摘要
微裂缝在不同程度上提高了灰岩地层孔隙的渗透性。为了厘清回注过程中微裂缝不同发育情况对钻屑废弃物回注能力的影响机制,确保钻屑回注安全实施,首先采用X射线CT(计算机断层摄影)扫描某气田采集到的灰岩岩心进行数字重构,得到其基质模型,研究废弃物颗粒在孔隙中的运移和沉积机制;然后基于数值算法构建裂缝-基质模型,引入裂缝连通系数与裂缝走向因子定量表征裂缝的连通性和走向,揭示裂缝开度对回注地层渗透率以及废弃物回注能力的影响。结果表明:随着裂缝走向因子增大,横向迂曲度呈减小趋势,减小幅度最大为35.21%,纵向迂曲度呈增大趋势,增大幅度最大为21.59%;f(裂缝连通系数)越大,裂缝-基质模型越容易出现优势通道效应(f≥0.7时尤为显著),渗透率和颗粒逃逸率也越大,其中,在裂缝开度为80μm时,渗透率相比基质模型增大了0.671 3μm^(2),颗粒逃逸率相比基质模型增大了15.06%。
Microcracks have increased the permeability of pores in limestone formations to varying degrees.In order to clarify the impact mechanism of different development of microcracks on the ability of drilling waste to be reinjected during the reinjection process and ensure the safe implementation of drilling waste reinjection,firstly,X ray CT(computed tomography)scanning was used to digitally reconstruct the limestone core collected from a certain gas field to obtain its matrix model,and the migration and sedimentation mechanism of waste particles in the pores were studied.Then,based on numerical algorithms,a fracture-matrix model is constructed,and the fracture connectivity coefficient and fracture orientation factor are introduced to quantitatively characterize the connectivity and orientation of fractures,and to reveal the influence of fracture opening on the permeability of reinjected formations and the ability of waste reinjection.The results have shown that as the crack direction factor increases,the lateral tortuosity shows a decreasing trend,with a maximum decrease of 35.21%,while the longitudinal tortuosity shows an increasing trend,with a maximum increase of 21.59%.The larger f(fracture connectivity coefficient),the more likely the fracture matrix model is to exhibit dominant channel effects(especially significant when f≥0.7),and the higher the permeability and particle escape rate.Compared with the matrix model,the permeability increases by 0.6713μm^(2),and the particle escape rate increases by 15.06%.
作者
魏德葆
纪佑军
王泽根
蒋国斌
Wei Debao;Ji Youjun;Wang Zegen;Jiang Guobin(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Oil&Gas Field Applied Chemistry Key Laboratory of Sichuan Province,Chengdu 610500,China;Ecological Security and Protection Key Laboratory of Sichuan Province(Mianyang Normal University),Mianyang 621000,Sichuan,China;Institute of Safety and Environmental Protection Technology Supervision,Southwest Oil and Gas Field Branch,China Petroleum,Chengdu 610095,China)
出处
《吉林大学学报（地球科学版）》
CAS
CSCD
北大核心
2024年第4期1339-1349,共11页
Journal of Jilin University：Earth Science Edition
基金
国家自然科学基金项目(41702340)
中国石油-西南石油大学创新联合体科技合作项目(2020CX020000)
四川省科技计划项目(2024NSFSC0103)
四川省科技计划重点研发项目(2022YFS0447)
国家科技重大专项(2017ZX05013-006-002)
生态安全与保护四川省重点实验室(绵阳师范学院)开放基金(ESP1406)。
关键词
钻屑
回注
灰岩
微裂缝
连通性
走向
浆液渗流
基质模型
drilling cuttings
reinjection
limestone
microfracture
connectivity
strike
slurry seepage
matrix model
