Application of polyacrylamide in tertiary oil recovery, profile control and water shutoff
Application in tertiary oil recovery
When the oilfield enters the tertiary oil recovery stage, a single water injection is used to drive oil, because its velocity is higher than that of the underground oil driven by it, the result will greatly reduce the sweep efficiency and increase the water consumption, so as to greatly improve the water content of the produced oil. In addition, the heterogeneity of reservoir geology also reduces sweep efficiency. In particular, when the reservoir is in positive rhythm deposition, it is thick at the top and thin at the bottom, and the permeability at the bottom is higher than that at the top. When the oil is driven by a single water, it often pushes along the bottom, while a large amount of unswept oil is left at the top of the reservoir. If the single water flooding is replaced by the addition of polyacrylamide, which can make water stickier, it will help to improve sweep efficiency, reduce the water content of oil recovery and increase the production of crude oil. The partially hydrolyzed polyacrylamide produced by our company fully meets the requirements of tertiary oil recovery in oil fields. Each ton of polymer can produce about 150 tons of crude oil for users. This is done by injecting a viscous polymer solution to improve the sweep coefficient of the injected fluid to block the large channel and force the flooding fluid into the small hole, ultimately increasing the oil recovery rate.
Application of profile control and water plugging
Water coming out of oil well is a common problem in oilfield development, especially in old oilfield developed by long-term water injection. Due to the heterogeneity of reservoir and the difference in viscosity of oil and water, water injection injects and points along the high permeable layer or fracture between injection well and production well, resulting in premature flooding of production well, decreased oil production and increased water cut. Injected water is easy to enter the high permeability band or crack and bypass the middle and low permeability zone, reducing the sweep coefficient of injected water, resulting in the middle and low permeability layer of low or not used at all. Water injection is widely used in China's oil fields. At present, the water cut of oil Wells has reached 90%, and many of them have reached more than 98%. At present, the water-soluble polymer represented by polyacrylamide is the most widely used and effective water plugging material at home and abroad, and our company's PAM products have achieved success in the application of profile control and water plugging in oil fields.
The basic principle of profile control and water plugging is: adding crosslinking agent in a certain concentration of polyacrylamide solution, so that the high price of metal ions in the crosslinking agent in the form of polynuclear hydroxyl bridge ions and polyacrylamide carboxyl group or amide group formed coordination combination. The specific reaction equation is as follows (M stands for high-priced metal ion) :
Application of drilling mud
Polyacrylamide can be used to increase mud viscosity, control mud weight, flocculate mud clay, cuttings, bring cuttings out, and prevent cuttings from settling in the mud and causing stuck drillings during stop-drilling.
The product can be crosslinked under the action of Al3+, Fe3+ and Ca3+ plasma, and part of the polymer compound changes from linear to body shape. It is insoluble in water, and adsorbs on the well wall and blocks the formation void, preventing the loss of drilling fluid.
Fluid loss agent
Mud cake to reduce permeability to protect shaft wall conditions, prevent shaft wall collapse, reduce oil layer pollution.