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Horstketter R.,National Oilwell Varco | Van Egeraat S.,Nederlandse Aardolie Maatschappij
SPE/IADC Drilling Conference, Proceedings | Year: 2015

The capability to produce 12 million m3/day of natural gas requires either multiple conventional wells or two large bore wells using 9-5/8 in. completions. Conventional wells can use a 13-5/8 in. 10, 000 psi BOP Stack. Large bore wells normally require an 18-3/4 in. 10, 000 psi BOP Stack, and a drilling rig of sufficient size to accommodate it. This results in a significant difference in cost per well between drilling conventional wells and drilling large bore wells. In the summer of 2013, a 13-5/8 in. 10, 000 psi BOP shearing system was in development with tandem piston hydraulic actuators that can utilize up to 5, 000-psi hydraulic operating pressure, generating over one million pounds of shearing force, and shear rams designed for more efficient and robust shearing. A shear-only version of the system could be available in March 2014, provided that the system met the equirements for the Norg wells. For evaluation purposes, a shearing demonstration was conducted on the most challenging pipe sizes planned for the Norg wells. The exercise demonstrated that the system is capable of meeting the pipe shearing requirements. Accordingly, well control protocols were developed based on the capabilities and limitations of the shear-only system. Through knowledge of the development of the new shear system, the operator was able to make use of the system in establishing the Norg gas storage and production wells. The operator was thus able to accomplish their goal with two large-bore wells instead of three smaller ones, at substantial cost savings. Copyright 2015, SPE/IADC Drilling Conference and Exhibition.

Gaupp R.,Friedrich - Schiller University of Jena | Okkerman J.A.,Nederlandse Aardolie Maatschappij
SEPM Special Publications | Year: 2011

The Permian Rotliegend clastic reservoirs form the main gas-bearing intervals in the Netherlands, Northwest Germany, and the Southern North Sea. We review and summarise the results of more than thirty years of diagenesis and reservoir-quality studies in Rotliegend sandstones of the Netherlands and adjacent areas. The Rotliegend sediments were deposited in an alluvial-wadi-aeolian dune-sandflat-playa lake depositional setting, marked by an arid to semiarid climate, in which drier and wetter climatic cyclicity drove sedimentary processes. Present depths of Rotliegend reservoirs in the range of 2 to ca. 4.5 km, are often referred to as maximum burial depths. Rotliegend clastics were exposed to temperatures between 60°C and180°C. Structural uplift during Late Jurassic and Cretaceous times influenced the Rotliegend pressure and fluid-flow regime. The paragenetic sequence is spatially variable and comprises a wide variety of authigenic minerals, with several early cements typical of continental red-bed sequences. Characteristic of semiarid (to arid) environments is reddening and the presence of grain-coating metal (Fe, Al, Mn, and Ti) oxides as well as smectitic, illitic, and chloritic grain-coating clays. Early blocky and often pore-filling cements include dolomite, gypsum, anhydrite, and halite, but also quartz and K- and Na-feldspar overgrowths. Burial-related authigenic precipitates are Fe-dolomite, calcite, siderite, and quartz cements, kaolinite, dickite, chlorite, and mainly fibrous illitic clay. Dissolution of feldspar and volcanic rock fragments, of soluble pore-filling carbonate, sulphate, and halite cements, and the formation and destruction of secondary porosity are important factors in determining current reservoir properties. Most of the variance in porosity and permeability can be explained by a small number of significant variables: carbonate (and anhydrite) cementation, initial mineralogy, grain size, clay matrix content, diagenetic clay association, diagenetic quartz, and feldspar dissolution. Pore-blocking anhydrite and carbonate cements are the most pronounced phases that impacted on porosity. Impairment of permeability is due mainly to authigenic clays (illite, kaolinite, chlorite). Even after pronounced diagenetic alteration the depositional setting remains as an important control on overall reservoir quality. Aeolian dunes and dry aeolian sandflat deposits remain the best potential reservoirs even under deep burial. However, pore-occluding blocky cements, mechanical compaction, or clay growth can heavily impair reservoir quality in optimum depositional facies, particularly under extended exposure times to high temperatures. Long-term or continuous gas fills preserve favourable reservoir properties. The spatial proximity of Carboniferous source rocks to Rotliegend reservoirs in the Netherlands is considered to be a smaller risk for reservoir quality compared to northern German subsurface analogues. Reservoir characterisation studies spanning more than three decades clarified the mechanisms, controlling factors, and relative timing of many diagenetic processes, but uncertainties about the quantities of resulting products remain. The multitude of interfering factors that control Rotliegend reservoir properties and the geological heterogeneity in the area does not favour conceptual models of regional applicability. Evaluation of the existing concepts on Rotliegend reservoir quality indicates the necessity of combining all available data to constrain the complexities of depositional facies, diagenesis, structuration, and charge history in the specific cases. Copyright © 2011 SEPM (Society for Sedimentary Geology).

