Deep And Ultra-deep Well Cementing Technology With Low Density Slurries In Tahe Oilfield

Long bare hole and long sealing cementation problems have been arisen since simplified well programs have been universally applied, although wells drilling period have been decreased. Dual stage cementing operations and liner cementing technique have been utilized, but the problem about formation leakage is still not solved, especially in Permian System easy leakage formations in the No.10, No.12 and Aiding area in Tahe Oilfield during second spud-in drilling jobs. More than ten wells happened fluid loss when cementing jobs done. Therefore, based on the analysis of the cementing problems in these areas, three types of cement slurry systems were developed; those are the fall ball and micro-silica low density cement slurry, 3M conesphere low density system and fly-ash composite low density cement slurry. Mainly factors influencing on cementing slurries properties were systematically investigated. The developed low-density cement slurry properties are as following: density is between 1.30～1.55g/cm3, API fluid loss is small than 50 mL, compressive strength more than 14MPa, flow pattern index number more than 0.7, no filtrate, good falling stability with smaller than 0.03 g/cm3 density difference. In the view of Tahe Oilfield formation characteristics, measures are put forward aimed at deep and ultra-deep wells cementing operations. Ten wells cementing job have been successfully completed with the developed cement slurries. The qualification rate with CBL is 100 percent. Good results achieved and the study will afford helps for future cementing operations.