Aqueous retarded acid formulation for stimulatio in carbonate reservoir

1. Aqueous Retarded Acid
Formulation For Stimulation
In Carbonate Reservoir
SUMMER INTERNSHIP-2022
May 18, 2022
PROJECT -
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2. Outline
 Introduction
 Matrix Acidizing
 Hydraulic Fracturing
 Main Case Study
 Experimental Procedure
 Results and Conclusion
 Another Case Study (Flow Assurance)
 Conclusion
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3. Introduction
Well Stimulation
 Acidizing
 Hydraulic fracturing
Most Commonly Used Well Stimulation Technique
 Well stimulation is an intervention technique designed to enhance the well production by
improving the flow of hydrocarbons from the drainage area into the well bore.
 Stimulation of Oil and Gas reservoirs, with a view of enhancing well performance or restore the
production in older wells.
 Well stimulation technique used for extending the perforation channels and fractures.
Acidizing 3

4. Acidizing
 Acidizing also termed as Acid Stimulation.
 Acid stimulation refers to using reactive acids to increase permeability in wells.
 It dissolves various acid-soluble solids naturally present in the rock matrix or as formation damage.
The Two basic types of acidizing :
 Matrix Acidizing - In Matrix acidizing acid is pumped into the formation below the fracture pressure
for removing acid-soluble damage. This method can be used in Both Carbonate and Sandstone
Formation.
 Fracture Acidizing - In Fracture acidizing acid is pumped into the well-bore, above the fracturing
pressure of reservoir rock for creating long and open channels in the low Permeability Reservoir.
Acid Retarding Agent Magnesium Chloride (MgCl2)
- 15% Hydrochloric acid (HCL)
- 10% Acetic acid (CH3COOH)
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5. Hydraulic Fracturing
 The objectives of hydraulic fracturing for well stimulation is to increase productivity of producing
zone by creating the highly conductive path (compared to the reservoir permeability) some
distance away from the well bore in to the formation.
 A fracturing treatment consists in breaking down a producing section hydraulically with a sand
carrying fluid, the sand being used to prop the resulting fracture. Usually conductivity is
maintained by propping with sand to hold the fracture face apart.
Proppant - The proppant is a granular material that prevents the created fractures from closing
after the fracturing treatment.
Types of proppant :
Hydraulic fracturing
 Silica sand
 Resin-coated sand
 Bauxite
 Ceramics
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6. Main Case Study
 One of the problem encountered much often in the application of acids in carbonate
reservoir, especially inorganic acids at elevated temperature (i.e. reservoir temperature) is
their excessive reaction rate.
 For example, HCl is highly reactive at elevated temperature (i.e. 200°F and higher) or at
low injection rates, favors facial dissolution over wormholing.
 For this reason, we aim to find a ‘Single Phase Aqueous Retarding Acid Formulation
for Stimulation in Limestone Reservoir’ which has optimum retarding capacity, at
elevated temperature condition, and cost effective retarding agent.
Problem Statement
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7. Main Case Study
 Rinse all the glass apparatus to avoid the contamination of any impurities.
 Take 25ml solution, each of 15% HCl in two beaker.
 Add 20mg Hexahydrate Magnesium Chloride (MgCl2.6H2O) as a retarding agent in one
beaker whereas no additives in the other beaker.
 To initiate the reaction, add 6mg Calcium chips in both the beaker and start the
stopwatch simultaneously.
 Now take the samples from both the beaker in different samples tubes at specific interval
and label them accordingly and measure their concentration in Automatic
Potentiometric Titrator.
 Note – The whole experiment is performed at room temperature. Working on the
experiment that is to be performed at elevated temperature (reservoir temperature).
Experimental Procedure
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8. Main Case Study
Observation
 The solution with retarding agent
(MgCl2) took much more time to
complete the reaction as compared with
the solution of 15% HCl alone.
 There was a significant decrease in the
amount of effervesces which shows the
retarded rate of dissolution of calcium
chips (or ions).
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9. Main Case Study
Results
 The concentration of Calcium (Ca2+) is
plotted against the time at which the
specific sample is collected.
15% HCl +
Retarding agent (MgCl2)
15% HCl
Time (sec)
Calcium
Concentration
(mg/L)
Time (sec)
Calcium
Concentration
(mg/L)
30 32384.7 30 72320.3
80 47735 60 73515.3
150 54652.2 90 89920.2
300 54419.7 120 89900.1
720 55522.4 300 111582.2
1500 56140 480 111478
2400 76550.9 720 115840.8
- - 1320 172193.4
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
0 500 1000 1500 2000 2500 3000
Calcium
Conc.
(mg/L)
Time (Sec)
Calcium Concentration Plot
With Additive Without Additive
Conclusion
 The addition of retarding agent (MgCl2)
has significantly retarded the reaction
rate or dissolution of Calcium chips.
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10. Another Case Study
Problem Statement
 Wax deposition is one of the most challenging flow
assurance issue during the production life of
reservoir.
 The paraffinic constituent of crude oil get
precipitated because of the cooling effect which
occurs when the oil flows from the high pressure
reservoir into the wellbore to the surface.
 The temperature loss induces the crystallization of
wax and the subsequent plugging of the well.
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11. Another Case Study
Results and Conclusion
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Procedure
 1 g of sample is taken in a thimble and placed in
the Soxhlet apparatus.
 150 ml of n-heptane and toluene is added in the
round bottom flask which extracts the organic
and inorganic constituents respectively.
 Temperature is increased with a heat source and
vapours evolved from solution moves upward and
dissolves their like components and condensed
into the liquid form.
 The fraction of different constituent of organic
and inorganic components has been analyzed in
further lab studies.
 Accordingly, the solution with specific volume
fraction of diesel, toluene is prepared to dissolve
the wax deposited in the tubing and well bore

12. धन्यवाद
ThankYou
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Mentor – Mr. M.Q. Zaman