页岩气平台井泡沫排水采气技术

Foam drainage gas recovery technology for shale-gas platform wells

井底积液是页岩气井生产过程中普遍面临的问题,需要尽早采取排水采气的工艺措施。泡沫排水(以下简称泡排)采气工艺具有成本低、见效快的优点,在国外页岩气开发中已被大量使用,但在国内还鲜有报道。为此,结合现场生产和集输工艺流程,通过优选泡排工艺流程、研制并持续改进平台整体橇装化远程控制起泡剂和消泡剂自动加注装置、优化起泡剂和消泡剂性能、建立消泡效果监控方法,形成了一套适用于四川盆地川南地区长宁区块页岩气平台井的整体泡排工艺技术。研究结果表明:①起泡剂从各井油套管环空注入、消泡剂从各井一级针阀后通过雾化器加注,能适用于集中计量平台和单井计量平台的起泡剂和消泡剂加注;②优化、改进了橇装化远程控制起泡剂和消泡剂自动加注装置,起泡剂装置采用单泵轮换加注,消泡剂装置采用一口井一台泵加注,具备自动配液、自动加注控制、自动故障报警、远程控制的功能,能够满足页岩气平台井泡排药剂加注的需要;③起泡剂配方优化后,5 min泡沫高度增加37%~50%,建立了消泡率评价方法及消泡剂性能指标要求,通过优化消泡剂配方,初始消泡率提高1.5%~3.0%,3 min消泡率提高0.7%~0.9%;④起泡剂用量为2.0 g/L、消泡剂用量介于4.0~5.0 g/L可以满足现场泡排及消泡要求;⑤通过对分离器和高级孔板阀排污口泡沫情况进行观察,以及取泡排返出水进行二次发泡评价来评估消泡效果,进而优化消泡剂加注制度来进一步提升消泡效果。结论认为,整体泡排技术可以明显提升该区页岩气的开发效果。

Bottom-hole liquid loading is a common problem in the production of shale gas wells,so it is necessary to take drainage gas recovery measures as soon as possible.The foam drainage gas recovery technology is advantageous with low cost and fast response,and it has been extensively applied abroad in shale gas production,but it has been rarely reported at home.Based on on-site production and gathering process,this paper developed a set of integral foam drainage technologies suitable for the shale-gas platform wells in the Changning Block of southern Sichuan Basin by optimizing the technological process of foam drainage,developing and continuously improving the skid-mounted,remote-controlled,automatic foaming agent and defoaming agent filling devices,optimizing the performance of foaming agent and defoaming agent and establishing the defoaming effect monitoring method.And the following research results were obtained.First,the foaming agent and defoaming agent filling method applicable to centralized metering platform and single-well metering platform is to inject foaming agent through the casing-tubing annulus and inject defoaming agent through an atomizer after one-stage needle valve in each well.Second,the skid-mounted,remote-controlled,automatic foaming agent and defoaming agent filling device is optimized and improved.The foaming agent device makes use of a single pump for alternate filling,and the defoaming agent device adopts one pump for filling at each well.It has the functions of automatic liquid distribution,automatic filling control,automatic fault alarm and remote control,and can meet the needs of foam drainage agent filling in shale-gas platform wells.Third,after the formulation of foaming agent is optimized,the foam height is increased by 37-50%in 5 min.The defoaming rate evaluation method and the performance indicators of defoaming agent are established.By optimizing the formulation of defoaming agent,the initial defoaming rate is increased by 1.5-3.0%and the defoaming rate in 3 min is increased by 0.7-0.9%.Fourth,setting the dosage of foaming agent at 2.0 g/L and that of defoaming agent at 4.0-5.0 g/L can meet the requirements of field foam drainage and defoaming.Fifth,the defoaming effect is evaluated by observing the foam at the outlets of separator and high-grade orifice valve and conducting a secondary foaming evaluation on the foam drained water.And accordingly the defoaming agent filling system is optimized to improve the defoaming effect further.In conclusion,the integral foam drainage technology can remarkably improve the production effect of shale gas in this block.