Experimental Studies On CO₂-EOR In Tight Oil Reserviors

Because the conventional oil resources are fast depleting,it becomes imperative to develop methods to harness unconventional oil resource like tight oil.Oil recovery in tight reserviors is a challenge.The recovery by waterflooding is very low,so there have been studies focused on CO₂ injection in tight oil reserviors.This paper first studies several important physical properties of CO₂-saturated tight oil,which include the saturation pressure,oil-swelling factor and oil viscosity.Then the slim-tube test is conducted to study the Minimum Miscible Pressure?MMP?.A new model of predicting MMP is built which is based on alternating conditional expectation.Experimentally,core samples collected from tight formations are utillized to conduct a series of CO₂ flooding experiments with different CO₂ injection rate,injection soaking time and fracture.One of major objective of this paper was to evaluate the viability of CO₂ huff n puff processes as primary means to enhance oil recovery in tight reservoirs and thereby optimize the corresponding key operating parameters of process.The effects of primary parameters,such as slug size,chasing gas,soaking time and strategies were optimized to lead to successful field application.The observations of this study suggest that the CO₂ huff n puff is a viable technique to enhance in tight reserviors.