1.
Carbonate Acidizing & Design

2.
Carbonate Rocks
 Carbonate rocks are a class
of sedimentary rocks.
 Composed primarily of two major types
of carbonate minerals.
1.Limestone
2.Dolostone or Dolomite

3.
Limesto
ne
Composed of skeletal
fragments of marine
organisms such as
coral or foraminifera.

4.
Dolomit
e
An anhydrous
carbonate
mineral
composed of
calcium
magnesium
carbonate,
ideally
CaMg(CO3)2 .

5.
Acidizing & Designing
 Acidizing involves pumping acid into a
wellbore or geologic formation that is
capable of producing oil and/or gas.
 Purpose of any acidizing is to improve a
well’s productivity or injectivity.
 Acidizing designing in which we selecte the
appropriate acids, after that ready to
design the treatment.

6.
Two types of acids are most
commonly used
 1.Hydrochloric acid in all formation types.
 2.Hydrofluoric acid in sandstones and
certain shales.
 Other types of acids, such as organic
acids, may also be used in specialized
situations

7.
Three general categories of
acid treatments are
 Acid washing
 Matrix acidizing
 Fracture acidizing

8.
Acid Washing
 Mostly used in carbonate formations
 Objective is simply tubular and wellbore
cleaning.
 Most commonly performed with
hydrochloric acid (HCl) mixtures to clean
out scale (such as calcium carbonate),
rust, and other debris restricting flow in the
well.

9.
Matrix Acidizing
 Mostly used in sandstone formations
 Acid is injected into the well penetrating rock
pores at pressures below fracture pressure.
 Used to either stimulate a well to improve flow
or to remove damage.
 During this process the acids dissolve the
sediments and mud solids within the pores
that are inhibiting the permeability of the rock.

10.
Fracture Acidizing
 Mostly used in carbonate formations
 Involves pumping highly pressurized
acid into the well,
 physically fracturing the reservoir rock
and dissolving the permeability inhibitive
sediments.
 Purpose is to restore or improve an oil
or gas well’s productivity

11.
Acidizing Refers to
Stimulation
 Well stimulation is a well intervention
performed on an oil or gas well
 To increase production by improving the
flow of hydrocarbons from the drainage
area into the well bore.

12.
Backflush Job
 After an acid job is performed,
 used acid and sediments removed from
the reservoir are washed out of the well
in a process called Backflush.

13.
Heterogeneous carbonate
fields challenging to produce
 Carbonates can exhibit highly varying properties
 (e.g., porosity, permeability, flow mechanisms)
within small sections of the reservoir,
 making them difficult to characterize.
 This involves detailed understanding of the fluids
saturation,
 pore-size distribution,
 permeability,
 rock texture,
 reservoir rock type,
 and natural fracture systems at different scales.

14.
Massive hydrocarbon
reserves
 It is estimated that more than 60% of the
world's oil and 40% of the world's gas
reserves are held in carbonate
reservoirs.
 The Middle East, is dominated by
carbonate fields, with around 70% of oil
and 90% of gas reserves held within
these reservoirs.

15.
Pakistan <3
 Most carbonate reservoir are present in
Pakistan ( Northern areas) in which 90% of
gas and 60% of oil are produces to fulfill
the demand of oil/gas for our country.
 But many reserves are remaining to
extract or evaluate the hydrocarbon,
because this reserve has an ability to fulfill
the demand of the energy in Pakistan.

16.
Conclusion
 Every nation depend on economy and
economy stable by profitable business,
 Oil & gas sector is more profitable business
in the whole world.
 More exploration get more profit and stable
the economy of any country.
 Government interest required in exploration.
 Carbonate acidizing and design is required
to produce well efficiently & economically.

17.
Refrences
 Internet
 Wikipedia
 Schlumberger
 Petro wiki
 SPE
 Etc….