HYDRAULIC FRACTURING

Presented By :A Shubham

(E10-0001)

INTRODUCTION• First hydraulic fracturing job was performed by Stanolind Oil in 1947 in

Hugoton field, Kansas.

• First commercially successful hydraulic fracking job was performed by Halliburton in 1949 in Oklahoma.

• Hydraulic fracturing is a stimulation technique performed in Oil & Gas wells to increase the productivity of the reservoir.

• Hydraulic fracturing is performed by water mixed with some fluid additives & sand, sand & water comprise of about 99.5% of the composition of fracking fluid.

Natural Flow(radial flow)

Stimulated Flow(Bilinear flow)

STAGES OF HYDRAULIC FRACTURING

• Pad Stage:

Fluid is pumped at a higher rate than it’s leak off rate at pressure higher than the fracturing pressure of rock.

• Slurry Stage:

Proppant is added to the fluid along with fluid additives & it is allowed to flow into the fracture to hold it from closing it.

INFLOW PERFORMANCE OF WELL

• The Inflow Performance of a Fracture Stimulated well is controlled by the dimensionless Fracture Conductivity

Where,

= fracture permeability (kf) *

conductive fracture width (w)

= formation permeability (k) *

conductive fracture single wing length (Lf)

ROCK MECHANICS

Behavior of rocks when subjected to various force fields.

Parameters considered for fracturing of rocks:

• In-situ Stress

• Elasticity

• Poroelastic Properties

σ1 is the vertical stressσ2 is the minimum horizontal stressσ3 is the maximum horizontal stress

PROPERTIES OF FLUIDS

• Compatibility with the formation

• Low leak off rate

• Ability to carry proppant

• Low friction loss

• Easy removal from the formation

• Stability at reservoir condition

• Availability

• Safety

• Cost

FLUID ADDITIVES• Gelling agent : Guar Gum

• Cross Linking agent : metal ions, borax

• Viscosity Breakers : ammonium per sulfate

• Clay Stabilizers : KCL water

• Surfactants : Isopropanol

• Fluid Loss Additives : Silica floor

• Bactericide : Formaldehyde

• PH stabilizers : Sodium carbonate

• Friction reducer : Polyacrylamide

TESTS PERFORMED BEFORE FRACKING

• Step Rate Test:

• Pump in/ Flowback Test :

This test determines closure pressure which helps to determine proppant of suitable strength.

Closure pressure is represented by the inflection point which is due to change in flow regime from linear to radial.

CONCLUSION

• Hydraulic fracturing technique is used to stimulate the wells for enhanced productivity.

• Technological advancements in hydraulic fracturing have made it possible to exploit shale gas, CBM reservoirs & low permeable reservoirs for production at economical rate.

• The parameters kept under consideration for performing a fracturing job are Insitu stress, elastic properties, poro elastic properties, fluid additives, fracture pressure etc.

REFERENCES

• Rock Mechanics, Tillerson& Wawersik(eds) ¸ 1992 Balkema, Rotterdam. I SBN 90 5410 0451

• Mechanics of Hydraulic Fracturing, M. KING HUBBERT, MEMBER AIME, DAVID G. WILLIS, JUNIOR MEMBER

AIME

• Theory of Flow and Fracture of Solids. A. NADAI. New York, McGraw-Hill Book Co., Vol. 1, 2nd edn., 1950.

• Thomas O. Allen & Alan P.Roberts, “Production Operations Vol 2 (Well Completions,Workover,and

Stimulation)”.

• K. Ben-Naceur, Michael J. Economides,” Dowel Schhm?berger, “The Effectiveness of Acid Fractures and

their Production Behaviour (SPE-18536)

• Mukherjee R. K. “Technical Manual for Production Operation”.