bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stratigraphic Expression of Upper Cretaceous Tectonics in the Balambo- Garau Sub-Basin of the Zagros Foldbelt: Implications for Reservoir Presence
Authors: Mosola Amanda B. , Braaksma Kelley S. , Tai Po C. , Volkmer John E. , Grabowski George J. , Kendall Jerry , Liu Chengjie 
Published: December 2015

Evaluation of the depositional environments of Upper Cretaceous strata in the Balambo-Garau sub-basin of the Zagros Foldbelt in western Iran into eastern Iraq provides insight into the distribution of reservoir and seal units, as well as potential trapping configurations. Such mapping within the upper sequences of the Cretaceous suggests a larger impact of Proto-Zagros flexure and localized re-activation of deeper seated structural trends in Iraq and Iran. Environment of deposition and unit thicknesses have been mapped and evaluated across western Iran into eastern Iraq using well logs and biostratigraphic data. From the middle Turonian to Santonian, outer-shelf argillaceous limestones overlie proximal to middle- shelf limestones. The deepening of the sub-basin, part of a broader trend of platform carbonates and associated deeper shelf and basinal facies, is concurrent with eustatic sea-level rise, but may also be affected by large-scale Cenomanian-Turonian adjustment. Environmental belts narrow and deposits lap onto highs exposed by localized uplifts as a result of the reactivation of deep-seated structural trends originating in the Permian (or possibly basement?). Outer- to middle-neritic sediments of the Ilam Formation, which onlap local structural highs, are higher quality reservoir facies of Coniacian–Santonian age and, where sealed, may be potential traps.
Deposits of the latest Campanian to Maastrichtian also show deepening of lower-shelf and basinal environments within the study area. Non-deposition and onlap of deeper water carbonate wackestone to marls onto highs in the Dezful embayment may further reflect the localized reactivation of deeper seated structural trends. Siliciclastic sediments of the Tanjero Formation shed from highs to the northeast are associated with paleogeographic reversal of the Proto-Zagros, depositing turbidites within the proximal thrust-front basin. Despite time-equivalent prolific oil-producing reservoir intervals in Iraq, ongoing deepening due to the Proto-Zagros Foreland Thrust results in largely non-reservoir marl facies of the Gurpi Formation acting as a seal to the underlying units. The Tarbur Formation, present in the Fars region, consisting of shallow-water rudist grainstone and packstone suggests a lack of accommodation created in association with the Proto-Zagros subsidence event.
Tectonostratigraphic trends of the Upper Cretaceous of the Zagros region of western Iran and eastern Iraq show the transition of a relatively quiescent ramp increasingly affected by localized effects of the Cenomanian-Turonian adjustment along with the Maastrichtian inception of Proto-Zagros thrusting and elucidates their impact on reservoir, seal and potential trap distribution within proven and unproven hydrocarbon systems in Iraq and Iran.
Modeling the Impact of Corrosion on Well Integrity for Offshore Wells
Authors: Narhi Ward , Kibey Sandeep , Kent David , Aylor Adam , Abdulhai Walid M. , Lam Gan Chee , Khemakhem A. S. David 
Published: December 2015

Abstract
Structural integrity of casings is critical for safe and economic operation of offshore wells and it can be compromised by external corrosion due to exposure to environment such as seawater. Assessing the impact of severe casing corrosion on the structural integrity of the well can be challenging due to complexities arising from local wall loss, non-uniform wall thickness, presence of holes due to severe corrosion, and non-bonded cement. Such complexities are not adequately addressed by existing codes/standards and available analytical equations.
This paper presents a study that utilized a combination of a thermo-mechanical well simulator and threedimensional (3D) finite element analysis (FEA) to model severely corroded offshore well casing strings towards assessing structural integrity of the wells. The goal of the study was to determine the extent of allowable corrosion in conductor and surface casing beyond which the wells would be at risk for failure, and if topping off the cement in the annulus would be beneficial for structural integrity.
A thermo-mechanical well simulator was utilized to model how corrosion wall loss evolved over time for both the conductor and surface casing, and the corresponding impact on their load capacity. In conjunction with the well simulator, full 3D FEA was conducted to model various complexities, such as the effect of corrosion holes and non-uniform corrosion. The 3D FEA helped assess the impact of remedial cementing on casing integrity and refine the critical wall thickness limit needed to withstand loads predicted by the well simulator. Compression and buckling were identified as governing failure modes and FEA results were compared with a buckled conductor in the field. The systematic, mechanics-based approach used in this study provided a basis for risk assessment where at-risk wells can be prioritized for remediation and/or abandonment.
A Collective Clay Stabilizers Review
Authors: AlMubarak Tariq , AlDajani Omar , AlMubarak Majed 
Published: December 2015

