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3rd EAGE/SPE Geosteering Workshop
- Conference date: November 2-4, 2021
- Location: Online
- Published: 02 November 2021
30 results
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Uncertainty Quantification on the Inversion of Geosteering Measurements using Deep Learning
Authors J.A. Rivera, J.A. Rivera, D. Pardo, J. Omella and C. Torres-VerdínSummaryWe propose the use of a Deep Learning (DL) algorithm for the real-time inversion of electromagnetic measurements acquired during geosteering operations. Moreover, we show that when the DL algorithm is equipped with a properly designed two-step loss function without regularization, it is possible to recover an uncertainty quantification map by analyzing certain cross-plots. We illustrate these ideas with a synthetic example based on piecewise 1D earth models.
The resulting uncertainty quantification map could be used to design better measurement acquisition systems for geosteering operations.
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P02: Prototype Concept of Reservoir-Profile-Update-Rate to Quantitatively Evaluate Efficiency of Reservoir Description with Different Services While Drilling
More LessSummaryUnder the current digital oil field development environment, reservoir profile update rate (RPUR) is introduced as a key quantitative indicator to evaluate the efficiency of 2D reservoir description and 2D reservoir profile update degree with specific services while drilling. RPUR is defined as the average of the boundary update rate (BUR) and the layer’s property update rate (LPUR). It greatly depends on DOD and resolution of the selected service while drilling to update boundaries and layers in different reservoirs. Deeper DOD and higher resolution for more boundaries and interlayer area detected with higher certainty, higher profile update degree with higher probability, and vice versa. Multiple examples presented advantages of different services for effective reservior description in specific reservoirs, which can be quantitatively evaluated by RPUR factor. The current RPUR concept is only a prototype with simplified factor and standard considered. More details should be input to refine this concept for more applicable reservoirs and situations.
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Mapping the OWC with extra-deep resistivity in the Lower Burgan reservoir, Kuwait
Authors T. El-Gezeery, Y. Halawah, M. Al Rashidi, S. Al Sabea, P. Sudiro and E. SitinjakSummaryThe Aptian Burgan reservoir, located in the Minagish Field of Kuwait, consists of a thick sequence of amalgamated channel sands providing good lateral connectivity; however, a fault network connecting the sands to the aquifer could potentially allow a premature water breakthrough. Moreover, several producers were drilled in the area, affecting the position of the OWC, because of a significant water rise in proximity of horizontal and vertical producers. The Burgan reservoir is, therefore, a challenging environment for the placing and completion of horizontal wells, requiring the accurate knowledge of the position of the OWC for optimal wellbore placement and completion planning. Kuwait Oil Company decided, therefore, to run a slim-hole BHA including a conventional azimuthal propagation resistivity tool in combination with an extra-deep azimuthal resistivity tool and multicomponent resistivity inversion modelling for the drilling of a new horizontal drain hole. This choice allowed both to successfully map the OWC and place the wellbore at the required position within the reservoir for the entire extension of the lateral section.
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Novel GTS for realistic geosteering training and optimization of well placement strategies
Authors B.E. Danielsen, F. Antonsen, M.V. Constable, M.E.T. De Oliveira, K. Hermanrud and S.A. PetersenSummaryA new geosteering training simulator (GTS) is in development to prepare even better for the real-time geosteering and to test if the geosteering strategy is possible to implement when the data is presented point-by-point along the trajectory as they will be presented for a given bottom-hole assembly during drilling. Pre-job model inversion results and log curves presented along a complete trajectory may look easier to interpret than the limited data set available real-time at specific decision points. A GTS-tool opens the possibility to do pre-job training for those involved in the geo operational support of a specific well or to introduce new personnel to the geosteering experience of making decisions while drilling. Having access to the GTS in the pre-job phase could be the difference between success and failure and save cost by avoiding unnecessary mistakes. The first prototype of the GTS has been applied in internal training of operational personnel. The next step will be to use this tool prior to real operations to validate the geosteering strategy and possible contingencies.
