Mathematical Modelling of the Drilling Process for Real-time Applications in Drilling Simulation, Interpretation and Assistance

For the last thirty years, mathematical modelling has been used to develop software solutions that support drilling engineering activities at the planning stage of drilling operations. But it is only for the last decade that mathematical models have been used for the real-time support of drilling operations. Moving from a pure engineering perspective to having models that can respect real-time requirements, necessitates many improvements of the subjacent mathematical modelling of the drilling process. First, it is not anymore possible to ignore transient behaviors that were somewhat irrelevant at the planning stage. Second, there is a need for solutions that should be fast enough to cope with the real-time constraints of the drilling process. With the perspective of creating applications that can support the drilling process in real-time, the following mathematical models have been developed: • Drilling fluid behavior. The properties of drilling fluids depend on their composition and pressure-temperature conditions. For instance, the pressure-temperature dependence of the mass density of drilling fluids, depends on the individual PVT-properties (Pressure-Volume-Temperature) of each of the components and their relative volume fractions. Therefore, the addition of drill-cuttings in the drilling fluid also changes the drilling fluid PVT-behavior. Furthermore, the rheological behavior of drilling fluids depends also on its composition. We have found that the rheological behavior of a KCl/polymer water-based mud is simultaneously modified by the relative proportion of barite and sand. Furthermore, it is known that drilling fluids are thixotropic. Yet, we found that the thixotropic behavior of drilling fluids is different from the one of other thixotropic fluids and we have determined that one of the causes for the discrepancy is related to the presence of solids in the fluid mix. We have developed a method to estimate the rheological behavior and its associated uncertainty, as a function of the modification of the solid proportions. • Drill-string mechanical sub-models coupled with hydraulic effects. Hydraulic pressure has also an impact on drill-string mechanical forces not only because the fluid mass density modifies buoyancy but more generally because viscous pressure gradients generate net forces along the drill-string. These hydraulic related forces are superposed to those engendered by mechanical friction and elastic deformation. • Steady state and transient drill-string mechanical models. Steady state torque and drag models utilizing the above-mentioned drill-string mechanical sub-models can be used to assess some characteristics of the drilling process when constant velocities are prevalent. But, during a drilling operation, there are many moments during which the drill-string displacement is in transient mode. Therefore, it is also important to have access to transient torque and drag models with a fast response time. • Transient cuttings transport model. The transport of cuttings is obviously influenced by hydraulic circulation but also drill-string rotational speed, at least in the deviated parts of a well. On the other hand, the presence of drill-cuttings in suspension or settling on the low-side of the borehole, influences pressure losses and mechanical forces along the drill-string. Therefore, the estimation of the transient displacement of drill-cuttings plays an important role in the overall estimation of the actual drilling conditions during a drilling operation. However, a transient cuttings transport model shall also be sufficiently fast, especially when it is used in real-time applications. Equipped with such models of the drilling process that are compatible with real-time constraints, then it is possible to solve problems that are relevant for the assistance of drilling operations. A first domain of application is related to the estimation, in real-time, of surface and downhole sensor values as a function of external commands like the block position and speed, the top-drive rotational velocity and the pump rates. We will refer to this domain of application as “drilling simulation”. However, comparison of measured values with simulated ones, require the proper modelling of the sensors and the impact of their actual position on the readings. For instance, drilling fluid is retained in the flowline and mud treatment equipment. Therefore, to simulate pit volumes, it is important to model the retention mechanism. Transient hydraulic, mechanical and heat transfer models, associated with precise modelling of sensor measurements, can then be used to interpret the current actual drilling conditions, because if their estimated parameters differ from the measurements, then a possible reason is that something unexpected is happening downhole. However, such drilling symptom detection method necessitates two additional conditions to be fulfilled: • The models shall be calibrated. Regardless of the quality of the drilling models, the inputs to these models are always known with a limited degree of accuracy and therefore their outputs may differ from measurements for that simple reason. However, it is important to distinguish between uncertainties that are related to properties that do not change substantially during a given drilling operation, from those that can change at any time. To avoid influencing the calibration of time invariant properties with possible side effects of the deterioration of the drilling condition, it is important to utilize drilling conditions by which undesirable side effects have no or little influence on the measurements that are used to calibrate the property. • Uncertainty of the modelled outputs shall be estimated. Calibration may reduce the uncertainty on the model outputs, but it does not eliminate it completely. It is therefore important to estimate the uncertainty of the predicted values. To achieve this, it is necessary to capture the precision by which the inputs of the process are known and to propagate that uncertainty throughout the modelling of the outputs. With continuously calibrated models and an estimation of the current downhole conditions, then it is possible to address some preliminary drilling process assistance functions: • Safety triggers. During the execution of automation functions, the situation awareness of the driller is reduced as he does not drive the drilling machines himself. Therefore, it shall not be attempted to automate any functions before a minimum set of protection functions are in place. Such safety triggers shall detect and react to incidents related to the axial and rotational movement of the drill-string and, of course, associated with pressure. Example of such safety triggers are: o Reactions to overpulls and set-down weights. o Reactions to abnormal torques. o Reactions to abnormal pressures. • Safeguards. Any drill-string or drilling fluid movements shall not generate a drilling incident. Therefore, commands to the drilling machines shall be kept within safe operational envelopes. For instance, upward movement of the drill-string shall not decrease the downhole pressure below the pore pressure or the collapse pressure of the open hole formations. Similarly, the applied flowrate combined with a possible downward movement and rotation of the drill-string shall not overpass the fracturing pressure of open hole formation rocks. • Automated procedures. Protected by safety triggers and operating within acceptable safeguards, then it is possible to automate some standard procedures. However, such automatic procedures must continuously be adapted to the current drilling conditions. For instance, the length of a friction must be modified to account for the current drill-string length and mechanical friction, or the flowrate applied during the ream-down sequence of a reciprocation procedure shall be reduced as a function of the current potential surging risk

