多底井注水泥用液体乳胶水泥浆

Multi-lateral well cementing using gel cement slurry

研究出的低失水高分散性防气窜乳胶水泥浆是一种以乳胶聚合物分散剂为主要成分的水泥浆,通常像合成橡胶。乳胶水泥浆与非乳胶水泥相比具有以下特性:①较高的抗折、抗拉强度;②较高的防裂性;③较小的渗透率和收缩率;④较好的粘结、抗压强度;⑤较好的防气侵能力;⑥不用分散剂就有较好的流变性;⑦较好的滤失性能;⑧较短的凝结时间;⑨较低的水灰比。室内试验结果表明,乳胶水泥浆确实具有以上这些特点。在多底井中用乳胶水泥通过侧孔进行尾管注水泥,能防止水泥石在连接点破裂和裂纹向整个水泥柱扩展,以免损害水泥胶结的完整性;乳胶水泥具有较好的抗脆裂性及较小的收缩性,能对尾管提供长期支撑,是多底井固井理想的水泥浆体系。

A kind of anti-channeling gel cement with low fluid loss and high dispersion is developed, which mainly contains a kind of emulsified polymer dispersing agent, such as synthetical rubber. As compared with non-gelling cement, the gel cement has the following characteristics; 1. higher breaking and tension strength; 2. higher fracture resistance; 3. minimized permeability and shrinkage factor; 4. better gelling and compressing strength; 5. gas migration controlling capability; 6. better rheological property without dispersing agent; 7. better fluid loss control; 8. shorter cementation time; 9. lower water to cement ratio; laboratory tests proved these advantages. When it is used for multi-lateral well cementing, the gel cement is pumped down through the side-hole for liner cementing, and it avoids the danger of cement rock breaking at the conjunction, which may even spread to the whole cement column and damage the integrity of the cementation. The gel cement has better embrittlement resistance and little shrinkage, and can provide long time supporting for the liner, thus it is an ideal select for multi-lateral cementing.