Titre du document / Document title

Prediction of Formation-Tester Fluid-Sample Quality in Highly-Deviated Wells

Auteur(s) / Author(s)

ANGELES Renzo ⁽¹⁾ ; TORRES-VERDIN Carlos ⁽¹⁾ ; SEPEHRNOORI Kamy ⁽¹⁾ ; MALIK Mayank ⁽²⁾ ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

⁽¹⁾ Dept. of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin, TX 78712-0228, ETATS-UNIS
⁽²⁾ Chevron Energy Technology Company, Houston, TX 77099, ETATS-UNIS

Résumé / Abstract

Fluid samples acquired with formation testers are often contaminated with mud filtrate. In some cases, it may take hours or even days to achieve acceptable levels of mud-filtrate contamination, thereby rendering the fluid-sampling operation undesirable for either economical or safety considerations. We apply 3D numerical algorithms to simulate formation-tester measurements acquired in highly-deviated wells using standard and focused-sampling probes. Because this approach is not restricted to the assumption of single-phase flow nor does it neglect presence of spatially asymmetric mud-filtrate invasion, numerical simulation enables the quantitative appraisal of realistic tool and formation properties under a wide range of deviation angles. Sensitivity studies consider the effects of permeability anisotropy, capillary pressure, gravity segregation, radius of mud-filtrate invasion, fluid viscosity, fluid density, probe diameter, and pumpout rate for oil- and dry-gas-bearing rock formations. Moreover, comparisons are made between sampling operations performed in wells drilled with water-based (WBM) and oil-based (OBM) mud. We also appraise the performance of recently-introduced focused fluid-sampling probes for the rapid acquisition of low-contamination fluid samples in highly-deviated wells. Our study indicates that gravity is detrimental to production cleanup times and it also affects focused-sampling probes which, at specific ratios between sample and guard assemblies, achieve cleaner samples than conventional probes. For the cases considered in this paper, the larger the angle of deviation (with respect to the vertical axis), the longer it takes to achieve oil breakthrough. Finally, gravity-segregated invaded formations strongly affect fluid sampling predictions, hence enforcing our notion that a numerical approach, such as the one implemented in this paper, is necessary to accurately predict production cleanup times in high-angle wells.

Revue / Journal Title

Petrophysics   ISSN 1529-9074 

Source / Source

2009, vol. 50, n^o1, pp. 32-48 [17 page(s) (article)] (3/4 p.)

Langue / Language

Anglais

Editeur / Publisher

SPWLA, Houston, TX, ETATS-UNIS  (2000) (Revue)

Mots-clés anglais / English Keywords

Formation fluid ; Petrophysics ; Performance ; Oil base mud ; Drilling ; Diameter ; Density ; Viscosity ; Gravity ; Capillary pressure ; Anisotropy ; Permeability ; Sensitivity analysis ; Numerical simulation ; Standards ; Safety ; Quality ; Tester (drilling) ;

Mots-clés français / French Keywords

Fluide formation ; Pétrophysique ; Performance ; Boue huile ; Forage ; Diamètre ; Densité ; Viscosité ; Gravité ; Pression capillaire ; Anisotropie ; Perméabilité ; Analyse sensibilité ; Simulation numérique ; Norme ; Sécurité ; Qualité ; Tester (forage) ;

Mots-clés espagnols / Spanish Keywords

Petrofísica ; Rendimiento ; Lodo aceite ; Sondeo ; Diámetro ; Densidad ; Viscosidad ; Gravedad ; Presión capilar ; Anisotropía ; Permeabilidad ; Análisis sensibilidad ; Simulación numérica ; Norma ; Seguridad ; Calidad ; Sacatestigo (sondeo) ;

Localisation / Location

INIST-CNRS, Cote INIST : 27342, 35400018538851.0020