Arcasolve™ is a patented acidizing method which uses acid precursors (not themselves acidic) in combination with catalysts. The catalysts, either enzyme or non-enzyme, act on the acid precursors to produce an organic acid in-situ following placement of the Arcasolve™ fluid within the wellbore, rock matrix or natural fracture network. i.e.

An Arcasolve™ treatment fluid is prepared at the well site by mixing the acid precursor with water or brine at the surface then adding the catalyst.  The fully mixed fluid is then pumped into the well.   

The catalyst acts on the acid precursor (the "substrate" in the case of an enzyme catalysed system)  to produce acid.   Typically 5 to 10% acetic acid is produced over one to two days. As the acid is produced, it becomes available for reaction with acid soluble materials.  The figure opposite illustrates substrate conversion to acid with time*.  *[Acid] represents total acid produced, not free acid concentration in solution, because the acid reacts as it is produced.

Almost all of the acid is produced after the fluid is placed downhole.   The fluid is essentially not reactive when placed so Arcasolve does not suffer from the placement problems associated with pumping reactive acids such as HCl or acetic acid which react on contact with carbonate.  Arcasolve™ acidizing  allows acid to be effectively delivered to the whole of the target zone, for example the whole of a long horizontal interval, deep into natural fracture networks or to fill the pore space to several metres radius of the wellbore in deep matrix acidizing (see applications of the Arcasolve process).

The amount of acid released and the rate of release can be controlled by using different Arcasolve™ formulations.  The amount of acid delivered is determined by the initial concentration of the precursor and the rate of production of the acid by the concentration of the catalyst. The catalysts used in the Arcasolve acidizing process are selected for their compatibility with the reservoir conditions; they are robust and active over a wide range of temperatures and salinity.  Typically, Arcasolve is formulated to produce 5-10% acid over one to two days.   The well may then be put on, or back on, production or injection. 

The ability to produce acid at a controlled rate and determine the amount of acid delivered gives Arcasolve a number of advantages in a number of acidizing applications, compared to other acidizing processes.

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