Waldmann S.,Friedrich - Schiller University of Jena | Busch A.,Royal Dutch Shell | Van Ojik K.,Nederlandse Aardolie Maatschappij | Gaupp R.,Friedrich - Schiller University of Jena
Chemical Geology | Year: 2014

Investigations of Rotliegend sandstones from the NE Netherlands have been carried out to determine the mineralogical composition and spatial mineral distribution, specific mineral and whole rock surface areas and the integration of these results in geochemical water-rock-CO2 simulations. Therefore, two scenarios were considered: (1) volumetric rock composition (derived from point counting on thin sections) and (2) effective mineralogy (derived from 2D pore lining image analysis) data which represent the percentage amount of each mineral phase exposed within open (or accessible) pores. Specific mineral surface areas were defined for each mineral phase, respectively and integrated in both model scenarios. Based on point counting data the volumetric compositions of the sandstones are dominated by the mineralogy of detrital grains like quartz and K-feldspar. Authigenic minerals, esp. clays, volumetrically make up a small portion of the bulk rock volume only but are exposed due to their small crystal size (nm- to μm-scale) and a large specific surface area (13 to 195m2/g) in comparison to e.g. feldspar grains (0.03 to 1.79m2/g). Hence the size, distribution and accessibility of detrital and authigenic minerals regulate the availability of chemical species for water-rock interactions in the pore space. The effective mineralogy of the sandstones is a function of the presence of grain covering and pore-filling authigenic minerals. In the two Rotliegend sandstones studied, approximately 23% and 43% of the detrital grains are covered by cements blocking the grain surface areas accessible for potential water-rock interactions. These minerals are Fe-oxide, clay cutans (mainly illite), kaolinite, quartz, carbonate (dolomite, ankerite and siderite), sulfate (anhydrite and barite) and galena. The specific surface area (SSA) of each mineral was calculated using (electron) microscopy to determine the sample geometry (e.g. size, thickness) and standard density values. For the volumetric and effective mineralogy data the total specific surface area of the bulk rock was calculated by summing the specific mineral surface areas in relation to their relative content in the rock, as determined using X-ray diffraction. These results were compared to surface area values determined using low pressure N2 adsorption (BET method) of the bulk rock (mean value 1.4m2/g). It is shown that the SSA values using the effective mineralogy approach (mean value of 0.46m2/g) are closer to the whole rock BET than the SSA for volumetric mineralogy (0.05m2/g). These different values for the volumetric and the effective mineralogy show significant differences in geochemical modeling results: The initial amount of K-feldspar, kaolinite, hematite and carbonate controls the availability of species for clay mineral precipitation (e.g. Mg-smectite) during CO2 storage. Effective mineral carbonation is calculated using the volumetric compared to the effective mineralogy. Within the first 100years carbonate precipitation occurs for the volumetric mineralogy but is absent for the effective mineralogy. Opposing trends are observed for long-term reactions (>100years). Similarly, when using the effective mineralogy, the porosity increases over the entire simulation time of 10,000years while it initially decreases for the volumetric mineralogy followed by an increase and a net zero porosity change after 10,000years. This implies that different results for CO2 trapping can be expected, depending upon the mineral assemblage and its effective mineralogy. © 2014 Elsevier B.V.

