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The aim of this paper is to summarize the experimental work carried out by IFP on rock samples taken from the Meuse/Haute Marne underground research laboratory host formation. The behavior of this clayey rock, called “argillite,” has been studied within the framework of Biot's mechanics of fluid saturated porous solids. Drained and undrained oedometric tests (i.e., uniaxial strain tests) have been performed to determine the poroelastic parameters for different stress levels. As the provided samples were not fully water-saturated, particular care has been taken over the definition of a preliminary resaturation phase and the estimation of each sample's final saturation level. Argillites poromechanical behavior appears to depend on the rock saturation state. Samples with a greater initial saturation seem to show a less apparent degree of overconsolidation and a higher compressibility. The obtained results also show the influence of the applied stress on the poroelastic parameters. Biot's coefficient decreases when the axial stress increases, while the drained bulk modulus and the shear modulus increase. The effect of the applied stress on Biot's modulus is more difficult to explain because its measure strongly depends on the saturation level of the sample.

Drilling technologies have made much progress the last twenty years. In the past, many wells had to be drilled before and during the development of an oil field. The first wells were devoted to exploration and appraisal and the following ones to development of the oil field. Today, with horizontal drilling a common technique, wells with complex geometry can be drilled in a reservoir allowing the oil to be extracted from different places. Extended reach wells allow oil from remote locations to be reached. Furthermore, capitalizing on drilling is an efficient way to reduce the costs of appraisal, development and exploitation of an oil or gas field. Drilling is a unique opportunity to acquire data in order to take real time decisions leading to a global optimization of the drainage system. All the new technologies such as measurement while drilling, data acquisition, data transfer or high speed computing give the opportunity to provide the geologist, the reservoir engineer and the drilling engineer with more accurate information for taking better decisions. However new tools have to be designed to allow an optimized use of this information. Raw data must be transformed to high level of information so that decisions can be taken quickly with a low level of risk. However there is still the need to perform real-time economic evaluation of the well so that the decisions to drill one meter more can be also taken on economic simulations. In this revue, different techniques to generate high quality information from drilling data will be discussed. Some results issued from research projects managed by IFP and its partners will be addressed.

Drilling a well is a complex process which needs to be monitored continuously to ensure that the well will reach its goals. For this purpose mud logging is performed with sensors installed on the rig. However, the direct use of these data is not sufficient to know precisely the state of the drilling process. Processing and interpretation are needed. IFP and Geoservices have collaborated for many years in a research program dedicated to mud logging data interpretation. A system has been designed to inform the driller about the problems encountered while drilling. The focus of this paper is to present the system called GetSMART, which aims at the detection while drilling of the main abnormal vibrations and hydraulic malfunctions. The system is based on the diagnosis trees methodology, which allows one to take into account the empirical knowledge of the driller to analyze the signals coming from sensors or physical models and also to generate alarms. Some results obtained on field malfunctions real cases show the interest and the pertinence of the GetSMART system. In the future, others diagnosis trees (i.e. wellbore stability) will be introduced in this system

The "geomechanical log" research project aims at estimating rock mechanical properties from a set of models, whose input data can be deduced from drilling logs and measurements on core samples (if these are available). The key point is to focus on defining relatively general and easy to handle models. In this paper, we propose various analytical models allowing one to estimate poroelastic and failure properties of limestones and sandstones directly from their porosity and, in the specific case of sandstone poroelastic characteristics, their mineralogical content. The properties obtained are in reasonable agreement with experimental data. The second step of the project will be to actually infer the input data for the models (here porosity and mineral content) from drilling logs and to compare the results obtained to tests on core samples. A geomechanical log could then be automatically created from standard logs and help to optimize drilling. We also intend to test the same approaches on rock plastic properties and shale behavior.

Failure due to fatigue is a very costly problem in oil and gas industry. Many investigators have previously addressed this problem, but its frequency of occurrence is still excessive. Torque and tension can be correctly predicted but computations of fatigue duration are still approximate. Regarding the fatigue failure of drillstring, this paper summarizes the state of the art. Prediction and calculation of fatigue duration are stated, including both history of the simplified approach based on Miner's rule and a few elements of the fracture mechanics theory. Existing inspection methods, their limitations and further recommendations are provided. Moreover, the fatigue tests are performed when human life and environment may be at risk. The loading conditions, the test frequency, the number and the size of test specimens are given. Environmental effects such as corrosion are recalled. Prevention and inhibitors are mentioned. Last chapter focuses on enhancement of drillstring. Drillpipes geometry improvement, connections re-design, steel properties such as toughness, tool-joints hardfacing and inspection of drillpipes are discussed.

