sandstones range 6–26% and 25–34% respectively. The porosity is still well preserved and reservoir quality of Lower-Middle Jurassic sandstones in well 7220/5-1 is very good.
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Characterization of Microscopic Pore Structure and its Effect on Macroscopic Physical Parameters in Tight Gas Reservoirs
Authors L.C. Zhang, S.F. Lu and D.S. XiaoSummaryA combination of mercury intrusion capillary pressure (MICP) and N adsorption experiments were performed on tight rock samples from the Shahezi formation in Xujiaweizi Default Depression in order to detect the applicability of the two techniques for characterizing the complete pore size distribution and gaining insight into the microscopic pore structure and its effect on macroscopic physical parameters. N adsorption and MICP measurements were used to analyze the pore size distribution of mesopores and macropores respectively. The result shows that tight gas reservoirs are characterized by complicated microscopic pore structure with a broad pore size distribution from 2nm to 200μm. The dominant pores range from 10nm to 2μm, which mainly consist of slit-shaped pores and ink-bottle shaped pores. Porosity, permeability and free fluid saturation decrease with the increase of the volume proportion of small pores (diameter< 50nm), and increase with the increase of the volume proportion of large pores (diameter>200nm). Furthermore, the relationship between the volume proportion of different pores and permeability and free fluid saturation is better than that with the porosity.
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New Insights on the Characterisation of the Pyroclastic-rich Bajo Barreal Fluvial Reservoir (Argentina)
SummaryThe Cretaceous fluvio-lacustrine Bajo Barreal Formation, known for its large hydrocarbon accumulations, consists of a 1) Lower Member made of floodplain mudstones with isolated channels with an upward increase of sandstone content, and an 2)Upper Member composed by grey and purple mudstones with thicker channel sand bodies. Both stratigraphical units are characterised by the presence of acid volcanoclastics and tuffaceous material mixed with siliciclastic sediments. Previous studies on the Bajo Barreal Formation suggest an active sedimentary input from contemporaneous volcanoclastic material derived from both direct fall-outs or rain-off processes. This material can make up to 15% of host rocks forming a so-called pseudomatrix produced by the disintegration of tuff and d pyroclastic material. In this contribution we present the preliminary results on the reservoir petrography and mineralogy focusing on the characterisation of its volcanic component and related neo-formed mineralization especially considering the clay and zeolite pore infill. The identification of key petrographically distinct stratigraphic units and the detailed quantification of their mineralogical composition (i.e. clay and zeolite content) has an important impact on characterisation of pore-filling material, porosity calculation from density-based wire-line log and the stratigraphic distribution of reservoir properties and hence definition of flow units.
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Relationship between Rock Typing and Petrography - A Case Study on the Fahliyan Formation in the Persian Gulf
Authors M. Goodarzi, M. Jamalian, D. Amirsardari, M. Jamalian and J. ShoghiSummaryThe Lower Cretaceous Fahliyan Formation in the Persian Gulf was the subject of this study. The main target of the study is investigation of relationship between different rock types and sedimentology study. In order to define rock types based on porosity-permeability data, hydraulic flow units were investigated based on Flow Zone Indicators (FZI). As a result, six hydraulic flow units were recognized in the Fahliyan Formation of the studied area. Moreover, productive intervals of the reservoir were identified using Normalized Cumulative Reservoir Quality Index (NCRQI).
Assessment of porosity and permeability data indicates that microfacies pertaining to shoal and channel facies belts with grain-supported texture have the best reservoir quality. This is due to abundance of interparticle porosity. These facies belts correspond with HFU-4, 5, and 6. According to Winland plot, the mentioned HFUs are comparable with macroport and megaport classes. Microfacies of tidal flat facies belt also have good reservoir quality due to fenestra porosity. Microporosity is dominant in most facies of the studied samples. The samples with microporosity pore type (such as most of the microfacies belong to shallow open marine and lagoon facies belts) do not have enough permeability to make a good reservoir zone.
