Effect of Perforation Orientations for Sand Prediction




Vimolsubsin, Pojana

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The purpose of this research is to study the rock behavior from different perforation orientations. The method used in this study is known as the Modified Lade Criterion which applies fully coupled poroelasticity. To investigate the rock behavior, an analytical model, which adopts the Modified Lade Criterion, is used to describe the stress distribution induced by an inclined, cased wellbore using superposition of the inclined cased wellbore system decomposed into the perforation plane. The critical drawdown represents the point at which sand production begins; the algorithm calculates the pressure reduction of a perforation tunnel until rock failure begins. This analytical model allows calculation of critical drawdown pressure to investigate the influence of well completion on sand production. Time-dependence, well inclinations, and perforation direction are also included into the study. This research focuses on four issues: the influence of well completion on the critical drawdown, the time-dependent behavior of the critical drawdown, the preferred perforating direction, and effect of the ratio between maximum and minimum horizontal stresses on the critical drawdown pressure behavior. The simulation indicates that a wellbore perforated in the direction of maximum horizontal stress results in high critical drawdown pressure near the wellbore which declines further in the radial distance. In addition, as time increases, the critical drawdown decreases and converges to the certain value. This research suggests that if sand production is allowed near a wellbore for short time periods, perforating in the direction of minimum horizontal stress in a cased wellbore is preferable to increase critical drawdown for a normal stress regime. However, for more accurate results, applying a 3D poroelastic model is recommended. A developed critical drawdown prediction model is proposed in this research which does not require any MATLAB background. The effect of all parameters on the critical drawdown pressure calculation is determined by sensitivity methods and the most significant parameters are identified. The sensitivity results guide the users before using the default values from the application.


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