Engineering Cementing Solution for Hutubi Underground Gas Storage Project

摘要

The underground gas storage is an important segment in China’s gas market because of the supply and demand misbalance of natural gas, the underground gas storage is made available during the peak winter season. In the west of China Hutubi dry gas field is to be used for Underground gas storage with a storage capacity of 4.5 billion cubic meters, a total of 37 wells will be drilled with 30 natural gas injection/withdrawal wells, five observation wells and 2 water injection wells. The Underground gas storage relies on a proper wellbore construction and the sealing function of the cap rock. The selection of the type of cement is crucial to have a healthy well that would last to meet the gas storage need of 30 years under high intensity injection. The gas injection and withdrawal will induce different stresses on the cement sheath and may destroy the seal by either de-bonding (micro-annulus) or cracking; the potential leakage of the gas due to poor cementation and flow through the cap rock can lead to an environmental disaster. A specialized cement technology was identified as a solution to the Underground Gas Storage (UGS) and was deployed successfully in the Hutubi field with great results. This paper will cover the challenges associated to the underground gas storage, the methodology and the steps taken to qualify the new sealant as well as some case histories on three wells.