摘要
In view of the inadequate cementing quality in the cementation for long isolation intervals ofoil and gas wells, and considering the field practice in Tarim Oilfield, a nanometer material LC-212 was introduced as the base stock to experimentally develop a new spacer system NMS-I, in combination with other materials, including a chemical gel plugging agent, carboxymethyl cellulose and barite. Experimental results indicated that the system had a wide adjustable range of density, good rheological property, static stability and compatibility with cement slurry. It also showed no flocculating or thickening effect on the water-base drilling fluid and low-density cement system. Meanwhile, the capacity of lost circulation control and the influence of the spacer on the second interfacial cementing strength were evaluated by a self-made lost circulation simulator and shearing test facility. The results showed that the spacer had favorable plugging and flushing effect, and the second interfacial cementing strength can be greatly improved. Moreover, based on the experiments, the mechanisms of spacer function were analyzed. The results obtained from the investigation offer a novel approach to resolving some practical problems in cementing jobs.
In view of the inadequate cementing quality in the cementation for long isolation intervals ofoil and gas wells, and considering the field practice in Tarim Oilfield, a nanometer material LC-212 was introduced as the base stock to experimentally develop a new spacer system NMS-I, in combination with other materials, including a chemical gel plugging agent, carboxymethyl cellulose and barite. Experimental results indicated that the system had a wide adjustable range of density, good rheological property, static stability and compatibility with cement slurry. It also showed no flocculating or thickening effect on the water-base drilling fluid and low-density cement system. Meanwhile, the capacity of lost circulation control and the influence of the spacer on the second interfacial cementing strength were evaluated by a self-made lost circulation simulator and shearing test facility. The results showed that the spacer had favorable plugging and flushing effect, and the second interfacial cementing strength can be greatly improved. Moreover, based on the experiments, the mechanisms of spacer function were analyzed. The results obtained from the investigation offer a novel approach to resolving some practical problems in cementing jobs.