Exploring Natural Products for New Taste Sensations

This paper discusses the discovery of uncommon taste or trigeminal active compounds and their associated sensory analysis using human tasting panels with the aim of enhancing the over all taste experience whilst reducing where possible the sugar and salt content of foods. The first example outlines the discovery of the sensory quality attributes of (R)-2-(carboxymethylamino)propanoic acid, named (R)-strombine, as assessed by a panel of 47 subjects to confirm its contribution to the typical taste of scallop muscle. The second example discusses the pungency and trigeminal effect of polygodial, which is compared with piperine and capsaicin, as well as the elucidation of a new structure eliciting a trigeminal effect, (±)-trans-2,3,3a,7a-tetrahydro-1H-indene-4-carbaldehyde, discoveredin Amomum tsao-ko. Finally, the time intensity trigeminal effect of (–)-menthol is compared with (1R,2RS,4RS)-1-isopropyl-4-methylbicyclo[3.1.0]hexan-2-ol, named dihydroumbellulol, a new cooling compound obtained by hemi-synthesis from umbellulone extracted from Umbellularia californica Nutt

Whirling dynamics of a drill-string with fluid–structure interaction

Fluid–structure interaction models for drill-string vibrations are often of reduced order. However, both the structure and the surrounding fluid are non-linear, which can lead to complex coupled dynamic. In this paper, a coupled fluid–structure model is developed, where the flow is reduced to multiple cross-sections and solved with the lattice-Boltzmann method, while the finite element method is employed to discretize a region of the drill-string. In sequence, the whirling dynamics and the fluid forces are analyzed for different configurations. The process is repeated disregarding the fluid-interaction with the aim of evaluating the fluid forces. The fluid forces estimated through the solution of the Navier–Stokes equation shows that the fluid acts in both dissipation and excitation of the vibrations. The dissipation is seen when high frequency dynamics is expected, whereas the lower frequencies are excited.publishedVersio

Application of the quemada viscosity model for drilling fluids

A number of different models are used to describe the shear rate dependent viscosity of drilling fluids. Most, such as the Herschel-Bulkley model, have a purely empirical basis. The Quemada model, while still empirical, is based on physical principles. It is based on the notion that structural units develop in the fluid at low shear rates which are then partially broken down as the applied shear rate increases. In the current work, drilling fluid rheological data are fitted to the Herschel-Bulkley and the Quemada model. The development of the Quemada model and the calculation of each model parameter are presented. We show that the Quemada model better fits measurements over a wider range of shear rates than the Herschel-Bulkley model. We describe how to select the parameters of the Quemada model. Knowing the difficulty of obtaining a known shear rate for fluids with yield stresses, we discuss how this can affect the quality of the Quemada model fit. Furthermore, in principle, the Quemada model is not applicable in presence a non-zero yield stress. Therefore, we show how to handle the yield stress using a (very high) zero shear rate viscosity.acceptedVersio