Abstract
Oil and gas fields encounter issues associated with clay minerals through drilling and production. Depending on the types of clay minerals, they pose the danger of swelling and migration upon exposure to incompatible water. Drilling introduces water through drilling mud, and production introduces water through different treatments such as acid stimulation and hydraulic fracturing.
The recovery of oil and gas from subterranean formations has been troublesome in formations that contain water-sensitive minerals, e.g., water-swellable clays, such as clays in the smectite group, and fines capable of migrating when disturbed, such as silica, iron minerals, and alkaline earth metal carbonates.
It has been common practice to add salts to the treatment fluids. The salts adsorb to the clay surfaces in an ion exchange process that can temporarily reduce the swelling and/or migration of the clays. Another method used is to coat the area with a polymer in order to physically block the surface of the clays.
This paper will mention the types of clays related to the oil industry, describe the structure of clays, mention the mechanisms behind swelling and migrating, and compare the different developments in the field of clay inhibition.
PreSDM Reprocessing of Dense WAZ Data - A Processing Team Delivers
Authors: Warzocha Stanislaw , Hermant Olivier , van de Rijzen Maurice 
Published: December 2015

Abstract
We present an example of how pre-stack depth migration (PreSDM) reprocessing of dense wide-azimuth (WAZ) data can improve imaging quality in areas with complex geology. The main challenges were the multiples hampering picking of proper primary signals, combined with a complex salt geometry. We will show that the experience gained over the years in using dense WAZ data for velocity model building and applying the latest technologies can significantly improve the imaging quality when compared to legacy processing.
Since 2010, the experience of working with dense WAZ data has built up especially on key processing steps like data preconditioning and velocity model updating.
In our case, there were two processing steps that were key to successful data preconditioning and residual moveout (RMO) picking: –Multiple removal by 3D dip filtering using local linear event extraction based on dip discrimination.–Using narrow-azimuth (NAZ) sectors instead of full WAZ data as input for picking.
For the velocity model building workflow, the most important aspects were: –The use of multi-layer non-linear slope tomography.–Salt scenario testing in areas with poor top salt visibility.–Intra-salt tomography.
RMO pick quality is critical for successful tomography for PreSDM. Most of the high amplitude train of multiples in the post-salt sediments could be removed using a dip-based demultiple algorithm. This allowed us to pick more stable and reliable RMO and dip information, which is a big improvement over the legacy PreSDM. Going back to azimuth sectors instead of using full WAZ data was mainly driven by experience. It was found that thorough and effective QC of RMO picks was easier and more accurate using MAZ data as opposed to WAZ data. As a consequence, more reliable and consistent pick information was used for tomography.
Using multi-layer tomography as an alternative to a layer stripping approach for velocity model building reduced the number of tomographic updates from five in the legacy PreSDM to three in the current project and produced more geologically consistent and accurate velocity models for PreSDM. Salt scenario testing improved the position of top salt and imaging below in areas with poor top salt visibility. Intra-salt tomography updated the smooth velocity within the salt and provided detailed velocity for intra-salt layers. Altogether this led to significant improvements in terms of velocity model building and imaging.
In this case study we present the results of the first PreSDM reprocessing of the first dense WAZ data acquired in the Sultanate of Oman. We explain in detail the methods used for data preconditioning and velocity model building and we show examples of the improvements achieved compared to legacy processing in terms of velocity model and imaging.
Gas Reservoir Management: How to Improve Gas Production Allocation Per Reservoir in Commingled Wells Using Geochemistry Technology?
Authors: Sabatier Lionel , Haidar-Qatargas Faesal , Mahdaoui Fatima , Dessort Daniel , Julien Philippe 
Published: December 2015

