Patent ID: 7653488
Filing Date: 2010-01-26
Classification: E21B

Abstract:
1. A computer-implemented method for predicting a start point at which sand production will begin at a production zone in a wellbore of a production facility, the computer-implemented method comprising: determining a first set of characteristics of a formation in the production zone, wherein determining uses a plastic model of the formation, and wherein the first set of characteristics comprises a yield surface, a failure surface, a stress total strain, an elastic strain, and a plastic-strain relationship; determining a relationship among a second set of characteristics of the wellbore using an effective stress model, wherein the second set of characteristics comprises a drawdown pressure, a production rate, pore pressure, a temperature and a viscosity of a fluid in the wellbore, a temperature of the production zone, a fluid flow pressure in the wellbore, a drag force of fluid flow in the wellbore, and a type of fluid flow in the wellbore; determining a critical total strain for the formation using the first set of characteristics and the relationship; calibrating the critical total strain using a thick wall test performed under in-situ conditions, wherein a calibrated critical total strain is formed; storing the calibrated critical total strain, wherein the calibrated critical total strain comprises the start point; displaying the start point on a graph of first stress invariants and second stress invariants of the formation; measuring a current stress point of the formation; displaying the current stress point on the graph; monitoring movement of the displayed current stress point relative to the start point in real time; and adjusting a producing wellbore parameter in response to monitoring to prevent the current stress point from reaching the start point.