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Irving A.D.,German Research Center for Geosciences | Irving A.D.,University College Dublin | Chavanne E.,Total S.A. | Faure V.,Total E and P UK | And 2 more authors.
Geological Society Special Publication | Year: 2010

Despite their significance, structural parameters are sometimes neglected in assessments of uncertainty on connected volumes and forecast production for compartmentalized reservoirs. A workflow is proposed for modelling multiple realizations of fault geometry and properties using 3D geomodelling software. Geometrical parameters that may be simulated include fault and horizon shape and location, fault displacement and fault pattern, while property variables include fault permeability, thickness and clay smears. Realizations are ranked by estimated connected volume, with selected models being exported for numerical flow simulation. Experimental design is used to assess sensitivity of forecast production and pressure to different parameters. The workflow is illustrated using a North Sea reservoir, in which structural heterogeneities cause considerable uncertainty on connected volumes, with implications for history matching and infill well planning. Fault geometry and permeability were the most important properties for all studied responses, however their relative significance could vary between early and late field life. A number of improvements are proposed, chiefly in the areas of connected volume estimation, handling of uncertain grid geometries and calculation of stress- or saturation-dependent fault permeabilities. Finally, the method can be integrated with conventional sedimentary and petrophysical uncertainties to investigate interactions and relative sensitivities with regard to structural parameters. © The Geological Society of London 2010.

Mohamed L.,Heriot - Watt University | Christie M.,Heriot - Watt University | Demyanov V.,Heriot - Watt University | Robert E.,Total E and P UK | Kachuma D.,Total E and P UK
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2010

Reservoir modelling is frequently used in the oil industry to measure the risk associated with alternative production scenarios. However, reservoir models themselves contain a high level of uncertainty because of the typically very limited, sparse and multi-scaled reservoir knowledge. The effect of this uncertainty can be assessed by producing a set of diverse models that match the production data reasonably well and using these models to quantify uncertainty in predicting the future performance of the reservoir. Evolutionary and swarm intelligence algorithms have become very popular for history matching due to their simplicity and parallel implementation capacity. This paper focuses on the application of Particle Swarm Optimisation (PSO) for history matching the Brugge field (a recent SPE benchmark case study). The parameterisation of the model is based on principal component analysis (PCA) for modelling spatially correlated random fields (e.g. porosity, net-to-gross and permeability) applied to the set of initial realisations which describe the range of prior beliefs. The PSO is then used to find the set of possible combinations of parameters, represented by the PCA eigenvalues, which match the historical data and honour the static data from the wells present in the initial realisations. We show that PSO is able to find multiple good and diverse history matched models for the Brugge reservoir without exhaustive sampling of the parameter space. Uncertainty of production forecasts are quantified by P10-P50-P90 uncertainty envelope obtained from the ensemble of PSO models. The history matching results are compared with the ones obtained with Ensemble Kalman Filter data assimilation method. These results show the ability of PSO to handle large history matching problems and obtain results comparable to the EnKF for this case study. Copyright 2010, Society of Petroleum Engineers.

Edwards J.,CNRS Georesources lab | Lallier F.,Total E and P UK | Caumon G.,CNRS Georesources lab | Carpentier C.,CNRS Georesources lab
2nd EAGE Integrated Reservoir Modelling Conference - Uncertainty Management: Are we Doing it Right? | Year: 2014

We propose a method to manage uncertainties about the layering of 3D reservoir models, using stochastic correlations of sedimentary units identified along wells, according to the sequence stratigraphy paradigm. A stratigraphic model represents the architecture of the stratigraphic succession of an area. Sequence stratigraphy is a common paradigm in reservoir studies to interpret and correlate local high resolution observations (outcrops, well logs and core samples) and more exhaustive but lower resolution data such as 3D seismic. The incompleteness of these data, their quantity and their varying quality, added to the fact that the processes that control the geometry and the conformability of the sequences are complex and poorly known, lead to uncertainties. The proposed method aims at building stratigraphic models honoring 1D interpretations along wells together with conceptual sequence stratigraphic rules formulated quantitatively as correlation costs. The algorithm chosen is a modified version of the Dynamic Time Warping algorithm. More than finding the best correlation using a set of rules, it handles different orders of sequences, takes in account the conformability of the horizons, and its output is a set of different possible correlations, allowing for generating alternative stratigraphic layerings. This methodology is demonstrated on the Teapot Reservoir, Wyoming.