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Practicalities of 3D Well Placement
Authors N. Clegg and A. WalmselySummaryWell placement operations, in which ultra-deep electromagnetic (EM) tools are deployed have relied on 1D and 2D inversion algorithms, to generate geological models displaying the distribution of formation and fluid boundaries as defined by variations in resistivity above and below the well bore. Well placement optimization has focussed on changes to a wells TVD or inclination based on analysis of the resultant models. Where geology is complex, due to the depositional environment and post depositional deformation of the reservoir, in additional to vertical changes, there can be major lateral changes in the position of resistivity boundaries. In wells targeting these reservoirs, treating well optimization as simply an up/down problem severely limits the potential for successful well placement. Recent advances in inversion technology into 2.5D and 3D allow an assessment of this lateral resistivity variability. When deployed real time these tools introduce the option of azimuthal corrections to a well path in response to analysis of lateral changes in the EM field to optimize the wells position within the target reservoir. This presentation examines the practicalities of identifying changes in the position of formation/fluid boundaries in 3D and what needs to be considered when attempting well placement optimization under these circumstances.
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Real Time Navigation in Complex Deltaic Scenario: The Role of Multiscale Approach for Geosteering Optimisation
By A. LeoneSummaryThis extended abstract would like to illustrate how the continuous interaction between multiple expertise, and the evaluation of datasets coming from different scales of investigation, is the key to face complex geological scenarios during operational activities. The reservoir target is part of a deltaic system, prograding along well azimuth and constituted by oil-bearing sandstones. Once drilled the top, the reservoir appeared very different and more complex than expectations, with the risk of compromise the whole operation and well success. Conversely, the continuous interaction between different scale domains such as logs, azimuthal images, UDAR inversion, 3D Geological model and Seismic, permitted to make the picture brighter and react in time for optimize the well placement, with further relevant good production results.
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The Use of High Performance and Cloud Computing in Well Placement Operations
By V. UsaitisSummaryModern drilling and well placement operations utilizing Electromagnetic (EM) inversion require high performance computational environments. These can be either on-premise as a high performance computer (HPC) or on the cloud as a collection of virtual machines. This presentation discusses some of the current uses of High - Performance and Cloud computing, the benefits this brings to well placement operations and how this can be used efficiently.
In addition, the presentation addresses the stability of the system. Uninterrupted services are a mainstay of real time drilling operations, fast, reliable data connections are required to transmit and receive data from the cloud. It is often discussed as an ephemeral resource but requires physical infrastructure. It is vulnerable to service interruptions, these can be anticipated, and contingencies put in place to limit their impact, but they need to be identified and understood prior to commencement of operations.
Computational resources need to be deployed efficiently to limit or exclude unnecessary costs. As this technology develops well placement software needs to remain agile to benefit from these advances. This will become more critical with the development of automated geosteering workflows and the associated increases in processing power required.
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Remotely navigating thin reservoirs in ERD wells. North Slope Alaska
Authors P. Sudiro, K. Hoffmeister, M. Howell, A. Small and I. SaysSummaryThe Alpine Field, located on the Coville River Delta on the North Slope of Alaska, has been developed exclusively with horizontal wells since 2000. Despite extensive knowledge accumulated throughout the development of the field, many geological uncertainties remain, due to the sedimentary and tectonic complexity of the field. The further development of the field included the drilling of a dual-lateral well targeting two sand layers at different stratigraphic positions within two siliciclastic depositional sequences separated by a major erosional surface stratigraphy of the target interval consists of divided by a major unconformity. Operations were further complicated by logistic consequences of the spreading of the Covid-19 pandemic, deeply affecting travel and physical interactions. These new work conditions would present a challenge to most operators on how to ensure fluid and timely communications between the geosteering team members working from different locations. Despite geological complexity, and the need for fully remote support, geosteering operations proved successful and achieved the desired planned objectives with 70% of the wellbore drilled within the target layer in the upper leg and 95% of the wellbore placed in the target layer in the lower leg.
