ADVERTISEMENT

Limitations for Compositional Modeling in Vaca Muerta Numerical Simulation

Vaca Muerta formation fluids run from medium black oils to very dry gas, according to source-rock maturity. High-shrinkage volatile oil and very rich gas condensate are found and compositional variation is areally continuous. Despite this huge difference in fluid nature, where saturation pressures are present, more than 200 kg/cm2 undersaturation is reported. Because of the complex dependence of fluid behavior with composition for near-critical gas condensate and volatile oil, the use of compositional modeling is mandatory. Cubic equations of state (CEOS) are the only types implemented until now in commercially available compositional numerical simulators. In this paper, the authors show the limitation of CEOS for modeling reservoir behavior of liquid-phase black and volatile oil in highly undersaturated reservoirs.

Introduction

The Vaca Muerta shale, located in the Neuquén Basin, Argentina, ranks among the top shale oil and gas resources in the world. It is characterized by its areal extent, high gross thickness, and high organic content. The first well was drilled and completed in 2010 and despite more than 650 wells to date, Vaca Muerta shale history is relatively recent compared with other known shale plays.

Source-rock thermal maturity seems to be the main driver for fluid distribution, running from dry gas in very mature zones, progressing through gas condensate and volatile oil, to black oils of less than 100 m3/m3 gas/oil ratio (GOR) in immature zones.

 

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 191822, “Vaca Muerta Numerical Simulation: A Warning in Compositional Modeling,” by Sergio Bosco, Mariano Suarez, SPE, and Elisabet Savoy, SPE, YPF, prepared for the 2018 SPE Argentina Exploration and Production of Unconventional Resources Symposium, Neuquén, Argentina, 14–16 August. The paper has not been peer reviewed.
...
This article is reserved for SPE members and JPT subscribers.
If you would like to continue reading,
please Sign In, JOIN SPE or Subscribe to JPT

Limitations for Compositional Modeling in Vaca Muerta Numerical Simulation

01 July 2019

Volume: 71 | Issue: 7

ADVERTISEMENT