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JAMES VAN BLARICUM
Imported Oil
To satisfy our appetite for petroleum, the United States has become increasingly dependent upon other countries for petroleum. In 1994 we purchased 45 percent of our petroleum from other countries.
Americans know this dependence can be dangerous. We were first alerted to the danger in 1973 when some Arab countries stopped shipping oil (called an embargo) to the United States. These countries belonged to an international trade group called the Organization of Petroleum Exporting Countries or OPEC for short.
OPEC members try to set production levels for petroleum. As a rule, the less oil they produce, the higher the price of oil on the world market. The more oil they produce, the lower the price. The OPEC countries don't always agree with each other. Some OPEC countries want to produce less oil to raise prices. Other OPEC countries want to flood the market with petroleum to reap immediate returns.
Americans learned some lessons from the 1973 oil shock. Gas-guzzling cars became about as wanted as last week's leftovers, and the nation raced to find ways to conserve energy. But more oil shocks followed.
JAMES VAN BLARICUM
Comparison to HCl
The rapid reaction between HCl and carbonate limits the penetration of HCl into carbonate formations. It is unlikely that HCl will remove deep formation damage and HCl is not suitable for deep matrix acidizing. Arcasolve™ can penetrate deeply and is suitable for both applications.
HCl is particularly corrosive to steel, aluminium or chromium plated equipment which are components of many pumps. Expensive corrosion inhibitors need to be used in these circumstances. This cost becomes very significant when treating formations at higher temperatures due to the requirement for higher doses of corrosion inhibitor. Corrosion inhibitors are not required with Arcasolve™.
The toxicity of corrosion inhibitors presents problems when disposing of spent HCl based acidizing fluid.. Arcasolve™ presents minimal chemical safety/toxicity problems to well process operators and is recognized to be a "green" product.
It is possible to use Arcasolve for drilling damage removal from horizontal wells by introducing Arcasolve™ through the drill string following drilling operations. Use of coiled tubing, commonly used to place HCl is not needed with Arcasolve™.
There is no requirement for additives to be added to Arcasolve™ to retard the rate of reaction. In particular high viscosity additives are not required, which present problems in applications such as fracture acidizing. Clean up following Arcasolve™ treatments is straightforward.
JAMES VAN BLARICUM
Comparison to Emulsified HCl
Emulsified HCl involves the use of both organic solvents and HCl. Both are hazardous before and after mixing . The emulsion may not give a good distribution of acid downhole.
The use of certain organic solvents in gas and water injection wells may reduce the gas or water relative permeability and permanently reduce well production. The use of a water based acidizing system with good penetration would be preferred for such wells allowing much easier control over the wetting characteristics of the formation.
Use of oil-external emulsified acids may be limited by the increased frictional resistance to flow of these fluids down well tubulars.
Arcasolve™ is lower hazard and does not suffer from injectivity or wettability problems.
JAMES VAN BLARICUM
Comparison to Acetic Acid
Although acetic acid reacts more slowly than HCl, the reaction is still sufficiently rapid to give the problems summarized in section 2. In contrast, generation of acetic acid in-situ using Arcasolve™ allows acid to be delivered much deeper into the formation and better placement of acid along extended well-bores. Arcasolve is therefore more effective, and offers a much higher degree of control of acidizing than acid formulations based on acetic acid or other organic acids.
JAMES VAN BLARICUM
Use of Arcasolve™ in Fracture Acidizing
Although not originally designed as a fluid for acid fraccing, the opportunity for Arcasolve™ in this application could be very significant.
The comparison indicates that Arcasolve™ may represent an ideal fracture acidizing fluid, able to penetrate long distances, etch fracture faces, increase the permeability of the matrix where the fluid enters the formation by diffusion, and remove any existing formation damage. In addition the low viscosity of the fluid means that maximum production rate should be attained quickly following the treatment.
Because acid is produced over a period of several hours or longer, acid fraccing treatments using Arcasolve™ may need to be performed in a different way to existing acid fraccing treatments. Fractures would need to be held open for at least several hours and possibly up to a day. The pad fluid used in conventional treatments would probably not be needed - Arcasolve™ would be injected directly.
JAMES VAN BLARICUM
Stimulation of Natural Fracture Networks using Arcasolve™
Arcasolve™ may be used to effectively stimulate natural fracture networks. Deep penetration along fractures can be achieved before acid is produced. Laboratory evaluation to date has been positive. Field trials are currently being conducted in the Austin Chalk.
Use of Arcasolve™ in Gel Breaking
Gel breaking is another application for Arcasolve™ for which additional patents are granted or pending. Arcasolve™ can be incorporated into acid sensitive gel systems such as borate cross linked guar so as to produce a complete break within a specific, desired time frame.
Very deep penetration of acid can be achieved if needed and the use of gels and surfactants, which might cause cleanup or wettability reversal problems is not needed.
As well as treating carbonate formations Arcasolve™ can be used to remove deep carbonate scale from sandstones.
Arcasolve™ comes very close to being the ideal system for matrix acidizing described in [2]. Depending on the pump rate, typically 90% or more of the acid is delivered after the fluid has been placed.
Matrix treatments designed to give a 20% increase in production rate (formation assumed to be undamaged) have given up to 80% increases in production (San Andres Dolomite, Texas) indicating effective damage removal even in wells considered undamaged.
JAMES VAN BLARICUM
Tags: blaricum, james, van.
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