Chemical Flooding: Rebuilding New Oilfields from "Three to Two"

Someone once counted such an account: When the recovery rate of old oil fields in China increases by one percentage point, it will increase the recoverable reserves by more than 100 million tons, equivalent to the discovery of a large new oil field of 300 million tons. As a result, the chemical flooding tertiary recovery technology that greatly increases the oil recovery has attracted attention, but the "alkaline + surfactant + polymer" ternary composite flooding technology has a fatal injury - due to alkali and injection system Scale. China Petroleum & Chemical Corporation Shengli Oilfield Company made a "from three to two" subtraction. In the process of developing the "surfactant + polymer" binary composite flooding technology, it has overcome the surface-free conditions only on the surface. The role of the active agent makes the oil-water interfacial tension reach the international problem of ultra-low, and continuously improve the oil recovery in practice, so that the binary compound high-efficiency oil-displacement technology has become China's tertiary oil recovery "flood defender."
The project leader, Sun Huanquan, deputy manager of Shengli Oilfield, introduced that in September 2003, they carried out a dual-component compounding drive test at Unit Ng 54-61 in the West District of Gudong Oilfield, and they began to see results in November 2004. From the maximum of 10.7 tons to 127.4 tons, an increase of 10.9 times; integrated water from the lowest 97.8% to 60.4%, a decrease of 37.4%; the recovery rate of 18.2 percentage points.
At present, the results have been widely applied in the Gudong Oilfield, Gudao Oilfield, Shengtuo Oilfield, and Jidong Oilfield in Shengli Oilfield. As of the end of 2009, it covered 171.35 million tons of geological reserves. In the past three years, cumulative production of crude oil was 4.083 million tons, realized an output value of 15.88 billion yuan, and achieved a profit of 11.07 billion yuan. It is predicted that the recoverable reserves will eventually increase by 19.4 million tons. Binary composite high-efficiency oil flooding technology has broad application prospects and can be extended to expand the application of similar oil reservoirs in the country.
Speaking of options ranging from three yuan to two yuan and from basic to non-alkali, Sun Huanquan stated that as early as the 7th Five-Year Plan period, Shengli Oilfield began the development of composite flooding technology and implemented it in Gudong Oilfield in 1992. China's first "base + surfactant + polymer" ternary compound drive field test. In 1997, they carried out conventional three-dimensional compound flooding test expansion in Gudao Oilfield and achieved major breakthroughs. Although the "base + surfactant + polymer" ternary composite flooding technology received significant results, due to chemical flooding resources in the Shengli Oil Field, 87% of the blocks in the Shengli Oilfield have high calcium and magnesium ions in the formation water. The combination of the alkali in the ASP flooding produced a large amount of precipitates, and the serious fouling problem became a fatal injury for the promotion of the ASP flooding technology. In 2000, Shengli Oilfield began to turn its attention to the research of the "surfactant + polymer" alkali-free binary system.
Sun Huanquan stressed that in order to greatly increase the efficiency of oil displacement in oil reservoirs, the key to reducing the interfacial tension of oil and water to ultra-low levels is the key. However, dual-component flooding has less "alkali" effect than Sanyuan. Therefore, the surface tension of the oil-water interface is achieved at high temperatures and high salt conditions. Therefore, the "strong washout" of residual oil becomes another problem.
The pioneers of dual-component flooding research can only advance in exploration. According to reports, for a period of time, researchers collected hundreds of surfactants that could be found on the market, tested and screened them all, hoping to find the ideal products and found no results. After the blind action of “take chance”, the researchers realized that we must start with basic research to clarify the structure-effect relationship of the molecule and find out the effective mechanism. Thus, a series of studies have been carried out on how polymers and surfactants work, how surfactants interact with crude oil, and how surfactants and additives in surfactants work.
After conducting in-depth research on research methods, flooding theory, and other aspects, they finally solved the problem of achieving efficient oil-displacement efficiency under alkali-free conditions. Among them, the most iconic achievement is the innovative development of the “oil agent similar enrichment, Yin non-addition and efficiency increase, poly-table inhibition separation” binary compound flooding theory, and under the guidance of this theory, invented the series Alkaline "anionic, non-ionic surfactant + polymer" binary composite flooding system, and its interfacial tension with crude oil reached ultra-low levels of 10~3mN/m under high temperature and high salt conditions. This result was considered by experts to have a good guiding role in the development of chemical flooding technology, and promoted the progress of compound flooding technology, which has a high value of promotion and application.
In order to produce more oil, innovation in Shengli Oilfield continues. Sun Huanquan said that they will further deepen the research on the mechanism of dual-component flooding, study the specific characteristics of different units, and study the formulas for high-efficiency binary compound flooding and expand the scope of application. In addition, the development of temperature-resistant salt-resistant flooding agents and the promotion of binary flooding technology to Class III high-temperature and high-salt oil reservoirs are also their next goals.

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