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Reservoir Characterization of Giant Gas Condensate Bearing Kangan and Dalan Formations
By S. DowlatiSummaryKangan and Dalan formations are a permo-triasic basin in the Persian Gulf Region which contains four lean-condensate gas bearing reservoir units named as K1, K2, K3, and K4 from top to bottom. These formations, outstretched in a vast area of Persian Gulf region, embedded gigantic reserves of gas condensate mainly deposited in Iran, Qatar, Saudi Arabia, Bahrain, and Abu Dhabi. Kangan/Dalan formations are synonymously called Khuff formation in southern countries of the Region, while in this paper Iranian part of the formations is studied.The purpose of this paper is to characterize reservoir properties of these four layers based on their well logs, special core analysis, rock typing methods, and PVT lab data. So a comprehensive approach applied to correlate porosity, permeability, capillary pressure, mineralogy, and rock typing of these layers and divide them into sub-layers to develop reservoir geological model.
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Geomechanically Calibrated Rock Physics Modelling for 4D Seismic Response Prediction
Authors M. Paydayesh and A. ShamsaSummaryDisturbing reservoir equilibrium by production or injection causes changes in saturation, pressure, and temperature, hence, substantial alterations on the stress state of a reservoir. In addition to vertical p-wave and s-wave velocity changes, the anisotropy parameters vary during production activities due to both pore pressure and saturation change. The anisotropic nature of stress-induced velocity change must be considered in 4D seismic analysis. Therefore, coupling fluid substitution with geomechanical modelling as demonstrated need to be considered. This work addresses the integrated modelling of 4D seismic response and how geomechanical stress direction calculation can be embedded in the petro-elastic modelling and fluid substitution.
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Structural Parameters Effect on the Sleipner CO2 Underground Storage Simulation History Match
More LessSummarySeismic history matching of the Sleipner CO2 injection simulation is a challenging and ongoing research area. At this paper, capacity of a number of seismic attributes in improving the structural interpretation of the baseline seismic data is demonstrated. In addition, effect of two structural uncertainties, namely, reservoir boundary and structural relief, on the Sleipner simulation history match is addressed. The simulation results illustrate potential of the alternative reservoir boundary on the Sleipner seismic history match improvement.
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Integrated Structural Reconstruction and History Matching Using Ensemble Filter and Low-frequency Electromagnetic Data
Authors C. Etienam, R. Villegas and M. BabaeiSummaryIn this work, we describe a new integrated structural reconstruction approach based on the level set technique and ensemble Kalman filter-based history matching1 using water saturation distribution from low-frequency electromagnetic techniques (Maxwell’s equations) 2 and initial stochastic realisations of permeability distribution. In this work, we discuss the use of the ensemble Kalman filter combined with the Level Set method3 to solve the severely ill-posed problem of parameter and shape reconstruction in history matching of 3D reservoirs. The developed algorithm utilizes Sequential Gaussian Simulation for the creation of the initial geostatistical guesses for permeability which will then be utilized in the ensemble Kalman filter for honoring dynamic production data. The production data here includes water and oil production rates and water saturation distribution from low frequency EM reconstruction. This integrated methodology allows to obtain a better match of the produtcion data honouring the water monitoring obtained from low frequency EM data and also considering the initial model uncertatinty based on geostatistical techniques. The methodology is applied to a 3D syntethic oil reservoir model, the simulator (Schlumberger’s ECLIPSE E100) has been employed for the forward modelling and our in house Fortran and matlab codes has been employed for the History Matching and Electromagnetic reconstruction.
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Geostatistical History Matching with Ensemble Updating
Authors M.J. Quintão, A. Soares and L. AzevedoSummaryIn this work we propose a new history matching methodology that couples within the same framework the benefits of using geostatistical sequential simulation and the principles of ensemble Kalman filters, denominated as history matching based on ensemble updating. The main idea is to use simultaneously the relationship between petrophysical properties and the dynamical results in this process, to update the static properties at each iteration and to define the areas of influence of each well. This relation is established through the experimental non-stationary covariances, simply computed in the several forms of the Ensemble Kalman Filters (EnKF) for history matching of hydrocarbon reservoirs. The proposed iterative history matching procedure was applied to a 2D synthetic reservoir, built to mimic a classical 5-spot configuration with 4 producers located near the corners of the model and an injector well in the center of the grid. In order to assess the performance of the proposed approach, comparison tests were carried out in order to distinguish the advantages of the two main enhancements proposed: the use of areas of influence and the ensemble updating.
