阿姆河右岸高温、高压、高含硫气田DST测试管柱优化设计

An optimal design of a DST string for high temperature,high pressure and sour gas fields on the Right Bank of the Amu Darya River,Turkmenistan

土库曼斯坦阿姆河右岸高温、高压、高含硫气田的地质结构复杂,具有高压力、低渗透的特点,且天然气中普遍含有H2S、CO2等腐蚀性气体,在测试作业过程中发生过井下测试管柱不密封、油管腐蚀损坏、压力泄露等问题,从而影响施工进度和人员、设备的安全。针对此类问题,从工艺和安全角度出发,本着简单实用的原则,通过对现用的4种DST管柱结构的应用特点及工艺进行分析,优化出一套适用于该区块的DST测试管柱(即射孔—测试—酸化—测试—挤压井管柱),其结构为:TCP管串+RTTS封隔器+安全接头+RD循环阀+RD安全循环阀+OMNI多功能循环阀(不带球)+校深短节+采油树。如果测试后直接投产,则可使用永久式插管封隔器来代替RTTS封隔器,即转换为射孔—酸化—测试—完井管柱。该优化后的管柱设计方案已经成功应用于5口井的测试作业,对指导高温、高压、高含硫井的测试施工设计,有效预防安全质量事故的发生,确保取全、取准地层数据和资料提供了技术支撑。

The high temperature,high pressure and sour gas fields on the Right Bank of the Amu Darya River,Turkmenistan,are featured by complex geological structures and low permeability.Natural gas there generally contains corrosive gases such as H2S,CO2.Many accidents occur in block testing,for example,unsealed downhole test string,corrosion and damage to tubings and pressure-resulted leakage,thus affecting the construction schedule and the safety of personnel and equipment.In order to prevent these accidents,from the perspective of process and safety,following the principle of ＂being simple and practical＂,we analyzed the application characteristics and technology of the existing four DST string structures to work out an optimal design of a drill stem test （DST） string （i.e.,perforation-testing-acidification-testing-bullheading string） for this block.The string is composed of a TCP string ＋ a RTTS packer ＋ a safety joint ＋ a RD circulation valve ＋ a RD safety circulation valve ＋ an OMNI multifunction circulation valve （no ball） ＋ a marker sub ＋ a christmas tree.If the well is put into production after testing,a permanent bayonet-tube packer can be used to replace RTTS packer,converting to perforation acidification-testing-completion string.The optimized string design has been successfully applied to the testing operations of five wells,providing a technical support for guiding the testing design of high temperature,high pressure and sour wells,effectively preventing incidents,and accurately acquiring all formation data.