Fracturing Technologies for Horizontal Wells in the Second-Class Shale Oil Reservoirs of the Lower Sweet Spot Areas in Jimusar
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摘要: 为了解决准噶尔盆地吉木萨尔页岩油因其流度低和储层层理发育缝高受限导致水平井提产困难的问题,提高下甜点二类储层的有效动用程度,开展了密切割改造提升缝控程度、薄互层穿层压裂增加纵向动用程度技术攻关。研究了密切割改造技术,将平均簇间距缩短至13.6 m,大幅提高了页岩储层缝控程度;提高了直井压裂施工的排量及冻胶用量,验证了下甜点二类储层具备穿层压裂的可行性,形成了以水平井12~14 m3/min大排量、冻胶和滑溜水多段塞泵注、中小粒径支撑剂组合和2.7 m3/m高加砂强度等为核心的穿层压裂关键技术,保证了层理转折裂缝有效支撑。现场试验表明,该技术能够提高水平井压裂动用体积,二类储层试验水平井压裂后第1年累计产油量达9 183 t,是前期水平井产油量的3倍以上。研究结果表明,水平井密切割穿层压裂技术可以解决二类储层多薄油层难动用的问题,为页岩油二类区有效动用提供了新的技术途径。Abstract: Technical research was carried out to enhance fracture control in fracturing with tight spacing and boost longitudinal production by cross layer fracturing in thin interbeddings. The research aims to address the difficult enhancement of horizontal well production induced by low fluidity and limited fracture height in beddings of the shale oil reservoirs in Jimusaer, Junggar Basin, and improve the production in the second-class shale oil reservoirs of the lower sweet spot areas in this region. The technique of fracturing with tight spacing was studied, with the average inter-cluster spacing reduced to 13.6 m, greatly strengthening the fracture control in shale oil reservoirs. The displacement and gel amount during vertical well fracturing were increased, and the feasibility of cross layer fracturing in the second-class reservoirs of the lower sweet spot areas was verified. As a result, the key technologies of cross layer fracturing, featured by large displacement (12–14 m3/min) in horizontal wells, multi-slug pumping of gel and slick water, proppant integrating medium and small particle sizes, and large sand addition (2.7 m3/m), were developed to provide strong support against the turning fractures in beddings.The annual cumulative oil production of the horizontal test wells in the second-class reservoirs achieved 9 183 t, more than three times that of previous horizontal wells.The field test demonstrates that the technologies can enlarge the fracturing volume in horizontal wells.The research results show that the cross layer fracturing with tight spacing for horizontal wells can solve the production problem of multiple thin oil layers in the second-class reservoirs and provide a new technical approach for the fracturing production of horizontal wells in such reservoirs.
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Key words:
- shale oil /
- horizontal well /
- bedding /
- thin interbedding /
- tightspacing /
- volumetric fracturing /
- cross layer fracturing /
- Jimusaer
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表 1 JA2井测试验窜施工参数
Table 1. Construction parameters of the channeling test in Well JA2
测试阶段 时间 油管(目的层2 773.50~2 776.50 m) 套管(目的层2 762.00~2 768.00 m) 结论 工作状况 抽汲液面/m 产液量/m3 工作状况 套管压力/MPa 产液量/m3 第1阶段 第1天 抽汲 1 250 6.34 关井 2.3 0 两层未窜通 第2天 抽汲 1 565 7.22 关井 2.6 0 第3天 抽汲 1 570 5.11 关井 3.0 0 第4天 抽汲 1 560 3.34 关井 3.2 0 第2阶段 第5天 测液面 1 490 0 开井 0 14.60 两层未窜通 第6天 测液面 1 430 0 开井 0 13.55 第7天 测液面 1 380 0 开井 0 12.67 第8天 测液面 1 330 0 开井 0 12.49 第3阶段 第9天 测液面 1 290 0 加压6次 10.0 0 两层未窜通 表 2 试验井施工参数及阵列声波测井解释结果
Table 2. Construction parameters of the test wells and interpretation results of array acoustic logging
井号 井段/m 隔层应力差/MPa 隔层厚度/m 冻胶排量/(m3·min–1) 冻胶用量/m3 解释缝高/m 解释缝高范围/m JB1 3 498~3 502 8.0 2.0 10.0 594.0 43 3 467~3 510 JB2 2 944~2 954 5.0 2.0 8.6 510.0 15 2 943~2 958 JB3 3 279~3 283 5.0 1.0 10.0 420.8 19 3 268~3 287 -
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