bluuebunny/crossref_metadata_2025_split huggingface dataset:
Faults, fracture corridors and diffuse fracturing: ranking the main structural heterogeneities within onshore Abu Dhabi fields
Authors: Bockel-Rebelle Marie-Odile , Hassall John K. , Silva Fernando P. , Lozano Jose A. , Al Deeb Maged , Salem Salem El Abd , Vesseron Marc , Al Mehsin Khalil 
Published: December 2007

Abstract
One of the most challenging issues within Abu Dhabi onshore fields is the definition, characterization and modeling of the main structural heterogeneities. Integration of structural, geometrical and dynamic understanding is the key to defining what is important from a field development and production viewpoint, since it may affect the economics of the fields.
A consistent analysis and approach is essential to be able to compare the fields taking into account the three different types of fracture (i.e. faults, fracture corridors and diffuse fracturing), and the potential geological events that postdate the fracturing (fluid circulation, diagenesis).
Diffuse fracturing was commonly described across most fields based on core observations and image log interpretation. However, this fracture type alone cannot explain the behavior of many wells.
A new look at the data reveals that several fields exhibit fracture corridors and/or subtle faults. Integrating the well behavior suggests this fracture type may have a significant impact in some fields. Unfortunately, this style of deformation is often below the seismic detection threshold.
The recent acquisition of 3D seismic across most of the Abu Dhabi onshore fields reveals all fields are faulted at the seismic scale. The fault style is often characterized by small throws. Recent improvements in seismic resolution reveal that what was previously interpreted as one fault is in fact made of numerous fault segments separated by relay areas. This new interpretation has obvious implications for the dynamic behavior of these fault zones. Indeed great discrepancies of the fault zone behavior are observed and discussed using six example fields which encompass a wide variety of carbonate reservoirs with varied depositional environments and reservoir properties. Given such a range of reservoir properties, faults and fractures with similar properties might be expected to have very different expressions in the way they affect fluid flow.
Inter-reservoir Communication Detection via Pressure Transient Analysis: Integrated Approach
Authors: Akresh Saud Bin , Al-Obaid Rashid , Al-Ajaji Abdulaziz 
Published: December 2007

Abstract
This paper presents a successful integration of pressure transient tests, production, and seismic data to detect inter-reservoir communication between Hanifa and Arab-D reservoirs in the southern dome of Abqaiq field in Saudi Arabia.
Even though Hanifa and Arab-D reservoirs are separated by about 300 feet of impermeable Carbonates, the two reservoirs are in pressure-fluid communication through conductive faults/fractures in the heavily faulted/fractured area of Abqaiq field.
Late time pressure anomalies on the log-log plots were observed on several field examples of transient tests in Hanifa reservoir and some were interpreted as external effects of pressure support from the communicating Arab-D reservoir. Simulation modeling was used to further analyze such pressure responses.
Better reservoir management decisions and more focused development strategies can be achieved through the utilization of the quantitative pressure transient analysis of those tests.
Petrophysical Measurements From Drill Cuttings an Added Value for the Reservoir Characterization Process
Authors: Egermann P. , Doerler N. , Fleury M. , Behot J. , Deflandre F. , Lenormand R. 
Published: December 2007

Abstract
Permeability and porosity are necessary for reservoir characterization and cuttings can provide quick and cheap measurements. In this paper, we present the first applications of the method on real reservoir characterization cases and the comparisons with logs and core data.
We first recall the method of permeability measurement from cuttings, which is based on a pressure pulse applied on a cell filled initially with cuttings saturated with viscous fluid and trapped gas at atmospheric pressure. The permeability is derived from the transient response of the oil invasion into the cuttings by using a numerical model. We also measured the porosity from dry drill cuttings using the routine helium technique. These methods were tested and validated by using various samples of crushed rock samples of known permeability and porosity. Both measurement techniques are fast, require light conditioning, are applicable over a large range of permeability and need only 1 ml of sieved rock to be realized.
Field applications of the drill cuttings measurements (permeability, porosity, T2 distribution) have been undertaken on various types of rocks (dolomite, carbonate, sandstone) obtained under several drilling conditions (WBM, OBM). The representativity issue of the cuttings towards the native reservoir is of primary importance and was checked by using adequate cleaning procedure and the preparation techniques and by comparing the consistency of the porosity measurements obtained from cuttings with other data (cores or logs). The overall results demonstrate the added value of K and ϕ measurements in addition to the data that are already collected in routine.
Bayesian Uncertainty Reduction for Log Evaluation
Authors: Spalburg M. R. 
Published: December 2007

