Acid injection into carbonate reservoir

Acid fracturing, friction reducers, 15 Acid hydrolysis, lignin, 173 Acid injection into carbonate reservoir, 610-611 Acid-rock reactions, rate, 15,16 Add wormholing in carbonate reservoirs, 608-620 in carbonate rocks, 610-611 Acidity-controlled redox reactions, 141-142 Addization... 

Acid-in-oil emulsion can extend the propagation of acid considerable distances into a reservoir because the continuous (oil) phase prevents or minimizes contact between the acid and the rock [4,678,689]. Emulsification also increases viscosity and will improve the distribution of the acid in layered and heterogeneous reservoirs. Acidizing foams are aqueous, in which the continuous phase is usually hydrochloric acid (carbonate reservoirs) or hydrofluoric acid (sandstone reservoirs), or a blend, together with suitable surfactants and other stabilizers [345,659]. Foaming an acidizing fluid increases its effective viscosity, providing mobility control when it is injected [678]. 

The dissolution of dolomite, calcimn magnesimn carbonate, in hydrochloric acid is a reaction of particular importance in the acid stimulation of dolomite oil reservoirs The oil is contained in pore space of the carbonate rrraterial and must flow through the small pores to reach the well bore. In matrix stimulation, HCl is injected into a well bore to dissolve the porous carbonate matrix. By dissolving the sohd carbonate the pores will increase in size, and the oil and gas will be able to flow out at faster rates, thereby increasing the productivity of the well. The dissolution reaction is... 

Most oil reservoirs (sandstone and carbonate) are heterogeneous with permeability varying from one layer to another. Acidizing such heterogeneous media is very difficult, because most of the injected acid will flow into the high permeability zones and only a small amount of the acid will flow into tight zones. This uneven distribution of the injected acid represents a major economic loss for the following reasons ... 

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