FORM-A-SEAL is a blend of sized, non-reactive carbon particles. It was designed specifically for these properties :
Ability to be added in large quantities . . . greater than 50 pounds per barrel, quickly, with any existing hopper, on any rig and not change the fluid viscosity or ECD.
Can be used in ANY drilling fluid, whether water base, oil base or synthetic, and will not react with any solvent . . . therefore, will not sheen, coalesce, fluoresce, swell or in any way change the physical characteristics of the fluid medium.
Provide particle size distribution capable of sealing cracks and crevices in the formation better than any other LCM known to be currently available.
Appearance Gray to black granule
Specific gravity 2.22-2.25
Dispersible (not soluble) Water & Oil
FORM-A-SEAL can be added to the active mud system and circulated while drilling, but the ideal application is to add from 10 to 50 pounds per barrel in sweeps.
Laboratory tests with synthetic oil fluid using a 190-micron disk reveal almost total sealing while testing at 2500 PSI and 250º F. This is a very severe test and very few products are able to seal with any efficiency. The base mud fails immediately with no control. FORM-A-SEAL is completely environmental safe. It can be land farmed, dumped overboard or spilled with no harmful effects. FORM-A-SEAL is packaged in multi walled paper bags at 50 pounds each.
- 5-lbs. synthetic field mud was used for testing at 200º F for 30 minutes. A Permeable Plugging Apparatus (PPA) was used with a stainless steel disc with a slot in the center 0.040 of an inch wide. The disc was constructed using the measurements of a ceramic disc so that it would fit into the PPA. Initially the slot fit against the orifice of the end cap. Each LCM sample tested failed. The test procedure in our opinion was inconclusive. All indications pointed to constructing a new disc that would have 4 slots the same width leaving the center closed over the orifice. Base mud was run through the new disc. The base mud would not go through the center of the disc because the orifice was resting on top of the disc thus, sealing it. A new end cap was constructed from stainless steel with a recessed ceiling approximately 0.055 of an inch. A ring approximately 1/4 inch around the bottom edge of the end cap sits against the slotted disc to keep it in place. The base mud was first tested to insure a quality test. There was no control and the fluid bled dry. A series of tests were conducted to determine:
- Whether the slotted test could be performed with a PPA.
- To determine the best LCM for a slotted disc test.
- If the best LCM in the slotted disc test was also the best using the traditional 190-micron ceramic disc?
After conducting the test it was determined that all samples failed or did not perform as desired. It did appear that some products performed better than others did. However, in extreme conditions, such as this slot test, large amounts of product would have to be used to seal effectively. In this case the fluid would be too thick to pump and/or the cost of effectively sealing the thief zone would be excessive. Based upon our knowledge of particle size distribution, a new and improved LCM was developed. Tests indicated that FORM-A-SEAL was better than the widely used LCM, using the slotted test and the traditional 190 micron ceramic disc test.
FORM-A-SEAL is packaged in a 50 pound, multi-wall bags.
Return Permeability Studies
Based upon recommendations from a major oil company, return permeability studies were conducted with a 5-micron ceramic disk. The procedure involved placing the disk in a Permeability Plugging Apparatus and determining the amount of time it would take to force 100 ml of saturated salt water through the disk. The amount of pressure used was 3 PSI.
The apparatus was rigged to flow backwards, or from the top down. 100 ml was placed in the reservoir that fits on the top and is normally used to collect the filtrate during a plugging test. A McDaniel Controls Inc. 30 PSI gage was plumed with a Tescom regulator. 100 PSI of continuous air pressure was placed on the inlet side. The air was regulated on the outlet side to 3 PSI continuous. A base permeability was determined by clocking how long it would take for 100 ml to pass through the disk and be collected at the bottom.
350 ml of mud was then placed in the cell behind the disk. The cell was sealed and 500 PSI of pressure was applied for one hour forcing the mud against the disk. Pressure application was made with a hydraulic pump that is normally supplied with the Plugging apparatus. After one hour, the pressure was released, the cell was unsealed and the mud removed. The disk was left undisturbed. The collector was drained and cleaned.