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Real-Time 3D Imaging of a North Sea Turbidite Reservoir
Authors S. Sinha, K. Riofrío, A. Walmsley, N. Clegg, S. Sviland-Østre and N. GuezeSummaryUltra-deep 3D EM inversion provides high-resolution 3D reservoir imaging that can be used for real-time operational decision making and as a complementary tool for reservoir modelling and geophysical surveillance. Subtle, fine scale mapping of internal reservoir architectural elements is now possible. Significant improvements in overall imaging quality compared to 1D and 2D inversion canvases can be observed in dipping stratigraphy or where there is some degree of reservoir complexity. The real-time functionality also provides this 3D data in time to support completions optimization decisions where required.
Correlation of multiwell 3D EM datasets against 3D seismic provides the basis for a consistent geological interpretation at field scale. Reservoir characteristics and mechanisms such as compensational stacking and lateral channel migration could previously only be inferred from reservoir modelling studies but now can be directly imaged in real-time.
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2D Inversion for Structure with Angular Unconformity on Example of Troll Field
Authors A. Astrakova, E. Konobriy, D. Kushnir, N. Velker and G. DyatlovSummaryAngular unconformity of bed boundaries and the oil-water contact is common for the Troll field in Norway. The depth of investigation and azimuthal sensitivity of extra-deep azimuthal resistivity (EDAR) measurements make it possible to image such complex structures. The paper describes an approach to real-time 2D inversion based on artificial neural networks (ANNs). We propose a 2D parametric model with two non -parallel boundaries suitable for scenarios with angular unconformity and pinch-out. The 2D inversion algorithm utilizes the Levenberg-Marquardt optimization method and the ANN-based solver. Training of the ANNs for the parametric model is performed using a synthetic database containing samples with the model parameters and corresponding tool responses. The inversion is performed interval by interval first with the 1D layer-cake model. If any “non-1D” behavior is observed in the data or the resulting picture, then we switch to the 2D model. On the example of one of the wells in the Troll field, we demonstrate that the described approach reconstructs the oil-water contact and the unconformable boundary with the performance fast enough for real-time.
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P01: Coal Seam Miming: a new frontier for advanced real-time modeling with deep azimuthal resistivity
Authors A. Martins Vianna Neto, K. Boyce and M. RamsaySummaryThe longwall-mining method is a continuous mining system that was developed for mining coal deposits (uniform in thickness and slope), where the overburden pressures may crush support pillars and for improving productivity. This method relies on the complete extraction of the coal in a designated area referred to as a panel (of solid coal). As the panel is mined, complete subsidence or caving of the overlying rock strata occurs into the mined-out area behind the working mine face. Prior to mining the panel, degasification is a mandatory process to extract gas in the coal seams. In order to maximize the coal seam understanding and minimize the number of side-tracks, anovel methodology in the mining industry has been implemented - utilising azimuthal propagation resistivity (APR), multi-layer inversion with uncertainty analysis and real-time 3D structural reservoir modelling.
The bed boundary mapping also allows for the future development of automated long wall mining. The automated system uses specialized remote guidance technology to continuously steer the longwall equipment by plotting its position in three dimensions, removing personnel directly from hazards and thereby increasing the safety of the process.
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Technical and intra-organizational implementations for improved geosteering and reservoir characterization
SummaryA workflow has been developed to conserve expert knowledge across the different disciplines relevant for geosteering, and to minimize real-time misinterpretations and suboptimal decisions. To enable the workflow, a dedicated geosteering expert group has been established. Technical advancements including 3D modelling capabilities and the possibility of creating automated model perturbations have been made within an inhouse geomodelling software. Furthermore, a geosteering training simulator (GTS) has been developed to make the geosteering “experience” available for personnel outside drilling hours. The GTS has been applied for training of internal personnel, but significant upgrades are expected due to high research priority. The overall workflow is in its early stage of operation and is designed to handle integration of future technical solutions as they become available. Currently, the expert group provide technical services to the assets and other personnel in volved in geosteering while the research group has a continuous focus on further developments. However, streamlining the workflow will require fully operational cloud solutions and data lakes where cross-organizational data and algorithms can be shared in a safe and efficient way.