Edwards J.,University of Lorraine | Lallier F.,Total E and P UK | Caumon G.,University of Lorraine
2nd Conference on Forward Modelling of Sedimentary Systems: From Desert to Deep Marine Depositioned Systems | Year: 2016

Conditioning a forward stratigraphic model to seismic or well data is still a challenge. So, such model cannot usually be used to run static or dynamic reservoir studies. In common methodologies, training images are built from FSM and used with Multiple Point Statistics methods to integrate the information in static geocellular models. Similarly, we present a method that uses a FSM as training model to generate 3D stratigraphic correlations of a set of units identified along wells. The wells are correlated iteratively, each new well being correlated to the result of the previous correlation. This ensures to take the 3D disposition of the wells into account. When the probability of association of the units is computed, we use the Dynamic Time Warping algorithm to build a consistent stratigraphic correlation. First results on synthetic data are presented, using a forward model built with the Sedsim algorithm and three wells. © 2016, European Association of Geoscientists and Engineers, EAGE. All rights reserved.

Grant P.,Total E and P UK | Lassus L.,Total E and P UK | Savari S.,Halliburton Co. | Whitfill D.L.,Halliburton Co.
SPE - International Association of Drilling Contractors Drilling Conference Proceedings | Year: 2016

Recently, there has been significant interest in understanding the material properties of lost circulation materials (LCM), including size degradation studies from mechanical compression tests and from shear flow. These types of tests are currently of particular importance because of increased drilling activity in mature fields, which often require LCMs as a background material. The objective of this work is to present the size degradation of LCMs from flow loop tests. A flow loop test was performed to study the size degradation of LCMs, mainly ground marble (GM) and resilient graphitic carbon (RGC). A predetermined amount of GM and RGC was added to an 80-bbl synthetic-oil-based drilling fluid. The flow loop consisted of 3-in. diameter flow lines. One circulation through this flow loop required approximately 8 minutes, which is equivalent to one circulation in the actual field application. The fluid with LCM was circulated through the flow loop at a 400-gal/min flow rate. Fluid samples were collected at different stages, and a wet sieve analysis was performed to determine the amount of material in the drilling fluid retained on each sieve. Comparing the amount after the flow with the amount before flow allowed estimations of the LCM size degradation. This provided the size degradation the LCM would experience as a result of flow through the loop. Another objective was to study the effect of a turbine, which was anticipated to be part of the bottomhole assembly (BHA) on the size degradation rate of LCMs. To evaluate this, a turbine was incorporated in the flow loop, and the fluid with LCM was again circulated at a 400-gal/min flow rate. Again, samples were collected at different times, with a wet sieve analysis performed to determine the size degradation of LCMs when flowing through the turbine and the flow loop. GM was subjected to a 35% size reduction resulting from the flow loop alone, compared to only a 16% size reduction of the RGC. When the turbine was added to the flow loop, GM was almost completely degraded (a total of 75% reduction) to a smaller size after only one circulation through the loop. Concurrently, the RGC experienced only a 20% reduction in size even after 160 minutes of flow (20 circulations) through the loop and the turbine. Size degradation studies of LCMs were conducted for the first time in a flow loop at a 400-gal/min circulation rate. The results show the importance of using a resilient LCM, such as RGC as part of a LCM background package when drilling lost circulation problem zones in mature fields. Copyright 2016, IADC/SPE Drilling Conference and Exhibition.