Due to the impact on productivity and oil in place estimates, reliable modeling of rock behavior is essential in reservoir engineering. This paper examines several aspects of rock poroelastic behavior within the framework of Biot's mechanics of fluid saturated porous solids. Constitutive laws of linear and nonlinear poroelasticity are first determined from a fundamental stress decomposition, which allows to clearly connect linear and nonlinear models. Concept of effective stress and rock compressibility are considered. Linear incremental stress-strain relations are derived from the proposed nonlinear constitutive law by defining tangent elastic properties. These characteristics are naturally functions of strains and pore pressure, but explicit expressions as functions of stresses and pore pressure are established herein. Experiments performed on a reservoir sandstone illustrate these points. A constitutive law of poroviscoelasticity is finally presented and applied to experimental data obtained on clay.

International audience; Seismic While Drilling (SWD), specifically encompasses the seismic techniques operated while the drillstring is lowered in the borehole, during effective drilling, during manSuvres or while connecting drill pipes. Two SWD techniques have been used by the industry: - drillbit-SWD, which consists in recording the seismic noise generated by a rock bit under effective drilling on any number of surface seismic sensors. This technique have been used steadily since 1986; - Vertical Seismic Profile While Drilling (VSP-WD), which consists in recording the seismic signal generated by a surface seismic source on seismic sensors integrated inside the downhole Borehole Assembly (BHA). This emerging technique have been operated since year 2000 about, mainly by Schlumberger. Two efficient wireline VSP techniques aimed at gathering geological information potentially useful to the drilling decision making process, and which could rightfully be assimilated to SWD techniques, will not be considered here: - the technique of Tube Logging Conveying (TLC), in particular the TLC-VSP, where a wireline VSP tool is lowered inside the drillstring through a side entry sub at the top of the drillstring; - the standard wireline logging technique of "intermediate VSP", which consists in recording a VSP with a set of wireline logs right before setting an intermediate casing, is used to predict geological features and possible overpressures in depth intervals located hundreds of meters below the intermediate drilled depth, with good success in some geographical regions. The recent developments achieved by IFP and its partners in SWD greatly benefited from the availability of a high rate and real time wireline transmission system while drilling called TRAFOR, allowing for fast field testing of the SWD methods. In the past 18 years (1986-2003), the drillbit-SWD technique practiced by the industry, aimed at a continuous application over the whole drilling depth span, with only a few surface sensors, and without any downhole measurement technology (MWD), reached a very mitigated success rate: although the geophysicists have been intrigued by the large amount of seismic energy imparted to the ground by some types of drillbits, the drillbit-SWD technique fails to yield any substantial results in many circumstances: in the early 1990's, the industry had already gathered an extensive enough experience so as to define the necessary conditions for obtaining any useful drillbit signal: drilling formations sufficiently hard, with a roller cone bit type equipped with milled teeth or inserts, and avoiding the lower range values for the Weight On Bit (WOB) and Round Per Minute (RPM) drilling parameters. The innovative drillbit-SWD technique input from IFP in the past decade is described in the present paper and consists in: - introducing downhole measurements while drilling, in order to understand the downhole process of seismic emission by roller cone rock bits mostly; - improving the mechanical design of the BHA, by integrating a shock absorber element in order to optimize the quality of the seismic signals imparted into the ground and to reduce the amplitudes of undesirable secondary seismic emissions, which considerably complicate the subsequent seismic processing and blur the final seismic image; - designing, manufacturing and validating an operational MWD assisted drillbit-SWD technique through a set of successive, complete and severe field tests achieved through several R&D projects in partnership with the industry; - restricting the application of drillbit-SWD technique to the reverse seismic walkaway configuration to be applied in geological-geographic areas ensuring the best chances of operational and economic success; - integrating the knowledge and know-how of multiple categories of specialists in the various domains of drilling, MWD and seismic, involved in the multidisciplinary applied SWD field operations. In a similar approach successfully applied to the drillbit SWD developments, the technique of VSP-while drilling has been investigated, resulting in several advanced achievements, namely: - definition of downhole seismic sensors able to withstand severe drilling conditions; - field testing the feasibility of the VSP-WD method as a whole, in order to evaluate the quality of the recorded seismic signal in comparison with the equivalent signals from the conventional wireline technique. Depending on the level of seismic signal quality obtained, the domain of application of the VSP-WD technique and the priorities in the successive technological developments to be implemented have been defined; - improving the precision of downhole clock to be embarked in an industrial wireless downhole recorder able to sustain the rough downhole drilling conditions of shock and temperature variations. Last, the present paper overviews the emergence of SWD technique in a brief preliminary history, and is ended with the expression of a few prospective views taking in account the developments achieved by other prominent industrial organizations active in the difficult and promising domains of seismic while drilling technique and field practice.