Abstract
In a commingled gas reservoir, it is crucial to determine the respective contribution of each produced reservoir for an efficient and reliable Reservoir Management, and to match the reservoir models. The Production Logging Tool (PLT) is commonly used to allocate the production to the individual layers. The limit of this process is that PLT results and therefore the layer-based equation change with time due to the evolution of reservoir characteristics such as reservoir pressure, mechanical skin, non-Darcy coefficient and sometimes PVT properties. PLT acquisition must be repeated to quantify this evolution and to determine time-dependent layer allocated equations. The repetition of PLT acquisition must be optimized taking into account the needs and the impact of time on results, but is as well highly constrained by cost and logistics, which prevent is some cases to get the desired frequency.
Geochemistry technology can provide additional and reliable data on the hydrocarbon fluid provenance in order to improve accuracy of the layer-allocated gas rate equations. Indeed sampling and geochemical analysis can be done at a higher frequency and much lower cost between each PLT. Fingerprinting is one of well-known techniques, which was tested recently in Qatargas in cooperation with Total and results appeared to be encouraging. All the analyses and data processing of the condensate samples were achieved in Qatar and a specific methodology was developed to get the best layer-based allocation process.
This geochemical approach is based on a statistical interpretation of High Resolution Gas Chromatography (HRGC) data of the condensate fraction from the produced fluids. There are several prerequisites for such a method to be applicable: identical separator conditions, excellent sample storage and handling, highest GC standards, appropriate statistical tools and availability of representative reservoir fluids. The individual reservoir fluids are considered as end-members which must be known to determine quantitatively the contribution of each reservoir in the produced well fluid.
This paper describes the details of the fingerprinting technique used, including how the samples are analyzed and how data are processed in an innovative way to get the most reliable results. In our case, the compositions of the different condensates show very subtil differences. As a result, we had sometimes to consider more than 1000 chromatograms peak ratios to differentiate the fluids coming from different layers. We concluded that geochemical production allocation was possible in some (but not all) areas of the field and that results were consistent with other types of dynamic and geological data.
These positive conclusions allowed us to envisage an operational application of this research feasibility study.
Insights on Potential Formation Damage Mechanisms Associated with Hydraulic Fracturing
Authors: AlMubarak Tariq A. , AlKhaldi Mohammed H. , Panda Saroj K. , AlMubarak Majed A. 
Published: December 2015

AbstractHydraulic fracturing technique, using water-soluble polymers, has been extensively used to improve the productivity of oil and gas wells, especially in low-permeability formations. However, the production enhancement by hydraulic fracturing can be hindered by the fracture conductivity damage and/or fracture face skin. This paper describes an approach to establish a suitable fracturing fluid cleanup process by analyzing the performance of different gel breaker types, especially in sours environments. In addition, the interaction of clay stabilizers with different gel breakers is investigated.Several experiments were conducted to assess the effect of different gel breakers on high temperature fracturing fluid as a function of time. Most commonly used breakers- inorganic oxidizers (bromate and persulfate salts), specific enzymes and acids- were used in this evaluation. The effectiveness of each breaker was evaluated using various techniques, such as Zeta Potential, Gel Permeation Chromatography (GPC), High-Pressure/High-Temperature (HP/HT) aging cells, H2S compatibility tests and Environmental Scanning Electron Microscope (ESEM). All experiments were performed on borate and zirconate crosslinked carboxymethyl-hydroxypropyl guar (CMHPG) guar gum system with loading up to 45 lb/1,000 gals in addition to clay control agents potassium chloride and polymer-based clay stabilizers.The results obtained from this study have shown that amount and size of the residual gel polymer chains, after its breakage, were mainly dependent on the type and loading of used gel breaker. Furthermore, it was found that both KCl and polymer-based clay stabilizers were effective in preventing clay-induced formation damage. However, laboratory tests have revealed that some gel breaker types may negatively affect the performance of polymer-based clay stabilizers. Additionally, this paper will highlight other negative interactions of common gel breakers, especially in sour environments.
Hyperspectral Remote Sensing for the Characterization of Dolomite Bodies: A Case Study in the Central Oman Mountains - Lower Khuff Analogue
Authors: Beckert Julia , Vandeginste Veerle , John Cédric M. , Guérillot Dominique , Foeken Jurgen 
Published: December 2015