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Retrofit Multilateral application - Innovative solution to unlock reservoir potential and increase recovery. Goliat experience
Authors C. Musca, G. Tosi, S. Ragaglia and L.L. NapoleoneSummaryRetrofit multilateral application has been applied for the first time in Barents Sea and on Norwegian continental shelf. This technology has unlocked potential, enabled fast track drilling (reduced time to market) and reduced capex in otherwise sub-economic targets. The conversion of single producers in multilateral, as retrofit application, allowed to accelerate production with limited additional required sub sea material.
The integration of Ultra Deep Azimuthal Electro-Magnetic tool with standard LWD technologies has helped the landing of the wells in the reservoir sections and has delivered the valuable geological information to successfully guide the navigation of the oil producers through the reservoir layers.
The presented two case studies are focusing on the operations while drilling, infill well results, main lessons learned and the way forward for the application of multilateral retrofit technology in other assets.
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Mapping of Water Slumping using Ultra-Deep EM Logging While Drilling Technology in carbonate Reservoirs Onshore-Abu Dhabi
Authors W. Fares, M. Singh, M. Al Manssori, V. Pandey, I. Seddik, S. Al Arfi, D. Boyd, N. Clegg and A. AkiSummaryUltra-deep EM - LWD technology - Reservoir Mapping - Water flood fronts - Carbonate Reservoirs.
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Enhancing the Understanding of a Mature Giant Oil Field from the Wellbore to Reservoir Scale
Authors M. Viandante, L. Pontarelli, S. Leveque, C. Longis, S. Finlay, S. Sen, D. Cross, D. Hartney, A. Azeem and O. OnyiaSummaryThe “Giant Oil Field” has been on production for 29 years and is currently developed using waterflood and more than 350 ERD horizontal wells, spread over 8 different reservoirs. Amongst the complexities of the drilling in a carbonate reservoir, the brown field nature of this mature field, adds a dimension to the difficulties associated with profitable oil extraction.
Developing optimally and understanding those reservoirs present multiple challenges, requiring a multidisciplinary approach to address them.
Therefore, a novel data acquisition plan based on Reservoir Mapping While Drilling Service (RMWD) allowed to bridge the gap and join the reservoir scale information (Surface Seismic, 4D Seismic and Production model) with near-by wellbore information (conventional LWD logs, core and cutting analysis for facies identification).
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Ultra-Deep EM LWD Mapping tool provided efficient geostopping solution to eliminate need for pilot holes Offshore-UAE
Authors A. Al Felasi, K. Honda, O. Al Mutwali, H. Khemissa, B. Al Dhafari, M. Ashraf, S. Al Hajeri, Y. Goraya, A. AlKhoori, W. Fares, A. Aki and N. CleggSummaryUltra-Deep, EM, Mapping, Geostopping
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Reducing 3D uncertainty by an ensemble-based geosteering workflow: an example from the Goliat field
More LessSummaryA probabilistic decision support system for geosteering coupled with automated data assimilation techniques has been shown to outperform many humans at least in sandbox 2D experiments. Utilizing probabilistic decision support for optimal positioning of real wells requires a 3D probabilistic earth model compatible with standard tools, and rapid generation of synthetic logs of extra-deep measurements.
We introduce a method for representing a 3D earth model with depth uncertainty in stratigraphic surfaces. The surfaces are parameterized using a multi-scale technique, capturing correlations and uncertainties on both large and small scales. The probabilistic earth model is updated by an ensemble-based method that assimilates extra-deep EM measurements acquired while drilling. A recently developed Deep Neural Network model ensures rapid simulation of extra-deep EM measurements. However, the model assumes local layer-cake geology and thus can only interpret 1D sensitivity for each measurement position.
