摘要
压裂充填是中高渗疏松砂岩储层稳产增产的关键技术,但在投产后,由于储层胶结疏松,支撑剂嵌入和地层出砂堵塞导致裂缝导流能力显著下降。目前尚缺乏预测此类复合作用下裂缝导流能力的方法。通过使用压裂充填模拟实验装置,在5~20 MPa闭合应力下,利用疏松岩板样品进行裂缝支撑剂嵌入与地层砂堵塞的复合实验。基于实验结果,分析主控因素并拟合构建支撑剂压实、嵌入导致的缝宽损失和地层砂堵塞引起的动态渗透率变化模型,形成相应的导流能力预测方法。结果表明:裂缝闭合后支撑剂嵌入压实会显著降低导流能力,其损失主要受闭合应力、储层强度、支撑剂与地层砂粒径等因素控制,地层砂堵塞存在时间效应,导致导流能力动态下降。在渤海油田某典型疏松砂岩储层中,裂缝缝宽损失约19.34%,渗透率损失约34.15%,地层出砂堵塞造成的渗透率损失约为22.89%,多因素共同作用下,导流能力损失约为59.06%。为避免过度堵塞,建议初始缝宽保持在12.5 mm以上,使用大粒径支撑剂,并在生产初期适当控制产量避免过度堵塞;并且较高强度的储层压裂充填增产效果更好。研究成果对优化疏松砂岩储层压裂充填防砂施工参数具有重要指导意义。
Fracturing and packing is a key technology for maintaining and enhancing production in medium-to high-permeability unconsolidated sandstone reservoirs.However,after production begins,the loose cementation of the reservoir,combined with proppant embedment and formation sand invasion,significantly reduces fracture conductivity.Currently,there is a lack of methods to predict fracture conductivity under the combined effects of proppant embedment and formation sand blockage in such reservoirs.A fracturing and packing simulation device was used to conduct composite experiments on proppant embedment and formation sand blockage under closure stresses ranging from 5 MPa to 20 MPa,unconsolidated rock plate samples were used to simulate fracture surfaces.Based on the experimental results,the controlling factors and developed models were analyzed to predict permeability loss due to proppant compaction,fracture width loss caused by embedment,and dynamic permeability changes due to formation sand blockage.The results show that proppant embedment and compaction after fracture closure significantly reduce fracture conductivity,with the main factors being closure stress,reservoir strength,and particle sizes of the proppant and formation sand.Formation sand blockage also exhibits a time-dependent effect,contributing to dynamic conductivity decline.In a typical unconsolidated sandstone reservoir in the Bohai Oilfield,the calculated fracture width loss due to embedment is approximately 19.34%,permeability loss from closure and compaction is about 34.15%,and dynamic permeability loss from formation sand invasion is around 22.89%.The combined effect of these factors results in a total fracture conductivity loss of approximately 59.06%.To prevent excessive blockage,it is recommended that the initial fracture width be maintained at no less than 12.5 mm,large-particle proppants be used,and production rates be controlled during the early production phase.The research results provide important guidance for optimizing fracturing and packing parameters and improving production in unconsolidated sandstone reservoirs.
作者
李国龙
董长银
张启龙
韩耀图
尹彬
白豪斌
张晓诚
LI Guo-long;DONG Chang-yin;ZHANG Qi-long;HAN Yao-tu;YIN Bin;BAI Hao-bin;ZHANG Xiao-cheng(Key Laboratory of Unconventional Oil&Gas Development,Ministry of Education,Qingdao 266580,China;School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,China;Tianjin Company of CNOOC(China)Co.,Ltd.,Tianjin 300459,China)
出处
《科学技术与工程》
北大核心
2025年第12期4975-4985,共11页
Science Technology and Engineering
基金
国家自然科学基金(52074331)
国家重点研发计划(2023YFC2811005)。
关键词
疏松砂岩储层
压裂充填
支撑剂嵌入
地层砂堵塞
裂缝导流能力
unconsolidated sandstone reservoir
fracturing and packing
proppant embedment
formation sand blockage
fracture conductivity
