大温差低密度水泥浆性能研究

Study on Performance of Low-Density Cement Slurry at Big Temperature Differences

长封固段大温差固井具有一次性封固段长、封固段底部与顶部温差大的特点,容易导致顶部水泥浆长时间无强度。目前针对大温差缓凝剂的研究较多,其他相关外加剂的大温差性能较少有关注,同时较少有针对100℃以上大温差固井的研究。针对大温差固井的特点,对降失水剂、分散剂和缓凝剂的大温差性能进行评价和筛选,降失水剂C-G86L和缓凝剂C-H42L具有良好的大温差性能,而分散剂对大温差性能有不利影响。构建了1.4 g/cm^(3)大温差低密度水泥浆体系,并引入丁苯胶乳,提高了水泥石在低温下的强度发展。此体系在温差110℃、顶部温度20℃下48 h强度达到858 psi(5.92 MPa)。

When cementing a long well section with big temperature difference between the top and bottom of the section in one stage,it is generally difficult for the top cement to develop strengths in a long period of time.Presently studies are focused on the retarders for big temperature differences,other cement additives for big temperature differences and cementing wells with temperature differences bigger than 100℃receive less attention.To solve problems encountered in cementing wells with big temperature differences between the two ends of the cementing sections,a 1.4 g/cm^(3) cement slurry with good performance in big temperature differences was developed based on laboratory study on the properties of filter loss reducers,dispersants and retarders at big temperature differences.It was found in the study that the filter loss reducer C-G86L and the retarder C-H42L show very good performance at big temperature differences.Introduction of butylbenzene latex into the cement slurry helps the development of the strength of the set cement at low temperatures.At temperature difference of 110℃,temperature at the top of cement of 20℃,the compressive strength of the set cement in 48 hours reached 5.92 MPa.The cement slurry was successfully used in cementing a well and the job quality was excellent.