1. The third oil recovery overview and basic principles
Oil is a non-renewable energy source. Oil recovery is not only a problem in the petroleum industry, but also a concern of the whole society. Because oil is a fluid deposit, it brings a unique way of mining.
Oil exploration is divided into three phases. The primary oil recovery relies on the formation energy for self-explosion mining, accounting for about 15-20% of the reserves. After the natural energy is depleted, artificial water injection or gas injection is used to supplement the reservoir energy to continuously extract the crude oil, which is called secondary oil recovery, and the recovery factor is 15-20%. After decades of secondary oil recovery, the remaining oil is trapped in the pores of the reservoir sandstone by discontinuous oil blocks. At this time, the water in the production fluid is 80-90%, and some even as high as 98%. There is no economic benefit. For this reason, there are about 60~70% of crude oil reserves, which can only be mined by other physical and chemical methods. Such mining is called tertiary oil recovery, and abroad is also known as EOR (Enhanced Oil Recovery) technology.
2. Alkaline flooding
Alkaline flooding is to control the pH of the injected water to about 12~13, generally by adding 1~5% (wt.) NaOH [2]. In the alkaline water flooding process, the alkali in the aqueous phase interacts with the petroleum acid in the crude oil to form a surfactant, which is adsorbed on the rock surface and the oil/water interface, changing the wettability of the oil layer rock and reducing The interfacial tension increases the oil recovery.
3. Polymer flooding
The polymer flooding mainly adds a thickener to the injected water to increase the viscosity of the water. The water-soluble polymer is selected and has a high viscosity at a concentration of 0.1%. Therefore, the injection of the polymer can reduce the fluidity of the water, increase the sweep coefficient, enlarge the sweep volume, and improve the oil displacement efficiency.
Currently commonly used polymers are polyacrylamides and biopolymers
4. Surfactant Flooding
The surfactant flooding is to inject the surfactant slug into the formation to inject the residual oil to achieve enhanced oil recovery. Surfactant flooding typically includes micellar flooding, microemulsion flooding, emulsion flooding, foam flooding, and the like.
5. ASP composite Flooding
ASP composite Flooding, (including surfactants, alkalis, polymers), has been able to achieve the oil displacement efficiency of the medium phase microemulsion flooding, and the cost is only 1/3 of the latter.
Shaoxing Shangyu Simo Research institute of organic Chemistry
Address: Room 1202, Jincheng Building, Shangyu City, Zhejiang Province, China
Tel: 0086-575-82639019
M/P: 008613857527142
E-mail: shenyuan@simochem.com
