A new type of enhanced oil recovery technology began to expand its application in Shengli Oilfield, which will increase oil recovery by 8.1 percentage points. This technology will rejuvenate the old oilfields with exceptionally high water content in the late Shengli period, and the economic validity period will be extended by more than 10 years.
       The application of the so-called heterogeneous composite flooding technology has greatly benefited the Gudao oil recovery plant.
       Gao Yang, director of the water drive room at the Institute of Geology, Gudao Island, introduced that before the implementation of the heterogeneous composite flooding, the comprehensive moisture content of the pilot test area had reached 98.2%, and it dropped to a maximum of 81.3% after implementation, a drop of 16.9 percentage points.
       Not only that, the oil increase effect is also very obvious, the test area daily production of oil increased from 3.3 tons to 79 tons, 1 tons of polymer injected into the ground to swap 23 tons of oil, improve oil recovery 8.5 percentage points, the ultimate recovery of 63.6%. At present, the technology has been promoted and applied.
       Gudao Oilfield was put into development in 1964. After many years of continuous oil production, since the end of the 1980s, the main oil fields such as Shengli and Gudao have taken the lead in entering the special high-water development stage. Water flooding has developed 1 ton of liquid, and over 90% of it is water. Only 10% is oil. In response to this situation, the oil field began to use polymer flooding. This technology has been applied in 30 mine units such as Gudao, Gudong, and Shengli Oil Production Plant, accumulatively increasing oil output by 19.3 million tons.
       However, after more than ten years of application, with the deep development of polymer flooding, the degree of recovery and moisture content of the reservoir are approaching the limit. At the same time, due to the characteristics of using polymer flooding, the effect of converting water into oil is very unsatisfactory. This means that the reservoir after polymer flooding is no longer in search of new, more cost-effective methods for enhanced oil recovery.
       This problem has not been solved internationally. In addition, there are currently no mature experiences for the reservoir conditions in Shengli Oilfield, such as high formation temperature, high formation water salinity, and high crude oil viscosity.
       How to solve this problem has become a major issue for researchers in the Institute of Exploration and Development.
       According to Guo Lanlei, chief expert of the Institute of Exploration and Development, the tertiary oil recovery in the oil field first experienced polymer flooding. This liquid is similar to the glue, because it is sticky, so as to ensure a certain pressure to drive the oil out. Later, a surfactant was added to the polymer, which can wash the oil out of the formation like detergent. After many years of application, the "common channel" of the oil displacement agent was formed in the formation, and the oil displacement agent ran along the channel, and the reservoir outside the channel could not be effectively affected, and the effect was no longer obvious.
       After many years of exploration, researchers have broken down the impediment that conventional particles cannot be used as a displacing agent and designed new soft solid particles that can be used to displace oil and add them to liquids such as polymers and surfactants to form a solid-liquid coexistence. The oil displacing agent, by virtue of its viscosity and the viscoelasticity of the particles, acts together to solve the turbulence problem of the fluid injected into the reservoir after the polymer flooding, and further increases the volume of fluid flow to form a new generation of chemical flooding methods.
       "PPG particles swell with water and have strong viscoelasticity. After swelling, they have the same toughness as rubber and can effectively seal large pores in the oil layer." Guo Lanlei said, "The image is like a millet porridge. There are liquids and particles. When the pressure is low, it can block the hole and increase the oil displacement area. Because of its elasticity, when the pressure increases to a certain degree, it can deform through the pores and migrate in the reservoir to reach the deeper part of the reservoir."
       This solid-liquid co-existence oil-displacement agent has multiple functions that can both block and displace oil and wash oil, effectively solves the problem of efficient development of reservoirs after polymer flooding, and realizes a leap in the oil displacement system. At present, this kind of system design is the first one at home and abroad. It has won the Chinese Patent Excellence Award and also obtained the US invention patent.
       In 2018, Heterogeneous Compound Drive technology has made new breakthroughs, and researchers have developed a new low-cost oil-repellent agent that has been reduced by 1,000 yuan per ton. At the same time, oil-dispersing agents are suitable for various types of reservoirs, further expanding reservoir coverage. scale.
       It is understood that the oilfield will be applied on site in eight projects in the old oil fields such as Gudao and Shengtuo, and experts say that during the “13th Five-Year Plan” period, the oil field will further increase the promotion of heterogeneous composite flooding technology. (SINOPEC News Network)