Abstract
The evaluation of petrophysical logs in terms of rock and fluid compositions can be ambiguous in the presence of possible complex lithology types, deep invasion effects, etc. In such circumstances the evaluation results tend to be strongly influenced by the choice of petrophysical evaluation parameters such as rock and fluid density, acoustic and electrical properties. In addition, different lithology types may require the use of different interpretation models or equations. Given these total or partial unknowns a rigorous log evaluation needs to scan through all possible combinations of evaluation parameters and models to determine which combinations of rock and fluid component abundances explain the measurements. It may be obvious that such an exercise can result in multiple solutions and that some type of Monte Carlo analysis is an appropriate mechanism to sample through all the combinations. The amount of calculations required to do this using a regular Monte Carlo analysis scheme is prohibitive large: in the order of 10^20. An implementation of a Bayesian inference method based on a Markov Chain Monte Carlo algorithm dramatically reduces the amount of evaluations required to some 1000 to 10000 per log increment. Any available geological, geophysical or production derived knowledge can be incorporated in the MCMC evaluation as a modification of the prior probability distributions for the evaluation parameters and models. The resulting properly correlated rock and fluid component abundances also enables the calculation of tool response probability distributions for (not yet) acquired logging tools and enables a quick analysis of the potential evaluation uncertainty reduction by those tools. A few carbonate and sandstone application examples illustrate log evaluation uncertainty with respect to rock mineral composition and oil/gas saturations and how the ability to predict the range of possible measurement results for possible additional logging tools can help optimize data acquisition programs.
Integration of 3D Seismic & Dynamic Data Improves Interpretation of Structural Features
Authors: Al Rougha Hamad Bu , Al-Henshiri M. Yousef , Khouri Naeema , Arisaka K. , Sultan A. 
Published: December 2007

Abstract
Well tests are often used to investigate reservoir heterogeneities such as fractures, conductivity of faults, and matrix permeability. Attributing a measured pressure response to a particular geological feature is problematic, as many different solutions will fit the same pressure response. Data integration is the key to understanding well pressure transients and the underlying geology controlling them.
A recently acquired and interpreted 3D seismic survey indicated the reservoir contained numerous strike slip faults. To reduce the uncertainty associated with reservoir characterization, a multidisciplinary team comprising of geophysicists, geologists and reservoir engineers selected an area of the reservoir to focus their efforts. The integration of the 3D seismic with dynamic data provides a possible means of validating the interpretation.
Anomalous transient pressure data were identified on five wells. Initial interpretations proved ambiguous with several possible geological reasons. Close examination of the 3D seismic data indicated in each case the presence of a fault. Faults were found to be the likely structural anomalies that have been detected by seismic and well test data. The fault throw, conductivity and its distance to the wellbore were estimated. The transient pressure data enabled us to evaluate the faults as sealing.
Once the integration perception was adopted, and high quality data became available, concerns with the 3D seismic interpretation data and the uncertainties associated with pressure transient data that were initially ambiguous began to make sense.
Best Practices from Super-Giant 3D-OBC Seismic Survey, Offshore Oil Field Abu Dhabi
Authors: Hagiwara Hiroshi , Belaid Kamal , Lilley Graham , Corless Denis , Al Kaabi Musabbah , Ajlani Ghiath , Ebed Atef , Suwaina Omar , Shimada Nobusuke , Najia Walid , Bu-Alrougha Hamad 
Published: December 2007

Abstract
This paper presents the best practices and the lessons learnt from a comprehensive offshore 3D ocean bottom cable (OBC) seismic survey, which was successfully carried out over a super-giant offshore production oil field in Abu Dhabi by an integrated multi-disciplinary team from three different companies. This work highlights a wide range of challenges and achievements throughout the steps, from the feasibility study, data acquisition, processing, interpretation and advanced reservoir characterization studies.
Pressure Transient Derivative Signatures In Presence of Stratiform Super-K Permeability Intervals, Ghawar Arab-D Reservoir
Authors: Gill Harmohan S. , Al-Zayer Rayed 
Published: December 2007

