H2S/CO2溶解度测试、预测及其与油套管完整性的相关性研究

Recently, sour gas has increasingly been one main source instead of conventional gas. Once casing and tubing failure accidents such as Sulfide Stress Cracking (SSC), Hydrogen Induced Cracking (HIC) etc. take place in field, the catastrophic consequences will be exerted on the wellbore and environment. The variation of material corrosion results have been found in different wellbores of a structure and different depth of one wellbore. The main reason for that may be the change of H2S/CO2 solubility in formation water. Based on the crucial dates of environment, material and casing programs, in this term, prediction model of H2S/CO2 solubility will be set up, and the solubility testing method of H2S/CO2 in formation water will be investigated. Then we can obtain the vital influential factors. After proposing a new testing measure way of environmental fracture toughness(KIC), we will optimize the correlation model between environmental fracture strength of oil country tubular goods (OCTG) and enviromental fracture toughness (KIC). Based on the H2S/CO2 solubility and KIC,we can obtain the correlation between H2S/CO2 solubility and KIC. Then we will make use of the influential laws of corrosion inhibitor on H2S/CO2 solubility, in order to seek another inhabit mechanism of corrosion inhibitor. Finally, the casing and tubing design and fit-for-purpose method will be put forward based on the environment fracture mechanics. Prediction and test method of H2S/CO2 solubility in formation water is firstly proposed in this term, besides a design and fit-for-purpose method for casing and tubing. Research results will provide important references not only for theory renovation, but also for academic interest, as well as field application.

酸性气藏已成为国家重要接替能源，开采中若油套管发生硫化物应力腐蚀开裂(SSC)、氢脆(HIC)等失效将威胁井筒本质安全和环境安全。在同区块不同井或同井的不同井段，油套管腐蚀差异很大，重要原因之一是H2S/CO2在液体介质中的溶解度变化所致。项目考虑环境因素、材料因素、井身结构等数据，建立H2S/CO2在地层水中的溶解度预测模型，提出H2S/CO2在地层水中的溶解度测试方法，分析影响H2S/CO2溶解度的因素；提出环境断裂韧性(KIC)测试新方法，完善管材环境断裂强度与KIC的关系模型，得到溶解度与KIC的相关性，探索缓蚀剂对H2S/CO2溶解度的影响规律及减缓腐蚀的其它机理；形成基于环境断裂力学的管柱设计和适用性评价方法。项目首次全面研究H2S/CO2在地层水中的溶解度计算和测试方法及其对油套管材料性能的影响规律，并提出油套管设计及适用性评价方法，具有较高的理论价值、学术价值和应用前景。

酸性气藏已成为国家重要接替能源，开采中若油套管发生硫化物应力腐蚀开裂(SSC)、氢脆(HIC)等失效将威胁井筒本质安全和环境安全。在同区块不同井或同井的不同井段，油套管腐蚀差异很大，重要原因之一是H2S/CO2在液体介质中的溶解度变化所致。项目考虑环境因素、材料因素、井身结构等数据，建立了H2S/CO2在地层水中的溶解度预测模型，提出了H2S/CO2在高温高压地层水中的溶解度测试方法，分析了温度、压力、矿化度对H2S/CO2溶解度的影响规律，得到了溶解度对温度、压力及矿化度的敏感程度；提出了环境断裂韧性(KIC)测试新方法，完善了管材环境断裂强度与KIC的关系模型，得到了溶解度与KIC的相关性，初步探索了缓蚀剂对H2S/CO2溶解度的影响规律及减缓腐蚀的其它机理；形成了基于环境断裂力学的管柱设计和适用性评价方法。项目首次全面研究了H2S/CO2在地层水中的溶解度计算和测试方法及其对油套管材料性能的影响规律，并提出了油套管设计及适用性评价方法，具有较高的理论价值、学术价值和应用前景。