机抽—速度管复合排水采气新工艺

为了提高目前常用的排水采气工艺的适应性,同时降低由排采工艺调整带来的额外的成本开销,利用空心抽油杆对机抽工艺进行了改进,结合应用所研发的空心防气排水采气专用泵,形成了机抽—速度管复合排水采气工艺,并在鄂尔多斯盆地苏里格气田某产水气井进行了现场试验。研究结果表明:①该工艺实现了机抽与速度管柱、气举、泡排等多种排采工艺的自由组合,并且可根据气井产水特点灵活调整适合的排采工艺,提高了工艺的适应性;②采用的游动阀及固定阀均依靠抽油机动力和空心抽油杆重力实现强制启闭,避免了气锁和砂卡引起的机抽失效;③该工艺的选井原则为气井初期产气量较高(大于1×10~4m~3/d)、产水量相对较高(介于3～30 m~3/d),且井口到液面的距离小于2500m;④针对产气量分别为2×10~4m~3/d、1×10~4m~3/d的气井,需采用外径为36 mm、壁厚为6 mm或外径为38 mm、壁厚为6 mm的空心抽油杆进行速度管排水采气,针对产气量为0.6×10~4m~3/d的气井,需采用外径为34 mm、壁厚为5.5 mm的空心抽油杆进行速度管排水采气。结论认为,该工艺可以明显提高产水气井的稳产气量,实现产水气井的连续、稳定生产,应用效果好。

New technology of gas recovery by the combined drainage of pumping–velocity strings

In order to improve the applicability of commonly used drainage gas recovery technologies while reducing the additional cost caused by the adjustment of drainage technologies, this paper improved the pumping process using the hollow sucker rod. And combined with the newly developed special air-proof hollow pump for drainage gas recovery, a gas recovery process by combined drainage of pumping-velocity string was formed. Then, field test was carried out at a water-production gas well in the Sulige Gas Field. And the following research results were obtained. First, in this new process, pumping, velocity string, gas lift, foam scrubbing and other drainage technologies can be combined freely, and drainage technologies can be flexibly adjusted according to the water production characteristics of the gas well. And thus the adaptability of the process is improved. Second, the traveling valve and the static valve adopted in this process all depend on the driving force of the pumping unit and the gravity of the hollow sucker rod to realize the forced opening and closing, so the mechanical pumping failure caused by the gas lock and sand sticking is avoided. Third, the selection principles of the gas well in this process include higher initial gas production rates (>1×104 m3/d), higher water production rates (3–30 m3/d) and short distances from the wellhead to the liquid surface (<2 500 m). Fourth, as for the gas wells with a gas production rate of 2×104 m3/d or 1×104 m3/d, it is necessary to adopt the hollow sucker rod 36 mm in outer diameter and 6 mm in wall thickness or 38 mm in outer diameter and 6 mm in wall thickness for the drainage gas recovery of velocity string. And for the gas wells with a gas production rate of 0.6×104 m3/d, it is necessary to adopt the hollow sucker rod 34 mm in outer diameter and 5.5 mm in wall thickness. In conclusion, the gas recovery process by combined drainage of pumping-velocity string can increase the stable gas production rate of water-production gas wells greatly and realize the continuous stable production of water-production gas wells, presenting good application effects.