Research On Low-temperature Slurry System

Low-temperature slurry system was developed and studied on the basis of previous research,which focus on low temperature,long setting time and slow force-development issues at the conditions of shallow,surfacial and offshore cementing.Firstly,DWZ series additives including accelerant,filtrate reducer,early strength agent were synthesized.Having measured the setting time of different formula,the formula and dosage of the accelerant were obtained at the temperature of between 0～30℃with initial and final setting time less than 120 min and 60 min,respectively.After mixing with filtrate reducer by a certain proportion,the formula and dosage of the accelerant were obtained with water loss less than 100 ml.Finally,the accelerant,filtrate reducer and early strength agent were mixed by a certain proportion,and the formula and dosage of early strength agent were obtained with compressive strength larger than 10 MPa/24h.DWZ-I Series formulas are shown as follows,which can meet the need of shallow,surfacial and offshore cementing.2～3%DWZ-A-7+4%DWZ-B+4%DWZ-C(0～20℃)2～3%DWZ-A-7+4%DWZ-B+3%～4%DWZ-C(20～30℃)The optimal formulas of DWZ-Ⅱseries are as follows:2～3%DWZ-A-7+4%DWZ-B+4%DWZ-C+5%micro-silica(0～20℃)2～3%DWZ-A-7+4%DWZ-B+3%～4%DWZ-C+5%micro-silica(20～30℃)The results show that the additives of DWZ-I series are compatible with the low-density cement slurry with density larger than 1.54g/cm~3 at the temperature of 20～30℃.Therefore, its characteristics meet the need of shallow,surfacial and offshore cementing.