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Different approaches for prediction of reservoir volume in slope channel complexes (Miocene, offshore Nile Delta, Egypt)
Authors S. Lang, G. von Halem, A.H. Hassan Soliman and U. LorangSummaryTurbidite channel complexes are important reservoirs. Due to their heterogeneous architecture it is difficult to quantify the gross reservoir volume. Three methods were tested at a prospect case study. Seismic data quality allowed the detailed mapping of four sets of amalgamated channels inside the channel complex. The reservoir volume was calculated by multiplying the horizon area by thickness. Afterwards, it was tried to obtain the reservoir volume by applying an amplitude cutoff to the seismic and multiplying the cumulative amplitude area with a thickness. In a third approach, an acoustic inversion has been carried out and calibrated at a nearby well. Sand bodies have been extracted as geobodies based on an impedance cutoff. All three gross reservoir volumes were divided by the channel complex volume in order to compare the resulting net/gross ratios and they vary from 5%–20%. These net/gross ratios are lower than the net/ gross encountered in a well in a nearby channel complex, which is in-line with an observed higher sand content on seismic at that well location. Therefore, estimating gross rock volume from seismic could reduce the uncertainty compared to using offset well data only.
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Stratigraphic Compartmentalization of the Alvheim Field
Authors A. Hjellbakk, A. Bang, A. Kotwicki, K. Langaas, M.A. Leonthin and K.L. StuartSummaryThe reservoir of the Alvheim Field is the upper part of the deep-marine deposited Palaeocene Heimdal Formation. It is located in the Northern part of the Norwegian North Sea with a small portion extending into the UK sector. Despite the reservoir’s high net to gross ratio of more than 85%, a 1.5–5 meter thick continuous mudstones exists and is in places causing reservoir compartmentalization, even resulting in multiple hydrocarbon columns. A tripartite subdivision of the reservoir was originally made based on log correlation, biostratigraphy and seismic interpretation. This reservoir subdivision was used as input to the reservoir models, which together with a new 4D seismic data set built a good basis for the 2015 infill-well planning. During the infill drilling of pilot wells with single, dual and trilateral producers, new and important information became available, including data from deep resistivity tools which were run in all horizontal branches. The well results were interesting and partly surprising, leading to a significant adjustment of the stratigraphic model. The incorporation of the persistent claystone units into static and dynamic 4D supported models is essential to get a realistic simulation of the reservoir behavior, and to locate undrained targets for future infill drilling.
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Mid-late Miocene Sea Level Falls, Gas Hydrates Decay, Submarine Sliding, and Tsunamites in the Black Sea Basin
Authors A.A. Kitchka, A.P. Tyshchenko and V.I. LysenkoSummaryFull range of structural settings and related features of extensional, translation and compressive domains of the submarine mass transport complexes (MTCs) has been recognized by thematic interpreting of the regional 2D seismic data covering Ukrainian deepwater area in the Black Sea. At the same the time the synchronous to deepwater MTCs the Sarmatian tempestites or even tsunamites known under local name heraclites as well as seismites are described and studied in the SW Crimea in the rock cliffs of the Heraclean Plateau south of Sevastopol. This study links the rapid pulses of the Black sea level fall in the Middle to Late Miocene epoch accompanied by erosion of the shelf break areas and formation of submarine incision valleys, dissociation of gas hydrates, slope failures and large scale rock downslides triggering tsunamis (that imprinted the shore sequences outcropping around the basin) as precursors and characteristic features of the Messinian crisis s.l. manifestation in the Paratethys sea belt further evolved during the Meotian to culminate in mid-Pontian time.
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Deep Water Depositional Architecture, Evolution and Reservoir Potential in the Rakhine Basin, Offshore Myanmar
More LessSummaryFrom 2004 to 2006, 3 biogenic gas fields (Shwe, Shwe Phyu, and Mya) were discovered in Rakhine Basin. Since then, the Rakhine Basin has been the focus of deep water exploration. In our research, industrial and high-resolution 2D and 3D seismic and well data were analyzed to study deepwater architectural elements, depositional evolution and hydrocarbon reservoir potential of the Rakhine.
Six different types of architectural elements are recognized in the Rakhine basin: submarine canyons, confined slope channel complexes, aggradational channel-levee complexes, frontal splays, isolated slope channels, and mass-transport complexes.
Deepwater depositional system showed continuous progradation, and the extent and scope strengthened and widened gradually from the Late Eocene to Pleistocene. The Oligocene mainly comprised confined slope channel complexes. The Miocene was dominated mainly by confined channel complexes and levee-overbank sediments. The Pliocene mainly consisted of confined slope channel complexes, frontal splays. The Pleistocene mainly developed aggradational channel-levee complexes, frontal splays, and mass transport complexes.