AbstractRecent ground-based studies of quarry cliff faces suggest hyperspectral imaging to be a convenient tool to distinguish highly similar carbonate phases in vertical cliff faces within short distances (Kurz et al., 2012). We take the technique further and use ground-based hyperspectral imaging to identify the presence of dolomite bodies along weathered and irregular shaped cliff faces. Dolomite bodies hosted in limestone successions, common in for example Khuff and Arab Formations in the Middle East, represent a challenging feature with respect to the characterisation and exploration of hydrocarbon reservoirs. For example, dolostones interfingered with limestones are present in the Ghawar and South Pars fields (Dasgupta et al., 2002; Ehrenberg, 2006; Ehrenberg et al., 2007). Detailed descriptions of fracture related dolomite bodies in the Ghawar field have been published by Cantrell et al. (2001), whereas Jones et al. (2011) recognized dolomite bodies in the North Field in Qatar. Other studies showed lithofacies controlled dolomitization in the Arab Formation (Clark et al., 2004; Honda et al., 1989). The exceptional importance of dolomite bodies is based on a potential increase of porosity of 13% or more (Weyl, 1960) compared to the non-dolomitized host rock. However, due to their commonly sub-seismic size these potentially highly porous zones often stay undetected on seismic profiles and thus require careful investigation. In this study, the distribution and shape problem has been approached by delineating dolomite bodies hosted in Lower Khuff outcrop analogues in the Central Oman Mountains by applying hyperspectral remote sensing. We examine the degree of precision of the remote sensing detection and characterisation of dolomite bodies at varying distances to the cliff face and assess its impact on a 3D geocellular model.
The Geverik Member of the Carboniferous Epen Formation, Shale Gas Potential in Western Europe
Authors: Zijp M. H. A. A. , Nelskamp S. , Verreussel R. , ter Heege J. 
Published: December 2015

Abstract
Since 2010 activity in shale gas exploration moved to the European continent. One of the potential targets identified in Western Europe is the Carboniferous Epen Formation (Lower Namurian A) and especially it's basal Geverik Member in the Netherlands, Belgium and Germany. In this study an updated investigation of the shale gas potential is presented using domestic geological information from the Netherlands and well data from the surrounding countries (Belgium and Germany), as well as a new basin modeling study.
Of the studied eighteen wells the bituminouos Geverik Member is found in eleven, where it is either deposited as a gradual transition from the underlying Dinantian strata or unconformably sitting on Dinantian carbonates. In seven of the wells the Geverik Member is locally absent either related to erosion or caused by a heterogeneous depositional pattern. Nevertheless it was attempted to correlate the Geverik Member over the whole study area using well log correlation which could be done succesfully. The overlying Main Epen Member is found to be greatly variying in thickness (250-1800 m) highlighting the drastic differences in accommodation space in the Basin during the deposition of the Epen Formation as well as erosion patterns.
The study shows that the area with highest shale hydrocarbon potential of the Epen Formation and the Geverik Member onshore can be found in the Northwestern provinces of Friesland and Groningen, the Eastern Netherlands bordering Germany, and the Southeastern province of Limburg. In the offshore region the northwestern corner has the highest potential, although exploration for these layers can be more demanding due to higher cost of drilling offshore. We conclude that especially the Namurian Geverik Member of the Carboniferous Epen Formation is a locally promising interval and should be farther investigated in smaller-scale studies, using seismic, core, well and outcrop analysis.
Regional Synthesis of Thermal-Burial Regimes in the Paleozoic-Proterozoic Series of the Taoudenni Basin, Adrar, Mauritania: Fluid Inclusion and Thermochronology Data
Authors: Girard J -P. , Eichenseer H. , Kabbej A. , Idris K. M. 
Published: December 2015

