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SPE/EAGE Workshop on Tar Mats and Heavy Oil
- Conference date: 01 Jun 2014 - 04 Jun 2014
- Location: Dubai, United Arab Emirates
- ISBN: 978-94-6282-044-9
- Published: 01 June 2014
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Heavy Oil Classification & Characterisation
By A. BakhorjiHeavy oil is characterized as viscous fluid having API ranges less than 22’. Seismic velocities are sensitive to heavy oil properties and especially to the reservoir properties, such as changing temperature, pressure conditions.
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Viscous Oil Occurrences, Biodegradation and Tar Mats. Advances and Knowledge Gaps
By S. LarterHeavy and viscous oil occurrences can be produced by a variety of in-reservoir mechanisms, including biodegradation of light oils, primary sourcing of heavy oil from type II-S kerogen rich source rocks, and by the segregation mechanisms related to oilfield charging and tectonic history that result in the formation of tar mats.
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The Challenge of Heavy Oil Fluid Characterization
By H. YarrantonThe characterization of heavy oil for modeling fluid behavior is challenging because so little of the fluid can be assayed with conventional methods such as distillation and gas chromatography. Recent progress in this area is reviewed focusing on heavy oil characterization for: robust equation of state models, asphaltene precipitation, and viscosity prediction.
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Application of Solar Energy to Heavy Oil EOR
By D. PalmerThe presentation will start with an overview of the energy requirements and emissions for thermal EOR and its implications for development of major new heavy oil resources. In addition some fundamentals regarding thermal EOR that are particularly critical for Solar applications will be introduced including steam conditions, water quality requirements and energy storage potential.
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How to Use Simulation for Heavy Oil / Tar Mat Recovery Methods?
More LessHeavy oil displacement processes pose severe challenges to reservoir simulators. Not only the physics is complex (thermal/steam, miscible effects, chemical reactions), also the mobility of displacing fluids is usually much higher than the mobility of the heavy oil, leading to displacement processes that are inherently unstable.
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Understanding the Timing of Hydrocarbon Generation and Oil-Source Correlation Using Rhenium-Osmium (Re-Os) Isotopes
By S. PorterUncertainties regarding the timing of oil generation and the source of the generated oil are common exploration problems. Understanding the chemical composition of petroleum source rocks and their associated oils provides critical information regarding the temporal and spatial controls on the formation of hydrocarbon deposits.
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Modelling of Some Practical Aspects of Heavy Oil Recovery
More LessThe objectives of this presentation is to present a review of research advances in the domain reservoir modeling of heavy oil recovery. The presentation will be illustrated with various production processes including Steam-Assisted Gravity Drainage and Chemical EOR.
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Production Monitoring and Surveillance
By L. BenedekAn ongoing focus area for Saudi Aramco is the optimum field development and depletion of the mobile oil in the tar area, which is limited in extent and occurs mainly along of the periphery of the southeast flank of the field. Unlike many tar mats in other fields, the tar in this field is patchy and has a complex distribution in the reservoir. In addition, areal and vertical tar extensions reveal great variations along with the existence of fractures in the area which imposes difficulties on the reservoir characterization as well as predicting fluid flow behavior.
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Field Case 3: Oman: Thermal Steam Production of 100,000 cP Oil
More LessA thermal steam trial is applied in a multi-billion barrel STOIIP oilfield with very complex reservoir and oil properties. With low permeability, and saturation, deep thinly laminated formation and ultra heavy oil viscosity (100,000 cp at reservoir temperature of 65o C), the field introduces extreme challenges for conventional thermal development. This requires innovative solutions to stretch the thermal development boundaries to achieve technical and commercial success. In order to accommodate such subsurface challenges, unique surface facilities were acquired which made it possible to inject heat at high pressures.
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Heavy Oil Characterization While Drilling
By G. G. HursanThe recognition heavy oil and bituminous zones is a critical input for well placement in many Saudi Arabian fields. Heavy oil composition and viscosity evaluation while drilling remains a great technical challenge to this day. An additional complexity stems from permeability variations due to the complex pore system of the carbonate reservoir rock. Saudi Aramco has successfully utilized existing methods and also pioneered new technology development to acquire these critical reservoir data. This presentation begins with an overview of logging and formation testing measurements that are available while drilling for heavy oil interpretation. This includes formation testing while drilling, nuclear magnetic resonance (NMR) logs and specialized mud logging techniques as well as indirect indicators on conventional logging measurements. The rest of the presentation comprises log examples from Saudi Arabia. These examples demonstrate a comprehensive petrophysical workflow that integrates key pieces of logging and formation testing data for heavy oil evaluation.
