In the past many drilling contractors stayed in areas that provided the easiest drilling conditions. This easy drilling (for example, no rocks, bed rock with no, or very little over burden, and little or no screen work required) was their Garden of Eden.
Now add the hydraulic casing hammer to the contractors list of tools and they can expand their Garden of Eden to include areas that have lots of overburden, drill larger holes, and require screen work. This produces more business and makes more profits.
Click for Atlas Hammer details
Click for Atlas Rotary Casing Driver Specifications
With a hydraulic casing hammer the casing can be driven ahead into water bearing sands or gravel to provide more accurate samples of the formations.
Click - Drill in heaving/running sands
Hydraulic Casing hammers are the most environmentally friendly method for driving pipe. No lubricants and other toxins are released into the air. No drilling fluids are pumped down the hole.
Click - Setting Screens
In the Pacific Northwest United States, Canada, Alaska, New Zealand, and Australia etc., every type of drilling method that you can name is being practiced. Casing Hammers have become the method of choice for driving casing and these areas are expanding. Casing hammers make the total operation very efficient and it is the cheapest per foot method available for installing casing.
Click - Advantages of Atlas Hammers
Contractors have had bad experiences with down hole casing advancing methods especially when ring bits fail and other things go wrong. Also, the down hole tools are limited to depth. Casing hammers can advance casing very quickly in most formations with just a tri-cone bit. There is no restriction on how fast you can advance.
DRILLING IN HEAVING SAND AND GRAVEL CONDITIONS
Hydraulic casing hammers are the most effective tool to use in this condition. This means when heaving sands and gravel conditions are encountered a hydraulic casing hammer uses hydraulics to drive the casing all the time and all the air is used only in the down the hole operations. Air hammers require air for the hammer operation and down the hole. Under these conditions the hammer operations tend to rob the air resulting in loss and/or reduction of circulation. In heaving sands and gravel material from the formation coming up inside the casing can lock up the tools. Being able to use all the air to keep the hole clean maintains the hole integrity while allowing the casing to be driven.
Back - to about Casing Hammers Click - Advantages of Atlas HammersSETTING SCREENS IN SAND FORMATIONS WITH A CASING HAMMER
The ability to set screens is an important talent in the water well drilling industry; one that is often overlooked and one that has little available instruction on the method and importance of this aspect of the business. Here are some pointers for setting your own screens:
During the drilling operation watch the samples from the discharge. When you come to the water bearing formations stop and test pump to see if it is producing. Often drillers drill through the water bearing formations and could end up drilling deeper than necessary wells or not find water at all.
When setting screens in fine sand formations (.0004 - .0006) some of the sand (Quadra sediments), especially with artesian condition, will lift into the bore hole. You will need to get rid of the plug (heave) in the pipe; do this with a suction bailer.
In order to set screens you will first need to measure the distance to the bottom by lowering the suction bailer down the hole to the bottom of the casing with the sand line. Place a mark on the sand line to identify the bottom of the well. This can be marked with paint or a better and more durable method is to install a small piece of nylon rope with a marlin spike.
1. Run the bailer down the hole and work it into the plug. When working with very fine sands it may be necessary to allow the suction bailer to set on the bottom for 5 - 10 seconds to allow the fine sand to settle in the bottom of the bailer to form a plug to seal the bottom flapper valve.
2. Gently pull the bailer off the bottom with the sand line and remove it slowly from the hole (if you pull to hard you may actually pull more plug into the hole). Before you remove the bailer from the water be sure to add the amount of water that the bailer displaces and a little more so that you are always maitaining the static. If you allow the water level in the well to drop below the static IT WILL HEAVE more material into the hole. Continue bailing until you have cleaned out the well.
3. For the last bail proceed as section 2 above to load the bailer. Pull very gently off the bottom and maintain the static level. When the bailer clears the top dump the screen immediately into the hole and let it sink to the bottom. Place a weight on the sand line and run it down the hole to set on top of the screen. Usually it is necessary to push the screen to the bottom. This will be done with the 5" bailer in a 6" hole. The screen hardly ever goes to the bottom when installed in wells with heaving formations since there will always be some remnants of sand that will settle out of the water column during the installation of the screen.
4. With the bailer now sitting on top of the screen you can tell where the bottom of the screen is by the marks you put on the sand line. Usually you will find 6" to a foot of plug below the screen. This will settle out some during the first foot or so of pulling the pipe.
5. The mark that you installed on the sand line before you installed the screen will now be the length of the screen plus the plug still in the well above the top of the pipe. Pull your pipe back until it is approximately one foot below that mark.
6. Gently bail the well (usually 1 to 4 hours) until the well clears.
Back - to about Casing Hammers
Advantages of using the drill-through casing driver include the following:
1. Wells can be drilled in unconsolidated geologic materials that may be difficult to drill with cable tool or other rotary methods.
2. Hydraulic casing hammers maintain a stabilized hole condition during the drilling operation by keeping the casing at the bottom of the hole eliminating cave ins.
3. Penetration rates are rapid even under difficult conditions.
4. Hydraulic casing hammers eliminate lost circulation problems. In a situation like limestone cavernous formation the driller can proceed through limestone cavern areas by using a casing hammer and an under reamer without the use of drilling fluids to fill the cavern. Breaking into a void there is an immediately loss of circulation however, with a casing hammer the driller can drill through and stabilization is regained the moment a new solid formation is encountered.
5. The casing hammer method of drilling allows water bearing formations to be more accurately identified than any other method of drilling.
6. Hydraulic casing drivers can be used in all weather conditions. In the cold, as long as the rig will start, a hydraulic casing hammer will work. There is nothing to freeze up.
7. Driving casing from the top eliminates the chance of breaking the casing verses other down hole methods.
8. It takes in excess of 50% less energy requirement to operate a hydraulic casing hammer versus an air hammer. Air Drilling Handbook quotes the significant efficiency of hydraulics over air operated hammers.
9. Hydraulic casing hammers do not require the use of down the hole pollutants such as anti-freezing agents, lubricants and other additives as the air hammers historically have, particularly in cold weather. With air hammers fumes from these anti-freezing agents and lubricants are exhausted into the drillers work area.
10. Samples taken from hydraulic casing hammers cuttings are not contaminated by additives as they are in other methods(air hammer).
11. Hydraulic casing hammers are the advancing technology as they are safest to operate and the most environmentally friendly casing advancement method.
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