偏心环空层流顶替滞留层边界位置研究  

A study on the replacement position of laminar flow in eccentric annulus at retention layer boundaries

作　　者：冯福平[1] 艾池[1] 杨丰宇[2] 孟翔[2] 钟鑫[2] 

机构地区：[1]东北石油大学提高油气采收率教育部重点实验室,黑龙江大庆163318 [2]大庆钻探工程公司钻井二公司,黑龙江大庆163413

出　　处：《石油学报》2010年第5期858-862,共5页Acta Petrolei Sinica

基　　金：国家自然科学基金项目(No.50974028)"水力压裂岩体损伤演化与微裂缝形成机理研究";黑龙江省教育厅科学技术研究项目(11531001)"天然气井防气窜封堵技术研究"联合资助

摘　　要：水泥浆顶替过程中环空边界处的泥浆所受的剪应力最大,随着顶替界面从环空最大流速位置处逐渐向两边扩展,泥浆层各处所受的剪应力逐渐减小,直到环空边界处的剪应力等于泥浆的动切力,顶替界面不再扩展,形成稳定的顶替边界。根据水泥浆顶替泥浆过程中顶替界面达到稳定的平衡条件,建立了偏心环空不同周向角下套管和井壁处的泥浆滞留层边界位置计算模型,通过计算表明:随着套管偏心度的增大,宽间隙处的剖面顶替效率变化不大,而窄间隙处的剖面顶替效率却急剧下降,易形成泥浆窜槽;泥浆滞留层首先在井壁处出现,井壁处的泥浆滞留层厚度和范围要明显高于套管处,严重影响第二胶结面固井质量,应重点加强第二胶结面顶替效率和固井质量技术的研究。The cement slurry at boundaries of annulus suffers the maximum shear stress in the process of replacement,as the replacement interface expands little by little from the maximum velocity position of annulus to both sides,the shear stress that mud layer suffers everywhere is gradually decreasing until the shear stress at boundaries of annulus is equal to the mud shear force,then as the expansion stops,a stable replacement interface is formed. Based on equilibrium conditions for the stabilization of the replacement interface,the present paper developed a model to calculate boundaries and thickness of mud retention layers at sidewalls and casing depths with different circumferential angles in eccentric annulus. The calculation showed that with the increase of casing eccentricity,the displacement efficiency at the wide gap changed little,while that at the narrow gap was falling sharply and mud channeling was more readily to form. Mud retention layers occurred first at sidewalls where the thickness and extent of retention layers were much greater than at casing depths,which significantly affected the cementing quality of the second cementation surface. Therefore,researches on the replacement efficiency of the second cementation surface and on techniques to guarantee cementing qualities should be strengthened.

关 键 词：偏心环空 滞留层 边界位置 剪应力 顶替界面 宾汉流体 

分 类 号：TE256[石油与天然气工程—油气井工程]