Abstract

The characteristics of tight oil reservoir are low porosity and ultra-low permeability, thus stimulated reservoir volume (SRV) should be conducted whether applying the mode of vertical wells or horizontal wells production. Tight oil reservoir is mostly developed by natural depletion or water flooding recently, but the problems are existed, including low recovery factor with natural depletion and the difficulty of water injection. To further improve the development effect of tight oil reservoir, CO2 flooding is proposed. Based on changing tight oil reservoir in Ordos Basin, an oil sample of typical block is selected. The PVT experiments are conducted. The compositional numerical model of five-spot pattern is established with a horizontal well in the middle and 4 vertical wells on the edge. Based on the model, several CO2 flooding scenarios of horizontal well with different completion measures are studied. Furthermore, parameters such as the formation pressure, production rate, shut-in gas-oil ratio and total gas injection volume are optimized. The results of this study show that the recovery factor of horizontal well with SRV is higher than those of horizontal well and conventional fractured horizontal well. The study gives new ideas of CO2 flooding with volume fractured horizontal well for the Ordos Basin tight oil reservoir. It can be helpful for rapid and effective development of tight oil reservoirs in Ordos Basin.

Highlights

  • In recent years, it is become a hot spot to develop unconventional reservoirs, such as tight oil, tight gas and shale gas [1,2]

  • Some studies have shown that CO2 flooding is an effective approach of enhanced oil recovery (EOR) in tight reservoirs [6,10,11]

  • The permeability and flow capacity of the reservoir have been greatly improved after larger scale simulated reservoir volume (SRV) measures, which makes it possible to inject an oil-displacing agent to develop of tight oil reservoir

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Summary

Introduction

It is become a hot spot to develop unconventional reservoirs, such as tight oil, tight gas and shale gas [1,2]. The simulated reservoir volume (SRV) can be formed around the horizontal well after segmented multi-cluster fracturing [5,6]. Parameters such as the formation pressure, production rate, shut-in gas-oil ratio and total gas injection volume are analyzed. Miscible gas flooding increases oil “swelling” and localized pressure or drive within the reservoir.

Results
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