Abadpour A.,Total E and P UK
ECMOR 2012 - 13th European Conference on the Mathematics of Oil Recovery | Year: 2012

Recently a significant effort has been made to characterize reservoir models benefiting from Ensemble Kalman filter as data assimilation technique. EnKF proved to be a powerful tool to deal with almost any sort of measurement also to be capable of handling different type of uncertainty in the simulation models and and being affordable from the computational point of view. Lately the technique has been deployed to assimilate on pressure transient and production logging data to update permeabilities and estimate layer skin factor. In the present paper EnKF methodology was used to characterize an offshore reservoir model against the well test pressure data as well as the pressure derivative to adjust cell by cell petrophysical properties, and the skin factor in each well perforation. The results showed that using the derivative observations to calibrate the uncertain parameters helps improving the quality of the match not only in the predicted derivative but also in better forecasting the pressure measurements. The importance of assimilation on skin as well as recalculation of well connection factors revealed. Moreover a new distance based localisation scheme based on the well drainage zone has been introduced to help reducing unnecessary changes in the model.

MacPherson C.S.A.,Total E and P UK | Keown R.,Total E and P UK | Hynd C.,Total E and P UK
Society of Petroleum Engineers - SPE International Conference and Exhibition on Health, Safety, Security, Environment, and Social Responsibility | Year: 2016

Most of Shetland is covered in blanket bog mainly consisting of peat, one of the rarest wildlife habitats in the world. Construction of the Shetland Gas Plant (SGP) required the stripping of a layer of this peat. Early surveys of the area proposed for SGP and its associated pipelines recorded significant numbers of otters living and breeding in the area. The import pipeline landfall was shown to be a particularly important area, with two otter (lutra lutra) families living there. The Shetland otter population is one of the densest and most important in Europe. The area is also home to numerous species of nesting birds. The focus of this paper is to describe the measures that have been taken to both preserve the peat during the construction of the SGP and minimise the adverse effects on the animals. A summary of the archaeological findings beneath the peat is also described. The paper will explore the learning's in detail, highlighting the importance of not tracking over peat with machinery, cutting turves regularly and peat turf storage. Peat handling and restoration is a unique challenge to the SGP development. Copyright 2016, Society of Petroleum Engineers.

Hoy A.,Total E and P UK
Society of Petroleum Engineers - SPE/APPEA Int. Conference on Health, Safety and Environment in Oil and Gas Exploration and Production 2012: Protecting People and the Environment - Evolving Challenges | Year: 2012

The Shetland Gas Plant (SGP) is being constructed as part of the Total E&P UK operated Laggan-Tormoregas condensate development, locatedto the west of the Shetland Islands. One of the first challenges was the extensive peat covering the onshore site. Total is committed to site restoration at the end of the plant's operating life and the peat has been excavated and stored on site for site restitution. This was considered the best practicable environmental option. The priority has been to ensure the peat remains saturated so that anaerobic conditions are maintained and the peat degradation is minimised. This extended abstract reviews the peat management process: planning, construction of the peat storage, peat handling, and the regulatory requirements for storage and long term monitoring at the site. Copyright 2012, SPE/APPEA International Conference on Health, Safety, and Environment in Oil and Gas Exploration and Production.

Blanchard T.D.,Total e and P UK
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

Separation of pressure and saturation changes from 4D Amplitude information is becoming more common. Current practice requires elastic properties to be estimated independently from amplitude information (AVO) with few constraints, and pressure and saturation to be estimated from these elastic parameters. We show that inherent uncertainties in the inversion for elastic parameters from 4D AVO data can be very poorly determined, potentially leading to the inability to detect changes in pressure and saturation. Using a calibrated poro-elastic model, we show that pressure changes produce elastic parameters that are poorly determined in the 4D AVO inversion, highlighting the need for using additional constraints in AVO inversion such as the time-shift.

Xu Y.,Total E and P UK Ltd | Thore P.,Total E and P UK | Duplantier O.,Total E and P UK Ltd
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

In this paper we present a new inversion scheme the "3D Propagation". We have applied it to a synthetic model composed of thin layers compared to seismic bandwidth. The synthetics have been created in order to mimic the behavior of a thin bed clastic reservoir from the West Shetland. The synthetic test shows that most of the thin bed boundaries as well as property values are accurately resolved by 3D propagation inversion. For comparison, a conventional deterministic inversion is conducted on the synthetic data. It also achieves a good job when a relatively accurate low frequency model is provided. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.

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