Microbubble Flooding Technology Controls Water & Stabilizes Oil in Changqing Oilfield

The field test of the new microbubble oil flooding technology carried out in Changqing Oilfield has achieved remarkable results. In the Chang 6 reservoir of Jing'an Oilfield, 16 injections and 68 production lines have been formed. Based on the test scale, the natural decline rate of the test well group dropped by 4.48 percentage points, and the water cut increase rate dropped by 1.56 percentage points. The cumulative oil increase in the stage reached 8,730 tons, and the recovery rate increased by more than 10 percentage points, providing stable water control and stability for ultra-low permeability reservoirs. oil and improve oil recovery, opening up a new path.

Located in the Ordos Basin, Changqing Oilfield has ultra-low permeability oil reservoir reserves accounting for nearly 30% of the total reserves, and the average water content has reached 62.1%. After long-term water flooding, the reservoir has development contradictions such as water breakthrough in multiple directions on the plane, thin interbedded distribution of remaining oil on the profile, and difficulties in injection and production control and potential tapping. For oil reservoirs with medium to high water content and high recovery degree represented by the Chang 6 reservoir in Jing'an Oilfield, the Changqing Oilfield scientific research team has successively carried out water plugging and profile control, layered water injection, density adjustment, periodic water injection, and deep polymer microsphere Through tests such as adjustment and flooding, good oil stabilization and oil reduction effects have been achieved. However, with the deepening of development, the contradictions in reservoir development have become increasingly prominent. Extra-low permeability and ultra-low permeability Class I and II reservoirs have encountered new bottlenecks in controlling water, stabilizing oil, and improving oil recovery.

In this regard, the Changqing Oilfield Oil and Gas Technology Research Institute and the China Petroleum Exploration and Development Research Institute jointly carried out technical research and clarified the mechanism of microbubble flooding technology to improve oil recovery, with "fine matching of injection medium and reservoir to improve oil displacement efficiency, gas and water The dispersion system can effectively replenish energy and expand the swept volume" as a technical idea, and a new microbubble flooding technology has been developed through research. Compared with traditional technology, this new technology uses physical methods to form an efficient microbubble dispersion system under specific temperature and pressure conditions. It achieves ion exchange by adjusting the system composition, water-gas medium ratio and the diameter of the dispersed phase fluid unit. The purpose is to peel off the oil film, change the seepage resistance and expand the swept volume, thereby improving the recovery rate.

Beginning in 2020, Changqing Oilfield has selected the Chang 6 reservoir of Jing'an Oilfield for testing after multiple investigations and demonstrations. At the same time, in order to further evaluate the adaptability of microbubble flooding technology in ultra-low permeability reservoirs, a new and expanded test well group was added, forming a pilot test scale of 16 injections and 68 production. Since the beginning of this year, in order to further improve the effect of microbubble flooding tests, scientific researchers have improved the correspondence between injection and production, and implemented measures to tap the potential of oil and water wells. At the same time, combined with the pilot test results of the Wuliwan oil area, optimization adjustments and effect evaluation were implemented on the first 4 well groups. The data shows that the injection performance of microbubble flooding is good, the water absorption pattern in the longitudinal section is significantly improved, the sweep range of planar water flooding is relatively expanded, and the overall production well has a significant effect in increasing the recovery rate.

At present, the microbubble flooding technology in Changqing Oilfield has made important breakthroughs in the system oil displacement mechanism, key devices and injection process modes. The microbubble flooding technology has become mature and has achieved large-scale stable injection for the first time in China, and has the adaptability of multi-layer reservoirs. It has continuously improved and built China Petroleum's first pilot test demonstration area, which has become a potential replacement technology for reducing decline, controlling water content, and effectively improving the recovery rate of low-permeability reservoirs. It also provides successful experience for improving the development level of similar domestic reservoirs.