Water-sealing performance assessment of the water curtain system in underground water-sealed oil-storage caverns

摘要

Underground water-sealed oil-storage caverns still face many challenges after completion, such as oil leakage and excessive water inflow into caverns. However, there is a lack of high quality and efficient operation precedent for large-scale underground caverns at present. The oil-storage efficiency of the reservoir rock is directly related to the water-sealing performance of the water curtain system. In order to evaluate the water-sealing performance of water curtain system, time-series monitoring information collected during investigation, construction, and operation were used to study the seepage characteristics. A short-term seepage pressure prediction was obtained using the exponential smoothing method, and the prediction accuracy was evaluated. Based on the concept of minimum seepage pressure, the seepage characteristics were simulated using finite element numerical model, whose results demonstrated that the minimum seepage pressure point ideally occurs near the cavern vault. The excessive water curtain pressure causes the increase of groundwater velocity and water head around the storage caverns, especially at the cavern vault. The seepage pressure on the neutrality line between two adjacent storage caverns exhibited the following three curve shapes: type "V", type "?", and type "similar to" corresponding to different possible seepage positions.