The collector was filled with 100 ml of saturated salt water and 3 PSI of pressure was again applied to the disk from top down as done previously.
100 ml of water was collected at the bottom of the cell in both cases. This test was conducted with a water base mud and a synthetic oil base mud. In both tests 100 ml of water was collected in 20 minutes. There was no return permeability impairment to the disk.
FORM-A-SEAL is completely inert. It performs sealing with particle distribution. Extreme shearing of the mud with FORM-A-SEAL present would not change the results of this test even if FORM-A-SEAL would be reduced in size. The reason being FORM-A-SEAL cannot be rendered colloidal and colloidal particles would be necessary to cause reservoir impairment. Further, FORM-A-SEAL resists the tendency to break into small particles and maximum sealing would be accomplished when pumped to the thief zone. Excess material would naturally go over the shaker like a cutting.
One of the ideal characteristics of FORM-A-SEAL is that it does not appreciably change the fluid viscosity even with amounts of 40 to 50 pounds per barrel included. Even if the particles were to be crushed, and it appears that case to be remote, the fluid viscosity would not suffer as a result.
Loss Of Circulation Squeeze
HERE ARE THE ATTRACTIVE ATTRIBUTES
CAN BE MIXED EASILY AND FAST BY ANY MUD ENGINEER FAST
RELATIVELY INEXPENSIVE LOW COST
MOST OF THE COMPONETS ARE ALREADY ON LOCATION IMMEDIATE ACTION
HIGHLY EFFECTIVE WORKS EXTREMELY WELL
PROBABLY BETTER THAN MOST COMMERCIAL SYSTEMS
The squeeze is introduced to the formation as a liquid that seals fractures and molds unconsolidated formations into a solid structure that can be drilled through without mud loss. The principle is mechanical and involves the use of rapid dehydration with pressure and an avenue for the filtrate to escape from the solids. It is formulated with appropriate dehydration, suspension and sealing additives that do not react with any solvent. Essentially…the liquid tends to follow the path of least resistance, dehydrate with rapid filtrate loss to the formation and form a hard cake that fills cracks and bridges fractures. When the plug has been spotted and activated it can easily be drilled through. The FORM-A-SEAL Squeeze can be used in any system whether oil or water.
APPLICATION & ADVANTAGES
The FORM-A-SEAL Squeeze is not a high molecular polymer, does not contain cement and does not utilize cross-linking mechanisms. Consequently, it has a thermal stability greater than 500º F. It is not a diatomaceous earth product and provides a hard plug and includes FORM-A-SEAL in case the formation is fractured but not permeable. Some permeability is required to dehydrate the liquid slurry, but the FORM-A-SEAL Squeeze is decidedly different than the typical high filtration squeeze. Some permeability will always be available. Otherwise, you would not be experiencing a loss. WHY IS IT DIFFERENT? The difference in this squeeze and others is the FORM-A-SEAL addition, which allows a greater amount of LCM per unit volume with no change in fluid viscosity for greater sealing capability than a fiber. The squeeze can be mixed on location with or without barite or calcium carbonate for density requirements. However, some barite addition makes a better sealing material.
Loss of Circulation
There are three basis situations where loss of circulation can be encountered.
- Exceeding the pressure the formation will withstand.
- Unconsolidated formations.
- Cavernous formations.
There are several remedies for the causes listed above.
- Reduce mud weight.
- Improve rheological properties to reduce the equivalent circulating density.
- Control mechanical practices that lead to induced fractures.
- Add loss circulation material to the active mud system.
- Use FORM-A-SEAL Squeeze.
Here is a list of the normally encountered loss circulation formations and the recommended remedy.
- POUROUS FORMATION - Gravel beds, seashell beds, vulgular limestone, etc.
Symptoms: Very rapid seepage loss.
Recommended: FORM-A-SEAL Squeeze
- HIGHLY PERMEABLE SANDS -
SYMPTOMS: More gradual seepage.
Recommended: FORM-A-SEAL incorporated in the existing mud and used as sweeps.
- FRACTURED FORMATIONS - Natural or induced.
Symptoms: Sudden, but not total loss…usually after trips.
