Abstract: High-quality reservoir is developed in the deep layers of the lower assemblage of the southern margin of Junggar Basin, where embeds tremendous oil and gas resources. However，the reservoir there has a general burial depth greater than 5 700 m，a temperature greater than 130 ℃，a closure stress gradient greater than 0.02 MPa/m，an average porosity less than 10%，an average permeability less than 0.1×10 -3 μm 2 and strong heterogeneity. Due to the poor physical properties，high Young's modulus and high Poisson's ratio of the reservoir，fracturing faces great challenges in respect of fracture initiation，high pump pressure and efficient use，which present higher requirements for wellbore integrity，fracturing materials and technology. Through field study and practices，a fracturing technical system for tight reservoir with high closure stress has been developed，which is centered on the technology to reduce wellhead operating pressure and integrated with proppant combination and optimization technology and treatment parameter optimization technology. Thus，the bottleneck of the fracturing technology for deep reservoir with high temperature and pressure has been broken through. It has been successfully applied in 3 wells since 2020. After fracturing treatment，well-GQ6 has seen significant effect: the maximum daily oil production is 97.97 m 3 and the daily gas production is 2.03×10 4 m. This technical system provides new perspective for deep oil and gas exploration in the southern margin of Junggar Basin.

Key words: high closure stress, tight reservoir, reservoir fracturing, weighted fracturing fluid, proppant

摘要： 准噶尔盆地南缘下组合深层优质储层发育，油气资源量大，但普遍埋藏深度大于 5 700 m、地层温度高于 130 ℃、闭合应力梯度大于 0.02 MPa/m、平均孔隙度小于 10%、平均渗透率小于 0.1×10 -3 μm 2 ，非均质性强，属低孔低渗透储层。由于储层物性差、杨氏模量高、泊松比高，压裂改造存在启裂难度大、施工压力高、高效动用难度大等特点，对井筒完整性、压裂材料和工艺等提出更高要求。通过现场研究与实践，形成了以降低井口施工压力技术为核心，支撑剂组合优化技术与施工参数优化技术相结合的高闭合应力致密储层改造技术体系，突破了深层高温高压储层改造技术瓶颈，2020—2021年应用 3井次，施工成功率 100%。通过压裂改造，GQ6井获最高日产油 97.97 m 3 ，日产气 2.03×10 4 m 3 ，取得重大储层改造效果，开启准噶尔盆地南缘深层油气勘探新领域。

关键词: 高闭合应力, 致密储层, 储层改造, 加重压裂液, 支撑剂