Analysis and Evaluation of Wellbore Thermal Washing Effect in Block X of Zhenyuan Oilfield

Wellbore wax deposition is a major problem faced by Block X of Zhenyuan Oilfield. Once wax deposition occurs on the tubing and rod strings, it reduces the oil flow passage, increases the load on the rod strings, and may even cause the rod strings to get stuck or break. However, as an important technology for wax removal, the optimal operating regime of thermal washing for the Block X is still unclear, and in-depth research are urgently needed. This paper takes the wellbore wax samples as the research object and uses high temperature steam thermal washing as the research means to explore the thermal washing technical parameters and operation management mode in Block X. It analyzes the wax deposition mechanism and rules, elaborates on the key technical indicators such as thermal washing time, temperature, cycle, and timing, establishes the optimal operating regime, and summarizes the thermal washing effect and economic benefits. The results show that: with the thermal washing time increases, the load difference shows a downward trend while the comparison of load differences gradually rises. After 4 h, the changes of both tend to stabilize. The optimal displacement for thermal washing is 1m3/h. For oil wells in the Jurassic stratum, the temperature of the injected steam should be higher than 115 °C, and for those in the Triassic stratum, it should be higher than 110 °C. The increase in water cut extends the wax deposition cycle to a certain extent. Thermal washing should be carried out immediately when the load increase amplitude of the oil well reaches 10% ~ 20%. After applying the optimized operating regime, the load difference has dropped to 13.15KN, which is a decrease of 1.9KN compared with the same period. A total of $39703 has been saved, and both the thermal washing effect and the economic benefits are extremely remarkable.