Résumé -Impact des hétérogénéités sur la production d'huiles lourdes mobiles par SAGD -L'augmentation de la demande en pétrole et l'existence de réserves conséquentes en huiles lourdes et bitumes vont motiver, dans les prochaines décennies, un effort important pour développer les réservoirs non conventionnels. Dans ce cadre, la production par drainage gravitaire soutenu par une injection de vapeur (SAGD) est une technique très prometteuse pour extraire les huiles lourdes des réservoirs épais et de forte perméabilité. Les tests pilotes conduits sur champ à ce jour ont souligné l'influence des hétérogénéités sur le développement de la chambre induite par l'injection de vapeur. Cette étude présente les résultats d'une analyse numérique visant à apprécier l'impact des hétérogénéités sur la quantité d'huile produite par SAGD dans des réservoirs contenant des huiles lourdes mobiles. Une population de modèles de réservoir contenant 0, 10, 15 ou 20 % d'argile a été générée aléatoirement. Puis, la production par SAGD a été simulée pour chacun de ces modèles. Il apparaît que l'influence des lentilles d'argile dépend de leurs positions par rapport aux paires de puits, la configuration la plus préjudiciable étant celle où les lentilles argileuses se situent entre le puits injecteur et le puits producteur. En outre, on observe qu'on obtient la moitié, le tiers et le quart seulement du volume produit cumulé pour le modèle homogène après 3 ans de SAGD lorsque les proportions d'argile sont respectivement de 10, 15 et 20 %. Parallèlement, on montre que le CSOR passe de 2 pour le modèle homogène à 3 pour les modèles avec 20 % d'argile. Abstract -Heterogeneity Impact on SAGD Process Performance in Mobile Heavy Oil Reservoirs -The increasing oil demand and the significant amount of heavy oil/bitumen reserves will motivate a huge effort on the development of heavy oil reservoirs in the next decades. Within this framework, Steam Assisted Gravity Drainage (SAGD) is a very promising technique to produce heavy oil from thick and high permeability reservoirs. The small scale field tests conducted up to now highlighted the influence of heterogeneities on the development of the steam chamber involved in SAGD. This work presents a numerical investigation of the effects of heterogeneity on

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SUMMARYThis work deals with the development of a constitutive law for fractured rocks. Fractures are considered as penny-shaped inclusions, whose constitutive law is deduced from an interface law and a regularization procedure. Such a method is applied to linear and non-linear interface behaviours in order to reproduce effects such as an increase in stiffness during fracture closing, dilatancy or asperity surface degradation. Then, considering the fractured rock as a composite material, we use a Mori-Tanaka method to estimate the homogenized properties of the rock. Numerical experiments illustrate the interest of the proposed homogenization procedure.

The Martin Linge field was discovered in the 1970's but never developed due to a number of uncertainties. The complex structural settings of the Brent reservoirs was the main issue: transmissibility through the numerous faults has a direct impact on the number and type of development wells required for an appropriate drainage of the field, hence on the economy of the project In 2009/2010 Total drilled an innovative appraisal well to de-risk this challenging development. The primary objective was to evaluate the dynamic connectivity through faults on the Upper Brent level of Martin Linge East with an Extended Well Test (EWT) A program for the EWT (6 months duration), was defined and implemented in order to ensure conclusive results for the development strategy. The well design included an innovative completion system with acoustic wireless down-hole gauges and a communication system to transfer the pressure data up to sub-sea well-head and then to shore via a communication link. This made it possible to obtain extended pressure build-up data after the rig had left. The test targeted the uppermost Brent reservoir of Balta only. Analytical models were used to evaluate the investigated volume. This volume turned out to be significantly greater than the Balta reservoir accumulation, proving that the faults allow communication not only laterally but also vertically with the underlying Upper Brent Tarbert reservoir. Due to the structural complexity of the field and the large investigation, the Eclipse reservoir model was also used to match the EWT data with the earth model. The EWT simulations in this model highlight the high lateral and vertical connectivity through major faults Thanks to the EWT results, a marginal field was successfully turned into a robust development project

Using a software integrator, a commercial reservoir simulator is tightly coupled with a commercial Transient Well Model. This is required when transient reservoir behaviour interacts with transient wellbore phenomena. It is the case in a tight gas field which is being developed since 2012 in China; long natural cycles of gas production in liquid loading regime followed by period of low or quasi nil-gas production are observed. Cyclic production is also being implemented to optimize the average gas production. In both cases, usual decline curve analysis is no longer valid. And computing long term production forecast becomes a challenge. The innovative application presented in this paper is an optimization of Cyclic Production in Liquid Loading Regime of a tight gas reservoir by coupling transient modelling of reservoir and wellbore. A workflow is implemented in the software integrator RESOLVE which enables the coupling between a well and its multiple hydraulically fractured reservoirs. It ensures consistent results between the reservoir model and the transient well model in terms of mass flow rate, transient inflow performance and bottom hole flowing pressure. It also enables to visualize the cross-flow which occurs between the two reservoirs, and some water imbibition into the matrix during shut-in periods. Tested on various reference wells, this new methodology represents properly the historical behaviour of the wells during steady-state flow and during self-killing periods. When modelling cyclic production, various shut-in / restart criteria can be handled by the workflow. It enables to optimize the average production of the wells and deliver some guidelines to the field operation teams. This is a great achievement compared with the need to implement long "cyclic production testing" campaigns. Also, two-month coupled cyclic production modelling is performed at regular yearly intervals. Combining these long term production forecasts with the evolution of "average static pressure vs. cumulative gas production" derived from reservoir standalone long-term forecast, enables to compute reliable long term production forecast which accounts for cyclic production in liquid loading regime. The current results show significantly larger production than the one derived from usual decline curves. Overall, the study is a leap forward in understanding transient well and reservoir interactions in order to improve field Estimated Ultimate Recovery. This field tested methodology can also be applied to many other situations when well instabilities interfere with reservoir transient behaviour (gas-lift heading, interference between unstable outflow and multi-layers inflow behaviour). To our knowledge, it is a "World First" of a coupling between a full commercial reservoir simulator and a commercial transient wellbore software.