Emulsion Characterization of the Heavy Oil-Alkaline Water System in Alkaline Flooding Mechanism Investigation Using a Combination of Modified Bottle Test and Sandpack Flooding

Zhiyu Xi,Na Jia,Ezeddin Shirif

doi:10.3389/fenrg.2021.600676

Abstract

Due to the diversity of alkali categories and reservoir conditions, the varied oil recovery driving mechanism of alkaline flooding is subjected to different types of emulsion generation. In this study, a modified bottle test method that assesses major emulsion type formation for preliminary prediction of alkaline flooding performance in oil recovery is introduced. The modified method considers the necessary energy input required for mixing immiscible bulk phases at low interfacial tension (IFT) regions to improve the representativity of emulsion formation in the bottle test to that of in porous media. To accurately evaluate the emulsion type and phase volume distribution from the bottle test, each emulsion phase after aging in the test bottle was sampled and its water content was measured through Karl Fischer titration. Afterward, material balance calculations other than pure volume observation were applied to quantify the emulsion volume and determine the major emulsion type formation. It is found that the majority of emulsion effluent type from the sandpack flooding test were in agreement with the bottle test forecast which proved the feasibility of the modified bottle test method. The statistically optimized experimental designs were implemented due to the simplicity of the new bottle test method and it considerably cut the time expense regarding the alkaline flooding performance prediction. The high versatility of the modified bottle test ensures that the alkali usage is not limited to the inorganic alkalis mentioned in this study; other type of alkaline solutions can also be used for further expanding the scope of its application.

Highlights

The heavy oil recovery process in field mainly undergoes three stages
According to the orthogonal bottle tests, changing alkali types, alkaline concentration, and salinity alters the major emulsion type generation which determines the alkaline flooding mechanisms to be achieved for facilitating the oil recovery
The emulsion type reversal in sandpack flooding with increasing Na2CO3 concentration is in good agreement with the Na2CO3 orthogonal bottle test study (Figure 9)

Summary

Introduction

The heavy oil recovery process in field mainly undergoes three stages. Initially, the primary production utilizes pressure depletion owing to formation rock expansion and solution gas drive to make oil produced spontaneously (Kokal and Abdulaziz, 2010). A series of modified bottle tests for two inorganic alkalis (NaOH and Na2CO3) with heavy oil under various temperatures, salinities (NaCl), and alkaline concentrations were conducted.

Results

Conclusion