The proposed method is applied to a synthetic study based on geosteering in the Goliat field. The results demonstrate that data assimilation of the extra-deep EM measurements successfully reduces uncertainty in the 3D model and updates it towards the truth. Moreover, we demonstrate 3D visualization of the probabilistic model compatible with standard geo-modelling tools, useful for decision support.
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Probabilistic forecasting for geosteering in fluvial successions using a generative adversarial network
Authors S. Alyaev, J. Tveranger, K. Fossum and A.H. ElsheikhSummaryQuantitative workflows utilizing real-time data to constrain ahead-of bit uncertainty have the potential to significantly improve geosteering. Fast updates based on real-time data is particularly important when drilling in complex reservoirs with high uncertainties in pre-drill models. However, practical assimilation of real-time data requires effective geological modelling and mathematically robust parameterization. We propose a generative adversarial deep neural network (GAN), which is trained to reproduce geologically consistent 2D sections of fluvial successions. Offline training produces a fast GAN-based approximation of complex geology parameterized as a 60-dimensional model vector with standard Gaussian distribution of each component. Probabilistic forecasts are generated using an ensemble of equiprobable model vector realizations. A forward-modelling sequence including a GAN, converts the initial (prior) ensemble of realizations into EM log predictions. An ensemble smoother minimizes statistical misfits between predictions and real-time data, yielding an update of model vectors and reduced uncertainty around the well. Updates can be then translated to probabilistic predictions of facies and resistivities. The present paper demonstrates a workflow for geosteering in an outcrop-based, synthetic fluvial succession. In our example, the method reduces uncertainty, and correctly predicts most of major geological features up to 500 meters ahead of drill-bit.
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Wellbore Trajectory Optimization Using Geological Inputs
Authors M. Abughaban and A. AlaliSummaryDirectional wellbore trajectory is a critical aspect of early well planning. Planning the optimum directional wellbore trajectory requires drilling engineers to integrate cross-domain inputs from geologists, geophysicists, and reservoir engineers.
In this paper, we introduce a system to optimize the wellbore trajectory during the planning phase of the well construction. The system will capitalize on early optimization by integrating cross-disciplinary data prior to drilling, allowing for higher spatial correction. The integration will produce a drilling hazard seismic attribute (DHSA) that correlates geologically induced drilling nonproductive time (NPT) from all offset wells per specific field and formation.
Through its cross-disciplinary approach of utilizing historical, geophysical, and drilling engineering, this system drives the full integration and automation process of the well trajectory evaluation. This process is centered on minimizing drilling risks, delivering the optimum well trajectory from the planning stage, and allow engineers to better understand the structural geology and geohazards from the surface to total depth (TD).
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Integration of Seismic and 3D Ultra-Deep Azimuthal Resistivity LWD
Authors M. Alexander, D. Salim, M. Etchebes and T. AkindipeSummaryAn innovative method to improve the delineation of the reservoir geometry and properties surrounding high -angle wells has been developed. The workflow begins by conditioning the surface seismic and creating geobodies. The surface seismic attributes are then combined with three-dimensional resistivity volumes built from the advanced interpolation of the two-dimensional electromagnetic azimuthal inversions of the Ultra-Deep Azimuthal Resistivity logging-while-drilling tool to develop an accurate geological model.
The method has been used on a horizontal well located in Alaska, USA. Key stratigraphic and structural features were revealed, such as fault identification and characterization and the bifurcation of the reservoir with high er net-to-gross reservoir properties being developed to the west.
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A multi-physic methodology for 3D structural delineation and geosteering in real-time using cloud computing
Authors M. Bower, D. Salim, M. Etchebes and V. WibowoSummaryReservoir Mapping While Drilling has helped improve the geosteering and reservoir mapping services for over a decade and bridges the gap between borehole and seismic scale data. This example illustrates how, by utilising cloud computing power and combining the analysis of seismic data with borehole derived full 3D electromagnetic LWD measurements, leads to an improved structural delineation and geosteering results in 3D space, all during real-time drilling operations.
