On-line Flow Rate Estimation And Early Fault Warning Methods For ESP Wells

Electrical Submerging Pump(ESP)oil production is a kind of artificial lift method that is widely used in offshore oil fields.Understanding the working states of ESP in real-time is important for improving production management of offshore oil fields and promoting construction of offshore smart oil fields.In this paper,the on-line flow rate measurement of ESP well installed with capillary-tubing downhole pressure monitoring system is studied.Based on the energy conservation principle that the pump input power is equal to the motor output power,combining with multi-phase flow theory in wellbore and performance calculation method of downhole motor,the mathematical model of on-line flow rate estimation for ESP well is established.Considering the influences,such as pump wear,a flow correction method based on measured flow rate on ground was proposed.In order to improve production management,the fault diagnosis database and fault solution database for ESP wells were established through on-site statistical data and theoretical analysis,and considering some typical fault types,such as leakage of the pipe string,the jamming of the electric pump,and the lack of liquid supply in the formation.According to fuzzy logic theory and time series data fault point detection theory,the time series data of fault characteristic parameters,such as current,voltage,temperature and pressure,was analyzed.Combining with production history information of ESP wells,the real-time early warning model and method for ESP well failures were established.Based on above studies,a program of on-line flow rate estimation and early fault warning for ESP wells was designed with VB.NET programming language and database technology.The proposed method was used in six offshore ESP wells.The relative error between the estimation results and the actual measured flow rate was less than 10%.It shows that the proposed method has a higher accuracy and could meet the requirements of on-line flow rate estimation in oilfields.The real-time fault warning method was performed in 3 off-shore ESP well and it was verified the reliability and applicability of the model.The results provide technical guidance for the intelligent production management of offshore ESP wells.