Polyanionic cellulose has been used as the main auxiliary agent of drilling mud for decades. Due to its suspension and film-forming properties, it can not only be used as mud to carry out a large amount of drilling soil, but also can protect the well wall. Economical and practical drilling mud additives. Two types of medium viscosity and high viscosity are generally used.
Polyanionic cellulose sodium salt (PAC) is a white or slightly yellow powder, non-toxic, tasteless, it can be dissolved in water, has good heat stability and salt resistance, strong antibacterial properties, low-viscosity PAC is A high-quality, low-molecular-weight, low-viscosity cellulose polymer. High-viscosity PAC is a high-quality, high-molecular-weight, high-viscosity cellulose polymer. The mud fluid prepared with this product has good water loss reduction, inhibition and high temperature resistance. It is widely used in oil drilling, especially salt water wells and offshore oil drilling.
1. Application in engineering fields such as oil and natural gas drilling and well excavation
Drilling fluid and completion fluid technology is an important part of petroleum drilling engineering. It plays a key role in ensuring safety, high quality and fast drilling. As a type of treatment agent used to adjust the performance of drilling fluids and completion fluids, the main function of cellulose derivatives is to reduce fluid loss and increase viscosity.
It is generally believed that the fluid loss reduction mechanism of polyanionic cellulose is mainly to improve the coalescence stability of the system by forming an adsorption solvation layer on the surface of the clay particles of the drilling fluid; to prevent the adhesion of the fine clay particles from becoming larger through the protective effect of the clay particles; Reduce the permeability of the mud cake by increasing the viscosity of the filtrate and blocking the pores.
2. Application in workover fluid
The workover fluid formulated with cellulose pac is low in solids, which will not block the permeability of the production layer due to solids, and will not damage the production layer; and it has a low water loss, which reduces the amount of water entering the production layer. The water will form a water-suppression phenomenon due to the blockage of the emulsion.
The workover fluid formulated with cellulose CMC provides advantages that other workover fluids do not have;
Protect the production layer from permanent damage;
It has the carrying capacity to clean the wellbore, and the workload of maintaining the wellbore is reduced;
It has the ability to resist the infiltration of water and sediment, and it rarely foams;
It can be stored or transferred from well to well, and the cost is lower than that of ordinary mud workover fluid;
3. The role of polyanionic cellulose PAC in fracturing fluid
The fracturing fluid prepared with polyanionic cellulose PAC can withstand 2% KCL solution (must be added when preparing the fracturing fluid) and has good solubility. It is easy to use, can be prepared on site, and has fast gel forming speed and strong sand-carrying ability. When used in formations with low osmotic pressure, the fracturing effect is more excellent.