A Mechanistic Model for Predicting and Optimising Oil-Sand Flow in Horizontal Wells

Oil & Gas Science and Technology, Nov 2011

Smart well completion technology for sand management is being used more and more in the petroleum industry to increase productivity and cumulative hydrocarbon production over that of classical sand control techniques. While an understanding of the geomechanics aspects of sand production has begun to emerge, predicting and optimising two-phase oil-sand flow performance characteristics in horizontal wellbores remains a challenge. This theoretical study analysed two-phase, oil-sand suspended flow in a horizontal well by developing a new phenomenological model to predict lift velocity and pressure drop profiles, which are key parameters for designing optimal deployment of horizontal wells in an unconsolidated reservoir. Computations of average pressure drop for two-phase oil-sand flow in a horizontal well are in reasonable agreement with values predicted by a previous model for a relatively wide range of operating conditions. However, the new model eliminates the need for empiricism in predicting the wellbore hydraulics for oil-sand multiphase flow in horizontal wells and is applicable to different wellbore geometries. The proposed computational methodology has been applied to a hypothetical case study to demonstrate its field applicability.Les techniques de complétions intelligentes de puits avec gestion de venues de sable sont de plus en plus utilisées dans l’industrie pétrolière. Comparées aux techniques classiques de gestion de venues de sable, elles améliorent la productivité et la production cumulée d’hydrocarbures. Cependant, alors que les aspects géomécaniques de la production de sable sont de mieux en mieux appréhendés, la prévision et l’optimisation des écoulements diphasiques huile-sable dans les puits horizontaux posent toujours problème. Dans cette étude, une analyse théorique de l’écoulement d’un mélange huile-sable en suspension dans un puits horizontal a été effectuée. Pour ce faire, des modèles phénoménologiques ont été développés pour prédire la vitesse de remontée optimale ainsi que les profils de perte de charge, qui sont les deux paramètres clés pour optimiser la conception d’un puits horizontal dans un réservoir non consolidé. Le calcul de la perte de charge moyenne pour un écoulement diphasique huile-sable dans un puits horizontal est en accord avec les valeurs prédites par un modèle précédent, même pour des conditions d’opération variées. Cependant, le nouveau modèle évite de recourir à l’empirisme pour prévoir le comportement du puits dans le cas d’un écoulement multiphasique. Il peut également être appliqué à différentes géométries de puits. La méthode de calcul proposée a été testée sur une étude de cas hypothétique, afin de démontrer son applicabilité sur le terrain.

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A Mechanistic Model for Predicting and Optimising Oil-Sand Flow in Horizontal Wells

Oil & Gas Science and Technology - Rev. IFP Energies nouvelles, Vol. A Mechanistic Model for Predicting and Optimising Oil-Sand Flow in Horizontal Wells O. Bello 1 G. Falcone 1 C. Teodoriu 0 I. Udong 1 0 Institute of Petroleum Engineering , Agricolastrasse 10, 38678 Clausthal-Zellerfeld - Germany 1 Department of Petroleum Engineering , 507 Richardson Building, 3116 TAMU , College Station , TX 77843-3116 - USA - A Mechanistic Model for Predicting and Optimising Oil-sand Flow in Horizontal Wells - Smart well completion technology for sand management is being used more and more in the petroleum industry to increase productivity and cumulative hydrocarbon production over that of classical sand control techniques. While an understanding of the geomechanics aspects of sand production has begun to emerge, predicting and optimising two-phase oil-sand flow performance characteristics in horizontal wellbores remains a challenge. This theoretical study analysed two-phase, oil-sand suspended flow in a horizontal well by developing a new phenomenological model to predict lift velocity and pressure drop profiles, which are key parameters for designing optimal deployment of horizontal wells in an unconsolidated reservoir. Computations of average pressure drop for two-phase oil-sand flow in a horizontal well are in reasonable agreement with values predicted by a previous model for a relatively wide range of operating conditions. However, the new model eliminates the need for empiricism in predicting the wellbore hydraulics for oil-sand multiphase flow in horizontal wells and is applicable to different wellbore geometries. The proposed computational methodology has been applied to a hypothetical case study to demonstrate its field applicability. - 980 NOMENCLATURES Γm Mass transfer (kg/m3s) Liquid viscosity (Pa.s) Liquid density (kg/m3) Particle density (kg/m3) Mixture density (kg/m3) Liquid velocity (m/s) Particle velocity (m/s) Mixture velocity (m/s) Critical velocity (m/s) The need to increase recovery from producing hydrocarbon formations has seen major advances in smart well technology development. Horizontal wells can better control water coning in relatively thin oil columns, increase waterflooding efficiency, improve productivity and reservoir recovery in thin reservoirs, and reduce capital expenditure when compared to conventional field development methods. Many of the newly discovered fields with high recoverable reserves are situated in less accessible environments with unconsolidated formations (Gulf of Mexico, North Sea and Gulf of Guinea). Conventional downhole sand completions (such as expandable sand screens, gravel packs, resin consolidation, frac and pack completions) strongly affect the overall well performance by introducing additional pressure drops (skin effects) and having higher installation and operating costs. As a result, sand management technology is getting more attention from the industry for its potential to increase reserve recovery, eliminate downhole sand exclusion systems, minimise problems associated with formation damage and impaired productivity, and reduce costs (Dusseault et al., 2001). The specific issues of the impact of sand production, ineffective sand transport, particle deposition and bed accumulation in horizontal and multi-lateral well sections are the prime focus of sand management technology. Impingement and deposition of sand particles in horizontal and multi-lateral wells results in erosion, corrosion, reduced wellbore flow capacity, unplanned well shut-down and increased downtime. Several models have been proposed to incorporate frictional pressure drop effects on horizontal well drawdown and productivity index (Dikkens, 1990; Asheim et al., 1992; Sien et al., 1993; Cho and Shah, 2000; Guo, 2010). Two-phase frictional pressure drop has also been developed for gas-liquid (Ouyang, 1998) and liquid-liquid (Inikori and Wajtanowicz, 2002) flow conditions in horizontal wells. Extensive studies on particulate flows in horizontal pipes with settling and nonsettling systems have been published (Wicks, 1971; Doron et al., 1987; Matousek, 1997; Gillies et al., 1999; Kaushal and Tomita, 2005; Yang et al., 2006; Govier and Aziz, 2008), but few research works have been reported for oil-sand flow in horizontal wells. Oil-sand flow occurs frequently in horizontal wells drilled in unconsolidated formations, even when sand management technology is implemented. The design of such horizontal wells depends on a detailed knowledge of oil-sand flow to predict wellbore hydraulic performance. Doan et al. (1996) used analytical and numerical modelling to investigate the transport of oil-sand flows with stationary sand bed loads in horizontal wells. The model considered a suspension of sand homogeneously dispersed in oil, where the particles are at least two diameters apart, flowing at isothermal conditions. This approach allows the particle-particle interactions to become negligibl (...truncated)


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O. Bello, G. Falcone, C. Teodoriu, I. Udong. A Mechanistic Model for Predicting and Optimising Oil-Sand Flow in Horizontal Wells, Oil & Gas Science and Technology, 2011, pp. 979-989, Volume 66, Issue 6, DOI: 10.2516/ogst/2010034