致密气井连续管完井一体化技术

Integrated Technology for Tight Gas Well Coiled Tubing Completion

长庆油田致密气为低渗高含水气藏,此前采用Φ60.3 mm常规油管接单根带压完井,施工复杂、效率低,加之油管管径较大,携液能力有限,只能满足投产初期生产的需求,在中后期生产时,当井内气体速度低于油管临界携液流速时井底开始积液,虽然可以采用较为成熟的泡沫排水、速度管柱、柱塞气举等排水采气工艺,但存在作用时间有限、需要分段实施等问题,效果差、成本高。选用Φ50.8 mm连续管作为致密气井生产管柱,创新研发了一体化节流堵塞器,具有封堵、节流、承接柱塞等多种功能,同时,设计了井口直座式悬挂器和双卡瓦重载连接器、转换接头,实现了Φ50.8 mm连续管直接连接和悬挂密封,在国内率先形成Φ50.8 mm连续管完井一体化技术,实现了气井高压期节流降压、低压期连续排液生产和间歇期柱塞气举的全生命周期生产。大量气井应用表明,与Φ60.3 mm油管带压完井作业相比较,Φ50.8 mm连续管完井一体化作业周期缩短50%以上,气井自然连续生产期延长1.5年。

Tight gas in Changqing oil field is a gas reservoir with low permeability and high water content.TheΦ60.3 mm tubing snubbing completion was completed by means of a single joint,which is complicated in construction and inefficient.In addition,the large diameter of the tubing has limited liquid carrying capacity,so it can only meet the needs of the initial production.In the middle and later stages of production,when the gas velocity in the well is lower than the critical liquid carrying flow rate of the tubing,liquid begins to accumulate at the bottom of the well.Although more mature drainage and gas production processes such as foam drainage,velocity string,plunger gas lift and so on can be used,there are issues such as limited action time and the need for segmented implementation,resulting in poor effectiveness and high costs.TheΦ50.8 mm coiled tubing as the production string of tight gas wells is selected,and the integrated throttle blocker has been innovatively developed,which has multiple functions such as plugging,throttling,and undertaking plunger.At the same time,the wellhead straight seat hanger,dual slip heavy load connector,and transfer joints have been designed to achieve direct connection ofΦ50.8 mm coiled tubing with suspension seals.The integrated technology ofΦ50.8 mm coiled tubing completion has been formed in China firstly.Full lifecycle production of gas wells during high⁃pressure throttling and pressure reduction,low⁃pressure continuous liquid discharge production,and intermittent plunger gas lift is realized.A large number of gas well applications show that compared with theΦ60.3 mm tubing snubbing completion,the operating cycle of theΦ50.8 mm coiled tubing completion integration is shortened by more than 50%,and the natural continuous production period of the gas well is extended by 1.5 years.