Research on heavy oil gas lift assisted with light oil injected from the annulus

H Q Zhong,X L Wang,W G Zeng,S Zhu,F Zhang

doi:10.1007/s13202-018-0437-4

Abstract

An experimental study on the multiphase flow of heavy oil gas lift was conducted on 18.25 m high vertical tube. Based on the experimental results and the wellbore heat transfer mechanism, a coupling model of wellbore pressure–temperature gradients was presented for the gas lift with light oil injected from the annulus. Moreover, the solution of coupling annulus flow with tubing flow was also established through cyclic iteration. Experimental results showed that gas injection enables heavy oil and light oil to mix rapidly and completely. Evaluation of pressure drop models shows that the error of the Ansari model is approximately 12.12%, by comparison it is the least. A novel method of gas lift assisted with light oil from the annulus was proposed to solve the actual situation wherein heavy oil cannot be easily lifted from the wellbore at Tuyuke Block in Tuha Oilfield. An instance design based on the sensitivity analysis of the gas injection rate and diluting rate was also completed. The instance design shows that the productivity of heavy oil well can be significantly improved using gas lift and blending diluting oil technology. In order to verify the feasibility and effect of gas lift assisted with light oil in heavy oil well, a pilot test was implemented in Tahe Oilfield, Xinjiang, China. The results of pilot test show clearly that the daily production rate increased from 11.6 to 38 t/day, and the ratio of light oil with heavy oil decreased from 11:1 to 4:1. From the above, gas injection can significantly reduce the usage of light oil needed, and gas lift assisted with light oil injected from the bottom hole can significantly enhance the productivity of heavy oil wells.

Highlights

The accurate prediction of the pressure and temperature profile of the wellbore is the basis of the technology of gas lift assisted with light oil
Considering that the technology of gas lift assisted with light oil for heavy oil exploitation has not yet been reported and based on the research of predecessors and the application status of gas lift for heavy oil, the author proposes a set of technologies for heavy oil lift that is suitable for the deep heavy oil reservoir
The experiment on heavy oil gas lift shows that, in the three-phase flow, the water phase mainly distributes near the tubing wall, whereas the gas and oil phases mainly distribute near the center of the tubing

Summary

Introduction

The accurate prediction of the pressure and temperature profile of the wellbore is the basis of the technology of gas lift assisted with light oil. From 1982 to 1984, heavy oil exploitation in the Urdaneta offshore oilfield of Lake Maracaibo of Venezuela achieved success using slug gas lift (Jaimes and Zimmerman 1985). In 1988, the lifting of heavy oil containing water and sand achieved success in eastern Venezuela using the gas lift technology of air chamber pump (Hernandez and Marcelo 2002). In 2005, heavy oil exploitation achieved success using continuous gas lift in Intercampo oilfield of Venezuela (Hong’en et al 2007). In view of the characteristics of an ultra-deep and complex wellbore in Tahe oilfield, Riyi et al (2006) conducted research on the pressure and temperature prediction method for heavy oil mixed with diluent and laboratory experiments on viscosity reduction with different diluting rates. Considering that the technology of gas lift assisted with light oil for heavy oil exploitation has not yet been reported and based on the research of predecessors and the application status of gas lift for heavy oil, the author proposes a set of technologies for heavy oil lift that is suitable for the deep heavy oil reservoir

Methods

Results

Conclusion