Zhao Zhiheng, Ma Yong, Zhang Yan, Lan Ke, Zhang Xingde
Research Institute of Natural Gas Technology, PetroChina Southwest Oil and Gas Field Company, Chengdu, Sichuan 610213, China.
PetroChina Southwest Oil and Gas Field Company, Chengdu 610015, China.
ACS Omega. 2023 Jul 11;8(29):26201-26205. doi: 10.1021/acsomega.3c02427. eCollection 2023 Jul 25.
In the middle and west of Sichuan Basin, the targeted carbonate formation exhibits features of deep burial and high temperatures at present. In order to obtain better acid fracturing results, the efficient gelled acid developed was investigated based on the carbonate formation characteristics. At the same time, the field application was conducted to prove its adaptability and effectiveness. The high-effective thickener is mainly polymerized by DMC and an allyl octadecyl trimethyl ammonium bromide monomer and a very small amount of diallyl polyethylene glycol. The efficient gelled acid has good compatibility with carbonate formation and formation water, and its thermal stability is great that the viscosity could obtain 25 mPa·s at a temperature of 180 °C after shearing at 30 min. Furthermore, compared with conventional gelled acid, the friction reduction rate of efficient gelled acid is higher of over 7-12%. Also, the induced fracture conductivity is more than 20 D·cm at a closure stress of 60 MPa, which is higher than that of conventional gelled acid with 16.81 D·cm. In addition, during the acidification fracturing of Well PS, the efficient gelled acid system exhibits a good friction reduction property. The flow rate could reach 6 m·min and the obvious pressure drop could be observed, which indicated that the efficient gelling acid reacted with the carbonate formation, creating acidified fractures. The test production of Well PS is 23 × 10 m·d and the acid fracturing adopted by the efficient gelled acid obtains a great break at a high-temperature carbonate formation.
在四川盆地中西部，目标碳酸盐地层目前呈现出深埋和高温的特征。为了获得更好的酸压裂效果，基于碳酸盐地层特性对研发的高效胶凝酸进行了研究。同时，开展了现场应用以证明其适应性和有效性。高效增稠剂主要由碳酸二甲酯（DMC）与烯丙基十八烷基三甲基溴化铵单体以及极少量的二烯丙基聚乙二醇聚合而成。高效胶凝酸与碳酸盐地层和地层水具有良好的配伍性，其热稳定性良好，在180℃温度下剪切30分钟后粘度可达25mPa·s。此外，与常规胶凝酸相比，高效胶凝酸的降阻率更高，超过7 - 12%。并且，在60MPa闭合应力下诱导裂缝导流能力大于20D·cm，高于常规胶凝酸的16.81D·cm。另外，在PS井酸化压裂过程中，高效胶凝酸体系表现出良好的降阻性能。流速可达6m·min，能观察到明显的压降，这表明高效胶凝酸与碳酸盐地层发生了反应，形成了酸化裂缝。PS井试产量为23×10m³/d，采用高效胶凝酸进行酸压裂在高温碳酸盐地层取得了良好效果。
