高压气井环空压力许可值确定方法及其应用

对于高压气井，在采气过程中环空带压现象非常普遍。环空压力过高可能导致潜在的安全生产事故；若环空压力过小，则井口处油套压差过大，安全系数过低，油管长期疲劳生产，也易发生事故。因此，针对高压气井，有必要给出环空压力安全范围，以指导安全生产。为此，借助ARP RP90海上油气井环空套压管理和NORSOK D-010 油气井钻井与作业时的完整性等2个公认的国际技术标准，将带压环空进行了分类：油管-生产套管环间、生产套管-技术套管环间、两层套管环间，然后用承压构件的强度、水泥环及保护液注柱压力对气井环空的安全性能进行综合评价，给出了适合塔里木油田的高压气井环空最大、最小压力许可值的确定方法，用以指导高压气井的方案设计和安全生产。该方法已经在该油田展开现场应用，对于高压气井的环空压力安全管理具有重要意义。

A method determining the safety range of the annulus pressure for a high-pressure gas well and its application

The abnormal annular pressure is quite normal for a high pressure gas well and downhole accidents may easily occur due to overly high pressure in annulus; however, if such pressure is too low, the safety factor will be driven down too much by the excessive differential pressure between the tubing and the casing at the wellhead, and that will bring the tubing into a long lasting fatigue state, which will also result in accidents. Thus, it is necessary to specify the safety range of annulus pressure of each high pressure gas well for a safer production. With the help of the two recognized international technical specifications including the ARP RP90 Annular Casing Pressure Management for Offshore Well and the NORSOK D-010 Well Integrity and Integrity Management for Drilling and Operation of Oil and Gas Wells, the pressurized annulus can be categorized into the annulus between the tubing and the production casing, the annulus between the production casing and the intermediate casing, and the annulus between the two layers of casings. Then, a comprehensive evaluation was made on the safety of gas well annulus in the aspects of the strength of compression members, the pressure of cement, and the hydraulic pressure of protective fluid. Finally, a method is developed for determining the upper and lower limits for the annulus pressure of high pressure gas wells in the Tarim Oil Field, which can be used to guide the design and production of high pressure gas wells. This method having been successfully applied in this field is of great significance to safety management of annulus pressure in high pressure gas wells.