High-precision monitoring and point location optimization method of natural gas micro-leakage in the well site of salt cavern gas storage

Abstract

The operation equipment in the well site of salt cavern gas storage is complicated. The potential leakage sources, such as wellhead, valve group and pipelines, are widely distributed, so the probability of micro-leakage events in the well site is very large under the long-term gas injection and production conditions. Aiming at the characteristics of well site layout and the existing problems of present gas detectors, such as low accuracy, multiple points, environmental influencing factors and poor stability, a high-precision monitoring and point location optimization method for natural gas micro-leakage at the well site was proposed. Firstly, an opposite-beam laser methane detector was selected after compared with different combustible gas monitoring methods, and used to monitor the gas micro-leakage at the key zones of well site which have the most probable leakage in real time. Then, a micro-leakage monitoring probability simulation model was established and the gas leakage diffusion law in the well site under different conditions were studied, such as different wind directions, wind speeds, gas leakage points and leakage rates. Finally, a high-precision monitoring method and a point location optimization scheme were proposed under the constraint conditions of economy and monitoring probability after compared with different layout paths. The detecting precision of leak gas concentration can be up to 1.0 ppm m after the improvement of the model. The real-time monitoring and effective early warning of micro-leakage in the well site of salt cavern gas storage can be realized, which can effectively reduce the risk of leakage event after the failure of gas storage leak proofness and ensure the long-term safety monitoring and efficient operation for salt cavern gas storage.