Polymer PAM polyacrylamide is not only an efficient flocculant, but also an excellent thickener because of the high viscosity of the aqueous solution. Due to its thickening, flocculation and rheological adjustment, PAM can be used as an additive for various purposes in oilfield oil production, such as drilling fluid, fracturing fluid and polymer flooding to enhance oil recovery (EOR). In oil extraction, the key to application lies in the rational design and selection of its composition structure, such as molecular morphology, molecular weight, ionicity, etc., and the correct construction process in combination with the conditions and requirements of use.
As a drilling fluid conditioner, PAM polyacrylamide can adjust the rheology of drilling fluid, carry cuttings, lubricate the drill bit, and facilitate drilling. In addition, it can greatly reduce sticking accidents, reduce equipment wear and tear, prevent lost circulation and collapse, and make well diameters regular. Partially hydrolyzed polyacrylamide is often used in this regard, which is obtained by hydrolysis of PAM or polyacrylonitrile.
Polyacrylamide plays an important role in the methods of enhancing oil recovery, and polymer flooding technology plays an important role. The function of the polymer is to adjust the rheology of the injected water, increase the viscosity of the driving fluid, improve the sweep efficiency of water flooding, reduce the permeability of the water phase in the formation, and enable the water and oil to flow forward at a uniform speed.
Polyacrylamide polymer flooding is to increase the viscosity of the injected water and improve the oil-water mobility ratio by adding a certain amount of flocculant polymer polyacrylamide to the injected water. Due to the adsorption and capture of polyacrylamide molecules by the oil layer, the permeability of the high and medium permeability layers or the high and medium water flooded layers is reduced, the seepage resistance of the injected water is increased, and the low permeability layer or the low water-free layer is reduced. The water absorption of the flooded layer increases, which expands the swept range of the injected water on the oil layer plane and the water flooded thickness in the vertical direction of the oil layer, thereby expanding the water flooded volume, displacing the crude oil that was not used during water flooding, so as to improve oil recovery.
In the process of oilfield production, due to the heterogeneity of the stratum, flooding problems often occur, and water plugging is required. Its essence is to change the permeability of water in the formation to achieve the purpose of reducing oilfield water production, maintaining formation energy, and improving ultimate recovery. PAM chemical water-blocking agent has selective effect on the permeation of oil and water, the permeability of oil is reduced less, and the permeability of water is reduced more. It can be used without cross-linking, or it can be cross-linked with aluminum salts, chromium salts, zirconium salts, etc. to form gels, and some resins can be added to form an interpenetrating polymer network to make it more resistant to temperature.
In fracturing and acidizing treatment, the polyacrylamide flocculant is formulated into an aqueous solution with a concentration of 0.01% to 4%, and is pumped into the underground formation to fracture the formation. Fracturing is an important stimulation measure for developing tight layers in oilfields. The fracturing fluid cross-linked by methylene polyacrylamide has high viscosity, low friction, good sand suspending ability, low fluid loss, good viscosity stability, less residue, wide supply, convenient preparation and low cost, thus widely used.