Perforating Requirements New

8/12/2019 Perforating Requirements New

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Perforating RequirementsFor Fracturing Stimulations


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Perforations

Communication between the welbore and the reservoir

In a fractured-stimulated wellbore, is the conduit between thefracture and the wellbore

Should minimize the near-wellbore pressure drops due toperforation friction, micro-annulus pinch points, multiple competing

fractures and fracture turtuosity.


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Micro-annulus pinch points

(SPE 30506)


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Near-wellbore fracture turtuosity

(SPE 30506)


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Underbalance perforating

! Insufficient underbalance does not remove all sand debris from theperforations.

! This debris creates an external filter cake in the perforation duringthe injection.! High pressure drops can be expected.


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Micro-annulus

Perforating can create micro-annulus

(SPE 59480)


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Micro-annulus width due to perforating

w width (in)! Poisson ratio

Pm Micro-annulus pressure (psi)PR Reservoir pressure (psi)

dw well diameter (in)

E Young modulus (psi)

For,

dw= 8-1/2-in, Pm-PR= 2000 psi

!=0.25, E = 1E06 psi

w = 0.0106-in

which, for a fluid velocity of 3.28 ft/s

corresponds to a rate of 99 bpd (for a viscosity

of 1 cp)


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Hard-rock hydraulic fracturing (I)(no micro-annulus, vertical wells)

! Dry gas wells, no liquid in wellbore,small hollow guns and 1 2 spf can

maintain good bond.

! Abass (SPE 28555)180 perfs at


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Hard-rock hydraulic fracturing (II)(no micro-annulus, vertical wells)

(SPE 59480)


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Hard-rock hydraulic fracturing (III)(no micro-annulus, vertical wells)

! Stadulis (29549) - 0 phase, 1 spf with proppant slugs to preventmultiple competing fractures and near-wellbore screen-outs.

! Three factors: low shot density, closed micro-annulus and proppantslugs. Which are driving to success ?

! Does a single or biwing fracture propagates with 0 phase ?! If a biwing is initiated, the wing opposite to the perfs will restrict flow

rate and may screen-out.

PFP

screen-out


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Hard-rock hydraulic fracturing (IV)(open micro-annulus, vertical wells)

Micro-annulus

Re-orientation

100

Preferred

Fracture Plane

100

Preferred

Fracture Plane

Multiple fractures

10 to 30


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Hard-rock hydraulic fracturing (V)(open micro-annulus, vertical wells)

(SPE 59480)


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Hard-rock hydraulic fracturing (VI)(deviated and horizontal wells, vertical fractures)

! If the well is the PFP, 180 oriented up and down.! ARCO uses this technique up to 65 deviation.! If the stress direction is not known, perforate up and down .! To minimize the initiation of multiple fractures, the higher the anglethe shorter the interval.! For deviation < 45,"10 ft perforated interval should be enough.! For deviation > 45, decrease the perforated interval.!

For deviation >75,

"

short clusters (less than 3 ft, multiplephases angles).


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Perforated interval

well

PFP

6

100 ft

10 ft

well

PFP

middle of the interval

multiple factures induced

decreased width


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Penetration depth

! 4 to 6 inches into the formation (maximum).! In theory, hole should be > 6 times proppant diameter.! In practice, hole should be > 10 to times the larger proppant

diameter.

!Large stress contrast favor 60 phase.


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Shots and hole size

! Pressure drop is a function of the injection rate per perforation andviscosity of the fracturing fluid.

! During the treatment, hole size increases due to erosion by the fluidand, mainly, by the proppant.

! For 0 and 180 phases, all the holes contribute to the fracture.! For 120, only two-thirds contribute to the fracture and for 60 only

one-third is connected.

! Pressure drop across perforations should be less than 25 psi.

Documents

Perforating Requirements New