An All-Electric Intelligent Completion System For Zonal Water Injection Well With Snubbing Operation

Abstract During the construction of water injection wells in low permeability oilfield, the wellhead usually has a pressure of over 1450 PSI. The conventional intelligent completion system, due to the hydraulic pipelines or the cable being placed outside the tubing, should release the pressure to drop below 72.5 PSI before the operation, which exists such problems as long-time occupation of wells, destroying the balance between injection and production, and discharging a large amount of sewage. This paper proposes an all-electric intelligent completion system for zonal water injection with snubbing service. The system is designed with a non-contact docking device, with the female connector running along with the completion string, and the male connector running down to the female connector center from the inside of the tubing using a cable after the packers are set. Based on the principle of electromagnetic induction, the power and signals can be wirelessly transmitted between the male and female connectors. In this way, the system could achieve control and monitoring of water distributors, and meet the snubbing operations. The core tools of this technology include ground control host, non-contact docking device, integrated intelligent water distributor and other devices. The ground control host can collect underground monitoring data from water distributors and control them to adjust the water injection volume in separate layers. The non-contact docking device consists of a male connector and a female connector, which are connected to the top water distributor and located at the upper end of the distributor. The docking device has an average power transmission efficiency of over 85%, a maximum power of 36W and a data communication efficiency of 4800bps. The integrated intelligent water distributor integrates a dual channel water distributor and a packer. A set of water distributor can monitor the pressure and flow rate of two zonal layers, infinitely regulate water injection volume of each layer and implement interlayer isolation. The flow rate of a single layer can be measured in the range of 31.45~629 bbl/day with the accuracy of ±3% Full Scale. The system has applied four wells in Jilin Oilfield of China National Petroleum Corporation, which can achieve 435 PSI snubbing operation, and can monitor and control zonal water injection parameters in real time. The all-electric controlled intelligent completion system for zonal water injection has advantages of being suitable for snubbing operation and real-time monitoring of water injection parameters in layers. It provides engineering and technical means to alleviate interlayer conflicts in injection wells that require snubbing operation, improve reservoir awareness, and ensure safe and green production in oil fields, with broad application prospects.