Water flooding had proved its value in oil recovery enhancement. Generally downhole data was obtained through electric cable which increased the cost significantly, meanwhile the communication was often interrupted due to sealing issues in the cable system.
This paper focused on theoretical modeling of electromagnetic waves as it propagated across different downhole mediums, including casing, cement, and reservoir with varied electrical resistivity. The preparedness of the telemetry system was presented from the perspective of field operation, finally the case study of water flooding operation with telemetry system equipped was described in details.
Based on the attenuation model, 6.25Hz electromagnetic wave could reach 3000m deep underground with residual strength of 0.1mV, provided the average electrical resistivity exceeded 10Ω·m which was not too demanding. The telemetry system comprised of three parts which are signal sender, metal connector and decoding device on the ground. Viability tests were carried out to optimize the frequency and power setup, making it adaptable for water flooding operations. The system was integrated with water injector and trialed in the oilfield, while electric cable was used to verify the wireless system. According to the feedback, the pressure and flowrate data were received through 5Hz electromagnetic waves in a real-time manner from 1025m deep underground, its accuracy was approved by the data obtained via electric cable, the flowrate control instruction was also passed through wireless system and the nozzle downhole responded correctly. The system could replace cable in the future popularization of water flooding operation, reducing the risk and the capex.
Intelligent oilfield has been the objective and pursued constantly, matured downhole wireless telemetry system was an integral part of this process. This study has expand our horizons the knowledge on this lucrative subject, successful application of wireless telemetry system in the water flooding operations gave us more insights in how to reach the goal.
