海洋深水高温高压气井环空带压管理

中国南海高温高压油气藏开发过程中,井筒环空带压问题突出,一旦超过允许值将会影响安全生产。为了保证气井的正常生产,需要确定环空压力的合理范围,为此基于ISO 16530-1:2017标准和API RP 90-2的推荐做法,研究并建立了考虑管柱承压能力和关键节点校核的深水高温高压气井环空带压控制值计算模型以及一套环空压力管理图版。研究结果表明:(1)管柱承压能力计算主要针对环空对应的油管和套管;(2)关键节点校核计算主要针对井口装置、封隔器、井下安全阀和尾管悬挂器等;(3)建立了环空最小预留压力计算模型,以确保对深水高地层压力或井底高流压气井的环空施加一定的备压,保证井下管柱和工具在合理环空压力范围内正常工作;(4)以某深水气井为实例进行了计算与分析,得到了考虑和不考虑壁厚减薄情况下随投产时间变化的各环空带压控制值。结论认为,所建立的模型及图版应用于海上深水高温高压气井,使用简便、可操作性强,可以为深水高温高压气井及类似井的井筒环空压力管理提供借鉴。

Annulus pressure management of marine deepwater HTHP gas wells

The problem of annulus pressure is prominent in the development process of high-temperature and high-pressure (HTHP) oil and gas reservoirs in the South China Sea. And once the annulus pressure exceeds the allowable value, the safety of production will be impacted. Therefore, it is necessary to determine the range of reasonable annulus pressure in order to ensure the normal production of gas wells. Based on the recommended practice in ISO 16530-1:2017 and API RP 90-2, this paper researched and established a model for calculating the annulus pressure control value of deepwater HTHP gas wells while considering the pressure bearing capacity of pipe string and the check of key nodes, as well as a set of annulus pressure management chart. And the following research results were obtained. First, the calculation of the pressure bearing capacity of pipe string is mainly aimed at the tubing and casing corresponding to annulus. Second, the check calculation of key nodes mainly focuses on wellhead device, packer, downhole safety valve and liner hanger. Third, a model for calculating the minimum reserved annulus pressure is established to apply a certain backup pressure in the annulus of the deepwater gas wells with high formation pressure and that with high bottom hole flow pressure and ensure the normal operation of downhole strings and tools in the range of reasonable annulus pressure. Fourth, the calculation and analysis are carried out by taking one deepwater well as an example. The control values of annulus pressure with the change of commissioning time with and without considering the reduction of wall thickness are obtained. It is concluded that the proposed model and chart are simple and can be operated easily when they are used in marine deepwater HTHP gas wells, and they provide reference for annulus pressure management of deepwater HTHP wells and similar wells.