Controlled by structural and depositional evolution, the Pliocene confined slope channel complexes and frontal splays have the best reservoir potential in the study area. In gentle fold belt, there are numerous frontal splays and various types of slope channels that remain untested.
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Sequence Stratigraphy of the Middle Jurassic Dhruma Formation in the Oman Mountains (Sultanate of Oman)
Authors M. Schlaich and T. AignerSummaryThis outcrop analog study focuses on a genetic understanding of the reservoir/seal potential and architecture of the Jurassic Dhruma Formation in Oman. As a joint project of the University of Tübingen (Germany) and Petroleum Development Oman (PDO) outcrop logging in nine sections in the Oman Mountains was carried out, supplemented by thin section analyses and spectral gamma-ray measurements. Observed facies types range from peritidal sandstones and microbial laminites to low-energy lagoonal deposits and high-energy, peloid and ooid dominated, shoal associated deposits. Cores and cuttings of the Dhruma, Tuwaiq Mountain and Hanifa/Jubaila Formations were logged over central and northern Oman. A sequence stratigraphic framework and 2D correlations were established based on litho-, chemo- and biostratigraphy. They reveal a clear decrease in thickness of the Dhruma Formation from west to east, which is due to (1) a small unconformity at the bottom and (2) a large Tithonian unconformity, which cuts down into Jurassic strata, eroding the whole Hanifa/Jubaila and Tuwaiq Mountain Formations as well as the top of the Dhruma Formation in outcrops. A 3D geo-cellular facies model was created with Petrel for the Dhruma, Tuwaiq Mountain and Hanifa/Jubaila Formations in central and northern Oman which has implications for the regional prospectivity.
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Sequence Stratigraphic Analysis of the Lower Cretaceous of South Pakistan
By S. MahmoudSummarySedimentological, chronostratigraphic, and sequence stratigraphic interpretations were integrated in order to predict four types of systems tracts, which were used as the building blocks of each interpreted sequence, which, in turn, were used in prediction the chronostratigraphic framework and depositional history of the Lower Indus Basin within the Jati Block. The study highlighted the importance of forced regressive sands of the Falling Stage systems Tract, as high-quality reservoirs encased in shelf mudstones, forming favorable targets for hydrocarbons due to the effective lateral and vertical seals and the expected maturity of intra-formational source rocks. Several lines of evidence support the frequent presence of these forced regressive sands as indicated from seismic attributes, well log sedimentology and sequence stratigraphy, well to well correlation, and from the established sequence models.
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Hydrocarbon Occurrences and Deformation Styles in the Zagros - A Focus on the Kurdistan and Lorestan HC Provinces
Authors R. Di Cuia, P. Pace, R. Bitonte and A. RivaSummaryThe Zagros Thrust Belt is a prolific hydrocarbon province. Intense exploration has been mainly focused on the productive Fars Zone and Dezful Embayement regions of Iran in the central sector of the Zagros thrust belt. During the last years, the NE-SW-trending northwestern sector of the Zagros, extending over the Kurdistan region of northeast Iraq and the Lorestan province of Iran has increasingly received attention related to a renewed interest for hydrocarbon exploration. In this study, compressional features over the Kurdistan and Lorestan regions were characterized from regional to local-scale by integrating various data and methodologies in order to contribute in a better understanding of the compressional deformation styles, mechanisms and evolution of the trap-forming structures and their impact on hydrocarbon occurrences.
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Detachment Folding in the Polar Urals Foreland -Structural Geology and Hidden Petroleum Potential
Authors K. Sobornov, V. Danilov, P. Prijmak and N. NikinovSummaryRegional interpretation of vintage and recently acquired geological and geophysical data provided new insight into structure and petroleum habitat of the Polar Urals foldbelt. The study shows that the deformations observed in the Polar Urals foreland are mainly related to the thrusting and detachment faulting. The principal detachment in the sedimentary cover is provided by the Upper Ordovician evaporates which is pinching out if the area of the Chernyshov swell. The updated structural model permits the identification of the new large exploration opportunities. Bulk of the new gas reserves is predicted in the folded zone in front of the Urals involving large thrust-related closures. Significant oil discoveries are expected in the transition zone between the Chernyshov swell and the Kosyu Rogov foredeep which is a focus of regional hydrocarbon migration. New seismic data provide evidence for the considerable development of the hypogenic karst and dolomitization of the Serpukhovian sulphates and carbonates capable increasing porosity of the reservoirs.
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