Investigation On The Microscopic Mechanisms Of Imbibition For Tight Oil Reservoir

In recent years,tight reservoirs have received significant attention as an unconventional oil and gas reservoir.Due to the characteristics of low porosity and low permeability in tight oil reservoirs,complicated reservoir forming mechanism and small pore throat,the development and exploration of tight oil reservoirs are extremely difficult.The imbibition based on capillary force has become an effective developing mechanism for such reservoirs.This paper aims at improving the drainage efficiency of tight oil reservoirs.The paper clarifies the static imbibition flow law of fluids in tight cores combining NMR experiments.Using the T₂spectrum and imaging map of the NMR experiment,the effects of the three factors of core permeability,viscosity of white oil,core length on the extent of static imbibition recovery were studied,and at the same time,the influence of the end open of boundary conditions on the extent of static imbibition recovery were studied,and Space flow and distribution of the two-dimensional fluid in the core was observed.By comparison,the degree of imbibition recovery in the NMR experiment is consistent with that obtained by the mass method,thus verifying the applicability of using the NMR experiment to study the imbibition law of tight reservoirs,and providing a solid theoretical basis for oil development.At the same time,combining core chip simulation glass etching chip experiments,an independently designed static imbibition experiment,was conducted to further study the effect of pore structure and surfactant on the degree of static imbibition recovery.Combining Bond coefficient and dimensionless time model,the normalization degree is optimized.Combined with the actual oilfield production conditions,these experiments can provide theoretical basis and on-site implementation conditions for low permeability tight reservoir imbibition,in order to improve the production efficiency of tight reservoirs.