The mere exposure effect depends on an odor’s initial pleasantness

The mere exposure phenomenon refers to improvement of one's attitude toward an a priori neutral stimulus after its repeated exposure. The extent to which such a phenomenon influences evaluation of a priori emotional stimuli remains under-investigated. Here we investigated this question by presenting participants with different odors varying in a priori pleasantness during different sessions spaced over time. Participants were requested to report each odor's pleasantness, intensity, and familiarity. As expected, participants became more familiar with all stimuli after the repetition procedure. However, while neutral and mildly pleasant odors showed an increase in pleasantness ratings, unpleasant and very pleasant odors remained unaffected. Correlational analyses revealed an inverse U-shape between the magnitude of the mere exposure effect and the initial pleasantness of the odor. Consequently, the initial pleasantness of the stimuli appears to modulate the impact of repeated exposures on an individual's attitude. These data underline the limits of mere exposure effect and are discussed in light of the biological relevance of odors for individual survival

CNES Approaching Guidance Experiment within FFIORD

This article outlines the relative orbit control (guidance algorithm and its preliminary performance tests evaluation) that will be tested by the CNES Team on FFIORD (Formation Flying In Orbit Ranging Demonstration) onboard PRISMA mission. After a brief summary of the PRISMA mission context, the paper provides a full description of the rendezvous function involved in the approaching guidance experiment. This FFIORD onboard function is detailed in terms of on-board algorithmic method (basic algorithm and enhanced alternative), sensibility analysis used to construct maneuver plans and preliminary tests results

Anti-Collision Function Design and Performances of the CNES Formation Flying Experiment on the PRISMA Mission

Within the framework of a partnership agreement, EADS ASTRIUM has worked since June 2006 for the CNES formation flying experiment on the PRISMA mission. EADS ASTRIUM is responsible for the anti-collision function. This responsibility covers the design and the development of the function as a Matlab/Simulink library, as well as its functional validation and performance assessment. PRISMA is a technology in-orbit testbed mission from the Swedish National Space Board, mainly devoted to formation flying demonstration. PRISMA is made of two micro-satellites that will be launched in 2009 on a quasi-circular SSO at about 700 km of altitude. The CNES FFIORD experiment embedded on PRISMA aims at flight validating an FFRF sensor designed for formation control, and assessing its performances, in preparation to future formation flying missions such as Simbol X; FFIORD aims as well at validating various typical autonomous rendezvous and formation guidance and control algorithms. This paper presents the principles of the collision avoidance function developed by EADS ASTRIUM for FFIORD; three kinds of maneuvers were implemented and are presented in this paper with their performances

Variability of Affective Responses to Odors: Culture, Gender, and Olfactory Knowledge

Emotion and odor scales (EOS) measuring odor-related affective feelings were recently developed for three different countries (Switzerland, United Kingdom, and Singapore). The first aim of this study was to investigate gender and cultural differences in verbal affective response to odors, measured with EOS and the usual pleasantness scale. To better understand this variability, the second aim was to investigate the link between affective reports and olfactory knowledge (familiarity and identification). Responses of 772 participants smelling 56-59 odors were collected in the three countries. Women rated odors as more intense and identified them better in all countries, but no reliable sex differences were found for verbal affective responses to odors. Disgust-related feelings revealed odor-dependent sex differences, due to sex differences in identification and categorization. Further, increased odor knowledge was related to more positive affects as reported with pleasantness and odor-related feeling evaluations, which can be related to top-down influences on odor representation. These top-down influences were thought, for example, to relate to beliefs about odor properties or to categorization (edible vs. nonedible). Finally, the link between odor knowledge and olfactory affect was generally asymmetrical and significant only for pleasant odors, not for unpleasant ones that seemed to be more resistant to cognitive influences. This study, for the first time using emotional scales that are appropriate to the olfactory domain, brings new insights into the variability of affective responses to odors and its relationship to odor knowledg