Investigation of flue gas water-alternating gas (flue gas–WAG) injection for enhanced oil recovery and multicomponent flue gas storage in the post-waterflooding reservoir

Flue gas fooding is one of the important technologies to improve oil recovery and achieve greenhouse gas storage.In order to study multicomponent fue gas storage capacity and enhanced oil recovery(EOR)performance of fue gas water-alternating gas(fue gas-WAG)injection after continuous waterfooding in an oil reservoir,a long core fooding system was built.The experimental results showed that the oil recovery factor of fue gas-WAG fooding was increased by 21.25%after continuous waterfooding and fue gas-WAG fooding could further enhance oil recovery and reduce water cut signifcantly.A novel material balance model based on storage mechanism was developed to estimate the multicomponent fue gas storage capacity and storage capacity of each component of fue gas in reservoir oil,water and as free gas in the post-waterfooding reservoir.The ultimate storage ratio of fue gas is 16%in the fue gas-WAG fooding process.The calculation results of fue gas storage capacity showed that the injection gas storage capacity mainly consists of N_(2) and CO_(2),only N_(2) exists as free gas phase in cores,and other components of injection gas are dissolved in oil and water.Finally,injection strategies from three perspectives for fue gas storage,EOR,and combination of fue gas storage and EOR were proposed,respectively.

Doxycycline and hydroxypropyl-b-cyclodextrin complex in poloxamer thermal sensitive hydrogel for ophthalmic delivery

The present study aimed to prepare a chemically and physically stable formulation of doxycycline(Doxy)in an in situ thermally sensitive hydrogel for ophthalmic delivery.An inclusion complex of Doxy and hydroxypropyl-b-cyclodextrin(HP-b-CD)was first developed to increase the stability of Doxy in aqueous solution.The physical characteristics(phase solubility profiles,thermal analysis,X-ray powder diffractograms and infrared spectra)of the Doxy-HP-b-CD inclusion complex indicated the formation of a stable 1:1 complex.Poloxamers P407(16–22%)and P188(0–5%)were mixed to obtain a hydrogel with an appropriate gelation temperature for opthalmic use.Formulation of the inclusion complex in the poloxamer hydrogel exhibited a suitable gelation temperature(33.3℃)after dilution with simulated tear fluid(Gel:STF=40:7,v/v).The release of Doxy from the poloxamer hydrogel followed a zero order equation suggesting it occurs through corrosion of the poloxamer hydrogel.Stability studies demonstrated that the inclusion of Doxy by HP-b-CD markedly improved its stability in aqueous solution both at 8 and 401C.This formulation of a doxycycline-HP-b-CD inclusion complex in an in situ thermally sensitive poloxamer hydrogel represents a potentially effective ophthalmic Doxy delivery system.