formation damage part 4

A Formation can be damaged mainly while one of following activities (ordered in timely manner).

1) During Drilling and Completions

2) During and after production and workover operations

3) During Injection 

Formation Damage Mechanisms:

3) During Injection :

At young age, you can walk or even run with your own legs (thats natural energy within you). After some time, when you can not run or walk, you require support in form of walking stick or wheel chair. Same thing is happening with our oil inside reservoir also.

With time oil also loses its energy.

After some production of oil, oil loses its energy to come out to surface, so we provide support energy as artificial lift, so that it can come from bottom of well to surface.

After some further time, oil loses more and more energy to flow inside reservoir also, so we try to give energy to oil for "pushing oil forward" in form of injection of gas or water at high pressure.

But as we remembered, clay particles are always waiting for water, and we are giving water to them. So, they will definitely create problems with our dear oil globules and lovely pores. (Its like, We are giving power to our enemy.)

So, due to injection of water, clay particles will get water to swell, and they will have chance to block pores and damage formation. (Clay swelling)

Another thing, clay particles can do with water is, dispersed clay particles can move with flowing water and can block the pores on its way.

(Clay particles are water wett, so it can easily mixed and flow with water.)

 It means, clay particles (kaolinite and mica needles), which were not at pores can also travel to there and can block it.

So, small amount of water production or injection can induce the fines to migrate. The detachment and migration of fines depends on the fluid velocity also, therefore flow rate also becomes an important factor.

This migration fines can occur if lesser saline aqueous fluid is injected in the formation.  Due to lesser concentration of divalent cations or potassium (less salinity), the mutual repulsion of clayey platelets increases.  The repulsive force overcomes the attractive forces then clay particle will be released and the released clayey particles can be carried to the vicinity of the well bore and choke the formation pores.

Sometimes, our crude is so difficult to remove due to its viscocity, so we add polymers into our injection water so that, our injection water will be thick enough to displace oil inside reservoir. But this create additional problems sometimes like, if polymers added are jot compatible with hydrocarbon or if polymer degrades and choke formation pores. This kind of formation damage is called polymer invasion.

lets, revise all.

Definition: Formation damage is impairment or resistance to fluid flow from or to Reservoir (Formation) near the wellbore area.(vicinity of wellbore).

Formation damage mechanism is divided into following types.

1) Due to increase in relative permeability of fluid other than desired fluid,

2) Due to viscosity increase,

3) Due to precipitations and deposition.

A Formation can be damaged mainly while one of following activities (ordered in timely manner).

1) During Drilling and Completions

    Invasion of foreign materials

    Clay swelling

         Emulsion Blocking

    Wettability reversal

      Mechanical damage

2) During and after production and workover operations

        

i) Due to increase in relative permeability of fluid other than desired fluid,

      Water blockage

      Gas breakout

      Condensate banking

ii) Due to viscosity increase,

      Emulsion blocking

iii) Due to precipitations and deposition,

      In-organic scales deposition

      Sludge formation with Acids

      Fines migration due to acid

      Asphaltene precipitation

      Wax or paraffin deposition

      Bacterial Damage

3) During Injection 

     Clay swelling

       Migration fines

     Polymer invasion.

hope, you enjoyed it. stay tuned. Enjoy your day.

  

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