Recommended: FORM-A-SEAL Squeeze
- CAVERNOUS FORMATIONS -
Symptoms: Drill bit drops free; Complete loss of mud and unable to fill cavern with water.
Recommended: Drill blind through cavern into competent formation. Set casing or cement. A FORM-A-SEAL Squeeze would not hurt and may seal a casing shoe at a lower cost than conducting test and squeezing cement.
FORM-A-SEAL Squeeze Formulation
First, determine the amount necessary to cover the thief zone. A one hundred-barrel pill is recommended. A premixing tank is recommend over the slugging tank depending on the slugging tank’s condition. Clear the slugging tank of existing mud if the slugging tank is used. Add bentonite to water first to obtain the required suspension properties. Bentonite will not yield if lime is added first. The formulation is based upon a simple formula:
Barite as necessary to achieve existing mud weight
That’s it! That’s all that is required!
Here is a simple chart to aid calculations when loss occurs.
For a 50 barrel slugging/mixing tank
Quantities are in bags
Mud Wt. Water/bbl Bentonite Lime FORM-A-SEAL Barite
- 0-11.0 41 2 18 35 mud weight
- 0-12.5 36 2 16 31 "
- 5-14.0 32 2 14 27 "
- 0-15.5 27 2 12 23 "
- 5-17.0 22 1 10 19 "
For a 100 barrel slugging/mixing tank
Mud Wt. Water/bbl Bentonite/Bags Lime FORM-A-SEAL Barite
- 0-11.0 82 4 36 70 mud weight
- 0-12.5 72 4 32 62 "
- 5-14.0 64 4 28 54 "
- 0-15.5 54 4 24 46 "
- 5-17.0 44 2 20 38 "
- Please clean the slugging/mixing tank before mixing each pill. The volumes in this chart take into effect volume increases with barite additions and leaves space in case water is needed to reduce viscosity. Mix the bentonite thoroughly until the viscosity increases enough to suspend the barite, lime and LCM.
- Add the lime and mix thoroughly. Add the FORM-A-SEAL and mix thoroughly. Add the appropriate amount of barite. Water additions will not effect performance, but the viscosity should be thin enough to pump and thick enough for maximum effect. Add water to thin if necessary. The formula does not have to be exact.
- Normally, you will not be able to pump the entire pill, or may not want to do so to prevent loss of prime.
With hole standing full-Close blowout preventers and insure the entire squeeze is clear of the drill pipe and pumped to the formation at a rate of 2-4 bbl per minute.
With the hole partially full- Displace the total volume of squeeze material from the drill pipe, open the fill-up line and slowly pump regular mud to force the squeeze material into the formation (100-500 PSI squeeze pressure).
Wait for at least three hours to allow the plug to form. Six hours would be better. Nine hours even better and 12 hours would be ideal. Time to heal without further damage is highly recommended. The dehydrated plug can then be easily drilled out leaving the thief zone sealed. This squeeze can be used in any water or oil base system. There is no contamination associated and it represents an easy method to stop whole mud loss. The procedures can be accomplished by any mud engineer and allows a quick end to whole mud loss. Normal drilling can resume if circulation is regained. This can be determined with the drill pipe in the casing and attempting to fill the hole. Repeat the procedure if circulation is not regained with the first squeeze.
This squeeze is somewhat like a gunk or Dial Seal M squeeze with a notable exception. Other squeezes will not perform in formations that are not permeable. Squeezes that are formed with cross-linking polymers work well, but require retarding additives or accelerators and do not perform in all formations. Further, they are not resilient against bit and tool contact, or thermal tolerant as often touted. The cross-linked polymer mix must be pumped soon after mixing or discarded since it will start yielding very soon after water contact. The FORM-A-SEAL Squeeze has been used in a variety of conditions and appears to be an improvement over existing technology.
PACKAGE & HANDLING
The only item needed for the FORM-A-SEAL squeeze that is not on location is FORM-A-SEAL. Start mixing bentonite and order the appropriate amount of FORM-A-SEAL. You will be ready to add it when it arrives. Better yet…keep FORM-A-SEAL on location just in case.