Steuber T.,The Petroleum Institute | Steuber T.,Nederlandse Aardolie Maatschappij | Schluter M.,Ruhr University Bochum
Earth-Science Reviews | Year: 2012

Numerical ages derived from strontium-isotope stratigraphy of 81 Late Turonian-Maastrichtian rudist localities from the Caribbean to Oman are used to establish stratigraphical ranges of readily identifiable taxa of rudist bivalves (Hippuritida). Based on these ranges, seven biozones for the Turonian-Maastrichtian of the central-eastern Mediterranean Tethys, and three biozones for the mid-Campanian-Maastrichtian of the Arabian Plate are established. Most of these are interval zones, each based on the first stratigraphical appearance of the nominal taxon. Micro-evolutionary patterns such as phyletic size increase have been demonstrated for some of the nominal species, as well as a trend of stratigraphical range expansion from the Turonian to the Maastrichtian. Implications of the geochronology of Late Cretaceous carbonate platforms for the biostratigraphy of other benthic fossils are briefly discussed.Three significant gaps in the stratigraphical distribution of rudist localities in the lower, middle, and uppermost Campanian, respectively, correlate with other records of sea-level change, indicating that they correspond to major eustatic sea-level falls. Only a limited number of rudist taxa is evaluated here, but the early and latest Campanian sea-level falls correspond to faunal turnover and extinction of characteristic associations of Late Cretaceous Hippuritida.The final extinction of the Hippuritida at the Cretaceous/Paleogene boundary is evaluated based on the available numerical ages of eighteen Late Maastrichtian localities. Eighteen genera are recorded at the six youngest localities, which thus have a species richness similar to older Late Cretaceous localities. While the ultimate cause for extinction of the Hippuritida must be evaluated on time scales beyond the resolution of strontium-isotope stratigraphy, the data set evaluated provides some insight into the pattern of their demise, which is considered to be the result of a high degree of endemism indicating limited exchange between increasingly isolated populations. This isolation was possibly related to the gradual decrease in the areal extent of Maastrichtian carbonate platforms due to a long-term cooling trend and local tectonics that affected carbonate platform growth in the regions studied. © 2012 Elsevier B.V.

Lohne A.,International Research Institute of Stavanger | Han L.,International Research Institute of Stavanger | Van Velzen H.,Nederlandse Aardolie Maatschappij | Twynam A.,British Petroleum | And 2 more authors.
SPE Journal | Year: 2010

In this paper, we describe a simulation model for computing the damage imposed on the formation during overbalanced drilling. The main parts modeled are filter-cake buildup under both static and dynamic conditions; fluid loss to the formation; transport of solids and polymers inside the formation, including effects of porelining retention and pore-throat plugging; and salinity effects on fines stability and clay swelling. The developed model can handle multicomponent water-based-mud systems at both the core scale (linear model) and the field scale (2D radial model). Among the computed results are fluid loss vs. time, internal damage distribution, and productivity calculations for both the entire well and individual sections. The simulation model works, in part, independently of fluidloss experiments (e.g., the model does not use fluid-leakoff coefficients but instead computes the filter-cake buildup and its flow resistance from properties ascribed to the individual components in the mud). Some of these properties can be measured directly, such as particle-size distribution of solids, effect of polymers on fluid viscosity, and formation permeability and porosity. Other properties, which must be determined by tuning the results of the numerical model against fluid-loss experiments, are still assumed to be rather case independent, and, once determined, they can be used in simulations at altered conditions as well as with different mud formulations. A detailed description of the filter-cake model is given in this paper. We present simulations of several static and dynamic fluidloss experiments. The particle-transport model is used to simulate a dilute particle-injection experiment taken from the literature. Finally, we demonstrate the model's applicability at the field scale and present computational results from an actual well drilled in the North Sea. These results are analyzed, and it is concluded that the potential effects of the mechanistic modeling approach used are (a) increased understanding of damage mechanisms, (b) improved design of experiments used in the selection process, and (c) better predictions at the well scale. This allows for a more-efficient and more-realistic prescreening of drilling fluids than traditional core-plug testing. Copyright © 2010 Society of Petroleum Engineers.

