摘要
四川盆地威远地区下志留统龙马溪组页岩普遍具有水平应力差高、非均质性强等特点,前期主体开发技术借鉴北美现场压裂经验,存在压裂缝网较为简单、压后效果差异大等问题。为进一步提升威远页岩气田缝控压裂关键参数的适应性、合理性,采用饱和覆盖、全域支撑的压裂设计理念,结合暂堵压裂数值模拟、支撑剂流动评价等方法,形成了以“主缝换缝网+暂堵换排量+粉砂换陶粒”为核心的新一代页岩缝控压裂关键技术。研究结果表明:(1)适度减少段内簇间距,以更密集的主缝替代前期不完善缝网系统能够保障裂缝对储层的充分覆盖;(2)暂堵时机、暂堵用量的优化能够提升多簇压裂条件下裂缝的均匀开启程度,其精确性和经济性较单一提升压裂排量更高;(3)提升粉砂比例+强化支撑剂用量的参数优化组合,能够实现各级裂缝的有效支撑。结论认为:(1)该技术在威远页岩气田现场应用100余井次,应用井平均千米测试产量较应用前增加7.2%,测算平均EUR增加4.3%,套变率下降约28.7%,压裂综合作业成本下降超过12%;(2)该技术能够有效提升页岩气储量的动用,为威远页岩气田压裂降本增效提供了有力支撑,同时也为川南地区页岩气压裂关键参数的精细优化提供了技术指导。
The Lower Silurian Longmaxi Formation shales in the Weiyuan area of the Sichuan Basin are generally characterized by high horizontal stress difference and strong heterogeneity.The early fracturing technologies,mainly formed with reference to the practices in the North America,are insufficient for simple hydraulic fracture networks and great varying postfrac effects.In order to improve the adaptability and rationality of the key parameters of fracture-controlled fracturing technology in the Weiyuan Shale Gas Field,a new generation of shale fracture-controlled fracturing technology,which pursues primary fractures instead of fracture networks,optimizes temporary plugging rather than displacement and replaces ceramsites with silts,is formed according to the fracturing design concept of saturated coverage and whole-domain support,combined with the numerical simulation of temporary plugging fracturing and the evaluation of proppant transportation.The following results are obtained.First,moderately reducing the cluster spacing in the section and replacing the earlier imperfect fracture network system with a denser main fracture can ensure the sufficient coverage of the reservoir by fractures.Second,the optimization of temporary plugging timing and dosage can improve the uniform fracture opening degree under the condition of multi-cluster fracturing,and it realizes higher accuracy and economy than simply increasing fracturing displacement.Third,the parameter combination of increasing silt proportion+enhancing proppant usage can achieve effective support of fractures at all levels.In conclusion,the technology has been applied practically more than 100 well times in Weiyuan shale,whose tested average production per kilometer is 7.2% higher,calculated average EUR is 4.3% higher,casing deformation rate is 28.7% lower and comprehensive fracturing operation cost is over 12% lower than the value before the application of the technology.What's more,this technology can effectively improve the utilization of shale gas reserves,and provide strong support for cost reduction and efficiency improvement of fracturing in Weiyuan Shale Gas Field,while providing technical guidance for the fine optimization of key parameters of shale gas fracturing in the southern Sichuan Basin.
作者
肖剑锋
何怀银
李彦超
沈建国
邓才
邹龙庆
李俊翔
王一萱
XIAO Jianfeng;HE Huaiyin;LI Yanchao;SHEN Jianguo;DENG Cai;ZOU Longqing;LI Junxiang;WANG Yixuan(CNPC Chuanqing Drilling Engineering Company Limited,Chengdu,Sichuan 610051,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2023年第7期63-71,共9页
Natural Gas Industry
基金
中国石油天然气集团有限公司科学研究与技术开发项目“水平井压裂缝网分布形态监测及诊断新技术研究”(编号:2021DJ4502)。
关键词
页岩气
缝控压裂
压裂缝网
暂堵优化
射孔簇开启
饱和覆盖
全域支撑
Shale gas
Fracture-controlled fracturing
Hydraulic fracture network
Temporary plugging optimization
Perforation cluster opening
Saturated coverage
Whole-domain support
