Abstract
On underground aquifer gas storages, wet gas and liquid water are both carried away by gathering lines from wellheads to gas treatment stations. Internal corrosion of these lines due to liquid water is the main time related damaging process. For the sake of the development of corrosion integrity management plans, it is essential to identify the most likely locations of internal corrosion. Water accumulation is one of the most influential factors in assessing the corrosion threat along a pipeline. The Dry Gas Internal Corrosion Direct Assessment methodology NACE Recommendation, proposes a simplified flow model to predict the critical angle at which water accumulates. However, because of its assumptions the applicability of this model is theoretically limited to the dry0gas lines. The goal of this paper is to estimate the operating conditions where gas flow can carry away liquid water accumulated at low spots. In order to evaluate the draining gas flow rate in a pipe, calculations of multi-phase flow were performed for different pipelines angles. Subsequently, new calculation rules were proposed for wet gas lines and integrated in a new tool to easily estimate this draining flow rate as a function of operating conditions.
