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This is very dependent upon the lithology and the specific fluid(s) being injected. For instance, if using CO2 as the injectant gas, then it could cause dissolution in the near wellbore region and probable precipitation of dissolved components deeper in the reservoir. CO2may also cause scaling - possibly both organic and inorganic. Or if injecting CO2 in certain mineralogies may increase the potential of fines migration. The injection water must also be considered for compatibility with the formation and formation water. Also, what water is being injected? Is it re-injection of produced water? If so, how is the water being treated? Does treatment reduce solids and contaminants sufficiently to maintain long-term injection? Some challenges are about process control. Gas has a high mobility ratio and thus has higher flow velocity. There will most probably be the need to consider volume/rate control because production might be optimal when gas-water flow at similar velocity. These are just some of the possible challenges of injection - but each system will have it's own challenges dependent (as stated above) on the unique lithology and fluid combinations.

Thanks for your comment. The measurement goes to such high pressures in an attempt to fill the total porosity and hence, describe the pore throat size distribution in the total porosity. It is not really an attempt to describe the capillary pressure at those naturally unrealistic pressures/heights. This is easily accomplished for clean sandstones and some more permeable carbonates but is not injected in highly clay rich systems and tight reservoirs - particularly “shale gas/oil” systems. Well log data will observe total porosity - including all of the nano-pores (and pico-pores). These can be a significant portion of the porosity in tight reservoir systems and source rocks (up to 50-60 % of total porosity).

geologists !

@@premiercorexwebinars thanks for the information

Glad you enjoy Bhaskar!

For an unsteady state (USS) experiment, effective permeability can only be "measured" before starting and at the end of the coreflood - to a single . Before starting, the mobile fluid phase is injected to obtain the effective permeability to that fluid phase. The immobile fluid phase remains immobile. For example, for an oil-water fluid pair, before starting an USS waterflood, the core plug will be at irreducible (immobile) water saturation (Swi), and mainly saturated with oil. Before the coreflood, oil is injected through the plug as the only mobile fluid phase. Therefore, the viscosity of oil is used in calculating effective oil permeability at Swi. At the end of the coreflood, only water is mobile and the water viscosity is used to determine effective water permeability at remaining oil saturation. During the waterflood, for most laboratories, effective permeability is not determined. Mostly, either the JBN or Jones-Roszelle method is used to estimate relative permeability from oil and water production data, together with differential pressure (dP) measurements. The method uses the Welge fractional flow equation: first, to determine fractional flow of oil and hence, kro - using the oil viscosity, and then using fw = 1 - fo, to determine krw, using the water viscosity. It is assumed that the oil and water phases are immiscible and flow independently - hence, there is no mixing of viscosity. Also, for most labs, since dP is measured from a single line, it is assumed that the dP impacts equally on both fluids. Very few labs measure dP of oil and dP of water separately - which would be very difficult in USS method since it would require a continuous, connected fluid column from inlet to outlet of both fluids.

@@6ftyoda I got it now, thank you very much Mr. Reed.

Hi Bhaskar, A very good point, and exactly the reason for discussing the base (or reference) permeability. There needs to be discussion between the geologist/petrophysicist/RE to discuss how the models will be set up and what values will be used to populate things like permeability, porosity, etc.

@@6ftyoda Thanks for replying. I will connect with you on LinkedIn. I had a Reservoir Engineering interview today. Just because I watched your video, I could answer the advantages and disadvantages of USS, SS and Centrifuge. Interviewer precise question was "Which data on Relperm graph is unlikely to be obtained from USS and SS?". Thanks to your video, I promptly said "Residual Oil Saturation and we get it from Centrifuge". Interviewer (& I) was delighted to hear that. 😇😇

@@6ftyoda I am going to watch all your videos and will leave questions/comments behind for further discussion.

I would refer you to the manufacturers/suppliers of these equipment, such as: Vindum Engineering or DCI Test Systems, to name two.

Hi Abdulhadi, if you can email sales@corex.co.uk with your contact details this can be arranged.

Hi Vikash, Many thanks for your comment. We have tried to respond through your email address provided but it states unrecognisable. Could you provide again.