Part III - Well stimulation methods

Hydraulic fracturing

Evaluating effect of hydraulic fracturing (McGuire and Sikora, 1960)

Stimulation Ratio, J/J0

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Hydraulic fracturing

Optimization of NPV

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Hydraulic fracturing

Different approaches to the hydraulic fracture modeling

I. Perkins, Kern (1961), Nordgren (1972) – PKN-model

Assumption:
				E 3q x	f	1/ 4
	h f p		p
w
				h f
	E

II. Khristianovich, Zheltov (1955), Geertsma, DeClerk (1969) – KGD-model

Assumption:
				E 3q 1/ 4
w	x f p		p
					1/ 4 x f 1/ 2
	E			h f

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Hydraulic fracturing

Fracture propagation and different approaches to the hydraulic fracture modeling

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Matrix Acidizing and

Acid Fracturing

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Matrix Acidizing and Acid Fracturing

Reaction kinetics

The major components controlling the kinetics of acid flow and attack in a reactive environment are:

Convective flux of the stimulation fluid into the formation

Diffusive flux caused by concentration gradient from the bulk of the acid solution to the reactive surface

Reaction at the reactive surface

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Matrix Acidizing and Acid Fracturing

Reaction kinetics

Type of reaction kinetics is determined by the reaction rate constant k

		E
k k0 exp
		RT

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Matrix Acidizing and Acid Fracturing

Reaction kinetics

Usually two types of reaction kinetics are distinguished:

Surface reaction limited kinetics

–Example: sandstone dissolution with HF / HCl mixtures, reaction of dolomite with HCl at low temperatures (T<50 0C)

Diffusion limited or mass-transfer limited kinetics

–Example: limestone dissolution with HCl at temperatures >0 0C, reaction of dolomite with HCl at high temperatures (T> 50 0C)

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Surface Reaction Limited Kinetics (SRLK)

There are two dimensionless parameters governing SRLK:

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Surface Reaction Limited Kinetics (SRLK)

Dependency of the front location and its sharpness on the acid capacity number Ac and Damkholer number Da

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