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Basic Knowledge
7.3 High temperature deep well cementing slurry system
  • Detailed description
Along with the development of the oil well in later-middle period, shallow resources are greatly reduced, in order to meet the growing industry needs, all countries in the world increase the strength of deep exploration. The steps of deep well cementing are same with the shallow wells’ but this kind of wells condition and well casing program is complicated. The cementing difficulty is bigger, so it usually to consider the factors of high temperature, high pressure formation and ring space narrow.
Deep and super deep well cementing usually need to consider the density of the slurry, the fluid loss, stability and thickening time etc, so deep well cementing job requires not only the corresponding machine but also take the corresponding technical measures. and it also need to have a variety of high performance additives and the admixtures supporting the use of material. With more and more deeply of the casing cementing, the materials and performances of slurry system become a key factor.
1、Latex system is prepared mainly by the material of latex, stabilizer, high temperature retarder ,defoamer and the admixture silicon powder. Its applicable temperature is up to 150 (BHCT). Latex as currently accepted good unti-fluid channeling agent, its weakness is its added amount is larger (10 ~ 40% BWOC), and cost is higher, so most of it is used in high temperature high pressure well.
2、High temperature infiltration system is prepared mainly by the fluid loss additive, high temperature retarder, dispersant at the same time match with silicon powder, density regulators. This system has good filtration reducing property, fluidity. Its applicable temperature is high and has no effect to compressive strength. Joining high temperature retarder can adjust the slurry system’s thickening time, and high temperature resistant can be up to 180 (BHCT). The SiO2 in Silicon powder react with the Ca (OH) 2 released from cement hydration reaction at high temperature and generate high temperature resistant CSH gel. The CSH gel can prevent the high temperature strength degradation of set cement, and has no adverse effect to the set cement compressive strength. This kind cement slurry can be applied to the wells of average 4500 meters depth.
Deep well drilling of the deep and super deep well is quite large, so the success or failure of well cementing directly related to the exploration achievement. In order to obtained success for cementing operations, it is need to provide a sufficient choice, good performance and stable cement slurry system.