Whether used for primary (placement of grout as a hydraulic seal in the wellbore) or secondary applications (remedial operations including leak repairs, splits, closing of depleted zones), the addition of silica fume enables a well to achieve full production potential. Besides producing a blocking effect in the oil well grout that prevents gas migration, it provides these advantages:
– Improved flow, for easier, more effective application
– Dramatically decrease permeability, for better control of gas leakage
– Increased durability and compressive strength
– Lightweight
Cementing is an important operation in the drilling process, and oil well cementing is an important material for sealing casing and the annular space of the wellbore. Because the well is deep and shallow, underground has atmospheric pressure and normal temperature, high pressure and high temperature, and there are various chemical substances in the stratum, so the oil well cementing is widely adaptable.
The optimization of cementing parameters is mainly concerned with the following aspects:
1. good stability, uniform material mixing, good fluidity, small initial consistency, good pump ability and low difficulty of field construction.
2. high slurry rate and good performance price ratio, can reduce the cementing cost and achieve the purpose of saving energy and reducing consumption.
3. high compressive strength and less free liquid, it can effectively reduce water loss and water separation of cement slurry, and can meet the requirements of cementing quality.
4. The low specific gravity of cement slurry after mixed, slurry will not cause the situation of leakage formation, and can meet the cementing of various complicated strata.
Advantage:
1. the use of silica fume low density formula cement is good mixing finished products, and there are less material in the well. It is convenient and concise in use. It improves the artificial mixing material and loading and unloading in the oilfield, reduces the working time and reduces the difficulty of the cementing operation.
2. the characteristics of high pulping rate of silica fume low density formula cement can reduce the usage of well entry materials and reduce the cementing cost. It is estimated that using silica fume low density formula cement can reduce 33% raw materials, high cost performance, and achieve the purpose of energy saving and consumption reduction.
3. due to the low density of silica fume low density formula cement, there will be well segments with poor cementing quality in permeable water layer and high-pressure gas well cementing section, but it can reduce the condition of long cementing and sealing section and pressure leakage. In response to this situation, there is still room for improvement in the use of silicon fume powder low density formula cement.
