Research on Separate Layer Polymer Injection Technology with Electrohydraulic Joint Control Single-Pipe in Offshore Oilfield
Conventional single-pipe subdivided polymer injection technology is insufficient for not-in-place of dropping and fishing of testing and regulating instrument,difficult allocation of polymer injection allocator and short effective period resulted from polymer adsorption.To solve these problems,an electrohydraulic joint control single-pipe separate layer polymer injection technology was developed.This technology includes core tools such as electro-hydraulic composite separate control device,hydraulically controlled multistage polymer injection allocator and non-contact heat conduction flowmeter.The electrohydraulic composite separate control device uses a main control cable to realize separate control of multiple hydraulically controlled tools by a hydraulically controlled pipeline,which greatly simplifies the number of pipelines in the wellbore.The hydraulically controlled multistage polymer injection allocator solves the problem of difficult flow regulation in the polymer injection process,achieving variable displace-ment regulation and large pressure difference injection.The non-contact flowmeter achieves long-term online moni-toring of polymer flow rate in the wellbore.This technology has been successfully applied in 3 wells,with the num-ber of separate layer injection layers of 2～3,and a maximum single-layer injection rate of 130 m3/d.Moreover,it has been adjusted through 21 tests,showing a testing accuracy of over 85%.It is still effective after about 600 days in the well.This technology meets the polymer injection requirements of offshore oilfields such as viscosity reten-tion,subdivision and long-term effectiveness,and it is highly worthy of popularization.
offshore oilfieldsingle-pipe separate layer polymer injectionelectrohydraulic joint controlre-al-time monitoring
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