Phalt-Seal SEALS SAND FORMATIONS, STABILIZES SHALE AND DRAMATICALLY REDUCES DIFFERENTIAL PIPE STICKING
Appearance - Dark Brown Powder
Bulk density - 40-lbs./cu. ft.
Moisture content - 10% ± 1%
pH, 10% solution - N/A
Ignition Point - >260º C.
Solubility - Water Dispersible
Recommended use level - 4 - 6 ppb
Differential pipe sticking is caused by poor particle size distribution and Phalt-Seal is an asphalt blend that has been perfected to provide the ideal particle size distribution to prevent this malady. The asphaltic sized particle blend combination approach allows Phalt-Seal to outperform ordinary Gilsonite and sodium/potassium asphalt sulfonates for sealing, torque and drag reduction and differential pipe sticking prevention at a lower cost. Phalt-Seal can be used in sodium systems and potassium systems at the operator’s preference.
Where previous wells have experienced hole problems, the addition of Phalt-Seal appears to prevent formation instability, prevent pipe sticking and reduce torque and drag. In some cases, Phalt-Seal is being added right out of surface, and it can be shown that money is being saved because of better formation stability. Phalt-Seal is compatible with all water based drilling fluid systems. In fluids where oil has been added, there does not appear to be any oil wetting of solids, nor flotation of asphalt on the surface. In permeability plugging tests and field trials, Phalt-Seal, with a seepage loss control agent, more adequately sealed depleted sand zones than other products including those with higher costs. The ideal use level requirement for this product is 4 to 6 pounds per barrel. With this amount of product in the system, HT/HP fluid loss control is much easier to control. In every case, the requirement for resin HT/HP agents is reduced and, in many cases, eliminated altogether.
Phalt-Seal IS AN EXCELLENT OIL BASE FLUID ADDITIVE THAT PROVIDES BETTER DOWN HOLE PERFORMANCE THAN ANY ORDINARY ASPHALT.
Very little change in viscosity or electrical stability occurs up to 10 ppb. For quantities added above 6 ppb small amounts of a secondary emulsifier retains ES.
IN A LAB PREPARED SYNTHETIC OIL MUD, Phalt-Seal DRAMATICLY REDUCED THE HT/HP FILTRATE BY HALF FROM 14 TO 7.
Phalt-Seal can be added to diesel oil or synthetic systems. Its particle size distribution will help seal sands along with reducing the HT/HP fluid loss. In a test with a leading asphalt sulfonate, Phalt-Seal maintained the viscosity of the base fluid. But, the competitor dropped the yield point to one-half the mud weight. The gel strengths dropped to zero and there was severe barite settlement. With Phalt-Seal, the ES remains the same at 6 pounds per barrel and only dropped from 662 to 554, without additions of wetter for the extra solids at 10 pounds per barrel. The asphalt sulfonate dropped the ES to 375…almost twice the amount of the original reading.
In the literature presented by a leading manufacturer of sulfonated asphalt it is stated their product is 70±5 percent soluble. It further explains that the better solubility of their product over nonreacted asphalt provides an improvement to shale stability because the filtrate from their product is inhibitive and prevents the sloughing of reactive shale. Other asphalt products do not provide adequate shale stability because their limited water solubility does not allow enough inhibitive filtrate to come in contact with the reactive shale.
Based upon years of research on shale stability it is apparent there does not exist a single product that represents a magic elixir for shale stability. We found for the most part, shale instability is caused by mechanical means, which is primarily fluid hydraulics. For chemical inhibition, the secret is to prevent shock base exchange to the clay particle. Unreactive shale formations do not require additives for inhibition since they are inert. Reactive shale formations, such as gumbo shale, are composed of calcium montmorillonite. Reactive shale formations will not swell, slough or disperse into the active mud system as long as they remain as calcium charged clays. If they are base exchanged to sodium, which is easily accomplished by using a sodium system, then they will yield in a manner to even close the flow line and all the asphalt in the world, regardless of how processed, will not prevent this.
For proof, we conducted a test with a popular sulfonated asphalt and Phalt-Seal. In that test 1/2 gram of product was added to 100 ml. of tap water that was heated to 110º F. and mixed thoroughly so as to dissolve all the particles as much as possible. Each sample was then subjected to a standard filter press at 100 psi and the fluid passed through a standard API approved filter paper until all the fluid had been filtered. The filter paper, with its deposit of product was dried and then weighed. According to this test the sulfonated asphalt sample was approximately 40% soluble, in that 60% of the product addition remained on the filter paper. The Phalt-Seal sample was 25% soluble as determined by the same extraction process.
If the only property desired is water solubility then sulfonated asphalt is a clear winner, although it does not appear to be as soluble as reported. However, it is not water solubility that is important, but rather it is the inhibitive nature of the filtrate. Therefore, using the filtrate from each sample, a wedge of gumbo shale obtained from the stabilizer of an off shore well in a known gumbo shale area was added. The sulfonated asphalt sample swelled, cracked and lost its original shape in 15 minutes. The Phalt-Seal sample had some softening and mudding up of the filtrate, but the shale sample retained its original shape after several hours. For this test, Phalt-Seal is a clear winner and it can be stated that water solubility is not a factor for promoting shale stability.
Most gumbo shale formation occurs in the upper hole. Several field tests were conducted where the spud mud was intentionally composed of gel, lime and occasionally some PHPA. Caustic soda was intentionally left out. The gumbo was drilled with no clogging and no problems. When caustic soda was added the gumbo yielded.
When drilling in depleted zones, it appears that the sand sections cause more trouble than swelling shale. In this regard, neither Phalt-Seal nor any other asphalt product will adequately seal depleted sand by itself. The requirement includes an additional sealing agent. In combination with another lost circulation materials like FORM-A-SEAL…Fine, Coarse, Phalt-Seal appears to have equal sealing performance to the most expensive asphalt product available and appears to be less dispersive.