When selecting polyanionic cellulose in offshore drilling, the following aspects can be considered:
1. Product performance indicators
Viscosity:
Appropriate viscosity can ensure that the drilling fluid has good suspension and carrying capacity to prevent drilling cuttings from sinking. In offshore drilling, due to the presence of seawater and complex geological conditions, polyanionic cellulose with appropriate viscosity needs to be selected according to the specific well depth, formation conditions and drilling process. Generally speaking, deeper wells and complex formations may require products with higher viscosity.
Viscosity stability is also important. Under different temperature, pressure and salinity conditions, polyanionic cellulose should be able to maintain a relatively stable viscosity to ensure the smooth progress of the drilling process.
Filtration control performance:
Good fluid loss control can reduce the loss of drilling fluid to the formation, reduce damage to the formation, and help maintain the stability of the well wall. When selecting polyanionic cellulose, its fluid loss under different conditions should be examined, including normal temperature and pressure, high temperature and high pressure, and different salinity environments.
The fluid loss control performance of polyanionic cellulose can be evaluated through laboratory tests, and products that can meet the specific requirements of offshore drilling can be selected.
Salt resistance:
Offshore drilling usually encounters salts in seawater and formations, so polyanionic cellulose needs to have good salt resistance. Products with strong salt resistance can still maintain good performance in high-salt environments and will not experience significant performance degradation due to the presence of salt. You can check the product's technical parameters or conduct actual salt resistance tests to determine its applicability in offshore drilling environments.
Thermal stability:
Offshore drilling may encounter high formation temperatures, and polyanionic cellulose should have good thermal stability and will not decompose or lose its key properties at high temperatures. Understand the thermal stability indicators of the product and choose polyanionic cellulose that can work stably within the expected drilling temperature range.
2. Compatibility with drilling fluid system
Compatibility with other treatment agents:
Offshore drilling fluids are usually complex systems composed of multiple treatment agents. Polyanionic cellulose needs to have good compatibility with other treatment agents such as bentonite, fluid loss reducers, lubricants, etc. When selecting polyanionic cellulose, compatibility tests should be conducted to ensure that it will not produce adverse reactions when used with other treatment agents, affecting the performance of the drilling fluid. For example, some treatment agents may interact with polyanionic cellulose, causing problems such as viscosity changes, precipitation or loss control failure. Products that are incompatible with the existing drilling fluid system should be avoided.
Overall impact on drilling fluid performance:
Consider the comprehensive impact of polyanionic cellulose on the rheology, loss, lubricity and other properties of the drilling fluid after adding it to the drilling fluid. Select polyanionic cellulose products that can play their specific advantages without compromising other important properties.
For example, some polyanionic cellulose may increase the viscosity of the drilling fluid too much while improving loss control, affecting drilling efficiency, and a balance needs to be struck between the properties.