Van Gent H.,RWTH Aachen | Urai J.L.,RWTH Aachen | de Keijzer M.,Nederlandse Aardolie Maatschappij
Journal of Structural Geology | Year: 2011

We present a first look at the large-scale, complexly folded and faulted internal structure of Zechstein salt bodies in NW Europe using 3D reflection seismic reflection data from two surveys on the Groningen High and the Cleaver Bank High. We focus on a relatively brittle, folded and boudinaged, claystone-carbonate-anhydrite layer (the Z3 stringer) enclosed in ductile salt. A first classification of the structures is presented and compared with observations from salt mines and analogue and numerical models. Z3 stringers not only are reservoirs for hydrocarbons but can also present a serious drilling problem in some areas. Results of this study could provide the basis for better prediction of zones of drilling problems. More generally, the techniques presented here can be used to predict the internal structure of salt bodies, to estimate the geometry of economic deposits of all kinds and locate zones suitable for storage caverns. Structures observed include an extensive network of zones with increased thickness of the stringer. These we infer to have formed by early diagenesis, karstification, gravitational sliding and associated local sedimentation. Later, this template was deformed into large-scale folds and boudins during salt tectonics. Salt flow was rarely plane strain, producing complex fold and boudin geometries. Deformation was further complicated by the stronger zones of increased thickness, which led to strongly non-cylindrical structures. We present some indications that the thicker zones also influence the locations of later suprasalt structures, suggesting a feedback between the early internal evolution of this salt giant and later salt tectonics. This study opens the possibility to study the internal structure of the Zechstein and other salt giants in 3D using this technique, exposing a previously poorly known structure which is comparable in size and complexity to the internal parts of some orogens. © 2010 Elsevier Ltd.

Liow E.,Nederlandse Aardolie Maatschappij | Goorhuis H.,Royal Dutch Shell
Institution of Mechanical Engineers - 12th European Fluid Machinery Congress | Year: 2014

A Double End Driven Compression train with Active Magnetic Bearings (AMBs), a novel concept on its own, has been chosen as the solution for the Groningen 2nd phase compression project. A development assurance program was followed by a team comprising of both Siemens and Shell specialists with the intent of ensuring that technical risks were identified and addressed as far as possible prior to field implementation. The paper will describe • The concept evaluation and selection • The creation of the development programme to assess technical risks • Technical challenges and learnings • Current status of the development and design maturity © The author(s) and/or their employer(s), 2014.

Kok W.T.,University of Amsterdam | Tudos A.J.,Royal Dutch Shell | Grutters M.,Royal Dutch Shell | Shepherd A.G.,Nederlandse Aardolie Maatschappij
Energy and Fuels | Year: 2011

Nonaqueous capillary electrophoresis was used for the separation and characterization of asphaltene samples from different sources. For the separation medium (background electrolyte), mixtures of tetrahydrofuran and a high-permittivity organic solvent could be used. The best results were obtained with an 80:20 mixture of tetrahydrofuran and acetonitrile, containing 1-10 mM of lithium perchlorate. In this separation medium, asphaltene samples were found to be composed of two fractions that could be clearly separated: one fraction of neutral species and a fraction that carries a positive charge in the solvent mixture employed. Between samples of different origin, differences were found in the relative amounts of the neutral and the charged fractions and in the average electrophoretic mobility of the charged components. Taylor dispersion analysis was applied to estimate the average diffusion coefficient of the asphaltene species in the solvent mixture used. From the results, it is concluded that the asphaltenes are present as nanoaggregate clusters of 3000-4000 Da and that the charged aggregates carry a net charge of approximately +1. The possible correlation between the electrophoretic properties of asphaltenes in crudes of different origin and their field behavior is discussed. © 2011 American Chemical Society.

