Products used in oil drilling are mainly CMC
1.The role of CMC in the oil and natural gas industry
During the drilling, drilling and workover of oil and natural gas, the well wall is prone to water loss, causing changes in the well diameter and collapse, making the project unable to proceed normally, and may even be abandoned halfway. Therefore, conditions such as well depth, temperature, and thickness should be varied according to the geological conditions of each region.
to adjust the physical parameters of drilling mud, and CMC is the best product that can adjust these physical parameters. Its main functions are:
Mud containing CMC can form a thin, hard, low-permeability filter cake on the well wall, which can prevent shale hydration, prevent drilling cuttings from dispersing, and reduce well wall collapse.
CMC-containing mud is an efficient fluid loss reducer. It can control water loss to a better level at a lower dosage (0.3-0.5%) without causing adverse effects on other properties of the mud. , such as the viscosity or shear force is too high.
CMC-containing mud can resist high temperatures and can generally be used in high-temperature environments around 140°C. Products with high substitution degrees and high viscosity can be used in high-temperature environments of 150-170°C.
CMC-containing mud is resistant to salt. The characteristics of CMC in terms of salt resistance are: not only can it still maintain the ability to reduce water loss well under a certain salt concentration, but it can also maintain certain rheological properties, with little change compared with those in fresh water environments; it not only Can be used as
Clay-free drilling fluid can also be used for mud in salt water environments. Some drilling fluids are still salt-resistant and have little change in rheology. In particular, the current "Jie" brand salt-resistant CMC has a viscosity change ratio that has increased to above 1 under 4% salt concentration and fresh water, that is, in a high-salt environment
There is almost no change in viscosity.
Mud containing CMC can control the rheology of the mud. CMC can not only reduce water loss, but also increase viscosity.
2.Application of CMC in drilling fluid
2.1 Improved filter loss performance and mud cake quality, and improved anti-jamming ability.
CMC is a good water loss reducing agent. Adding it to the mud will increase the liquid viscosity, thereby increasing the seepage resistance of the filtrate, thus reducing the water loss.
The addition of CMC makes the mud cake dense, tough and smooth, thereby reducing pressure differential stuck aluminum and drilling tool remote movement blocking phenomenon, reducing the resistance moment to the rotating aluminum rod and alleviating the suction phenomenon in the well.
In general mud, if the amount of CMC medium-viscous products is 0.2-0.3%, the API water loss will be reduced a lot.
2.2 Improves the rock carrying effect and increases mud stability.
Since CMC has good thickening properties, adding an appropriate amount of CMC at a low soil moving content is enough to maintain the viscosity required to carry cuttings and suspended barite, and improve mud stability.
2.3 Resist the dispersion of clay and help prevent collapse
The water loss reduction performance of CMC slows down the hydration rate of the mud shale on the well wall. In addition, the long chain of CMC covers the rock on the well wall, which strengthens the rock structure and makes it less likely to peel off and collapse.
2.4CMC is a mud treatment agent with good compatibility
CMC can be used with various treatment agents in mud of various systems and achieves good results.
3. Application of CMC in cementing isolation fluid
The normal construction of cementing and cementing is an important part of ensuring the quality of cementing. The isolation fluid prepared by CMC has the advantages of reducing flow resistance and convenient construction.
4.Application of CMC in workover fluid
In oil testing and workover operations, if high solid phase mud is used, it will cause serious pollution to the oil layer, and it will be more difficult to eliminate this pollution. If clean water or brine is simply used as the workover fluid, serious accidents will occur in some cases. Water lost from leakage and filtration into the oil layer causes water lock
phenomenon, or cause the muddy part in the oil layer to expand, damaging the permeability of the oil layer, and bringing a series of difficulties to the work.
CMC is used as workover fluid, which can successfully solve the above problems. For low-pressure wells or high-pressure wells, the formula can be selected according to the leakage situation:
Low pressure layer: slight leakage: clean water +0.5-0.7% CMC; general leakage: clean water +1.09-1.2% CMC; severe leakage: clean water +1.5% CMC.
