【摘要】 为解决在煤矿采空区施工煤层气井时出现的钻井液恶性漏失、掉块卡钻、下套管遇阻等问题,以采空区覆岩特征为研究基础,通过对比激活剂、悬浮剂及降失水剂的不同添加量对堵漏液性能的影响,确定了各添加剂的最优添加量,形成了一种具有固化功能的无机胶凝材料钻井堵漏液,其配方为:100%水+5%激活剂+0.5%悬浮剂+3%降失水剂+54%矿渣。该堵漏液在30℃条件下流动度为21cm,稠化时间在61 min以内,1 d抗压强度大于6 MPa,其性能指标满足煤矿区煤层气浅井堵漏要求。为进一步分析该堵漏液的作用机理,采用扫描电镜、X-射线及热重分析等现代测试分析方法对形成的固化体进行测试,结果表明:堵漏液中的胶凝材料与水接触后发生水化反应生成C—S—H凝胶,随着时间的增加,C—S—H凝胶越来越多,最终水化产物的结构越来越致密形成了较高的抗压强度。宏观表征即:具有良好流动性的堵漏液通过泵送进入地层裂缝,浆液填充裂缝直至裂缝被充满,随着水化反应的进行堵漏液逐步失去流动性,最终原裂隙发育地层形成一个胶结具有承压能力的整体,实现了堵漏。更多还原

【Abstract】 The leakage of drilling fluid,block stuck,and casing resistance is a severe problem when constructing coalbed methane wells in coal mine gobs.Based on the characteristics of overburden of gob,the ideal adding amount of each additive is determined by comparing the effects of different amount of activator,suspension concentrate,and fluid loss additive on the performance of plugging fluid. An inorganic cementsolidifying drilling plugging solution is developed,the formula of which is 100% water,5% activator( JHQ),0.5% suspending agent( CMC),3% fluid loss agent( G33 S),and 54% slag. This drilling plugging fluid has fluidity of 21 cm at 30 ℃,thickening time within 61 min,and 1 d compressive strength of over 6 MPa. The performance parameters meet the requirements for plugging fluid used in shallow well in coal mines. To further analyze the mechanism of the plugging solution,the formed solidified body was tested using modern testing methods such as SEM,XRD,and thermal analysis. The results show that when contacting with water,hydration reaction occurred on the cementation material of plugging solution,producing C-S-H gelation which increases with time. The structure of the final hydration product becomes denser gradually,resulting in higher compressive strength. The whole process that the plugging fluid realizes plugging can be described as three steps-the plugging fluid with good fluidity is first pumped into the formation crack,filling the crack until full,then the plugging fluid gradually loses fluidity as the hydration reaction proceeds,and finally forms a cementation in the original fissure to realize plugging.更多还原