Production Rate Calculation Using Choke Correlation, Improving Matching Field Data on Vaca Muerta Formation.

Abstract

Abstract Usually when the Production Engineer needs to follow a DrawDown Curve to maximize production of the well, a methodology to calculate dynamic pressure at sand face (PWF) is needed. To calculate PWF, the Gas and Liquid Rate and wellhead conditions need. On many occasions, there is no separator to run a production test so, as a consequence, a methodology to calculate production rates becomes vital. This paper uses the choke correlation developed by Bellini et al. to calculate total mass and use a workflow to find Water Cut and GOR using Equation of state to split total mass in Gas, Oil and Water mass, and transform them to volumetric rates. In Non-Conventional fields, wellhead chokes are widely used to, for example: regulate the flow rate of the well, to impose sufficient back pressure on the face of the sand so as not to exceed values excessive drawdown. Many authors use choke correlation to find Gas or Liquid Rates but not all at same time and uses many times wrong correlation with error higher than 20%. The workflow presented in this paper, combines high confidence multiphase choke correlation to predict mass rate and use Equation of State (EOS) to predict GOR and Water Cut relations, this combinations of both make sure best confidence calculations. This new workflow was tested with several oil wells at non-Conventional reservoir and its performance is more confidence to existing methodology used nowadays. The Volumetric rates calculation need to use the best technical practices combining fluids thermodynamic and production knowledge to reach the minimal error we can do. Examples and back test of volumetric rate calculation vs separator measurements on wells from "Vaca Muerta" Formation, will be compared a showed as result of this job. Finally, an application of Well performance analysis will be showed, in order to evaluate choke sensitivities to maximize liquid production rate and maintain Well DD into optimal Drawdown Curves to make sure maximize EUR as we can.