摘要
为了探究水力割缝技术对于天然气水合物储层改造的适用性,开展了模拟水合物储层的地面水力割缝模拟试验。采用大尺寸试样,分析了喷射压力、喷嘴直径和加砂体积分数对套管及模拟试样的割缝形态、成孔特征以及破坏形式的影响。研究结果表明:水力喷射切割过程中,由于高压射流的冲击力及冲蚀作用,模拟水合物储层中形呈近似椭圆锥体孔眼,内表面凹凸,并出现裂缝、凹坑及其他不规则形状;近喷嘴端孔眼会形成冲蚀空腔,孔眼直径较大,而随着孔眼深度增加,孔眼直径逐渐缩小;模拟水合物储层在水力切割后呈现破碎、不规则冲蚀、扩孔、冲刷、侧向裂缝等多种复杂破坏形式,比常规砂岩、煤岩的破坏形式更为复杂;孔眼深度随着喷嘴直径增加先增大后减小,而孔眼深度随着喷射压力逐渐增大;当喷射压力为25 MPa,喷嘴直径为5 mm,含砂体积分数为6%时,可形成深度约92 cm,最大直径约为14 cm的椭圆形孔眼;在套管与水合储层直接接触条件下,切割套管缝宽受喷嘴直径、喷射压力和加砂体积分数的影响,缝长主要由喷嘴移动距离决定。射流对水合物储层的破坏作用影响因素多,不仅与水射流及冲蚀条件有关,还与水合物储层的物化性质密切相关。
In order to explore the applicability of hydraulic blasting technology in natural gas hydrate reservoir reconstruction,abrasive jet cutting tests were carried out on simulated hydrate reservoir.The impact of jet pressures,nozzle diameters and sand concentrations on slot shapes,morphologies,and failure mode was investigated.The results show that an approximate elliptic cone hole forms with uneven,cracks,pits and other irregular inner surfaces during the hydraulic jet cutting process.Due to the effect of impact and erosion of the highpressure jet,the hole diameter near the nozzle end is larger and hole diameter decreases gradually with the increase of depth.Besides,there are various characteristics of formed holes in simulated samples after abrasive jet cutting,like broken,irregular erosion,reaming,scour,lateral crack damage in the matrix.Compared with conventional sandstones and coalbeds,the hole characteristics and formation mechanisms of simulated samples are more complex.Furthermore,the cutting hole depth firstly increases and then decreases with the nozzle diameter increasing,while it gradually increases with the jetting pressure rising.An oval hole can be obtained with a depth of 92 cm and a maximum diameter of 14 cm when the jet pressure is set as 25 MPa,volume fraction of sand is 6%and nozzle diameter is 5 mm.Furthermore,cutting slot forms depend on nozzle diameter,jet pressure and sand concentration,especially slot width.Its length is controlled by the moving distance of nozzle.The process abrasive jet cutting is complicated,which is mainly determined by hydraulic parameters,erosion conditions,as well as physical properties of hydrate reservoirs.
作者
廖华林
王鄂川
董林
牛文龙
牛继磊
戴子健
闫传梁
LIAO Hualin;WANG Echuan;DONG Lin;NIU Wenlong;NIU Jilei;DAI Zijian;YAN Chuanliang(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;China National Petroleum Corporation Offshore Engineering Company Limited,Beijing 100028,China)
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2022年第3期924-932,共9页
Journal of Central South University:Science and Technology
基金
国家重点研发计划项目(2021YFE0111400)
国家自然科学基金资助项目(51974353)。
关键词
天然气水合物
水力割缝
孔眼形态
成孔机制
喷嘴直径
natural gas hydrate
abrasive jet cutting
hole morphology
hole formation mechanism
nozzle diameter
