Research progress of micro/nano mechanical problems in unconventional oil and gas exploitation

Unconventional oil and gas resources have a promising development prospect due to their abundant reserves. The exploitation of them involves a series of micro/nano mechanical problems. To enhance the oil recovery, polymer flooding and nanofluid flooding are employed. The microscopic displacement mechanisms of these two methods have attracted wide attention. Shale gas, which is stored in adsorbed state and bulk state in the micro/nano pores of shale, flows into the fractures with the displacement of injection gases. Recent research progress of micro/nano mechanical problems in unconventional oil and gas exploitation based on our previous study was reviewed. The microscopic displacement mechanisms of polymer and nanofluid flooding were discussed. Then, the adsorption of shale gas, displacement of injection gases and the mechanisms of micro flow were reviewed. Finally, the direction and key point of future work were discussed.