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P03: Jurassic gas. Geosteering with reservoir mapping technology in Jurassic deposits of Zapadno-Yurkharovskoe field in Russia
Authors V. Sayfitdinova, R. Khabibullin, E. Skorikova, T. Berdnikova and A. ShakunovSummaryThe country’s powerful mineral resource base is a guarantee of its security and successful development. A significant share of Russian mineral resource base are hydrocarbons: oil and natural gas, the production of which should be maintained at the achieved level in the long term. Over time, this task becomes more and more difficult to fulfill due to the depletion of proven reserves. Thus, oil and gas industry is increasingly interested in the not previously developed «border-economic» hydrocarbon reserves, which is also facilitated by tax incentives, a well-developed infrastructure of old production complexes and, of course, the latest technologies for productive formations characterization. This article describes the experience of geosteering using the technology of remote boundary detection while drilling to solve the versatile problems of developing hard-to-recover reserves of the Middle Jurassic oil and gas complex of Zapadno-Yurkharovskoe field.
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Using a real-time 3D-reservoir-mapping tool to image a complex deep-water reservoir in a producing oil field
More LessSummaryThe Laverda Field is a deep-water slope canyon on the North-West margin of Australia operated by Woodside Energy Ltd. with Mitsui E&P Australia Pty Ltd as a Joint Venture Participant. Development drilling in 2018–2019 comprised five long producer and injector wells that were geo-steered in thin high quality oil bearing reservoirs. The field successfully came on stream in July 2019 but a re-drill of one production well, located 30 metres downdip and parallel to the original well, was required in June 2020. The re-drill offered the chance to use new real-time 3D reservoir mapping tool technology. This new technology significantly improved the imaging of the reservoir in both a vertical sense and up to 30 metres laterally either side of the wellbore including the original well. Its greater depth of investigation and higher resolution enabled an optimised well path and a successful completion programme in a geologically complex reservoir.
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Similar geology, same stochastic inversion, different azimuthal resistivity tools - lessons learned from well placement experience
Authors D. Nemuschenko, P. Shpakov, P. Bybin, K. Ronzhin and M. SviridovSummaryNowadays proactive geosteering has become almost mandatory for drilling horizontal wells, because using this method you can predict boundaries position and avoid exit from desired zone. One of the best method of proactive geosteering is deep-azimuthal resistivity and inversion as method to analyze it. This article includes the results of applying the developed stochastic inversion to Novatek data from ADR (Halliburton) and AziTrak (Baker Hughes) tools in similar geological conditions of the terrigenous formation of West Siberia.
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Azimuthal geosteering technique
Authors T. Popov, D. Leontyev, I. Evdokimova, Y. Selivanov and V. KimSummaryToday geosteering mostly focused at 2D models along planned borehole azimuth. This approach allows to adjust trajectory by changing the inclination based on comparing synthetic and real-time logs and interpretation of images and boundary detection tools. However, there are cases which required drilling at single TVDSS, but there are remained structural uncertainties. Consequently, it is required to perform geosteering to keep the wellbore inside the target formation, for example while drilling the laterals in oil rims at the edge of structures with steep formation dips. In such cases trajectory azimuth adjustments needed for changing stratigraphical position of the borehole. Conventional geosteering approach doesn’t provide accurate decisions assessment and new techniques are required. Abstract describes an approach of azimuthal trajectory adjustments for well placement. Different methods of azimuthal steering reviewed in this paper in dependence on formation strike and dip. Provided calculations could be utilized for quick decision-making process while geosteering. Additional data of LWD images and boundaries detection tools evaluated in respect to azimuth adjustment technique and efficiency of its applications.
