南海超高温高压气井裸眼完井测试关键技术

南海莺琼盆地超高温高压区块油气资源潜力巨大，随着超高温高压区块勘探力度的逐步加大，海上超高温高压气井裸眼完井测试的需求逐渐上升。目前海上超高温高压气井的裸眼完井测试存在巨大的风险和挑战:高密度测试液清喷困难，极端条件下易造成测试液稠化沉淀堵塞测试管柱；超高温高压测试条件下，测试管柱配置较为复杂，同时管柱伸长量设计不合理，存在测试工具失效的风险；井壁岩石不稳定性风险较高，存在着井壁坍塌、地层出砂、埋卡封隔器等风险。为解决上述难题，自主研发了一套适用于海上高效勘探开发的超高温高压气井裸眼完井测试关键技术:研发了沉降稳定型测试液，通过在原完钻钻井液基础上添加抗高温降滤失剂和增加石灰含量增强沉降稳定性能；在常规测试管柱的基础上增加RD循环阀和选择性测试阀并合理计算测试管柱的伸长量，优化设计了测试管柱结构；合理优化海上平台的测试管线流程和装置布局，有效降低了测试过程中的风险；考虑测试过程中井壁不发生剪切破坏的前提下，制定了合理的测试压差和测试时间。该技术在南海超高温高压气井DF13-Y-Y井中进行了现场应用并取得了圆满成功，为后续海上超高温高压井的裸眼完井测试积累了宝贵经验。

Key technologies for the open hole completion testing of ultrahigh temperature and high pressure gas wells in the South China Sea

There is immense potential of oil and gas resources in the ultrahigh temperature and high pressure block of the Yingqiong Basin, the South China Sea. And with the gradual increase of exploration intensity in the ultrahigh temperature and high pressure block, the demand on the open hole completion testing of offshore ultrahigh temperature and high pressure gas well increases gradually. At present, the open hole completion testing of offshore ultrahigh temperature and high pressure gas well is faced with huge risks and challenges as follows. High-density testing fluid can be hardly blown out, which can easily result in the thickening settlement of the testing fluid in the extreme conditions so as to block the testing string. Under the testing conditions of ultrahigh temperature and high pressure, the configuration of testing string is relatively complicated while the string elongation is not designed reasonably, which brings about failure risk to testing tools. The sidewall rocks are of higher instability risk, and there are the risks of hole collapse, sand production and packer burying and sticking. In order to solve these difficulties, this paper developed independently a set of key technologies suitable for the open hole completion testing of ultrahigh temperature and high pressure gas well of offshore efficient exploration and development. The testing fluid of stable settlement type is developed, whose settlement stability is strengthened by adding high-temperature fluid loss agent and increasing lime content on the basis of the original drilling and completion fluid. The structure of the testing string is optimally designed by adding RD circulation valve and selective testing valve on the basis of the conventional testing string and calculating the elongation of the testing string reasonably. The testing pipeline flow and device layout of offshore platform are optimized reasonably, so that the risks in the testing process are reduced effectively. Reasonable testing pressure difference and testing time are set under the premise that no shear damage happens on the sidewall during the testing. These technologies have been successfully applied in Well DF13-Y-Y, an ultrahigh temperature and high pressure gas well in the South China Sea. The successful application of these technologies accumulates valuable experience for the following open hole completion testing of offshore ultrahigh temperature and high pressure wells.