红星地区吴家坪组超深层页岩压裂实践及认识

Practices and Insights of Fracturing for Ultra-Deep Shale Reservoirs of the Wujiaping Formation in Hongxing Area

  • 摘要: 红星地区吴家坪组页岩具有高灰质含量、高抗压强度、高应力差和层理缝发育等特点,压裂时存在施工压力高、压力窗口窄、加砂困难、复杂缝形成难度大、高闭合压力下支撑剂破碎和嵌入严重等难题。为此,进行了多轮工艺迭代优化,采用“深穿透+前置酸”组合工艺,降低页岩破裂压力5 MPa以上;采用大排量与交替变黏施工,微地震监测缝网复杂度提升10.5%;采用以粉砂为主的“微细支撑”的改造理念,进一步扩大了支撑范围,并形成了“降破压、促复杂、增导流”为核心的压裂技术体系。X-9HF最大埋深4 855.4 m,现场应用后测试产量25.72×104 m3/d,实现了超深层页岩气勘探突破,新增探明储量超千亿立方米。红星地区吴家坪组突破为其他深层超深层页岩气勘探开发提供了理论依据与技术借鉴。

     

    Abstract: The Wujiaping Formation shale in the Hongxing area is distinguished by high calcareous content, high compressive strength, high differential stress, and well-developed bedding planes. These lithological and mechanical properties cause high fracturing pressures, narrow operating windows, difficult proppant placement, limited generation of complex fractures, and severe proppant crushing and embedment under high closure stress. To address these issues, multiple rounds of process optimization were carried out. A combined technique of deep-penetration perforation and acid pre-treatment lowered the fracture breakdown pressure by more than 5 MPa. High-rate pumping with alternating-viscosity fluids improved fracture network complexity by 10.5%, as confirmed by microseismic monitoring. A micro-proppant strategy, primarily using fine sand, effectively expanded the propped area. Based on these measures, a fracturing technology system was established, focusing on three core objectives: reducing breakdown pressure, promoting fracture complexity, and enhancing fracture conductivity. Well X-9HF, with a maximum burial depth of 4855.4 m, was tested under this system and delivered a gas production rate of 25.72×104 m3/d. This successful field application marked a breakthrough in ultra-deep shale gas exploration and added over 100 billion cubic meters of proved reserves. The experience gained from the Hongxing area offers a valuable reference for future deep and ultra-deep shale gas development in China.

     

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