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New multiscale measurement approach for geosteering in low resistivity and low contrast reservoirs: Cygnus field
Authors M. Dupouy, K. Simpkin, M. Covill and M. BowerSummaryDecember 2016, with 60% of the reserves being found in the Leman Formation. The Leman was initially developed in the best reservoir quality fault blocks via horizontal wells drilled with Periscope HD and borehole images. As the development progressed, poorer reservoir quality intervals were targeted. The 2012 FDP envisaged completion via fracture stimulation with associated risks and costs.
To address challenges in the latest Cygnus reservoir section, the worldwide first combination of measurements from the Geosphere HD and Periscope HD was utilised; combining two scales of depth of investigation and resolution. The results allowed for accurate placing within the thinly bedded and low contrast reservoir intervals, while being able to understand the well’s true stratigraphic position and the character of the Carboniferous subcrop in real time. The multiscale measurements helped Neptune to optimize the well path position and delivered greater confidence in decision-making whilst drilling.
Once the well was completed, it tested at higher rates than would have been expected and avoided a fracture stimulation. This tool combination has opened new development targets within other low reservoir quality areas on Cygnus.
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Integrating time-indexed archives of past drilling data improves the reliability of geosteering and monitoring activities
More LessSummaryGeosteering is predicated on the concurrent observation of data transmitted from the drilling operation characterizing the rocks and fluids encountered at or close to the drilling bit, and existing models and predictions used to plan the well. In an ideal world they should match, indicating that the models and predictions were correct and that the drilling is located at exactly the right 3-dimensional location relative to the surrounding formations and the area of interest within the formation. Of equal importance is the use of measurements from prior drilling activities geographically close or having penetrated formations similar to the current well. Their availability can provide insights into current events. The use of a time-indexed repository that contains the records of the data coming from prior real-time data transmissions allows for a direct comparison and assessment of live data channels compared to historical ones. This facilitates the application of analytics and the training of machine-learning systems.
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Mapping Reservoir in Complex Fluvial Channel Sand with 3D Mapping Reservoir Mapping While Drilling
SummaryThe novel ultra-deep 3D bed boundary mapping technology was first ever implemented in case study well with the objective to map the various sand bodies in 3D while cutting down structure through the entire Wara section. The following paper discusses the key aspect of this technology and the results that followed.
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Accurate reservoir description and well placement using distance data, zone logs and depth to fluid contact
Authors P. Dahle, A. Almendral Vazquez and A. SektnanSummaryWe show how distance data derived from inversion of logging-while-drilling directional resistivity (DDR) measurements can be used to constrain both the surfaces confining the reservoir and the well being drilled.
For geosteering, it is important to know where the well is relative to the reservoir surfaces and contacts while their absolute positions in space is irrelevant. DDR measurements provide the perfect data for this. We have used a Bayesian kriging framework to include DDR data directly in predictions of surfaces and wells. Taking into account uncertainties in distance data, surface depth, and the TVD position of the well, this method can be used to continuously update the position of reservoir surfaces and well while drilling,
For a real reservoir, we demonstrate how the prediction uncertainty can be reduced by adding different kinds of well data to the prediction, and how the prediction uncertainty increases when the well path TVD uncertainty is accounted for. We also show how the free water level can be taken into account in the surface prediction.
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Finding the needle in a haystack: Multi-solution integration for multiple challenges, a case study from UAE
Authors J. Maalouf, S.M. Lyonga, S. Suleiman, W. Siddiqui, C. Shrivastava, M. Ashraf, H. Khemissa and Y. GorayaSummaryIn this case study, a Maximum Reservoir Contact (MRC) had multiple objectives to achieve in a 3ft thick limestone layer.
First it needed to detect the high risk water zones.
Second, the areas with high Gas Oil Ratio (GOR) needed to be identified and avoided
Third, that thin layer needed to fall within a certain permeability range.
Fourth, the geology is uncertain with fast changing dip and faults.
Several technologies were combined including a first in the UAE, the ElectroMagnetic (EM) images in Oil Based
Mud OBM, to resolve for all these challenges and deliver a successful 13000ft long horizontal.
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