An Intelligent Separated Zone Oil Production Technology Based on Electromagnetic Coupling Principle

Abstract Separated zone oil production technology is an important means to solve the interlayer and planar contradiction, fully develop the middle and low permeability layers, reduce the ineffective water circulation, and realize the remaining oil exploration in the high water cut stage of the oilfield. The existing technologies suffer from many problems, such as unsuitable for pump inspection operation, short working life, and poor communication reliability. This paper proposes an intelligent separated zone oil production technology based on electromagnetic coupling principle. The release-sub-involved pipe string structure is adopted, in which the production pipe string from the ground to the pump is connected by external binding cables, and multiple intelligent production allocators (IPAs) of the allocation pipe string are also connected by cables. The electromagnetic coupling principle is used to realize the close-range wireless transmission of power and data between the production and allocation strings. After the docking, the allocation pipe string can be powered from the ground, and two-way communication can be realized. This technology provides a repeatable downhole docking and detaching channel of power and data transmission, which eliminates the need to lift out the allocation pipe string during routine pump inspection operation, effectively increasing the working life of the IPA and reducing operation cost. The main components of this technology include ground communication controller (GCC), downhole electromagnetic coupling device (DECD), and IPA of each layer. The GCC is used to collect downhole monitoring data and adjust the zonal fluid production. The DECD consists of an inner cylinder tool and an outer cylinder tool. The inner cylinder tool is connected to a tubular pump, while outer cylinder tool is connected to the IPA. The average transmission efficiency and power of the DECD is 94% and 52 W respectively, and the error rate of data transmission is less than 1%. The IPA has the functions of temperature, pressure, flow rate monitoring and zonal fluid production adjusting, with a flow rate measurement range of 5∼100m3/d, an accuracy of ±3% FS and a flow control valve of maximum overflow diameter of 15mm. The field trials of this technology were carried out in Daqing Oilfield and the experimental well was divided into two layers. The results showed that DECD was successfully docked. The measured downhole temperature was about 46°C, the maximum flow rate was 35 m3/d, and the bottomhole flowing pressure was 9 MPa. This technology has the advantages of suitable for pump inspection operation, high communication reliability, and long working life, providing a new engineering technical means for alleviating the interlayer contradiction and improving reservoir recognition, which is expected to have a broad application prospect.