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

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.

High-Efficiency High-Temperature-Resistant Nanosilica Viscosity Reducer for Extra-Heavy Oil Viscosity Reduction

“…Figure shows the shortcomings of the commonly used heavy oil viscosity reduction methods at present. For example, Heating viscosity reduction consumes a lot of energy. − The diluted oil mixed with the diluted viscosity reduction method needs to be dehydrated in the early stage before it can be mixed with the heavy oil, and the mixed liquid after production needs to be dehydrated again. − The ultrasonic propagation distance used in the ultrasonic viscosity reduction method is limited, which limits its effectiveness. − Microbial viscosity reduction method has high requirements for microorganisms, which narrows its application. − Although the emulsification viscosity reduction method has been widely used in the oil industry, it still has certain challenges. This is because the anionic surfactant has poor salt-resistance and is easy to precipitate with high valence cations in crude oil.…”

“… 8 − 11 The diluted oil mixed with the diluted viscosity reduction method needs to be dehydrated in the early stage before it can be mixed with the heavy oil, and the mixed liquid after production needs to be dehydrated again. 12 − 14 The ultrasonic propagation distance used in the ultrasonic viscosity reduction method is limited, which limits its effectiveness. 15 − 18 Microbial viscosity reduction method has high requirements for microorganisms, which narrows its application.…”

Temperature Field Study of Offshore Heavy Oil Wellbore with Coiled Tubing Gas Lift-Assisted Lifting

“…The calculation results of the model were compared with the measurement results of the field sensors, and the results showed that the model has good accuracy. [15] conducted an experimental study on annular injection of light oil-assisted heavy oil gas lift and established a coupled pressure-temperature model for annular injection of light oil gas lift wellbore using experimental results and basic theory of heat transfer. Model calculations show that the use of gas lift with diluted oil injection technology can significantly increase the capacity of heavy oil wells.…”

New Method to Predict the Viscosity of Bitumen Diluted with Light Oil Using a Modified Van Der Wijk Model under Reservoir Temperature and Pressure

“…4 , 5 However, in countries like Venezuela, the dilution of bitumen with light oils is one such method used to increase the recovery factor, especially if coupled with either artificial lift or gas lift. 6 − 9 …”

“…The dilution of heavier crude with light crude to give a mixture with flow properties in between those of the initial components has been widely used to facilitate the transportation of bitumen. , However, in countries like Venezuela, the dilution of bitumen with light oils is one such method used to increase the recovery factor, especially if coupled with either artificial lift or gas lift. − …”