WOG - Well Optimization by Geosteering: A Pilot Software for Cooperative Modeling onInternet—IFP has recently started the development of a new data management system named WOG for“Well Optimization by Geosteering”. In this project, our aim is to distribute the information through thenetwork so as to share knowledge. The key advantage of this software is to allow visualization for each of the fields involved. Hence, the driller will have the view that he uses currently, the geophysicist will havethe type of view that he sees every day, and so one for each specialties.WOG uses three recent developments: 3D Geopilot, EpiSEM-Action and G3Server.3D Geopilot is software that computes parametric links between the different layers and faults so as toallow future updating during the drilling process. Using the 3D Geopilot, engineers specializing ingeology and geophysics could start from classical workstation interpretation information to set up a firstversion of a multi-discipline Earth model based on the same conceptual Earth model.The EpiSEM-ActionTM project proposes a new approach to ensure the collaboration between SharedEarth Model (SEM) applications on Internet or intranet and the capitalisation of value-added businessknowledge. Web services are provided to manage this business knowledge on the Web with optimizedsecurity between servers and applications. This enables models for coping with various hypotheses andinterpretations to be produced and managed.The G3Server product is a powerful Corba server whose objective is to distribute standardized IFPbusiness objects between Java or C++ applications. The internal model (the IFP communication model)was defined so as to be easily used with Open Spirit and Rescue business data objects. Its role in theWOG project is to distribute data between application components. It can be called by specializedactivities and can access Open Spirit servers, Rescue files and IFP proprietary business objects. Thedomain covered is the well, the reservoir, and seismic information., WOG- Optimisation des forages par Geosteering : plate-forme logicielle de modélisationcoopérative par Internet — L’IFP a commencé le développement d’un nouveau système demanagement de données appelé WOG - Well Optimization by Geosteering. Dans le cadre de ce projet,l’information est distribuée et partagée à travers le réseau Internet. Le plus grand avantage de ce systèmeest d’offrir à chaque utilisateur (géologue, géophysicien, foreur, etc.) une vision propre à sa spécialité etqui lui est familière.WOG utilise trois développements récents : Géopilote 3D, EpiSEM-Action et G3Server.Géopilote 3D est un logiciel qui permet de calculer des relations paramétriques entre les différentes couchesstratigraphiques et les failles afin d’établir une mise à jour compatible avec l’avancement du forage. Enutilisant Géopilote 3D, le géologue et le géophysicien peuvent, à partir de l’information disponible sur unestation de travail classique, construire un modèle géologique montrant différents types de valeurs reliées àdes champs disciplinaires variés mais toutes rattachées à un même conceptual Earth model.Le projet EpiSEM-ActionTM propose une nouvelle approche permettant la collaboration entre modèlesgéologiques partagés sur Internet ou intranet et la capitalisation des connaissances métier qui viennent s’yajouter. Les services Web fournissent les outils nécessaires pour manager ces connaissances spécifiquesavec une sécurité optimale entre serveurs et applications. Ceci permet de produire et de manager desmodèles basés sur des hypothèses et des informations différentes.G3Server est un serveur Corba dont la finalité est de distribuer de façon standardisée les objets IFP entrel’application Java ou C++. Son modèle interne (le modèle de communication IFP) a été défini pour êtrefacilement utilisable avec les outils Open Spirit et Rescue. Son rôle dans le projet WOG est de distribuerles données entre les différents modules applicatifs. Il peut être utilisé par les différentes activités etaccéder aux serveurs Open Spirit, aux fichiers Rescue et aux objets IFP. Les domaines couverts sont lepuits, le réservoir et la sismique.

In case of a prolonged shutdown and an inopportune cooling, the crystallization of a crude oil takes place and hinders the production of these petroleum products. Because of the gel-like network formed by the crystals entrapping the oil, a restarting pressure is required to start-up flow. In order to predict the necessary pressure, the restart process and the corresponding mechanical behavior of the gelled oil must be assessed. In this paper, a set of two experimental approaches is presented and discussed in relationship with the restart process. The solid-like behavior of the gelled bulk oil was investigated thanks to a set of mechanical test cells. The rheological behavior of the gelled waxy crude oil was studied with a vane test apparatus and a controlled-stress rheometer. Eventually, the two experimental methods gave complementary and converging results revealing how a crude oil stuck inside a pipeline would react during a restarting operation. They help the understanding of the physical mechanism of the flow restart and release the data required for prediction.

Abstract In order to study the poroelastic behavior of shales, a set of experiments have been performed in an uniaxial strain setup. The shales were cored at a depth about 450m. Assuming Biot's poroelastic theory, the Biot coefficient was determined in a uniaxial strain loading system. At several steps of the mechanical loading in the plastic domain, the poroelastic properties are determined, A particular attention is paid to the evaluation of the Biot tensor by combining the results of 2 different mechanical unloadings. One consists in decreasing the total stress, the other consists in increasing the pore pressure, Since the shales are anisotropic rocks, measurements have been performed on samples cored perpendicular to the bedding plane or parallel to the bedding plane. Three different rock samples have been tested and measurements have been performed in both directions, The Biot coefficient is shown to change while loading is increased, on the other hand no significant difference is observed as a function of the orientation with regard to the bedding plane. P. 515