Abstract
This paper describes case studies of observed pressure derivative signatures in the presence of stratiform Super-K permeability intervals in Ghawar field, Arab-D oil reservoir. The case studies (presented in order of increasing complexity) include: 1) an open-hole vertical well intersecting the Super-K interval, 2) a slant horizontal well intersecting the Super-K interval and, 3)a horizontal well at the top of a layered reservoir, not in contact with the Super-K interval and separated from the Super-K interval by low permeability layers.
The stratiform Super-K permeability intervals in Ghawar can be visualized as being like horizontal pancakes of multi-darcy permeability. Since these Super-K intervals are not continuous but rather show up as patches of high permeability, the typical effect on the pressure derivative of a vertical open-hole well is that of a radial composite system.
The most complex derivative signature is observed when a horizontal well is separated from the non-intersecting Super-K interval by low permeability layers. It is very easy to misinterpret this derivative signature without integrating all the available geological and production log data.
The derivative signatures are demonstrated by numerically simulated responses of actual case studies. The importance of identifying these pressure derivative signatures is illustrated in this heterogeneous, multiphase, layered, reservoir where data quality is sometimes poor due to wellbore phase redistribution.
Comparing the Accuracy of Fluid Saturation Derived from Different Logging Measurements: Past, Present and Future Methodology
Authors: Belgaied Adel , Al-Farisi Omar , Al-Ghusain Subhi , Al-Muntheri Hiyam , Al-Marzouqi Mariam , Petricola Mario 
Published: December 2007

Abstract
Obtaining the water and hydrocarbon saturations in any reservoir are one of the main applications of many logging instruments. Resistivity has been used with relative success in many fields and can be considered the main open-hole "saturation" measurement, even though true formation resistivity remains elusive. Pulsed neutron capture is the basic cased-hole "saturation" measurement when formation water salinity is known and high enough. While either one has its own limitations, they often agree well enough that they reinforce the user confidence in their respective accuracy. Thus, they are generally considered adequate for reservoir management decisions.
Occasionally, acquiring and comparing a large number of different measurements that respond to fluid distribution in the formation shows that two measurements dose not give the same answer. As a result, Petrophysicists face the task of reconciling and explaining those discrepancies to extract additional and valuable information.
In this paper, we review the principles, advantages and limitations of a certain number of measurements acquired in both open and cased hole. We briefly review how data was handled in the past and the way it is handled today. We then review how discrepancies are reconciled today and make suggestions and recommendations as to which measurements are the most appropriate for various types of environments.
In the last part of the paper, we are suggesting new ways to acquire, process and interpret log data. Logs free of environmental effects will be obtained through the acquisition of auxiliary measurements that define the Wellbore environment accurately. Models are used to evaluate and correct for the environmental variations that are not resolved by in-built sensors. Tool planners are expanded to become true artificial experts that recommend the right measurements for a given formation and borehole environment. In addition, the uncertainty on the logs, parameters and models will be propagated to the output uncertainty in a meaningful and representative manner.
Simulation Study of Miscible Gas Injection for Enhanced Oil Recovery in Low Permeable Carbonate Reservoirs in Abu Dhabi
Authors: van Vark W. , Masalmeh S. K. , van Dorp J. , Al-Nasr M. Abu , Al-Khanbashi S. 
Published: December 2007

Abstract
In this paper we will present the outcome of a study conducted to evaluate the feasibility of large scale injection of sour and/or acid gas into a low permeable carbonate reservoir to enhance oil recovery.
Other than for disposal, H2S containing mixtures have rarely been injected as a miscible agent in oil recovery projects. Moreover, the very few projects that have actually been executed are relatively small (generally less than 10 MMscf/d).
In this study different recovery processes were evaluated such as water flooding, lean gas injection, sour gas (natural gas with a large H2S content) injection, acid gas injection, acid gas (mixture of H2S and CO2) after a slug of sour gas and CO2 injection. To evaluate these different (EOR) recovery processes, a detailed reservoir description is essential and for this purpose element-models were used.
The critical importance of a thorough understanding of reservoir geology and rock properties for miscible gas injection schemes has been confirmed by the experiences of water breakthrough and over-ride in a number of reservoirs in Abu Dhabi and the poor performance of some miscible gas injection projects in the industry.
The simulation study shows that miscible acid gas injection is the preferred recovery mechanism for part of the reservoir under study. This is a result of several key factors, including the favorable miscibility with the native oil (lower miscibility pressure with reservoir crude), better solvent for asphaltene, a more favorable mobility ratio due to high acid gas viscosity and density and availability of large quantities of acid gas from the underlying formation. Acid gas is therefore an attractive, low cost, miscible, enhanced oil recovery agent, provided fully adequate corrosion mitigation procedures and HS&E management systems are implemented in the development.
New Method of Incorporating Immobile and Non-vaporizing Residual Oil Saturation Into Compositional Reservoir Simulation of Gasflooding
Authors: Hiraiwa T. , Suzuki K. 
Published: December 2007

