During 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, so that the project cannot be carried out normally, or even abandoned halfway. Therefore, it is necessary to adjust the physical parameters of the drilling mud according to the changes in the geological conditions of each region, such as well depth, temperature, and thickness. CMC is the best product that can adjust these physical parameters. Its main functions are:
The mud containing CMC can make the well wall form a thin, firm and low-permeability filter cake, which can prevent shale hydration, prevent drilling cuttings from dispersing, and reduce well wall collapse.
The mud containing CMC is a kind of high-efficiency fluid loss control agent, it can control the water loss at a better level at a lower dosage (0.3-0.5%), and it will not cause adverse effects on other properties of the mud , such as too high viscosity or shear force.
CMC-containing mud can resist high temperature, and generally can be used in a high-temperature environment of about 140°C, such as high-substitution and high-viscosity products, can be used in a high-temperature environment of 150-170°C.
Muds containing CMC are resistant to salt. The characteristics of CMC in terms of salt resistance are: not only can it maintain a good ability to reduce water loss under a certain salt concentration, but it can also maintain a certain rheological property, which has little change compared with that in a freshwater environment; it is both It can be used in clay-free drilling fluid and mud in salt water environment. Some drilling fluids can still resist salt, and the rheological properties do not change much. Under 4% salt concentration and fresh water, the viscosity change ratio of salt-resistant CMC has been increased to more than 1, that is, the viscosity can hardly be changed in a high-salt environment.
CMC-containing mud can control the rheology of the mud. CMC can not only reduce water loss, but also increase viscosity.
1. CMC-containing mud can make the well wall form a thin, hard and low-permeability filter cake, reducing water loss. After adding CMC to the mud, the drilling rig can get a low initial shear force, so that the mud can easily release the gas wrapped in it, and at the same time, the debris can be quickly discarded in the mud pit.
2. Like other suspension dispersions, drilling mud has a certain shelf life. Adding CMC can make it stable and prolong the shelf life.
3. The mud containing CMC is rarely affected by mold, and there is no need to maintain a high pH value and use preservatives.
4. CMC-containing mud has good stability and can reduce water loss even if the temperature is above 150 degrees.
Post time: Jan-09-2023