高含硫探井转开发井的腐蚀评价

The Corrosion Evaluation in Transforming Exploration Well with High Sulfur Content into the Development Well

对于含硫油气区域的探井、探井兼开发井,如果油气产能、H2S含量及分布带有不确定性而选用镍基合金油套管,则可能会造成投资过大的风险。选用H2S酸性环境抗开裂的碳钢和低合金钢后,H2S、CO2、元素硫及地层水对油套管的电化学腐蚀变成了主要问题。这时可以通过优化完井技术,增加油套管壁厚来降低应力水平,以防止氢应力开裂;同时,增加壁厚又可以增加腐蚀余量,延长服役寿命。在概述目前国内含硫油气区域油套管腐蚀评价、防腐蚀措施和存在的问题的基础上,详细分析了基于电化学腐蚀的适用性评价、模拟元素硫的腐蚀环境设计、地层水的腐蚀与模拟试验,及自行研制的高温高压循环流动腐蚀试验仪的工作原理与流程,介绍了探井转开发井腐蚀评价实例,列举了探井转开发井投产的风险和目前已具备的条件,给出了科学的现场风险管理措施。

For exploration wells and exploration/development wells in oil and gas field with high sulfur content, the risk of over-investment maybe occur if nickel-base alloy tubing and casing are chosen with uncertainty on oil-gas production rate, H2 S content and its distribution. When H2 S acid condition is chosen for increasing the crack resistance of carbon steel and low alloy steel, the major problem will become that H2S, CO2 and element sulfur cause the electrochemical corrosion to tubing and casing. Thickening tubing and casing wall to lower stress level, which is one of completion optimization technologies, is an effective way to prevent the hydrogen stress cracking. Also, thickening wall increases corrosive allowance and prolong service life. After summarizing corrosion evaluation, anticorrosion methods and the existing problems in oil and gas field with high sulfur content, this paper is organized in the following way： 1. Give a detail analysis on the evaluation of the electrochemical corrosion applicability, the simulation design of sulfur corrosion environment, and the simulation experiment of formation water corrosion. 2. Describe the principle and process of self-developed high temperature and high pressure circulation corrosion experi- mental apparatus. 3. Introduce the corrosion access cases of exploration well transforming into development wells. 4. Enumerate the risk of exploration well transforming into development well and the currently possessed requirement. 5. Give the scientific risk management method in field.