Multi-component thermal fluid huff-and-puff pilot has been conducted in Bohai oilfield since 2008. Owing to the limitations of the temperature tolerance of some tools and facilities, the steam injection tubing and production tubing are applied separately during the development. That is, two work-over operations for tubing changes are required in each huff-and-puff cycle, which would increase the cost greatly and lower the development effect.

The objective of our present work is to design an integrated tubing with the functions of both steam injection and oil production to decrease the high cost caused by work-over of tubing change. First, we studied the artificial lift method that might be used for lift of fluid with temperature over 250°C e.g., electric submersible pump (ESP in short), gas lift, progressive cavity pump, and sucker-rod pump. Taking into account the degree of technology maturation, applicability in offshore oilfield and its temperature tolerance, the high-temperature electric submersible pump is selected for artificial lift of the integrated tubing.

On the basis of the ESP artificial lift, the integrated tubing with a Y-joint is designed. The steam injection string is connected with the main channel of the Y-joint and inserted into the production interval. The ESP is connected to the bypass of the Y-joint which could be used for fluid lifting during the production process. For the realization of the integrated tubing, high temperature tolerance tools such as the subsurface safety valve, and packer are developed. The maximum temperature-telorance value of the improved tools could meet the requirements of realizing the integrated tubing

In comparison with the previous techniques, application of the integrated tubing could greatly decrease the cost for thermal production and improve the economic benefit.

You can access this article if you purchase or spend a download.