Stability modelling applied to wellbore design

Tipo di pubblicazione: Articolo su rivista
Tipologia MIUR: Contributo su Rivista > Articolo in rivista
Titolo: Stability modelling applied to wellbore design
Autori: Rocca V; Verga F.
Autori di ateneo:
Titolo del periodico: GEAM. GEOINGEGNERIA AMBIENTALE E MINERARIA
Tipo di referee: Tipo non specificato
Editore: Pàtron Editore
Volume: XLV
Numero: 3
Intervallo pagine: pp. 5-12
Numero di pagine: 8
ISSN: 1121-9041
Abstract: When a well is drilled in a hydrocarbon reservoir, the thermodynamic equilibrium of virgin rocks is altered, the natural stresses are redistributed, and a stress concentration occurs around the hole. The alteration of original equilibrium can lead to wellbore yield, evidenced as shear banding and dilatation, circumferential crack, and microfissuring process. Borehole instability represents the main cause for loss of drilling fluids and consequent potential kick problems, and can be so severe to determine the wellbore abandonment. Loss of time associated with stability problems is estimated to account for between 12 and 15% of drilling cost world-wide. Physical and mechanical processes occurring within and around the borehole because of interaction between drilling fluids and rocks can degrade the stability of the wellbore especially in shale intervals, which can make up over 75% of drilled formations. In fact, due to their fine-grained nature and low permeability, in association with high porosity and high fluid saturation, shale minerals are particularly sensitive to time-dependent stability degrade. In order to accurately analyse the complex behaviour of shale minerals, the effects of mechanical deformation, hydraulic diffusion and temperature gradient, as well as their combination must be taken into account. The classic poro-elastic theory, which allows consideration of the coupled phenomena of time-dependent pore fluid diffusion and formation stress variation, fails to capture the effects of temperature gradient and plastic deformation, particularly remarkable in the shale behaviour analysis. So a thermo-poro-mechanical approach, coupling constitutive equations with thermal and hydraulic laws, is necessary to perform accurate time-dependent analyses of stress, pore pressure and temperature distribution around the wellbore in shale formations. This paper presents the analytic formulation of a thermo-poro-mechanical model, in which the basic Desai's model is used to describe the rock plastic behaviour for a mono-dimensional, axisymmetric problem in plane state of strain. With the aid of an in-house software, the proposed model was first validated, also by comparison with the output of a well-known geomechanical numerical simulator available on the market, and then applied to several real and synthetic cases. Based on the results of one of the examined case history, the paper shows how the borehole stability modelling approach is fundamental to systematically take into consideration the stress variations around the hole and the associated rock deformation and pore pressure changes during drilling. The prediction of natural equilibrium time-dependent alterations allows drilling engineers to improve the design phase, to take decisions on critical effects potentially occurring during drilling as well as to optimize completion (e.g. casing placement and/or cementing) of a well
Data: 2008
Status: Pubblicato
Lingua della pubblicazione: Inglese
Parole chiave: desai model, thermo-poro-mechanical model, wellbore instability in shale formations
Dipartimenti (originale): DITAG - Ingegneria del Territorio, dell'Ambiente e delle Geotecnologie
Dipartimenti: DIATI - Dipartimento di Ingegneria dell'Ambiente, del Territorio e delle Infrastrutture
URL correlate:
    Area disciplinare: Area 09 - Ingegneria industriale e dell'informazione > IDROCARBURI E FLUIDI DEL SOTTOSUOLO
    Data di deposito: 17 Mar 2009 17:13
    Data ultima modifica (IRIS): 07 Lug 2012 01:58:36
    Data inserimento (PORTO): 27 Ott 2014 17:08
    Permalink: http://porto.polito.it/id/eprint/1939531
    Link resolver URL: Link resolver link
    Citazioni:

    Il campo presenta il numero di citazioni presenti sulle banche dati Scopus e Web of Science e permette di accedere ai relativi record. Visualizza inoltre il link al record presente su Google Scholar.

    Possono verificarsi discrepanze rispetto ai dati presenti sulle banche dati per i seguenti motivi:

    • Differenze tra i dati riportati su IRIS e quelli presenti nelle banche dati.
    • Il numero di citazioni riportate su PORTO viene estratto mensilmente. Il dato citazionale presente sulle singole banche dati è aggiornato in tempo reale
    • Il numero di citazioni per WoS viene calcolato sulla base delle collezioni in abbonamento (Science citation index Expanded e Conference Proceedings Citation Index)

    Per informazioni o segnalazioni contattare scrivia/porto

    +
    -

    Allegati

    [img] PDF (Stability_modelling_applied_to_wellbore_design) - Postprint
    Accesso al documento: Non visibile (accessibile solo al proprietario del dato)
    Licenza: Non pubblico - Accesso privato / Ristretto.

    Download (448Kb (458872 bytes)) | Spedisci una richiesta all'autore per una copia del documento

    Azioni (richiesto il login)

    Visualizza il documento (riservato amministratori) Visualizza il documento (riservato amministratori)