Abstract
In compositional simulation of gas injection processes, it is often observed that grid-block oil saturations decrease far beyond the user-defined residual oil saturation, even under immiscible conditions. This numerical phenomenon occurs since oil components are allowed to vaporize into the gas phase as much as the phase equilibrium obtained with an equation of state (EoS) permits. Especially in the vicinity of gas injectors, the oil saturation of zero is sometimes predicted. On the other hand, such significant low oil saturation is rarely seen in laboratory data such as coreflood experiments and slimtube tests.
The reason of the discrepancy between simulation results and laboratory results described above is thought that bypassed oil located in dead-end pores or caused by subgrid scale heterogeneities is not considered in the current compositional simulation practice. To overcome this, we developed an innovative method of incorporating laboratory-based residual oil saturations. The proposed method can restrict the excessive vaporization and maintain the prescribed residual oil by accommodating a novel application of the transport coefficient (Ref. 1).
Hazard Management Considerations for Sour Gas Development During Concept Selection
Authors: Kamath A. R. Ramachandra , van Dorp Johan , Johnson Andy , Alcock Jane , Keith Ian 
Published: December 2007

Abstract
A systematic hazard management approach was used to identify, assess and mitigate hazards at the conceptual design stage of a large onshore sour gas development in Abu Dhabi. The potential environmental impact of sulphur block production and poor prospects of a sulphur market led to a concept involving injection of dense phase acid gas back into the formation. Significant Health, Safety and Environmental (HSE) challenges were addressed relating to the scale of the sour gas development which included the gathering, processing and injection of sour/acid gas containing 33% – 80% H2S. Quantitative Risk Assessment and H2S dispersion calculations were performed to evaluate the risk reduction effectiveness of specific HSE design considerations including material selection, pipeline design, pipeline routing, well design and the location of the processing facility and sour/acid gas wells. These HSE design considerations were integrated into the concept selection. Best industry practices in design and operation of sour gas facilities and emerging technologies in leak detection were adopted as a minimum standard to minimize the HSE risks.
High-Resolution Sequence Stratigraphy of the Kharaib Formation (Lower Cretaceous, U.A.E.)
Authors: Strohmenger Christian J. , Weber L. J. Jim , Ghani Ahmed , Rebelle Michel , Al-Mehsin Khalil , Al-Jeelani Omar , Al-Mansoori Abdulla , Suwaina Omar 
Published: December 2007

Abstract
A new sequence stratigraphie framework is proposed for the Lower Cretaceous Kharaib Formation (Barremian and Lowermost Aptian) of the United Arab Emirates. This framework is based on the integration of core and well-log data from Abu Dhabi oil fields with outcrop data from Wadi Rahabah, Ras Al-Khaimah (U.A.E.).
The Kharaib Formation is part of the late transgressive sequence set of a second-order supersequence, built by two third-order composite sequences. Fourteen fourth-order parasequence sets build into two third-order composite sequences and show predominantly aggradational and progradational stacking patterns, typical of greenhouse cycles.
On the basis of faunal content, texture, sedimentary structures, and lithologic composition, eleven reservoir lithofacies and eight non-reservoir "dense" lithofacies are identified from core. These same lithofacies are also identified in time-equivalent rock exposures studied in Wadi Rahabah. The analyzed lithofacies range from open platform, lower ramp to restricted platform subtidal to intertidal environments. Intensively bioturbated wackestone and packstone, and interbedded organic- and siliciclastic-rich limestone characterize the three so-called dense zones (Lower, Middle, and Upper Dense Zone). Locally, mud-cracks, blackened grains, and rootlets are observed. The two reservoir zones (Lower and Upper Kharaib Reservoir Unit) correspond to the late transgressive and, dominantly, highstand systems tracts characterized by parasequence sets that show shallowing-upward trends from open platform, burrowed skeletal wackestone to skeletal, peloidal packstone and algal, coated-grain grainstone/rudstone, and rudist, algal floatstone/rudstone. Well-developed Thalassinoides firmgrounds (Glossifungites surfaces) indicate temporary cessation in sedimentation and cap several parasequence sets and parasequences.
Stylolitic intervals within the reservoir units predominantly correspond to major facies changes related to third-, fourth-,and fifth-order sequence boundaries, parasequence set boundaries, and parasequence boundaries.
In outcrop, low-angle clinoforms that cannot be seen in core data are observed within the highstand systems tract of the upper third-order composite sequence (Upper Kharaib Reservoir Unit). Integration of subsurface and outcrop data leads to more insightful and realistic geological models of subsurface stratigraphy.