深层页岩气水平井压后生产管理与排采技术

doi:10.13809/j.cnki.cn32-1825/te.2021.01.013

摘要/Abstract

摘要：

川南深层页岩气井采用测-采-输一体化作业模式,实现了降成本、减排放、快投产、早收益的开发目标,但在一体化作业实施中大量采用矿场经验做为决策依据,缺乏通用指导性。针对压后焖井、返排制度及排采对策三方面内容开展了覆压核磁共振渗吸、渗透率应力敏感及气液两相渗流实验,模拟计算了井筒流态及压力剖面分布,并开展了现场30余口气井排采效果评价。研究结果表明：压裂液渗吸进入储层有利于提高页岩裂缝复杂程度,川南页岩气井最优焖井参考周期为4~10 d;形成6阶段返排优化方案,建立了压后排采指导图版。确定以流态转变时机为下油管及人工举升工艺介入时机,油管最佳下入位置为井斜70°~85°,提出了排水采气对策。研究结果对于指导深层页岩气井压后生产管理及排采技术具有较好的指导意义。

关键词: 深层页岩气, 核磁共振, 应力敏感, 井筒流态, 排采技术, 油管设计

Abstract:

The shale gas fields in Southern Sichuan are developed in an integration mode of testing, production and transmission, which has realized the development goals of cost reduction, emission reduction, fast production commissioning and early returns. However, a lot of empirical practices serve as reference of decision-making during implementation of integration practices. There is a lack of general guidance. In order to study the post-frac soaking, the flowback system and the drainage measures, the experiments of overpressured NMR imbibition, permeability stress sensitivity and gas-liquid two phase percolation are conducted, the flow regime and the distribution of pressure profile are simulated, and the discharge and production effect of more than 30 wells in Southern Sichuan shale gas field has been evaluated. The results show that the entry of fracturing fluids into reservoir through imbibition is beneficial to increasing the complexity of shale cracks, and the optimal shut-in time of Southern Sichuan shale gas field is 4~10 days. Meanwhile, a six-staged flowback system is formed, and a post-frac drainage guide chart is established. It is determined that tubing and manual lifting should be implemented when the flow regime changes and the tube should be installed at the well deviation of 70° ~ 85°. Besides, the drainage strategy is also proposed. In general, the research results are of great significance for guiding post-frac production control and drainage technology.

Key words: deep shale gas, NMR, stress sensitivity, wellbore flow regime, drainage technology, tubing design

中图分类号:

TE377

杜洋,雷炜,李莉,赵哲军,倪杰,刘通. 深层页岩气水平井压后生产管理与排采技术[J]. 油气藏评价与开发, 2021, 11(1): 95-101.

Du Yang,Lei Wei,Li Li,Zhao Zhejun,Ni Jie,Liu Tong. Post-frac production control and drainage technology of deep shale gas wells[J]. Reservoir Evaluation and Development, 2021, 11(1): 95-101.

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序号	阶段	生产表象	排采对策	阶段目标
1	焖井	由停泵压力下降至稳定	参考：威荣<5 d;永川7~10 d	增加裂缝复杂程度,达到渗吸平衡
2	初期纯排液	开井返排至井口见气, 点火并连续燃烧	3~5 mm油嘴逐级上调排液, 每级油嘴至少持续3 d	单相流动控制速度,降低裂缝应力敏感,防止支撑剂回流
3	见气初期	井口见气至产气量快速上升、井口压力由平稳变为上升阶段	5~7 mm逐级上调, 每级油嘴至少持续3 d	气液两相流动,降低裂缝应力敏感,防止裂缝快速闭合
4	气相突破	产气量快速上升、井口压力由下降或稳定变为上升	7~9 mm快速逐级上调, 每级油嘴持续1~2 d	气相渗透率大增,基质和缝网供给,减少地层能量损失
5	稳定测试	产气量、井口压力趋于稳定	8~10 mm稳定测试,持续稳定5 d	生产压差稳定,评价气井产能
6	管输生产	测试结束后,进入外输管网生产	5~8 mm油嘴配产生产	根据产能评价合理配产,及时助排

项目	依靠气井自身能量型举升方法
项目	泡排	毛细管	速度管柱	柱塞气举
目前最大排液量（m³/d）	100	40	50	<30
目前最大井深（m）	4 500	5 000	6 248	4 000
水平井井身结构适应性	适应	适应	适应	适应
地面及环境条件	无要求	装置小,要求低	施工对场地要求高	井口流程需要改造
产气量要求	高于临界携泡流量	高于临界携泡流量	高于管径下的临界携泡流量	低,主要是气井压力恢复能力
高气液比	适应	适应	适应	适应
出砂	适应	可用于解堵	适应	有除砂柱塞
设计难易	容易	容易	容易	较易
维修管理	方便	方便	方便	方便
投资成本	低	较低	较低	较低
运转效率（%）	100	100	100	100
灵活性	很好	很好	不能重复利用	很好
免修期	无	>1 a	无	>1 a
在页岩气井适应性	适应	适应	适应	适应

项目	人工补充能量型举升方法
项目	车载气举	机抽	电潜泵	射流泵
目前最大排液量（m³/d）	可连续排液	100	1 000	300
目前最大井深（m）	3 500	2 700	4 500	3 000
水平井井身结构适应性	适应	受限	受限	适宜
地面及环境条件	视井场条件	装置大而重,较适宜	装置小,适宜高压电源	动力源可远离井口,适宜
产气量要求	无	无	无	无
高气液比	适应	气液分离,较适宜	较敏感,较适宜	较敏感,较适宜
出砂	可用于排砂	较差	<0.5 %	无运动条件,很适宜
设计难易	容易	较易	较复杂	较复杂
维修管理	方便	不方便	不方便	不方便
投资成本	较低	较低	较高	较高
运转效率（%）	>95	<30	<65	最高34
灵活性	移动性强	产量可调	变频可调,很好	喷嘴可调,很好
免修期	>1 a		0.5~1 a
在页岩气井适应性	适应	不适应	较适应	较适应