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Uncertainty Management in History Matching and Forecasting a Field
More LessSouth of Oman is rich of many heavy oil fields which contain multi billion barrels of heavy oil. However, these fields come with a sharp contrast in their accumulative and flow reservoir characteristics. Thus, the range of uncertainties is wide and an educated method should be developed to manage them. The following presentation is a showcase of the process used to reduce the associated uncertainties with modeling such fields mainly for forecasting and history matching. Such methods were used to decide on pattern development and observation wells locations. The method used is evolving as more data is acquired along the projects life.
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Staged Approach to Thermal Development of a formation with Tar Mat
By A. AlwazeerAs primary recovery declines in a heavy oil field an EOR process becomes an essential long term field development mechanism. There are several EOR methods to select from and thermal EOR is gaining momentum as experience and successful developments are becoming wide spread. Monitoring and surveillance has also improved in part due to technology advancements to operate in extreme thermal conditions. There is a need to carefully approach a thermal development and this presentation will discuss the staged approach taken to better facilitate the following thermal development. It is believed that a heavy oil field in South Oman has a tar Mat like base (permeability barrier in the oil column) where water in the aquifer is shielded from the producible layer. Analysis work done on viscosity indicated that primary production can be achieved and thermal phase should follow. This was confirmed by trials done on selected wells. Leading to the implementation of a “staged approach” starting with cold recovery, followed by cyclic steam stimulation and then steam drive. The improved plan required a change in surface pipe lines and facility and also well completion designs to accommodate as much as possible both modes of recovery (cold and thermal). This presentation will go over the staged approach for the thermal development and the challenges experienced in getting there.
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Challenges in Evaluation of Heavy Oil & Tar Mats
By M. ZeybekHeavy oil field characterization and development processes, including well placement, reserves assessment, well-testing and simulation, require accurate knowledge of in-situ fluid properties for optimal results. Heavy oil/tar delineation can be challenging for reservoirs containing heavy oil underneath of black oil and all underlain by a tar mat at oil-water contact. The viscosities in the black oil section can be similar throughout the field. In contrast, the mobile heavy oil section of the column usually contains a large, continuous increase in asphaltene content with increasing depth extending to the tar mat. In this presentation, in-situ heavy oil characterization are presented with the integration of logs and advanced formation tester viscosity measurements during sampling. Accurate determination of fluid density and viscosity properties can be quite challenging in water-based-mud environments; especially in those cases of water-dominated flow, strongly emulsified fluids or high fraction of sediments in the flow line. Field examples are shown with large viscosity variation, driven by asphaltene gradient in heavy oil column. Results are compared with laboratory analysis of the samples with the order of magnitude variation. A new Equation of State (EoS) based on Flory-Huggins-Zuo (FHZ) formalism with capable of modeling such gradients in asphaltene content is found to successfully model the asphaltene content gradient.
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Field Case 2 Saudi Arabia: The 300 ft Tar Mat Challenge
By S. LyngraThis presentation reviews the development history and heavy oil characterization of a heavy oil accumulation associated with one of the super-giant Saudi Arabian onshore carbonate fields. This heavy oil accumulation was discovered in 1941 as one of first discoveries on the Arabian Peninsula. The heavy oil has been on continuous production since 1947 as feedstock for a road oil (asphalt) plant, but the total recovery over the last 67 years is less than 2% of oil-in-place. A pilot production scheme from two horizontal producers was started in 2007, but has been hampered with technical difficulties related to artificial lift. An extensive data acquisition program to further characterize the reservoir with focus on spatial understanding of the oil properties has been taking place over the past few years. During this evaluation, it has become clear that the mobile heavy oil is underlain by 300 ft of tar that totally separates the oil column from the aquifer. The first pilot injector placed on top of this tar mat was drilled in 2010. The historical aspects of the development is reviewed, including the spatial oil characterization results and pertinent details related to the pilot producers and injector. The workshop participants will then be prompted to participate in a discussion on what is required for a full development of this heavy oil accumulation. This will also include identifying critical uncertainties that are yet to be assessed and potential for including the 300 ft tar mat as part of the hydrocarbon development resource.
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Field Case 4: Saudi Arabia: Identification & Characterization Of Heavy Oil Tar In A Gigantic Carbonate Field
By M. AlshehriThe development of a gigantic carbonate oilfield in Saudi Arabia had to take into account a confirmed heavy oil ring or layer that was a risk to reservoir pressure support by peripheral injection In order to strategically develop the field and do so optimally, the heavy oil ring had to be correctly identified through careful mapping throughout the field. This presentation will cover some of the old methods used to prove the existence of the heavy oil and then cover the latest technologies used to identify the heavy oil layer, examples from the field and anomalies of various field cases will be shared and discussed thoroughly.
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