Chinyelu A.G.,Nederlandse Aardolie Maatschappij
Society of Petroleum Engineers - SPE Offshore Europe Conference and Exhibition, OE 2015 | Year: 2015

Our industry is highly dependent on competent, innovative and motivated professional workforce to deliver the world energy needs now and years to come. Resourcing the business with the right numbers and skill level at all strata of the organization requires that we continue to develop our young professionals and also provide opportunities for the experienced professionals to continue to grow. This paper discusses current best practices deployed and the impact on the business, using the Production Technology (PT) Discipline as a case study. Development of young professionals is achieved through 3 key ways: In-role development, mentoring and coaching and formal learning. These 3 mode of training follow the 70:20:10 approach to maximize learning where it is expected that 70% of learning occurs through on-the-job experience and learning as you carry out tasks; 20% through interactions with others (coaching, demonstrations, peer-to-peer sharing, etc.); and 10% through formal learning (e-learning, classroom, etc.). Operator X Graduate Programme (SGP) and the Advanced Graduate Programme (SATP) are some of the recent modes deployed to ramp up the technical capabilities of new graduates. These have aided in cutting down the number of years to "autonomy" while maintaining the quality and efficiency of the technical professionals. For the more experienced staff, operator X has tailored their role specific needs through the technical learning portfolios which include the Project Academy and the Production Academy. The mode of delivery of the trainings is tailored toward the learning objective, for example-awareness training versus on-the-job learning support, etc. In many technical learning portfolios, the blended learning mode is more favored (with emphasis on adequate preparation prior to the classroom event (f2f), more hands-on during f2f and the continuation of learning after the f2f). The formation of Subject Matter Expert (SME) networks to address different subject areas in the Discipline has also helped in deepening the skills of the experienced staff while accelerating learning for the less experienced. The Production Technology career Path Plan provides a vehicle to deploy these tools and processes and consequently transform talented but in-experienced graduates to seasoned and motivated professionals. © Copyright 2015, Society of Petroleum Engineers.

Zakharov A.,Nederlandse Aardolie Maatschappij
Society of Petroleum Engineers - SPE EOR Conference at Oil and Gas West Asia, OGWA 2016 | Year: 2016

Two novel methods are presented, that allow estimating downhole P&T conditions by using wellhead measurements in the Schoonebeek steamflood development: one method allows determining flowing bottomhole pressure (fBHP) and the other bottomhole temperature (fBHT). The resultant estimates are confirmed by fluid level measurements and observation well pressure data. The fBHP calculation is based on the fact that rod loads are dependent on fluid level. A simple but robust model is presented, which accounts for impact of other parameters (pump speed, watercut, etc.) and allows fine-Tuning to match available downhole measurements. The fBHT is estimated by using a simplified analytical wellbore heat loss model that is history matched to wellhead temperatures (WHT) at different well rates. Both models are applied in the Schoonebeek field steam flood development. Their creation was necessary because operational constraints severely restricted usage of standard surveillance techniques like fluid level measurement and use of downhole gauges on hot producers. The presented methods allow acquiring robust estimates of downhole P&T regime for flowing producers by using easily accessible SCADA data that is continuously collected at the wellhead. These data are normally used to optimize the rod pump operation and have been recorded since the start of the steamflood (2011-2015); hence, by using simplified rod load models and some statistical analysis it was possible to recover and validate the full fBHP/fBHT history for the hot wells - even for the periods when the fluid level measurements were unavailable or inconsistent. The models were tested and matched against historical field measurements (fluid level measurements and data from observation wells) and were found to provide sufficient accuracy for use in normal operations (P&T within a few bars / 10 degrees C). The novelty of the methods is in the ability to use existing wellhead data to come up with robust estimates for downhole P&T conditions on flowing wells. Nowadays continuous SCADA are industry standard; thus, near-continuous fBHP and fBHT monitoring can be achieved without using any additional equipment. Clear benefits are surveillance cost reduction together with improved well/reservoir management; also, extra data helps improving reservoir model history match quality and forecast accuracy. Copyright 2016, Society of Petroleum Engineers.

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