A Novel Downhole Communication Strategy Using Loading Wave Conduction on Sucker-Rod Pumping System for Intelligent Lifting

Summary An effective and accurate downhole communication strategy is crucial for the fabrication of an intelligent lifting system for onshore oil wells. Traditional communication approaches based on the wired cable, acoustic wave, vibration wave, or fluid pressure are usually limited by downhole conditions, and issues such as cumbersome implementation, limited communication, and unstable signal modulation are encountered. Herein, a novel downhole communication strategy is proposed using the loading waves in the sucker-rod pumping system (SRPS). The loading wave is altered at the downhole pump at an extremely low frequency, and its significant variation could be captured by the surface load sensor. A controlled valve is installed between the chamber of the pump and the wellbore. The valve opening regulates the pressure in the pump chamber, leading to the generation of the controlled loading waves. The field tests are further carried out and prove the effective coding between the downhole and surface with an acceptable delay (~0.154 seconds for a well with a depth of 1000 m). For the loading wave transmission on the sucker-rod string system, the finite element method is used to solve the theoretical model considering the real circumstances, such as the coupling damping, centering device friction, and stuffing box friction. The impacts of operating parameters of the lifting system, wellbore conditions, and modulation of excitation signal on the communication process are systematically discussed. The transmission evaluation standard, applicable conditions, coding tactic, and potential engineering values are presented for the downhole communication system.