Fluidic Oscillation Technique in Conjunction with Acid Stimulation Improves Gas Wells Productivity

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractGenerally, the most common reason for low productivity of gas wells in the offshore Mediterranean Sea operations of Egypt is near-wellbore formation damage. Near-wellbore formation damage, referred to as "skin" in petroleum engineering parlance, causes a huge reduction in native formation permeability, thus adversely affecting productivity. Skin damage can occur from one or more of the following reasons: mud and cement damage, mechanical damage from drilling, damage from perforating guns, scale deposition, paraffin and asphaltene depositions, water blocks, gas blocks, acid sludges, emulsions, etc. Dependent upon the type of damage, the stimulation technique will vary; however, the prevalent techniques available to stimulate damaged formations are hydraulic fracturing and matrix acid stimulation.A new technique called "fluidic oscillation" was proposed to overcome many of the limitations of the previous two techniques. This technique would be especially applicable when there are uncertainties regarding rock mineralogy. In these instances the possibility of further damage exists if incompatible treatment fluids are pumped/"squeezed" into the formations. "Fluidic Oscillation" is primarily a mechanical, nonfluid invasive stimulation technique; (i.e., it is not essential to inject the treatment fluid into the reservoir to break down damage though it does not preclude its use in that manner). The damaged formations are stimulated by subjecting them to alternating bursts of pressure waves generated by pumping fluids through a fluidic oscillator. The treatment fluid can be plain water, diesel, or any other solvent that is desired to pass through the affected zones and be circulated out of the hole. The continuous cycling of these pressure waves causes the skin damage to reach its fatigue failure point. After this, a small amount of acid/solvent blend can be pumped to wash the damaging materials out of the well bore. The fluidic oscillator