Abstract
Exploration for oil and gas in the ancient Paleozoic–Proterozoic Taoudenni cratonic basin has been revived in the recent years following the documentation of a viable and efficient petroleum system in the Adrar region of Mauritania. In order to gain better knowledge of the thermal history prevailing in the prospective area (Ta7-Ta8 blocks), extensive fluid inclusion and thermochronology studies have been conducted on outcrop samples as well as cores from recent and older wells in the Paleozoic and Proterozoic sections. The results indicate that the Adrar region was affected by complex and variable burial-thermal regimes. A major cooling-uplift event is documented at ~100–150 Ma, possibly resulting in as much as ~3 km sediment removal. Maximum burial temperature in the Proterozoic formations reached ~140–180°C depending on location. Higher temperatures (&gt;200°C) are recorded which are attributed to short-lived heating events related to diabase emplacement, but no evidence supports a uniform thermal event of regional extension. Cooler burial-thermal regimes may have prevailed in the North-Eastern part of the prospective area. Record of petroleum migration is limited to the Meso-Protrozoic and lowermost Neo-Proterozoic formations, below the Lower Assabet (I14) regional seal. This work provides valuable information for future exploration of the Proterozoic section in this part of the Taoudenni basin.
Multiple Deployments of Large Diameter Hybrid Drill Bits with Optimized Drilling Systems Prove Enhanced Efficiency in Exploration Wells
Authors: Omar M. G. , Lee R. , Holliday A. , Taha M. , El Touny S. , El Touny S. , Al-Sarraf A. , Abdullah M. , Mahalanobis P. 
Published: December 2015

Abstract
In Kuwait's largest reservoir, the Burgan Field, exploration wells have large potential for drilling optimization and savings; specifically a 22 inch hole, that is drilled conventionally using multiple roller cone bits in multiple trips through challenging inter-bedded formations. Hybrid drill bit technology, roller cone combined with Polycrystalline Diamond Compact, was introduced in search for an economically viable solution to deliver wells faster and achieve yearly operator targets. This paper analyzes the breakthrough drilling performance achieved by a 22 inch hybrid bit in comparison to conventional roller cones offsets and provides conclusions on economic viability.
The main challenges drilling the 22 inch section are drill bit durability and drilling vibrations through inter-bedded formation layers of limestone, shale and sandstone. In addition to curing fluid losses in certain porous formations that negatively affect Rate Of Penetration (ROP). Typically two roller cone bits are used on rotary drive to drill this section at 15 feet per hour, consuming seven drilling days. Using Polycrystalline Diamond Compact (PDC) bit with a performance motor to increase ROP performance is not an economically viable solution. Using hybrid drill bit on rotary drive combines the benefits of PDC blades' durability and higher cutting efficiency with the cones' stability by grinding and gouging into the formation.
The deployment of the hybrid technology was a collaboration project between a national oil company and a major oil services company. The teams focused on optimizing the complete drilling system including the bottom hole assembly, hydraulics, drilling parameters and geological factors to match the hybrid drill bit mechanism.
The hybrid design selection and drilling optimization resulted in a 142-percent ROP improvement from offsets average performance. The hybrid designs consistently drilled the 22 inch hole after casing shoe to section total depth at 31 feet per hour, using one bit, in three drilling days in comparison to seven days average performance. The total operator savings from e section was approximately USD 175,000 in the first deployment. The second and third deployments established performance consistency. Such remarkable economical savings and technical optimization proved that the hybrid technology is the viable solution for two prolific exploration applications.