提高矿渣石高温高压强度的方法探讨

Study on the methods for improving the HTHP strength of slag MTC cement

MTC固井技术对中深井和深井高温高压井段固井质量均差于浅井。通过室内实验分析可知,水灰比、矿渣活性、激活剂、助剂种类以及加量、分散剂、钻井液加量、降失水剂、pH值及其它水化物质都影响矿渣石高温高压强度。对提高矿渣石高温高压强度的方法进行了探讨,并提出了相应的措施。即:设计出合理的矿渣浆密度;选择具有良好配伍性的降失水剂;选用活性高的矿渣,活性的判断可采用MTC法;加入20％-35％的预水化钻井液,根据井底温度确定加量;加强设备的管理和维修,确保固井施工的连续和注浆的泵速;实验确定激活剂、助剂比例关系;采用高效分散剂或者复配其它缓凝剂增加助剂的加量,最终提高矿渣石的高温高压强度。现场应用表明,通过采用上述方法提高矿渣石高温高压强度,提高了中深井和深井高温高压井段的固井质量。

As compared with its using in the shallow well, the MTC cementing technology in the medium deep wells and the HTHP intervals often results poor cementing quality. It is known that such factors as water to cement ratio, slag activation, type and dosage of the activator and promotor, amount of dispersant, filtrate reducer and drilling fluid used, pH value and other minerals all influence the HTHP strength of the slag cement. Methods for improving the HTHP strength are investigated and with corresponding measures proposed. These methods involve designing of reasonable slag slurry density; selection of fluid loss agent with better compatibility; using highly activated slag; adding of 20% to 35% of pre-hydrated drilling fluid, with the exact amount in accordance with the downhole temperature; enhancing the management and maintenance of equipment; determining the ratio of activator and promotor by lab tests; using high effective dispersant or other retardant, etc. By adopting these methods, the cementing quality in the deep wells and HTHP intervals is effectively improved.