Acid fracturing treatment procedures

The CFA technique is also appHcable as a separate treatment procedure in naturally ftactured formations and in previously created ftactures, including propped ftactures. However, the primary application of CFA is as a final matrix acidizing stage followuig an acid fracturing treatment. 

C-2. Generic acid fracturing treatment for a tight limestone (viscous fingering procedure closed-fracture acidizing [CFA] method).262... 

In the 1960s, treatment design and fluid development were emphasized. Since then, many acid fracturing systems and procedures have been developed to control fluid loss and to retard reaction rates. 

It is sometimes necessary to break down perforations by temporarily pumping acid above fracturing pressme to initiate production or injection of a subsequent treatment, such as hydraulic fracturing. Typically, HCl is used in concentrations ranging from 5% to 20%, with 15% HCl being standard. As this is a routine procedure in certain areas, it will not be discussed in further detail here. 

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