Project Full Name：Research and Application of Nanofluids Permeation Flooding for Tight/Shale Reservoir

Company：Key Laboratory of Oilfield Chemicals, CNPC

Awarded：Cost Reduction & Efficiency Enhancement Technology

Standard:  International  Advanced Level

Projec Number：ECF-2022-SEP-1006

Principal Accomplishers： Geng Xiangfei, Liu Weidong, Ding Bin, Guan Baoshan, Shi Yang, Sun Jianfeng, Chen Weidong, Wang Chen, Jiang Ke

Core Shell Structure Nanofluid Permeability Enhancement and Oil Displacement System

Key Innovation Points：：

(1)Invented an Undecylene oil soluble disassociating agent working as the core of micro-emulsion, which realized the nano scale dispersion of oil aggregates and significantly improved the fluidity of crude oil;

(2)) Invented the diphenyl ether type water-soluble Gemini surfactant working as the shell, which realized the stable coating of the core. The interfacial tension was as low as 10-4mN/ m, and the matrix penetration enhancement effect was improved;

(3)) Invented a nanofluid permeation and oil displacement system, which integrates nano size, permeability enhancement of reservoir pore throat matrix, and improvement of crude oil mobility. The average particle size was reduced to 10nm, and wettability was changed single-phase wetting to two-phase wetting. According to experimental evaluation, the starting pressure gradient was reduced by more than 50 times compared with water injection, the swept volume was expanded by 65%, and the average imbibition displacement efficiency reached 60%.

Main Application and Technical Principal： 

Energy storage before fracturing energy enhancement during fracturing, energy supplement by huff and puff after fracturing, and improvement of water flooding for tight/shale reservoirs.

Technical mechanism: The core-shell structure nanofluid is used to greatly increase the percolation capacity of the injected fluid and crude oil in the matrix, and solve the technical problem of “the fluid can be injected into the matrix and the crude oil can be recovered”. Nanofluids effectively enter the matrix pores due to its core-shell spherical structure, having shell water phase, core oil phase, and size of 10-30nm. The core-shell structure improves the mobility of crude oil and is conducive to recovery because when it encounters the oil, it releases the core disassociating agent, which weakens or even eliminates the association effect of components of crude oil, and "breaks" crude oil into "small-sized oil". This effect greatly improves the

mobility and recovery capacity of crude oil reservoir

技术应用： 

纳米流体增渗驱油体系已在中石油致密/页岩油藏压裂蓄能驱采、压后吞吐补能和改善水驱提高采收率领域应用30口井次，施工成功率100%，累计增油超过27000吨，投入产出比1:2.55~1:5.15；

纳米流体增渗驱油体系具有丰富的应用场景，在致密/页岩油藏高效开发和提高采收率领域推广应用前景广阔：

致密/页岩油藏压前蓄能/压中增能与提高初产及EUR

致密/页岩油藏压后吞吐补能与提高采收率

致密/页岩油藏压后同井同步/异步补能与提高采收率

致密/页岩油藏压后井组同步/异步补能与提高采收率

低渗/致密油藏水驱后进一步提高采收率